ClabureDB: Classified Bug-Reports Database

   /**
    * eCryptfs: Linux filesystem encryption layer
    * In-kernel key management code.  Includes functions to parse and
    * write authentication token-related packets with the underlying
    * file.
    *
    * Copyright (C) 2004-2006 International Business Machines Corp.
    *   Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
    *              Michael C. Thompson <mcthomps@us.ibm.com>
   *              Trevor S. Highland <trevor.highland@gmail.com>
   *
   * This program is free software; you can redistribute it and/or
   * modify it under the terms of the GNU General Public License as
   * published by the Free Software Foundation; either version 2 of the
   * License, or (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful, but
   * WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   * General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software
   * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
   * 02111-1307, USA.
   */
  
  #include <linux/string.h>
  #include <linux/syscalls.h>
  #include <linux/pagemap.h>
  #include <linux/key.h>
  #include <linux/random.h>
  #include <linux/crypto.h>
  #include <linux/scatterlist.h>
  #include "ecryptfs_kernel.h"
  
  /**
   * request_key returned an error instead of a valid key address;
   * determine the type of error, make appropriate log entries, and
   * return an error code.
   */
  static int process_request_key_err(long err_code)
  {
          int rc = 0;
  
          switch (err_code) {
          case -ENOKEY:
                  ecryptfs_printk(KERN_WARNING, "No key\n");
                  rc = -ENOENT;
                  break;
          case -EKEYEXPIRED:
                  ecryptfs_printk(KERN_WARNING, "Key expired\n");
                  rc = -ETIME;
                  break;
          case -EKEYREVOKED:
                  ecryptfs_printk(KERN_WARNING, "Key revoked\n");
                  rc = -EINVAL;
                  break;
          default:
                  ecryptfs_printk(KERN_WARNING, "Unknown error code: "
                                  "[0x%.16x]\n", err_code);
                  rc = -EINVAL;
          }
          return rc;
  }
  
  /**
   * ecryptfs_parse_packet_length
   * @data: Pointer to memory containing length at offset
   * @size: This function writes the decoded size to this memory
   *        address; zero on error
   * @length_size: The number of bytes occupied by the encoded length
   *
   * Returns zero on success; non-zero on error
   */
  int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
                                   size_t *length_size)
  {
          int rc = 0;
  
          (*length_size) = 0;
          (*size) = 0;
          if (data[0] < 192) {
                  /* One-byte length */
                  (*size) = (unsigned char)data[0];
                  (*length_size) = 1;
          } else if (data[0] < 224) {
                  /* Two-byte length */
                  (*size) = (((unsigned char)(data[0]) - 192) * 256);
                  (*size) += ((unsigned char)(data[1]) + 192);
                  (*length_size) = 2;
          } else if (data[0] == 255) {
                  /* Five-byte length; we're not supposed to see this */
                  ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
                                  "supported\n");
                  rc = -EINVAL;
                  goto out;
          } else {
                  ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
                 rc = -EINVAL;
                 goto out;
         }
 out:
         return rc;
 }
 
 /**
  * ecryptfs_write_packet_length
  * @dest: The byte array target into which to write the length. Must
  *        have at least 5 bytes allocated.
  * @size: The length to write.
  * @packet_size_length: The number of bytes used to encode the packet
  *                      length is written to this address.
  *
  * Returns zero on success; non-zero on error.
  */
 int ecryptfs_write_packet_length(char *dest, size_t size,
                                  size_t *packet_size_length)
 {
         int rc = 0;
 
         if (size < 192) {
                 dest[0] = size;
                 (*packet_size_length) = 1;
         } else if (size < 65536) {
                 dest[0] = (((size - 192) / 256) + 192);
                 dest[1] = ((size - 192) % 256);
                 (*packet_size_length) = 2;
         } else {
                 rc = -EINVAL;
                 ecryptfs_printk(KERN_WARNING,
                                 "Unsupported packet size: [%d]\n", size);
         }
         return rc;
 }
 
 static int
 write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
                     char **packet, size_t *packet_len)
 {
         size_t i = 0;
         size_t data_len;
         size_t packet_size_len;
         char *message;
         int rc;
 
         /*
          *              ***** TAG 64 Packet Format *****
          *    | Content Type                       | 1 byte       |
          *    | Key Identifier Size                | 1 or 2 bytes |
          *    | Key Identifier                     | arbitrary    |
          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
          *    | Encrypted File Encryption Key      | arbitrary    |
          */
         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
                     + session_key->encrypted_key_size);
         *packet = kmalloc(data_len, GFP_KERNEL);
         message = *packet;
         if (!message) {
                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
                 rc = -ENOMEM;
                 goto out;
         }
         message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
                                           &packet_size_len);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
                                 "header; cannot generate packet length\n");
                 goto out;
         }
         i += packet_size_len;
         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
         i += ECRYPTFS_SIG_SIZE_HEX;
         rc = ecryptfs_write_packet_length(&message[i],
                                           session_key->encrypted_key_size,
                                           &packet_size_len);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
                                 "header; cannot generate packet length\n");
                 goto out;
         }
         i += packet_size_len;
         memcpy(&message[i], session_key->encrypted_key,
                session_key->encrypted_key_size);
         i += session_key->encrypted_key_size;
         *packet_len = i;
 out:
         return rc;
 }
 
 static int
 parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
                     struct ecryptfs_message *msg)
 {
         size_t i = 0;
         char *data;
         size_t data_len;
         size_t m_size;
         size_t message_len;
         u16 checksum = 0;
         u16 expected_checksum = 0;
         int rc;
 
         /*
          *              ***** TAG 65 Packet Format *****
          *         | Content Type             | 1 byte       |
          *         | Status Indicator         | 1 byte       |
          *         | File Encryption Key Size | 1 or 2 bytes |
          *         | File Encryption Key      | arbitrary    |
          */
         message_len = msg->data_len;
         data = msg->data;
         if (message_len < 4) {
                 rc = -EIO;
                 goto out;
         }
         if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
                 ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
                 rc = -EIO;
                 goto out;
         }
         if (data[i++]) {
                 ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
                                 "[%d]\n", data[i-1]);
                 rc = -EIO;
                 goto out;
         }
         rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
         if (rc) {
                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
                                 "rc = [%d]\n", rc);
                 goto out;
         }
         i += data_len;
         if (message_len < (i + m_size)) {
                 ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
                                 "is shorter than expected\n");
                 rc = -EIO;
                 goto out;
         }
         if (m_size < 3) {
                 ecryptfs_printk(KERN_ERR,
                                 "The decrypted key is not long enough to "
                                 "include a cipher code and checksum\n");
                 rc = -EIO;
                 goto out;
         }
         *cipher_code = data[i++];
         /* The decrypted key includes 1 byte cipher code and 2 byte checksum */
         session_key->decrypted_key_size = m_size - 3;
         if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
                 ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
                                 "the maximum key size [%d]\n",
                                 session_key->decrypted_key_size,
                                 ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
                 rc = -EIO;
                 goto out;
         }
         memcpy(session_key->decrypted_key, &data[i],
                session_key->decrypted_key_size);
         i += session_key->decrypted_key_size;
         expected_checksum += (unsigned char)(data[i++]) << 8;
         expected_checksum += (unsigned char)(data[i++]);
         for (i = 0; i < session_key->decrypted_key_size; i++)
                 checksum += session_key->decrypted_key[i];
         if (expected_checksum != checksum) {
                 ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
                                 "encryption  key; expected [%x]; calculated "
                                 "[%x]\n", expected_checksum, checksum);
                 rc = -EIO;
         }
 out:
         return rc;
 }
 
 
 static int
 write_tag_66_packet(char *signature, u8 cipher_code,
                     struct ecryptfs_crypt_stat *crypt_stat, char **packet,
                     size_t *packet_len)
 {
         size_t i = 0;
         size_t j;
         size_t data_len;
         size_t checksum = 0;
         size_t packet_size_len;
         char *message;
         int rc;
 
         /*
          *              ***** TAG 66 Packet Format *****
          *         | Content Type             | 1 byte       |
          *         | Key Identifier Size      | 1 or 2 bytes |
          *         | Key Identifier           | arbitrary    |
          *         | File Encryption Key Size | 1 or 2 bytes |
          *         | File Encryption Key      | arbitrary    |
          */
         data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
         *packet = kmalloc(data_len, GFP_KERNEL);
         message = *packet;
         if (!message) {
                 ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
                 rc = -ENOMEM;
                 goto out;
         }
         message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
         rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
                                           &packet_size_len);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
                                 "header; cannot generate packet length\n");
                 goto out;
         }
         i += packet_size_len;
         memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
         i += ECRYPTFS_SIG_SIZE_HEX;
         /* The encrypted key includes 1 byte cipher code and 2 byte checksum */
         rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
                                           &packet_size_len);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
                                 "header; cannot generate packet length\n");
                 goto out;
         }
         i += packet_size_len;
         message[i++] = cipher_code;
         memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
         i += crypt_stat->key_size;
         for (j = 0; j < crypt_stat->key_size; j++)
                 checksum += crypt_stat->key[j];
         message[i++] = (checksum / 256) % 256;
         message[i++] = (checksum % 256);
         *packet_len = i;
 out:
         return rc;
 }
 
 static int
 parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
                     struct ecryptfs_message *msg)
 {
         size_t i = 0;
         char *data;
         size_t data_len;
         size_t message_len;
         int rc;
 
         /*
          *              ***** TAG 65 Packet Format *****
          *    | Content Type                       | 1 byte       |
          *    | Status Indicator                   | 1 byte       |
          *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
          *    | Encrypted File Encryption Key      | arbitrary    |
          */
         message_len = msg->data_len;
         data = msg->data;
         /* verify that everything through the encrypted FEK size is present */
         if (message_len < 4) {
                 rc = -EIO;
                 printk(KERN_ERR "%s: message_len is [%Zd]; minimum acceptable "
                        "message length is [%d]\n", __func__, message_len, 4);
                 goto out;
         }
         if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
                 rc = -EIO;
                 printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
                        __func__);
                 goto out;
         }
         if (data[i++]) {
                 rc = -EIO;
                 printk(KERN_ERR "%s: Status indicator has non zero "
                        "value [%d]\n", __func__, data[i-1]);
 
                 goto out;
         }
         rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
                                           &data_len);
         if (rc) {
                 ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
                                 "rc = [%d]\n", rc);
                 goto out;
         }
         i += data_len;
         if (message_len < (i + key_rec->enc_key_size)) {
                 rc = -EIO;
                 printk(KERN_ERR "%s: message_len [%Zd]; max len is [%Zd]\n",
                        __func__, message_len, (i + key_rec->enc_key_size));
                 goto out;
         }
         if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
                 rc = -EIO;
                 printk(KERN_ERR "%s: Encrypted key_size [%Zd] larger than "
                        "the maximum key size [%d]\n", __func__,
                        key_rec->enc_key_size,
                        ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
                 goto out;
         }
         memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
 out:
         return rc;
 }
 
 static int
 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
 {
         int rc = 0;
 
         (*sig) = NULL;
         switch (auth_tok->token_type) {
         case ECRYPTFS_PASSWORD:
                 (*sig) = auth_tok->token.password.signature;
                 break;
         case ECRYPTFS_PRIVATE_KEY:
                 (*sig) = auth_tok->token.private_key.signature;
                 break;
         default:
                 printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
                        auth_tok->token_type);
                 rc = -EINVAL;
         }
         return rc;
 }
 
 /**
  * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
  * @auth_tok: The key authentication token used to decrypt the session key
  * @crypt_stat: The cryptographic context
  *
  * Returns zero on success; non-zero error otherwise.
  */
 static int
 decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
                                   struct ecryptfs_crypt_stat *crypt_stat)
 {
         u8 cipher_code = 0;
         struct ecryptfs_msg_ctx *msg_ctx;
         struct ecryptfs_message *msg = NULL;
         char *auth_tok_sig;
         char *payload;
         size_t payload_len;
         int rc;
 
         rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
         if (rc) {
                 printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
                        auth_tok->token_type);
                 goto out;
         }
         rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
                                  &payload, &payload_len);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
                 goto out;
         }
         rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Error sending message to "
                                 "ecryptfsd\n");
                 goto out;
         }
         rc = ecryptfs_wait_for_response(msg_ctx, &msg);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
                                 "from the user space daemon\n");
                 rc = -EIO;
                 goto out;
         }
         rc = parse_tag_65_packet(&(auth_tok->session_key),
                                  &cipher_code, msg);
         if (rc) {
                 printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
                        rc);
                 goto out;
         }
         auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
         memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
                auth_tok->session_key.decrypted_key_size);
         crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
         rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
         if (rc) {
                 ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
                                 cipher_code)
                 goto out;
         }
         crypt_stat->flags |= ECRYPTFS_KEY_VALID;
         if (ecryptfs_verbosity > 0) {
                 ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
                 ecryptfs_dump_hex(crypt_stat->key,
                                   crypt_stat->key_size);
         }
 out:
         if (msg)
                 kfree(msg);
         return rc;
 }
 
 static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
 {
         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
         struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
 
         list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
                                  auth_tok_list_head, list) {
                 list_del(&auth_tok_list_item->list);
                 kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
                                 auth_tok_list_item);
         }
 }
 
 struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
 
 /**
  * parse_tag_1_packet
  * @crypt_stat: The cryptographic context to modify based on packet contents
  * @data: The raw bytes of the packet.
  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
  *                 a new authentication token will be placed at the
  *                 end of this list for this packet.
  * @new_auth_tok: Pointer to a pointer to memory that this function
  *                allocates; sets the memory address of the pointer to
  *                NULL on error. This object is added to the
  *                auth_tok_list.
  * @packet_size: This function writes the size of the parsed packet
  *               into this memory location; zero on error.
  * @max_packet_size: The maximum allowable packet size
  *
  * Returns zero on success; non-zero on error.
  */
 static int
 parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
                    unsigned char *data, struct list_head *auth_tok_list,
                    struct ecryptfs_auth_tok **new_auth_tok,
                    size_t *packet_size, size_t max_packet_size)
 {
         size_t body_size;
         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
         size_t length_size;
         int rc = 0;
 
         (*packet_size) = 0;
         (*new_auth_tok) = NULL;
         /**
          * This format is inspired by OpenPGP; see RFC 2440
          * packet tag 1
          *
          * Tag 1 identifier (1 byte)
          * Max Tag 1 packet size (max 3 bytes)
          * Version (1 byte)
          * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
          * Cipher identifier (1 byte)
          * Encrypted key size (arbitrary)
          *
          * 12 bytes minimum packet size
          */
         if (unlikely(max_packet_size < 12)) {
                 printk(KERN_ERR "Invalid max packet size; must be >=12\n");
                 rc = -EINVAL;
                 goto out;
         }
         if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
                 printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
                        ECRYPTFS_TAG_1_PACKET_TYPE);
                 rc = -EINVAL;
                 goto out;
         }
         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
          * at end of function upon failure */
         auth_tok_list_item =
                 kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
                                   GFP_KERNEL);
         if (!auth_tok_list_item) {
                 printk(KERN_ERR "Unable to allocate memory\n");
                 rc = -ENOMEM;
                 goto out;
         }
         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
                                           &length_size);
         if (rc) {
                 printk(KERN_WARNING "Error parsing packet length; "
                        "rc = [%d]\n", rc);
                 goto out_free;
         }
         if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
                 rc = -EINVAL;
                 goto out_free;
         }
         (*packet_size) += length_size;
         if (unlikely((*packet_size) + body_size > max_packet_size)) {
                 printk(KERN_WARNING "Packet size exceeds max\n");
                 rc = -EINVAL;
                 goto out_free;
         }
         if (unlikely(data[(*packet_size)++] != 0x03)) {
                 printk(KERN_WARNING "Unknown version number [%d]\n",
                        data[(*packet_size) - 1]);
                 rc = -EINVAL;
                 goto out_free;
         }
         ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
                         &data[(*packet_size)], ECRYPTFS_SIG_SIZE);
         *packet_size += ECRYPTFS_SIG_SIZE;
         /* This byte is skipped because the kernel does not need to
          * know which public key encryption algorithm was used */
         (*packet_size)++;
         (*new_auth_tok)->session_key.encrypted_key_size =
                 body_size - (ECRYPTFS_SIG_SIZE + 2);
         if ((*new_auth_tok)->session_key.encrypted_key_size
             > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
                 printk(KERN_WARNING "Tag 1 packet contains key larger "
                        "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES");
                 rc = -EINVAL;
                 goto out;
         }
         memcpy((*new_auth_tok)->session_key.encrypted_key,
                &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
         (*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
         (*new_auth_tok)->session_key.flags &=
                 ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
         (*new_auth_tok)->session_key.flags |=
                 ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
         (*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
         (*new_auth_tok)->flags = 0;
         (*new_auth_tok)->session_key.flags &=
                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
         (*new_auth_tok)->session_key.flags &=
                 ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
         list_add(&auth_tok_list_item->list, auth_tok_list);
         goto out;
 out_free:
         (*new_auth_tok) = NULL;
         memset(auth_tok_list_item, 0,
                sizeof(struct ecryptfs_auth_tok_list_item));
         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
                         auth_tok_list_item);
 out:
         if (rc)
                 (*packet_size) = 0;
         return rc;
 }
 
 /**
  * parse_tag_3_packet
  * @crypt_stat: The cryptographic context to modify based on packet
  *              contents.
  * @data: The raw bytes of the packet.
  * @auth_tok_list: eCryptfs parses packets into authentication tokens;
  *                 a new authentication token will be placed at the end
  *                 of this list for this packet.
  * @new_auth_tok: Pointer to a pointer to memory that this function
  *                allocates; sets the memory address of the pointer to
  *                NULL on error. This object is added to the
  *                auth_tok_list.
  * @packet_size: This function writes the size of the parsed packet
  *               into this memory location; zero on error.
  * @max_packet_size: maximum number of bytes to parse
  *
  * Returns zero on success; non-zero on error.
  */
 static int
 parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
                    unsigned char *data, struct list_head *auth_tok_list,
                    struct ecryptfs_auth_tok **new_auth_tok,
                    size_t *packet_size, size_t max_packet_size)
 {
         size_t body_size;
         struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
         size_t length_size;
         int rc = 0;
 
         (*packet_size) = 0;
         (*new_auth_tok) = NULL;
         /**
          *This format is inspired by OpenPGP; see RFC 2440
          * packet tag 3
          *
          * Tag 3 identifier (1 byte)
          * Max Tag 3 packet size (max 3 bytes)
          * Version (1 byte)
          * Cipher code (1 byte)
          * S2K specifier (1 byte)
          * Hash identifier (1 byte)
          * Salt (ECRYPTFS_SALT_SIZE)
          * Hash iterations (1 byte)
          * Encrypted key (arbitrary)
          *
          * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
          */
         if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
                 printk(KERN_ERR "Max packet size too large\n");
                 rc = -EINVAL;
                 goto out;
         }
         if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
                 printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
                        ECRYPTFS_TAG_3_PACKET_TYPE);
                 rc = -EINVAL;
                 goto out;
         }
         /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
          * at end of function upon failure */
         auth_tok_list_item =
             kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
         if (!auth_tok_list_item) {
                 printk(KERN_ERR "Unable to allocate memory\n");
                 rc = -ENOMEM;
                 goto out;
         }
         (*new_auth_tok) = &auth_tok_list_item->auth_tok;
         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
                                           &length_size);
         if (rc) {
                 printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
                        rc);
                 goto out_free;
         }
         if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
                 rc = -EINVAL;
                 goto out_free;
         }
         (*packet_size) += length_size;
         if (unlikely((*packet_size) + body_size > max_packet_size)) {
                 printk(KERN_ERR "Packet size exceeds max\n");
                 rc = -EINVAL;
                 goto out_free;
         }
         (*new_auth_tok)->session_key.encrypted_key_size =
                 (body_size - (ECRYPTFS_SALT_SIZE + 5));
         if (unlikely(data[(*packet_size)++] != 0x04)) {
                 printk(KERN_WARNING "Unknown version number [%d]\n",
                        data[(*packet_size) - 1]);
                 rc = -EINVAL;
                 goto out_free;
         }
         ecryptfs_cipher_code_to_string(crypt_stat->cipher,
                                        (u16)data[(*packet_size)]);
         /* A little extra work to differentiate among the AES key
          * sizes; see RFC2440 */
         switch(data[(*packet_size)++]) {
         case RFC2440_CIPHER_AES_192:
                 crypt_stat->key_size = 24;
                 break;
         default:
                 crypt_stat->key_size =
                         (*new_auth_tok)->session_key.encrypted_key_size;
         }
         ecryptfs_init_crypt_ctx(crypt_stat);
         if (unlikely(data[(*packet_size)++] != 0x03)) {
                 printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
                 rc = -ENOSYS;
                 goto out_free;
         }
         /* TODO: finish the hash mapping */
         switch (data[(*packet_size)++]) {
         case 0x01: /* See RFC2440 for these numbers and their mappings */
                 /* Choose MD5 */
                 memcpy((*new_auth_tok)->token.password.salt,
                        &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
                 (*packet_size) += ECRYPTFS_SALT_SIZE;
                 /* This conversion was taken straight from RFC2440 */
                 (*new_auth_tok)->token.password.hash_iterations =
                         ((u32) 16 + (data[(*packet_size)] & 15))
                                 << ((data[(*packet_size)] >> 4) + 6);
                 (*packet_size)++;
                 /* Friendly reminder:
                  * (*new_auth_tok)->session_key.encrypted_key_size =
                  *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
                 memcpy((*new_auth_tok)->session_key.encrypted_key,
                        &data[(*packet_size)],
                        (*new_auth_tok)->session_key.encrypted_key_size);
                 (*packet_size) +=
                         (*new_auth_tok)->session_key.encrypted_key_size;
                 (*new_auth_tok)->session_key.flags &=
                         ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
                 (*new_auth_tok)->session_key.flags |=
                         ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
                 (*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
                 break;
         default:
                 ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
                                 "[%d]\n", data[(*packet_size) - 1]);
                 rc = -ENOSYS;
                 goto out_free;
         }
         (*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
         /* TODO: Parametarize; we might actually want userspace to
          * decrypt the session key. */
         (*new_auth_tok)->session_key.flags &=
                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
         (*new_auth_tok)->session_key.flags &=
                             ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
         list_add(&auth_tok_list_item->list, auth_tok_list);
         goto out;
 out_free:
         (*new_auth_tok) = NULL;
         memset(auth_tok_list_item, 0,
                sizeof(struct ecryptfs_auth_tok_list_item));
         kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
                         auth_tok_list_item);
 out:
         if (rc)
                 (*packet_size) = 0;
         return rc;
 }
 
 /**
  * parse_tag_11_packet
  * @data: The raw bytes of the packet
  * @contents: This function writes the data contents of the literal
  *            packet into this memory location
  * @max_contents_bytes: The maximum number of bytes that this function
  *                      is allowed to write into contents
  * @tag_11_contents_size: This function writes the size of the parsed
  *                        contents into this memory location; zero on
  *                        error
  * @packet_size: This function writes the size of the parsed packet
  *               into this memory location; zero on error
  * @max_packet_size: maximum number of bytes to parse
  *
  * Returns zero on success; non-zero on error.
  */
 static int
 parse_tag_11_packet(unsigned char *data, unsigned char *contents,
                     size_t max_contents_bytes, size_t *tag_11_contents_size,
                     size_t *packet_size, size_t max_packet_size)
 {
         size_t body_size;
         size_t length_size;
         int rc = 0;
 
         (*packet_size) = 0;
         (*tag_11_contents_size) = 0;
         /* This format is inspired by OpenPGP; see RFC 2440
          * packet tag 11
          *
          * Tag 11 identifier (1 byte)
          * Max Tag 11 packet size (max 3 bytes)
          * Binary format specifier (1 byte)
          * Filename length (1 byte)
          * Filename ("_CONSOLE") (8 bytes)
          * Modification date (4 bytes)
          * Literal data (arbitrary)
          *
          * We need at least 16 bytes of data for the packet to even be
          * valid.
          */
         if (max_packet_size < 16) {
                 printk(KERN_ERR "Maximum packet size too small\n");
                 rc = -EINVAL;
                 goto out;
         }
         if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
                 rc = -EINVAL;
                 goto out;
         }
         rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
                                           &length_size);
         if (rc) {
                 printk(KERN_WARNING "Invalid tag 11 packet format\n");
                 goto out;
         }
         if (body_size < 14) {
                 printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
                 rc = -EINVAL;
                 goto out;
         }
         (*packet_size) += length_size;
         (*tag_11_contents_size) = (body_size - 14);
         if (unlikely((*packet_size) + body_size + 1 > max_packet_size)) {
                 printk(KERN_ERR "Packet size exceeds max\n");
                 rc = -EINVAL;
                 goto out;
         }
         if (data[(*packet_size)++] != 0x62) {
                 printk(KERN_WARNING "Unrecognizable packet\n");
                 rc = -EINVAL;
                 goto out;
         }
         if (data[(*packet_size)++] != 0x08) {
                 printk(KERN_WARNING "Unrecognizable packet\n");
                 rc = -EINVAL;
                 goto out;
         }
         (*packet_size) += 12; /* Ignore filename and modification date */
         memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
         (*packet_size) += (*tag_11_contents_size);
 out:
         if (rc) {
                 (*packet_size) = 0;
                 (*tag_11_contents_size) = 0;
         }
         return rc;
 }
 
 static int
 ecryptfs_find_global_auth_tok_for_sig(
         struct ecryptfs_global_auth_tok **global_auth_tok,
         struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
 {
         struct ecryptfs_global_auth_tok *walker;
         int rc = 0;
 
         (*global_auth_tok) = NULL;
         mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
         list_for_each_entry(walker,
                             &mount_crypt_stat->global_auth_tok_list,
                             mount_crypt_stat_list) {
                 if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX) == 0) {
                         (*global_auth_tok) = walker;
                         goto out;
                 }
         }
         rc = -EINVAL;
 out:
         mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
         return rc;
 }
 
 /**
  * ecryptfs_verify_version
  * @version: The version number to confirm
  *
  * Returns zero on good version; non-zero otherwise
  */
 static int ecryptfs_verify_version(u16 version)
 {
         int rc = 0;
         unsigned char major;
         unsigned char minor;
 
         major = ((version >> 8) & 0xFF);
         minor = (version & 0xFF);
         if (major != ECRYPTFS_VERSION_MAJOR) {
                 ecryptfs_printk(KERN_ERR, "Major version number mismatch. "
                                 "Expected [%d]; got [%d]\n",
                                 ECRYPTFS_VERSION_MAJOR, major);
                 rc = -EINVAL;
                 goto out;
         }
         if (minor != ECRYPTFS_VERSION_MINOR) {
                 ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "
                                 "Expected [%d]; got [%d]\n",
                                 ECRYPTFS_VERSION_MINOR, minor);
                 rc = -EINVAL;
                 goto out;
         }
 out:
         return rc;
 }
 
 int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,
                                       struct ecryptfs_auth_tok **auth_tok,
                                       char *sig)
 {
         int rc = 0;
 
         (*auth_tok_key) = request_key(&key_type_user, sig, NULL);
         if (!(*auth_tok_key) || IS_ERR(*auth_tok_key)) {
                 printk(KERN_ERR "Could not find key with description: [%s]\n",
                        sig);
                 rc = process_request_key_err(PTR_ERR(*auth_tok_key));
                 goto out;
         }
         (*auth_tok) = ecryptfs_get_key_payload_data(*auth_tok_key);
         if (ecryptfs_verify_version((*auth_tok)->version)) {
                 printk(KERN_ERR
                        "Data structure version mismatch. "
                        "Userspace tools must match eCryptfs "
                        "kernel module with major version [%d] "
                        "and minor version [%d]\n",
                        ECRYPTFS_VERSION_MAJOR,
                        ECRYPTFS_VERSION_MINOR);
                 rc = -EINVAL;
                 goto out;
         }
         if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD
             && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {
                 printk(KERN_ERR "Invalid auth_tok structure "
                        "returned from key query\n");
                 rc = -EINVAL;
                 goto out;
         }
 out:
         return rc;
 }
 
 /**
  * ecryptfs_find_auth_tok_for_sig
  * @auth_tok: Set to the matching auth_tok; NULL if not found
  * @crypt_stat: inode crypt_stat crypto context
  * @sig: Sig of auth_tok to find
  *
  * For now, this function simply looks at the registered auth_tok's
  * linked off the mount_crypt_stat, so all the auth_toks that can be
 * used must be registered at mount time. This function could
 * potentially try a lot harder to find auth_tok's (e.g., by calling
 * out to ecryptfsd to dynamically retrieve an auth_tok object) so
 * that static registration of auth_tok's will no longer be necessary.
 *
 * Returns zero on no error; non-zero on error
 */
static int
ecryptfs_find_auth_tok_for_sig(
        struct ecryptfs_auth_tok **auth_tok,
        struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
                crypt_stat->mount_crypt_stat;
        struct ecryptfs_global_auth_tok *global_auth_tok;
        int rc = 0;

        (*auth_tok) = NULL;
        if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
                                                  mount_crypt_stat, sig)) {
                struct key *auth_tok_key;

                rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
                                                       sig);
        } else
                (*auth_tok) = global_auth_tok->global_auth_tok;
        return rc;
}

/**
 * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
 * @auth_tok: The passphrase authentication token to use to encrypt the FEK
 * @crypt_stat: The cryptographic context
 *
 * Returns zero on success; non-zero error otherwise
 */
static int
decrypt_passphrase_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
                                         struct ecryptfs_crypt_stat *crypt_stat)
{
        struct scatterlist dst_sg[2];
        struct scatterlist src_sg[2];
        struct mutex *tfm_mutex;
        struct blkcipher_desc desc = {
                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
        };
        int rc = 0;

        if (unlikely(ecryptfs_verbosity > 0)) {
                ecryptfs_printk(
                        KERN_DEBUG, "Session key encryption key (size [%d]):\n",
                        auth_tok->token.password.session_key_encryption_key_bytes);
                ecryptfs_dump_hex(
                        auth_tok->token.password.session_key_encryption_key,
                        auth_tok->token.password.session_key_encryption_key_bytes);
        }
        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
                                                        crypt_stat->cipher);
        if (unlikely(rc)) {
                printk(KERN_ERR "Internal error whilst attempting to get "
                       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
                       crypt_stat->cipher, rc);
                goto out;
        }
        rc = virt_to_scatterlist(auth_tok->session_key.encrypted_key,
                                 auth_tok->session_key.encrypted_key_size,
                                 src_sg, 2);
        if (rc < 1 || rc > 2) {
                printk(KERN_ERR "Internal error whilst attempting to convert "
                        "auth_tok->session_key.encrypted_key to scatterlist; "
                        "expected rc = 1; got rc = [%d]. "
                       "auth_tok->session_key.encrypted_key_size = [%d]\n", rc,
                        auth_tok->session_key.encrypted_key_size);
                goto out;
        }
        auth_tok->session_key.decrypted_key_size =
                auth_tok->session_key.encrypted_key_size;
        rc = virt_to_scatterlist(auth_tok->session_key.decrypted_key,
                                 auth_tok->session_key.decrypted_key_size,
                                 dst_sg, 2);
        if (rc < 1 || rc > 2) {
                printk(KERN_ERR "Internal error whilst attempting to convert "
                        "auth_tok->session_key.decrypted_key to scatterlist; "
                        "expected rc = 1; got rc = [%d]\n", rc);
                goto out;
        }
        mutex_lock(tfm_mutex);
        rc = crypto_blkcipher_setkey(
                desc.tfm, auth_tok->token.password.session_key_encryption_key,
                crypt_stat->key_size);
        if (unlikely(rc < 0)) {
                mutex_unlock(tfm_mutex);
                printk(KERN_ERR "Error setting key for crypto context\n");
                rc = -EINVAL;
                goto out;
        }
        rc = crypto_blkcipher_decrypt(&desc, dst_sg, src_sg,
                                      auth_tok->session_key.encrypted_key_size);
        mutex_unlock(tfm_mutex);
        if (unlikely(rc)) {
                printk(KERN_ERR "Error decrypting; rc = [%d]\n", rc);
                goto out;
        }
        auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
        memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
               auth_tok->session_key.decrypted_key_size);
        crypt_stat->flags |= ECRYPTFS_KEY_VALID;
        if (unlikely(ecryptfs_verbosity > 0)) {
                ecryptfs_printk(KERN_DEBUG, "FEK of size [%d]:\n",
                                crypt_stat->key_size);
                ecryptfs_dump_hex(crypt_stat->key,
                                  crypt_stat->key_size);
        }
out:
        return rc;
}

/**
 * ecryptfs_parse_packet_set
 * @crypt_stat: The cryptographic context
 * @src: Virtual address of region of memory containing the packets
 * @ecryptfs_dentry: The eCryptfs dentry associated with the packet set
 *
 * Get crypt_stat to have the file's session key if the requisite key
 * is available to decrypt the session key.
 *
 * Returns Zero if a valid authentication token was retrieved and
 * processed; negative value for file not encrypted or for error
 * conditions.
 */
int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
                              unsigned char *src,
                              struct dentry *ecryptfs_dentry)
{
        size_t i = 0;
        size_t found_auth_tok;
        size_t next_packet_is_auth_tok_packet;
        struct list_head auth_tok_list;
        struct ecryptfs_auth_tok *matching_auth_tok;
        struct ecryptfs_auth_tok *candidate_auth_tok;
        char *candidate_auth_tok_sig;
        size_t packet_size;
        struct ecryptfs_auth_tok *new_auth_tok;
        unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
        struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
        size_t tag_11_contents_size;
        size_t tag_11_packet_size;
        int rc = 0;

        INIT_LIST_HEAD(&auth_tok_list);
        /* Parse the header to find as many packets as we can; these will be
         * added the our &auth_tok_list */
        next_packet_is_auth_tok_packet = 1;
        while (next_packet_is_auth_tok_packet) {
                size_t max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);

                switch (src[i]) {
                case ECRYPTFS_TAG_3_PACKET_TYPE:
                        rc = parse_tag_3_packet(crypt_stat,
                                                (unsigned char *)&src[i],
                                                &auth_tok_list, &new_auth_tok,
                                                &packet_size, max_packet_size);
                        if (rc) {
                                ecryptfs_printk(KERN_ERR, "Error parsing "
                                                "tag 3 packet\n");
                                rc = -EIO;
                                goto out_wipe_list;
                        }
                        i += packet_size;
                        rc = parse_tag_11_packet((unsigned char *)&src[i],
                                                 sig_tmp_space,
                                                 ECRYPTFS_SIG_SIZE,
                                                 &tag_11_contents_size,
                                                 &tag_11_packet_size,
                                                 max_packet_size);
                        if (rc) {
                                ecryptfs_printk(KERN_ERR, "No valid "
                                                "(ecryptfs-specific) literal "
                                                "packet containing "
                                                "authentication token "
                                                "signature found after "
                                                "tag 3 packet\n");
                                rc = -EIO;
                                goto out_wipe_list;
                        }
                        i += tag_11_packet_size;
                        if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
                                ecryptfs_printk(KERN_ERR, "Expected "
                                                "signature of size [%d]; "
                                                "read size [%d]\n",
                                                ECRYPTFS_SIG_SIZE,
                                                tag_11_contents_size);
                                rc = -EIO;
                                goto out_wipe_list;
                        }
                        ecryptfs_to_hex(new_auth_tok->token.password.signature,
                                        sig_tmp_space, tag_11_contents_size);
                        new_auth_tok->token.password.signature[
                                ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
                        crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
                        break;
                case ECRYPTFS_TAG_1_PACKET_TYPE:
                        rc = parse_tag_1_packet(crypt_stat,
                                                (unsigned char *)&src[i],
                                                &auth_tok_list, &new_auth_tok,
                                                &packet_size, max_packet_size);
                        if (rc) {
                                ecryptfs_printk(KERN_ERR, "Error parsing "
                                                "tag 1 packet\n");
                                rc = -EIO;
                                goto out_wipe_list;
                        }
                        i += packet_size;
                        crypt_stat->flags |= ECRYPTFS_ENCRYPTED;
                        break;
                case ECRYPTFS_TAG_11_PACKET_TYPE:
                        ecryptfs_printk(KERN_WARNING, "Invalid packet set "
                                        "(Tag 11 not allowed by itself)\n");
                        rc = -EIO;
                        goto out_wipe_list;
                        break;
                default:
                        ecryptfs_printk(KERN_DEBUG, "No packet at offset "
                                        "[%d] of the file header; hex value of "
                                        "character is [0x%.2x]\n", i, src[i]);
                        next_packet_is_auth_tok_packet = 0;
                }
        }
        if (list_empty(&auth_tok_list)) {
                printk(KERN_ERR "The lower file appears to be a non-encrypted "
                       "eCryptfs file; this is not supported in this version "
                       "of the eCryptfs kernel module\n");
                rc = -EINVAL;
                goto out;
        }
        /* auth_tok_list contains the set of authentication tokens
         * parsed from the metadata. We need to find a matching
         * authentication token that has the secret component(s)
         * necessary to decrypt the EFEK in the auth_tok parsed from
         * the metadata. There may be several potential matches, but
         * just one will be sufficient to decrypt to get the FEK. */
find_next_matching_auth_tok:
        found_auth_tok = 0;
        list_for_each_entry(auth_tok_list_item, &auth_tok_list, list) {
                candidate_auth_tok = &auth_tok_list_item->auth_tok;
                if (unlikely(ecryptfs_verbosity > 0)) {
                        ecryptfs_printk(KERN_DEBUG,
                                        "Considering cadidate auth tok:\n");
                        ecryptfs_dump_auth_tok(candidate_auth_tok);
                }
                rc = ecryptfs_get_auth_tok_sig(&candidate_auth_tok_sig,
                                               candidate_auth_tok);
                if (rc) {
                        printk(KERN_ERR
                               "Unrecognized candidate auth tok type: [%d]\n",
                               candidate_auth_tok->token_type);
                        rc = -EINVAL;
                        goto out_wipe_list;
                }
                ecryptfs_find_auth_tok_for_sig(&matching_auth_tok, crypt_stat,
                                               candidate_auth_tok_sig);
                if (matching_auth_tok) {
                        found_auth_tok = 1;
                        goto found_matching_auth_tok;
                }
        }
        if (!found_auth_tok) {
                ecryptfs_printk(KERN_ERR, "Could not find a usable "
                                "authentication token\n");
                rc = -EIO;
                goto out_wipe_list;
        }
found_matching_auth_tok:
        if (candidate_auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
                memcpy(&(candidate_auth_tok->token.private_key),
                       &(matching_auth_tok->token.private_key),
                       sizeof(struct ecryptfs_private_key));
                rc = decrypt_pki_encrypted_session_key(candidate_auth_tok,
                                                       crypt_stat);
        } else if (candidate_auth_tok->token_type == ECRYPTFS_PASSWORD) {
                memcpy(&(candidate_auth_tok->token.password),
                       &(matching_auth_tok->token.password),
                       sizeof(struct ecryptfs_password));
                rc = decrypt_passphrase_encrypted_session_key(
                        candidate_auth_tok, crypt_stat);
        }
        if (rc) {
                struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;

                ecryptfs_printk(KERN_WARNING, "Error decrypting the "
                                "session key for authentication token with sig "
                                "[%.*s]; rc = [%d]. Removing auth tok "
                                "candidate from the list and searching for "
                                "the next match.\n", candidate_auth_tok_sig,
                                ECRYPTFS_SIG_SIZE_HEX, rc);
                list_for_each_entry_safe(auth_tok_list_item,
                                         auth_tok_list_item_tmp,
                                         &auth_tok_list, list) {
                        if (candidate_auth_tok
                            == &auth_tok_list_item->auth_tok) {
                                list_del(&auth_tok_list_item->list);
                                kmem_cache_free(
                                        ecryptfs_auth_tok_list_item_cache,
                                        auth_tok_list_item);
                                goto find_next_matching_auth_tok;
                        }
                }
                BUG();
        }
        rc = ecryptfs_compute_root_iv(crypt_stat);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error computing "
                                "the root IV\n");
                goto out_wipe_list;
        }
        rc = ecryptfs_init_crypt_ctx(crypt_stat);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error initializing crypto "
                                "context for cipher [%s]; rc = [%d]\n",
                                crypt_stat->cipher, rc);
        }
out_wipe_list:
        wipe_auth_tok_list(&auth_tok_list);
out:
        return rc;
}

static int
pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
                        struct ecryptfs_crypt_stat *crypt_stat,
                        struct ecryptfs_key_record *key_rec)
{
        struct ecryptfs_msg_ctx *msg_ctx = NULL;
        char *payload = NULL;
        size_t payload_len;
        struct ecryptfs_message *msg;
        int rc;

        rc = write_tag_66_packet(auth_tok->token.private_key.signature,
                                 ecryptfs_code_for_cipher_string(crypt_stat),
                                 crypt_stat, &payload, &payload_len);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
                goto out;
        }
        rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error sending message to "
                                "ecryptfsd\n");
                goto out;
        }
        rc = ecryptfs_wait_for_response(msg_ctx, &msg);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Failed to receive tag 67 packet "
                                "from the user space daemon\n");
                rc = -EIO;
                goto out;
        }
        rc = parse_tag_67_packet(key_rec, msg);
        if (rc)
                ecryptfs_printk(KERN_ERR, "Error parsing tag 67 packet\n");
        kfree(msg);
out:
        kfree(payload);
        return rc;
}
/**
 * write_tag_1_packet - Write an RFC2440-compatible tag 1 (public key) packet
 * @dest: Buffer into which to write the packet
 * @remaining_bytes: Maximum number of bytes that can be writtn
 * @auth_tok: The authentication token used for generating the tag 1 packet
 * @crypt_stat: The cryptographic context
 * @key_rec: The key record struct for the tag 1 packet
 * @packet_size: This function will write the number of bytes that end
 *               up constituting the packet; set to zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_1_packet(char *dest, size_t *remaining_bytes,
                   struct ecryptfs_auth_tok *auth_tok,
                   struct ecryptfs_crypt_stat *crypt_stat,
                   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
        size_t i;
        size_t encrypted_session_key_valid = 0;
        size_t packet_size_length;
        size_t max_packet_size;
        int rc = 0;

        (*packet_size) = 0;
        ecryptfs_from_hex(key_rec->sig, auth_tok->token.private_key.signature,
                          ECRYPTFS_SIG_SIZE);
        encrypted_session_key_valid = 0;
        for (i = 0; i < crypt_stat->key_size; i++)
                encrypted_session_key_valid |=
                        auth_tok->session_key.encrypted_key[i];
        if (encrypted_session_key_valid) {
                memcpy(key_rec->enc_key,
                       auth_tok->session_key.encrypted_key,
                       auth_tok->session_key.encrypted_key_size);
                goto encrypted_session_key_set;
        }
        if (auth_tok->session_key.encrypted_key_size == 0)
                auth_tok->session_key.encrypted_key_size =
                        auth_tok->token.private_key.key_size;
        rc = pki_encrypt_session_key(auth_tok, crypt_stat, key_rec);
        if (rc) {
                printk(KERN_ERR "Failed to encrypt session key via a key "
                       "module; rc = [%d]\n", rc);
                goto out;
        }
        if (ecryptfs_verbosity > 0) {
                ecryptfs_printk(KERN_DEBUG, "Encrypted key:\n");
                ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
        }
encrypted_session_key_set:
        /* This format is inspired by OpenPGP; see RFC 2440
         * packet tag 1 */
        max_packet_size = (1                         /* Tag 1 identifier */
                           + 3                       /* Max Tag 1 packet size */
                           + 1                       /* Version */
                           + ECRYPTFS_SIG_SIZE       /* Key identifier */
                           + 1                       /* Cipher identifier */
                           + key_rec->enc_key_size); /* Encrypted key size */
        if (max_packet_size > (*remaining_bytes)) {
                printk(KERN_ERR "Packet length larger than maximum allowable; "
                       "need up to [%td] bytes, but there are only [%td] "
                       "available\n", max_packet_size, (*remaining_bytes));
                rc = -EINVAL;
                goto out;
        }
        dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
        rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
                                          (max_packet_size - 4),
                                          &packet_size_length);
        if (rc) {
                ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
                                "header; cannot generate packet length\n");
                goto out;
        }
        (*packet_size) += packet_size_length;
        dest[(*packet_size)++] = 0x03; /* version 3 */
        memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
        (*packet_size) += ECRYPTFS_SIG_SIZE;
        dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
        memcpy(&dest[(*packet_size)], key_rec->enc_key,
               key_rec->enc_key_size);
        (*packet_size) += key_rec->enc_key_size;
out:
        if (rc)
                (*packet_size) = 0;
        else
                (*remaining_bytes) -= (*packet_size);
        return rc;
}

/**
 * write_tag_11_packet
 * @dest: Target into which Tag 11 packet is to be written
 * @remaining_bytes: Maximum packet length
 * @contents: Byte array of contents to copy in
 * @contents_length: Number of bytes in contents
 * @packet_length: Length of the Tag 11 packet written; zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
                    size_t contents_length, size_t *packet_length)
{
        size_t packet_size_length;
        size_t max_packet_size;
        int rc = 0;

        (*packet_length) = 0;
        /* This format is inspired by OpenPGP; see RFC 2440
         * packet tag 11 */
        max_packet_size = (1                   /* Tag 11 identifier */
                           + 3                 /* Max Tag 11 packet size */
                           + 1                 /* Binary format specifier */
                           + 1                 /* Filename length */
                           + 8                 /* Filename ("_CONSOLE") */
                           + 4                 /* Modification date */
                           + contents_length); /* Literal data */
        if (max_packet_size > (*remaining_bytes)) {
                printk(KERN_ERR "Packet length larger than maximum allowable; "
                       "need up to [%td] bytes, but there are only [%td] "
                       "available\n", max_packet_size, (*remaining_bytes));
                rc = -EINVAL;
                goto out;
        }
        dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
        rc = ecryptfs_write_packet_length(&dest[(*packet_length)],
                                          (max_packet_size - 4),
                                          &packet_size_length);
        if (rc) {
                printk(KERN_ERR "Error generating tag 11 packet header; cannot "
                       "generate packet length. rc = [%d]\n", rc);
                goto out;
        }
        (*packet_length) += packet_size_length;
        dest[(*packet_length)++] = 0x62; /* binary data format specifier */
        dest[(*packet_length)++] = 8;
        memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
        (*packet_length) += 8;
        memset(&dest[(*packet_length)], 0x00, 4);
        (*packet_length) += 4;
        memcpy(&dest[(*packet_length)], contents, contents_length);
        (*packet_length) += contents_length;
 out:
        if (rc)
                (*packet_length) = 0;
        else
                (*remaining_bytes) -= (*packet_length);
        return rc;
}

/**
 * write_tag_3_packet
 * @dest: Buffer into which to write the packet
 * @remaining_bytes: Maximum number of bytes that can be written
 * @auth_tok: Authentication token
 * @crypt_stat: The cryptographic context
 * @key_rec: encrypted key
 * @packet_size: This function will write the number of bytes that end
 *               up constituting the packet; set to zero on error
 *
 * Returns zero on success; non-zero on error.
 */
static int
write_tag_3_packet(char *dest, size_t *remaining_bytes,
                   struct ecryptfs_auth_tok *auth_tok,
                   struct ecryptfs_crypt_stat *crypt_stat,
                   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
        size_t i;
        size_t encrypted_session_key_valid = 0;
        char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
        struct scatterlist dst_sg[2];
        struct scatterlist src_sg[2];
        struct mutex *tfm_mutex = NULL;
        u8 cipher_code;
        size_t packet_size_length;
        size_t max_packet_size;
        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
                crypt_stat->mount_crypt_stat;
        struct blkcipher_desc desc = {
                .tfm = NULL,
                .flags = CRYPTO_TFM_REQ_MAY_SLEEP
        };
        int rc = 0;

        (*packet_size) = 0;
        ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
                          ECRYPTFS_SIG_SIZE);
        rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
                                                        crypt_stat->cipher);
        if (unlikely(rc)) {
                printk(KERN_ERR "Internal error whilst attempting to get "
                       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
                       crypt_stat->cipher, rc);
                goto out;
        }
        if (mount_crypt_stat->global_default_cipher_key_size == 0) {
                struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);

                printk(KERN_WARNING "No key size specified at mount; "
                       "defaulting to [%d]\n", alg->max_keysize);
                mount_crypt_stat->global_default_cipher_key_size =
                        alg->max_keysize;
        }
        if (crypt_stat->key_size == 0)
                crypt_stat->key_size =
                        mount_crypt_stat->global_default_cipher_key_size;
        if (auth_tok->session_key.encrypted_key_size == 0)
                auth_tok->session_key.encrypted_key_size =
                        crypt_stat->key_size;
        if (crypt_stat->key_size == 24
            && strcmp("aes", crypt_stat->cipher) == 0) {
                memset((crypt_stat->key + 24), 0, 8);
                auth_tok->session_key.encrypted_key_size = 32;
        } else
                auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
        key_rec->enc_key_size =
                auth_tok->session_key.encrypted_key_size;
        encrypted_session_key_valid = 0;
        for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
                encrypted_session_key_valid |=
                        auth_tok->session_key.encrypted_key[i];
        if (encrypted_session_key_valid) {
                ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
                                "using auth_tok->session_key.encrypted_key, "
                                "where key_rec->enc_key_size = [%d]\n",
                                key_rec->enc_key_size);
                memcpy(key_rec->enc_key,
                       auth_tok->session_key.encrypted_key,
                       key_rec->enc_key_size);
                goto encrypted_session_key_set;
        }
        if (auth_tok->token.password.flags &
            ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET) {
                ecryptfs_printk(KERN_DEBUG, "Using previously generated "
                                "session key encryption key of size [%d]\n",
                                auth_tok->token.password.
                                session_key_encryption_key_bytes);
                memcpy(session_key_encryption_key,
                       auth_tok->token.password.session_key_encryption_key,
                       crypt_stat->key_size);
                ecryptfs_printk(KERN_DEBUG,
                                "Cached session key " "encryption key: \n");
                if (ecryptfs_verbosity > 0)
                        ecryptfs_dump_hex(session_key_encryption_key, 16);
        }
        if (unlikely(ecryptfs_verbosity > 0)) {
                ecryptfs_printk(KERN_DEBUG, "Session key encryption key:\n");
                ecryptfs_dump_hex(session_key_encryption_key, 16);
        }
        rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
                                 src_sg, 2);
        if (rc < 1 || rc > 2) {
                ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
                                "for crypt_stat session key; expected rc = 1; "
                                "got rc = [%d]. key_rec->enc_key_size = [%d]\n",
                                rc, key_rec->enc_key_size);
                rc = -ENOMEM;
                goto out;
        }
        rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
                                 dst_sg, 2);
        if (rc < 1 || rc > 2) {
                ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
                                "for crypt_stat encrypted session key; "
                                "expected rc = 1; got rc = [%d]. "
                                "key_rec->enc_key_size = [%d]\n", rc,
                                key_rec->enc_key_size);
                rc = -ENOMEM;
                goto out;
        }
        mutex_lock(tfm_mutex);
        rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
                                     crypt_stat->key_size);
        if (rc < 0) {
                mutex_unlock(tfm_mutex);
                ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
                                "context; rc = [%d]\n", rc);
                goto out;
        }
        rc = 0;
        ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
                        crypt_stat->key_size);
        rc = crypto_blkcipher_encrypt(&desc, dst_sg, src_sg,
                                      (*key_rec).enc_key_size);
        mutex_unlock(tfm_mutex);
        if (rc) {
                printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
                goto out;
        }
        ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
        if (ecryptfs_verbosity > 0) {
                ecryptfs_printk(KERN_DEBUG, "EFEK of size [%d]:\n",
                                key_rec->enc_key_size);
                ecryptfs_dump_hex(key_rec->enc_key,
                                  key_rec->enc_key_size);
        }
encrypted_session_key_set:
        /* This format is inspired by OpenPGP; see RFC 2440
         * packet tag 3 */
        max_packet_size = (1                         /* Tag 3 identifier */
                           + 3                       /* Max Tag 3 packet size */
                           + 1                       /* Version */
                           + 1                       /* Cipher code */
                           + 1                       /* S2K specifier */
                           + 1                       /* Hash identifier */
                           + ECRYPTFS_SALT_SIZE      /* Salt */
                           + 1                       /* Hash iterations */
                           + key_rec->enc_key_size); /* Encrypted key size */
        if (max_packet_size > (*remaining_bytes)) {
                printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
                       "there are only [%td] available\n", max_packet_size,
                       (*remaining_bytes));
                rc = -EINVAL;
                goto out;
        }
        dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
        /* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
         * to get the number of octets in the actual Tag 3 packet */
        rc = ecryptfs_write_packet_length(&dest[(*packet_size)],
                                          (max_packet_size - 4),
                                          &packet_size_length);
        if (rc) {
                printk(KERN_ERR "Error generating tag 3 packet header; cannot "
                       "generate packet length. rc = [%d]\n", rc);
                goto out;
        }
        (*packet_size) += packet_size_length;
        dest[(*packet_size)++] = 0x04; /* version 4 */
        /* TODO: Break from RFC2440 so that arbitrary ciphers can be
         * specified with strings */
        cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
        if (cipher_code == 0) {
                ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
                                "cipher [%s]\n", crypt_stat->cipher);
                rc = -EINVAL;
                goto out;
        }
        dest[(*packet_size)++] = cipher_code;
        dest[(*packet_size)++] = 0x03;        /* S2K */
        dest[(*packet_size)++] = 0x01;        /* MD5 (TODO: parameterize) */
        memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
               ECRYPTFS_SALT_SIZE);
        (*packet_size) += ECRYPTFS_SALT_SIZE;        /* salt */
        dest[(*packet_size)++] = 0x60;        /* hash iterations (65536) */
        memcpy(&dest[(*packet_size)], key_rec->enc_key,
               key_rec->enc_key_size);
        (*packet_size) += key_rec->enc_key_size;
out:
        if (rc)
                (*packet_size) = 0;
        else
                (*remaining_bytes) -= (*packet_size);
        return rc;
}

struct kmem_cache *ecryptfs_key_record_cache;

/**
 * ecryptfs_generate_key_packet_set
 * @dest_base: Virtual address from which to write the key record set
 * @crypt_stat: The cryptographic context from which the
 *              authentication tokens will be retrieved
 * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
 *                   for the global parameters
 * @len: The amount written
 * @max: The maximum amount of data allowed to be written
 *
 * Generates a key packet set and writes it to the virtual address
 * passed in.
 *
 * Returns zero on success; non-zero on error.
 */
int
ecryptfs_generate_key_packet_set(char *dest_base,
                                 struct ecryptfs_crypt_stat *crypt_stat,
                                 struct dentry *ecryptfs_dentry, size_t *len,
                                 size_t max)
{
        struct ecryptfs_auth_tok *auth_tok;
        struct ecryptfs_global_auth_tok *global_auth_tok;
        struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
                &ecryptfs_superblock_to_private(
                        ecryptfs_dentry->d_sb)->mount_crypt_stat;
        size_t written;
        struct ecryptfs_key_record *key_rec;
        struct ecryptfs_key_sig *key_sig;
        int rc = 0;

        (*len) = 0;
        mutex_lock(&crypt_stat->keysig_list_mutex);
        key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
        if (!key_rec) {
                rc = -ENOMEM;
                goto out;
        }
        list_for_each_entry(key_sig, &crypt_stat->keysig_list,
                            crypt_stat_list) {
                memset(key_rec, 0, sizeof(*key_rec));
                rc = ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
                                                           mount_crypt_stat,
                                                           key_sig->keysig);
                if (rc) {
                        printk(KERN_ERR "Error attempting to get the global "
                               "auth_tok; rc = [%d]\n", rc);
                        goto out_free;
                }
                if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID) {
                        printk(KERN_WARNING
                               "Skipping invalid auth tok with sig = [%s]\n",
                               global_auth_tok->sig);
                        continue;
                }
                auth_tok = global_auth_tok->global_auth_tok;
                if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
                        rc = write_tag_3_packet((dest_base + (*len)),
                                                &max, auth_tok,
                                                crypt_stat, key_rec,
                                                &written);
                        if (rc) {
                                ecryptfs_printk(KERN_WARNING, "Error "
                                                "writing tag 3 packet\n");
                                goto out_free;
                        }
                        (*len) += written;
                        /* Write auth tok signature packet */
                        rc = write_tag_11_packet((dest_base + (*len)), &max,
                                                 key_rec->sig,
                                                 ECRYPTFS_SIG_SIZE, &written);
                        if (rc) {
                                ecryptfs_printk(KERN_ERR, "Error writing "
                                                "auth tok signature packet\n");
                                goto out_free;
                        }
                        (*len) += written;
                } else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
                        rc = write_tag_1_packet(dest_base + (*len),
                                                &max, auth_tok,
                                                crypt_stat, key_rec, &written);
                        if (rc) {
                                ecryptfs_printk(KERN_WARNING, "Error "
                                                "writing tag 1 packet\n");
                                goto out_free;
                        }
                        (*len) += written;
                } else {
                        ecryptfs_printk(KERN_WARNING, "Unsupported "
                                        "authentication token type\n");
                        rc = -EINVAL;
                        goto out_free;
                }
        }
        if (likely(max > 0)) {
                dest_base[(*len)] = 0x00;
        } else {
                ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
                rc = -EIO;
        }
out_free:
        kmem_cache_free(ecryptfs_key_record_cache, key_rec);
out:
        if (rc)
                (*len) = 0;
        mutex_unlock(&crypt_stat->keysig_list_mutex);
        return rc;
}

struct kmem_cache *ecryptfs_key_sig_cache;

int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
        struct ecryptfs_key_sig *new_key_sig;
        int rc = 0;

        new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
        if (!new_key_sig) {
                rc = -ENOMEM;
                printk(KERN_ERR
                       "Error allocating from ecryptfs_key_sig_cache\n");
                goto out;
        }
        memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
        mutex_lock(&crypt_stat->keysig_list_mutex);
        list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
        mutex_unlock(&crypt_stat->keysig_list_mutex);
out:
        return rc;
}

struct kmem_cache *ecryptfs_global_auth_tok_cache;

int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
                             char *sig)
{
        struct ecryptfs_global_auth_tok *new_auth_tok;
        int rc = 0;

        new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
                                        GFP_KERNEL);
        if (!new_auth_tok) {
                rc = -ENOMEM;
                printk(KERN_ERR "Error allocating from "
                       "ecryptfs_global_auth_tok_cache\n");
                goto out;
        }
        memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
        new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
        mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
        list_add(&new_auth_tok->mount_crypt_stat_list,
                 &mount_crypt_stat->global_auth_tok_list);
        mount_crypt_stat->num_global_auth_toks++;
        mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
        return rc;
}