ClabureDB: Classified Bug-Reports Database

   /*
    * linux/ipc/shm.c
    * Copyright (C) 1992, 1993 Krishna Balasubramanian
    *         Many improvements/fixes by Bruno Haible.
    * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
    * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
    *
    * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
    * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
   * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
   * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
   * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
   * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
   * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
   *
   * support for audit of ipc object properties and permission changes
   * Dustin Kirkland <dustin.kirkland@us.ibm.com>
   *
   * namespaces support
   * OpenVZ, SWsoft Inc.
   * Pavel Emelianov <xemul@openvz.org>
   */
  
  #include <linux/slab.h>
  #include <linux/mm.h>
  #include <linux/hugetlb.h>
  #include <linux/shm.h>
  #include <linux/init.h>
  #include <linux/file.h>
  #include <linux/mman.h>
  #include <linux/shmem_fs.h>
  #include <linux/security.h>
  #include <linux/syscalls.h>
  #include <linux/audit.h>
  #include <linux/capability.h>
  #include <linux/ptrace.h>
  #include <linux/seq_file.h>
  #include <linux/rwsem.h>
  #include <linux/nsproxy.h>
  #include <linux/mount.h>
  #include <linux/ipc_namespace.h>
  
  #include <asm/uaccess.h>
  
  #include "util.h"
  
  struct shm_file_data {
          int id;
          struct ipc_namespace *ns;
          struct file *file;
          const struct vm_operations_struct *vm_ops;
  };
  
  #define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))
  
  static const struct file_operations shm_file_operations;
  static struct vm_operations_struct shm_vm_ops;
  
  #define shm_ids(ns)        ((ns)->ids[IPC_SHM_IDS])
  
  #define shm_unlock(shp)                        \
          ipc_unlock(&(shp)->shm_perm)
  
  static int newseg(struct ipc_namespace *, struct ipc_params *);
  static void shm_open(struct vm_area_struct *vma);
  static void shm_close(struct vm_area_struct *vma);
  static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
  #ifdef CONFIG_PROC_FS
  static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
  #endif
  
  void shm_init_ns(struct ipc_namespace *ns)
  {
          ns->shm_ctlmax = SHMMAX;
          ns->shm_ctlall = SHMALL;
          ns->shm_ctlmni = SHMMNI;
          ns->shm_tot = 0;
          ipc_init_ids(&ns->ids[IPC_SHM_IDS]);
  }
  
  /*
   * Called with shm_ids.rw_mutex (writer) and the shp structure locked.
   * Only shm_ids.rw_mutex remains locked on exit.
   */
  static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
  {
          struct shmid_kernel *shp;
          shp = container_of(ipcp, struct shmid_kernel, shm_perm);
  
          if (shp->shm_nattch){
                  shp->shm_perm.mode |= SHM_DEST;
                  /* Do not find it any more */
                  shp->shm_perm.key = IPC_PRIVATE;
                  shm_unlock(shp);
          } else
                  shm_destroy(ns, shp);
  }
  
  #ifdef CONFIG_IPC_NS
 void shm_exit_ns(struct ipc_namespace *ns)
 {
         free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
 }
 #endif
 
 void __init shm_init (void)
 {
         shm_init_ns(&init_ipc_ns);
         ipc_init_proc_interface("sysvipc/shm",
                                 "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
                                 IPC_SHM_IDS, sysvipc_shm_proc_show);
 }
 
 /*
  * shm_lock_(check_) routines are called in the paths where the rw_mutex
  * is not necessarily held.
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
         struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
 
         if (IS_ERR(ipcp))
                 return (struct shmid_kernel *)ipcp;
 
         return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
                                                 int id)
 {
         struct kern_ipc_perm *ipcp = ipc_lock_check(&shm_ids(ns), id);
 
         if (IS_ERR(ipcp))
                 return (struct shmid_kernel *)ipcp;
 
         return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 {
         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 }
 
 
 /* This is called by fork, once for every shm attach. */
 static void shm_open(struct vm_area_struct *vma)
 {
         struct file *file = vma->vm_file;
         struct shm_file_data *sfd = shm_file_data(file);
         struct shmid_kernel *shp;
 
         shp = shm_lock(sfd->ns, sfd->id);
         BUG_ON(IS_ERR(shp));
         shp->shm_atim = get_seconds();
         shp->shm_lprid = task_tgid_vnr(current);
         shp->shm_nattch++;
         shm_unlock(shp);
 }
 
 /*
  * shm_destroy - free the struct shmid_kernel
  *
  * @ns: namespace
  * @shp: struct to free
  *
  * It has to be called with shp and shm_ids.rw_mutex (writer) locked,
  * but returns with shp unlocked and freed.
  */
 static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
 {
         ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
         shm_rmid(ns, shp);
         shm_unlock(shp);
         if (!is_file_hugepages(shp->shm_file))
                 shmem_lock(shp->shm_file, 0, shp->mlock_user);
         else
                 user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
                                                 shp->mlock_user);
         fput (shp->shm_file);
         security_shm_free(shp);
         ipc_rcu_putref(shp);
 }
 
 /*
  * remove the attach descriptor vma.
  * free memory for segment if it is marked destroyed.
  * The descriptor has already been removed from the current->mm->mmap list
  * and will later be kfree()d.
  */
 static void shm_close(struct vm_area_struct *vma)
 {
         struct file * file = vma->vm_file;
         struct shm_file_data *sfd = shm_file_data(file);
         struct shmid_kernel *shp;
         struct ipc_namespace *ns = sfd->ns;
 
         down_write(&shm_ids(ns).rw_mutex);
         /* remove from the list of attaches of the shm segment */
         shp = shm_lock(ns, sfd->id);
         BUG_ON(IS_ERR(shp));
         shp->shm_lprid = task_tgid_vnr(current);
         shp->shm_dtim = get_seconds();
         shp->shm_nattch--;
         if(shp->shm_nattch == 0 &&
            shp->shm_perm.mode & SHM_DEST)
                 shm_destroy(ns, shp);
         else
                 shm_unlock(shp);
         up_write(&shm_ids(ns).rw_mutex);
 }
 
 static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
 {
         struct file *file = vma->vm_file;
         struct shm_file_data *sfd = shm_file_data(file);
 
         return sfd->vm_ops->fault(vma, vmf);
 }
 
 #ifdef CONFIG_NUMA
 static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
 {
         struct file *file = vma->vm_file;
         struct shm_file_data *sfd = shm_file_data(file);
         int err = 0;
         if (sfd->vm_ops->set_policy)
                 err = sfd->vm_ops->set_policy(vma, new);
         return err;
 }
 
 static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
                                         unsigned long addr)
 {
         struct file *file = vma->vm_file;
         struct shm_file_data *sfd = shm_file_data(file);
         struct mempolicy *pol = NULL;
 
         if (sfd->vm_ops->get_policy)
                 pol = sfd->vm_ops->get_policy(vma, addr);
         else if (vma->vm_policy)
                 pol = vma->vm_policy;
 
         return pol;
 }
 #endif
 
 static int shm_mmap(struct file * file, struct vm_area_struct * vma)
 {
         struct shm_file_data *sfd = shm_file_data(file);
         int ret;
 
         ret = sfd->file->f_op->mmap(sfd->file, vma);
         if (ret != 0)
                 return ret;
         sfd->vm_ops = vma->vm_ops;
 #ifdef CONFIG_MMU
         BUG_ON(!sfd->vm_ops->fault);
 #endif
         vma->vm_ops = &shm_vm_ops;
         shm_open(vma);
 
         return ret;
 }
 
 static int shm_release(struct inode *ino, struct file *file)
 {
         struct shm_file_data *sfd = shm_file_data(file);
 
         put_ipc_ns(sfd->ns);
         shm_file_data(file) = NULL;
         kfree(sfd);
         return 0;
 }
 
 static int shm_fsync(struct file *file, struct dentry *dentry, int datasync)
 {
         int (*fsync) (struct file *, struct dentry *, int datasync);
         struct shm_file_data *sfd = shm_file_data(file);
         int ret = -EINVAL;
 
         fsync = sfd->file->f_op->fsync;
         if (fsync)
                 ret = fsync(sfd->file, sfd->file->f_path.dentry, datasync);
         return ret;
 }
 
 static unsigned long shm_get_unmapped_area(struct file *file,
         unsigned long addr, unsigned long len, unsigned long pgoff,
         unsigned long flags)
 {
         struct shm_file_data *sfd = shm_file_data(file);
         return get_unmapped_area(sfd->file, addr, len, pgoff, flags);
 }
 
 int is_file_shm_hugepages(struct file *file)
 {
         int ret = 0;
 
         if (file->f_op == &shm_file_operations) {
                 struct shm_file_data *sfd;
                 sfd = shm_file_data(file);
                 ret = is_file_hugepages(sfd->file);
         }
         return ret;
 }
 
 static const struct file_operations shm_file_operations = {
         .mmap                = shm_mmap,
         .fsync                = shm_fsync,
         .release        = shm_release,
         .get_unmapped_area        = shm_get_unmapped_area,
 };
 
 static struct vm_operations_struct shm_vm_ops = {
         .open        = shm_open,        /* callback for a new vm-area open */
         .close        = shm_close,        /* callback for when the vm-area is released */
         .fault        = shm_fault,
 #if defined(CONFIG_NUMA)
         .set_policy = shm_set_policy,
         .get_policy = shm_get_policy,
 #endif
 };
 
 /**
  * newseg - Create a new shared memory segment
  * @ns: namespace
  * @params: ptr to the structure that contains key, size and shmflg
  *
  * Called with shm_ids.rw_mutex held as a writer.
  */
 
 static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
 {
         key_t key = params->key;
         int shmflg = params->flg;
         size_t size = params->u.size;
         int error;
         struct shmid_kernel *shp;
         int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
         struct file * file;
         char name[13];
         int id;
 
         if (size < SHMMIN || size > ns->shm_ctlmax)
                 return -EINVAL;
 
         if (ns->shm_tot + numpages > ns->shm_ctlall)
                 return -ENOSPC;
 
         shp = ipc_rcu_alloc(sizeof(*shp));
         if (!shp)
                 return -ENOMEM;
 
         shp->shm_perm.key = key;
         shp->shm_perm.mode = (shmflg & S_IRWXUGO);
         shp->mlock_user = NULL;
 
         shp->shm_perm.security = NULL;
         error = security_shm_alloc(shp);
         if (error) {
                 ipc_rcu_putref(shp);
                 return error;
         }
 
         sprintf (name, "SYSV%08x", key);
         if (shmflg & SHM_HUGETLB) {
                 /* hugetlb_file_setup takes care of mlock user accounting */
                 file = hugetlb_file_setup(name, size);
                 shp->mlock_user = current->user;
         } else {
                 int acctflag = VM_ACCOUNT;
                 /*
                  * Do not allow no accounting for OVERCOMMIT_NEVER, even
                   * if it's asked for.
                  */
                 if  ((shmflg & SHM_NORESERVE) &&
                                 sysctl_overcommit_memory != OVERCOMMIT_NEVER)
                         acctflag = 0;
                 file = shmem_file_setup(name, size, acctflag);
         }
         error = PTR_ERR(file);
         if (IS_ERR(file))
                 goto no_file;
 
         id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
         if (id < 0) {
                 error = id;
                 goto no_id;
         }
 
         shp->shm_cprid = task_tgid_vnr(current);
         shp->shm_lprid = 0;
         shp->shm_atim = shp->shm_dtim = 0;
         shp->shm_ctim = get_seconds();
         shp->shm_segsz = size;
         shp->shm_nattch = 0;
         shp->shm_file = file;
         /*
          * shmid gets reported as "inode#" in /proc/pid/maps.
          * proc-ps tools use this. Changing this will break them.
          */
         file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
 
         ns->shm_tot += numpages;
         error = shp->shm_perm.id;
         shm_unlock(shp);
         return error;
 
 no_id:
         fput(file);
 no_file:
         security_shm_free(shp);
         ipc_rcu_putref(shp);
         return error;
 }
 
 /*
  * Called with shm_ids.rw_mutex and ipcp locked.
  */
 static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
 {
         struct shmid_kernel *shp;
 
         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
         return security_shm_associate(shp, shmflg);
 }
 
 /*
  * Called with shm_ids.rw_mutex and ipcp locked.
  */
 static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
                                 struct ipc_params *params)
 {
         struct shmid_kernel *shp;
 
         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
         if (shp->shm_segsz < params->u.size)
                 return -EINVAL;
 
         return 0;
 }
 
 asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
 {
         struct ipc_namespace *ns;
         struct ipc_ops shm_ops;
         struct ipc_params shm_params;
 
         ns = current->nsproxy->ipc_ns;
 
         shm_ops.getnew = newseg;
         shm_ops.associate = shm_security;
         shm_ops.more_checks = shm_more_checks;
 
         shm_params.key = key;
         shm_params.flg = shmflg;
         shm_params.u.size = size;
 
         return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
 }
 
 static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
 {
         switch(version) {
         case IPC_64:
                 return copy_to_user(buf, in, sizeof(*in));
         case IPC_OLD:
             {
                 struct shmid_ds out;
 
                 ipc64_perm_to_ipc_perm(&in->shm_perm, &out.shm_perm);
                 out.shm_segsz        = in->shm_segsz;
                 out.shm_atime        = in->shm_atime;
                 out.shm_dtime        = in->shm_dtime;
                 out.shm_ctime        = in->shm_ctime;
                 out.shm_cpid        = in->shm_cpid;
                 out.shm_lpid        = in->shm_lpid;
                 out.shm_nattch        = in->shm_nattch;
 
                 return copy_to_user(buf, &out, sizeof(out));
             }
         default:
                 return -EINVAL;
         }
 }
 
 static inline unsigned long
 copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
 {
         switch(version) {
         case IPC_64:
                 if (copy_from_user(out, buf, sizeof(*out)))
                         return -EFAULT;
                 return 0;
         case IPC_OLD:
             {
                 struct shmid_ds tbuf_old;
 
                 if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
                         return -EFAULT;
 
                 out->shm_perm.uid        = tbuf_old.shm_perm.uid;
                 out->shm_perm.gid        = tbuf_old.shm_perm.gid;
                 out->shm_perm.mode        = tbuf_old.shm_perm.mode;
 
                 return 0;
             }
         default:
                 return -EINVAL;
         }
 }
 
 static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
 {
         switch(version) {
         case IPC_64:
                 return copy_to_user(buf, in, sizeof(*in));
         case IPC_OLD:
             {
                 struct shminfo out;
 
                 if(in->shmmax > INT_MAX)
                         out.shmmax = INT_MAX;
                 else
                         out.shmmax = (int)in->shmmax;
 
                 out.shmmin        = in->shmmin;
                 out.shmmni        = in->shmmni;
                 out.shmseg        = in->shmseg;
                 out.shmall        = in->shmall; 
 
                 return copy_to_user(buf, &out, sizeof(out));
             }
         default:
                 return -EINVAL;
         }
 }
 
 /*
  * Called with shm_ids.rw_mutex held as a reader
  */
 static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
                 unsigned long *swp)
 {
         int next_id;
         int total, in_use;
 
         *rss = 0;
         *swp = 0;
 
         in_use = shm_ids(ns).in_use;
 
         for (total = 0, next_id = 0; total < in_use; next_id++) {
                 struct shmid_kernel *shp;
                 struct inode *inode;
 
                 shp = idr_find(&shm_ids(ns).ipcs_idr, next_id);
                 if (shp == NULL)
                         continue;
 
                 inode = shp->shm_file->f_path.dentry->d_inode;
 
                 if (is_file_hugepages(shp->shm_file)) {
                         struct address_space *mapping = inode->i_mapping;
                         struct hstate *h = hstate_file(shp->shm_file);
                         *rss += pages_per_huge_page(h) * mapping->nrpages;
                 } else {
                         struct shmem_inode_info *info = SHMEM_I(inode);
                         spin_lock(&info->lock);
                         *rss += inode->i_mapping->nrpages;
                         *swp += info->swapped;
                         spin_unlock(&info->lock);
                 }
 
                 total++;
         }
 }
 
 /*
  * This function handles some shmctl commands which require the rw_mutex
  * to be held in write mode.
  * NOTE: no locks must be held, the rw_mutex is taken inside this function.
  */
 static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
                        struct shmid_ds __user *buf, int version)
 {
         struct kern_ipc_perm *ipcp;
         struct shmid64_ds shmid64;
         struct shmid_kernel *shp;
         int err;
 
         if (cmd == IPC_SET) {
                 if (copy_shmid_from_user(&shmid64, buf, version))
                         return -EFAULT;
         }
 
         ipcp = ipcctl_pre_down(&shm_ids(ns), shmid, cmd, &shmid64.shm_perm, 0);
         if (IS_ERR(ipcp))
                 return PTR_ERR(ipcp);
 
         shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 
         err = security_shm_shmctl(shp, cmd);
         if (err)
                 goto out_unlock;
         switch (cmd) {
         case IPC_RMID:
                 do_shm_rmid(ns, ipcp);
                 goto out_up;
         case IPC_SET:
                 ipc_update_perm(&shmid64.shm_perm, ipcp);
                 shp->shm_ctim = get_seconds();
                 break;
         default:
                 err = -EINVAL;
         }
 out_unlock:
         shm_unlock(shp);
 out_up:
         up_write(&shm_ids(ns).rw_mutex);
         return err;
 }
 
 asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
 {
         struct shmid_kernel *shp;
         int err, version;
         struct ipc_namespace *ns;
 
         if (cmd < 0 || shmid < 0) {
                 err = -EINVAL;
                 goto out;
         }
 
         version = ipc_parse_version(&cmd);
         ns = current->nsproxy->ipc_ns;
 
         switch (cmd) { /* replace with proc interface ? */
         case IPC_INFO:
         {
                 struct shminfo64 shminfo;
 
                 err = security_shm_shmctl(NULL, cmd);
                 if (err)
                         return err;
 
                 memset(&shminfo,0,sizeof(shminfo));
                 shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
                 shminfo.shmmax = ns->shm_ctlmax;
                 shminfo.shmall = ns->shm_ctlall;
 
                 shminfo.shmmin = SHMMIN;
                 if(copy_shminfo_to_user (buf, &shminfo, version))
                         return -EFAULT;
 
                 down_read(&shm_ids(ns).rw_mutex);
                 err = ipc_get_maxid(&shm_ids(ns));
                 up_read(&shm_ids(ns).rw_mutex);
 
                 if(err<0)
                         err = 0;
                 goto out;
         }
         case SHM_INFO:
         {
                 struct shm_info shm_info;
 
                 err = security_shm_shmctl(NULL, cmd);
                 if (err)
                         return err;
 
                 memset(&shm_info,0,sizeof(shm_info));
                 down_read(&shm_ids(ns).rw_mutex);
                 shm_info.used_ids = shm_ids(ns).in_use;
                 shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
                 shm_info.shm_tot = ns->shm_tot;
                 shm_info.swap_attempts = 0;
                 shm_info.swap_successes = 0;
                 err = ipc_get_maxid(&shm_ids(ns));
                 up_read(&shm_ids(ns).rw_mutex);
                 if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
                         err = -EFAULT;
                         goto out;
                 }
 
                 err = err < 0 ? 0 : err;
                 goto out;
         }
         case SHM_STAT:
         case IPC_STAT:
         {
                 struct shmid64_ds tbuf;
                 int result;
 
                 if (!buf) {
                         err = -EFAULT;
                         goto out;
                 }
 
                 if (cmd == SHM_STAT) {
                         shp = shm_lock(ns, shmid);
                         if (IS_ERR(shp)) {
                                 err = PTR_ERR(shp);
                                 goto out;
                         }
                         result = shp->shm_perm.id;
                 } else {
                         shp = shm_lock_check(ns, shmid);
                         if (IS_ERR(shp)) {
                                 err = PTR_ERR(shp);
                                 goto out;
                         }
                         result = 0;
                 }
                 err=-EACCES;
                 if (ipcperms (&shp->shm_perm, S_IRUGO))
                         goto out_unlock;
                 err = security_shm_shmctl(shp, cmd);
                 if (err)
                         goto out_unlock;
                 memset(&tbuf, 0, sizeof(tbuf));
                 kernel_to_ipc64_perm(&shp->shm_perm, &tbuf.shm_perm);
                 tbuf.shm_segsz        = shp->shm_segsz;
                 tbuf.shm_atime        = shp->shm_atim;
                 tbuf.shm_dtime        = shp->shm_dtim;
                 tbuf.shm_ctime        = shp->shm_ctim;
                 tbuf.shm_cpid        = shp->shm_cprid;
                 tbuf.shm_lpid        = shp->shm_lprid;
                 tbuf.shm_nattch        = shp->shm_nattch;
                 shm_unlock(shp);
                 if(copy_shmid_to_user (buf, &tbuf, version))
                         err = -EFAULT;
                 else
                         err = result;
                 goto out;
         }
         case SHM_LOCK:
         case SHM_UNLOCK:
         {
                 struct file *uninitialized_var(shm_file);
 
                 lru_add_drain_all();  /* drain pagevecs to lru lists */
 
                 shp = shm_lock_check(ns, shmid);
                 if (IS_ERR(shp)) {
                         err = PTR_ERR(shp);
                         goto out;
                 }
 
                 err = audit_ipc_obj(&(shp->shm_perm));
                 if (err)
                         goto out_unlock;
 
                 if (!capable(CAP_IPC_LOCK)) {
                         err = -EPERM;
                         if (current->euid != shp->shm_perm.uid &&
                             current->euid != shp->shm_perm.cuid)
                                 goto out_unlock;
                         if (cmd == SHM_LOCK &&
                             !current->signal->rlim[RLIMIT_MEMLOCK].rlim_cur)
                                 goto out_unlock;
                 }
 
                 err = security_shm_shmctl(shp, cmd);
                 if (err)
                         goto out_unlock;
                 
                 if(cmd==SHM_LOCK) {
                         struct user_struct * user = current->user;
                         if (!is_file_hugepages(shp->shm_file)) {
                                 err = shmem_lock(shp->shm_file, 1, user);
                                 if (!err && !(shp->shm_perm.mode & SHM_LOCKED)){
                                         shp->shm_perm.mode |= SHM_LOCKED;
                                         shp->mlock_user = user;
                                 }
                         }
                 } else if (!is_file_hugepages(shp->shm_file)) {
                         shmem_lock(shp->shm_file, 0, shp->mlock_user);
                         shp->shm_perm.mode &= ~SHM_LOCKED;
                         shp->mlock_user = NULL;
                 }
                 shm_unlock(shp);
                 goto out;
         }
         case IPC_RMID:
         case IPC_SET:
                 err = shmctl_down(ns, shmid, cmd, buf, version);
                 return err;
         default:
                 return -EINVAL;
         }
 
 out_unlock:
         shm_unlock(shp);
 out:
         return err;
 }
 
 /*
  * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
  *
  * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
  * "raddr" thing points to kernel space, and there has to be a wrapper around
  * this.
  */
 long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
 {
         struct shmid_kernel *shp;
         unsigned long addr;
         unsigned long size;
         struct file * file;
         int    err;
         unsigned long flags;
         unsigned long prot;
         int acc_mode;
         unsigned long user_addr;
         struct ipc_namespace *ns;
         struct shm_file_data *sfd;
         struct path path;
         fmode_t f_mode;
 
         err = -EINVAL;
         if (shmid < 0)
                 goto out;
         else if ((addr = (ulong)shmaddr)) {
                 if (addr & (SHMLBA-1)) {
                         if (shmflg & SHM_RND)
                                 addr &= ~(SHMLBA-1);           /* round down */
                         else
 #ifndef __ARCH_FORCE_SHMLBA
                                 if (addr & ~PAGE_MASK)
 #endif
                                         goto out;
                 }
                 flags = MAP_SHARED | MAP_FIXED;
         } else {
                 if ((shmflg & SHM_REMAP))
                         goto out;
 
                 flags = MAP_SHARED;
         }
 
         if (shmflg & SHM_RDONLY) {
                 prot = PROT_READ;
                 acc_mode = S_IRUGO;
                 f_mode = FMODE_READ;
         } else {
                 prot = PROT_READ | PROT_WRITE;
                 acc_mode = S_IRUGO | S_IWUGO;
                 f_mode = FMODE_READ | FMODE_WRITE;
         }
         if (shmflg & SHM_EXEC) {
                 prot |= PROT_EXEC;
                 acc_mode |= S_IXUGO;
         }
 
         /*
          * We cannot rely on the fs check since SYSV IPC does have an
          * additional creator id...
          */
         ns = current->nsproxy->ipc_ns;
         shp = shm_lock_check(ns, shmid);
         if (IS_ERR(shp)) {
                 err = PTR_ERR(shp);
                 goto out;
         }
 
         err = -EACCES;
         if (ipcperms(&shp->shm_perm, acc_mode))
                 goto out_unlock;
 
         err = security_shm_shmat(shp, shmaddr, shmflg);
         if (err)
                 goto out_unlock;
 
         path.dentry = dget(shp->shm_file->f_path.dentry);
         path.mnt    = shp->shm_file->f_path.mnt;
         shp->shm_nattch++;
         size = i_size_read(path.dentry->d_inode);
         shm_unlock(shp);
 
         err = -ENOMEM;
         sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
         if (!sfd)
                 goto out_put_dentry;
 
         file = alloc_file(path.mnt, path.dentry, f_mode, &shm_file_operations);
         if (!file)
                 goto out_free;
 
         file->private_data = sfd;
         file->f_mapping = shp->shm_file->f_mapping;
         sfd->id = shp->shm_perm.id;
         sfd->ns = get_ipc_ns(ns);
         sfd->file = shp->shm_file;
         sfd->vm_ops = NULL;
 
         down_write(&current->mm->mmap_sem);
         if (addr && !(shmflg & SHM_REMAP)) {
                 err = -EINVAL;
                 if (find_vma_intersection(current->mm, addr, addr + size))
                         goto invalid;
                 /*
                  * If shm segment goes below stack, make sure there is some
                  * space left for the stack to grow (at least 4 pages).
                  */
                 if (addr < current->mm->start_stack &&
                     addr > current->mm->start_stack - size - PAGE_SIZE * 5)
                         goto invalid;
         }
                 
         user_addr = do_mmap (file, addr, size, prot, flags, 0);
         *raddr = user_addr;
         err = 0;
         if (IS_ERR_VALUE(user_addr))
                 err = (long)user_addr;
 invalid:
         up_write(&current->mm->mmap_sem);
 
         fput(file);
 
 out_nattch:
         down_write(&shm_ids(ns).rw_mutex);
         shp = shm_lock(ns, shmid);
         BUG_ON(IS_ERR(shp));
         shp->shm_nattch--;
         if(shp->shm_nattch == 0 &&
            shp->shm_perm.mode & SHM_DEST)
                 shm_destroy(ns, shp);
         else
                 shm_unlock(shp);
         up_write(&shm_ids(ns).rw_mutex);
 
 out:
         return err;
 
 out_unlock:
         shm_unlock(shp);
         goto out;
 
 out_free:
         kfree(sfd);
 out_put_dentry:
         dput(path.dentry);
         goto out_nattch;
 }
 
 asmlinkage long sys_shmat(int shmid, char __user *shmaddr, int shmflg)
 {
         unsigned long ret;
         long err;
 
         err = do_shmat(shmid, shmaddr, shmflg, &ret);
         if (err)
                 return err;
         force_successful_syscall_return();
         return (long)ret;
 }
 
 /*
  * detach and kill segment if marked destroyed.
  * The work is done in shm_close.
  */
 asmlinkage long sys_shmdt(char __user *shmaddr)
 {
         struct mm_struct *mm = current->mm;
         struct vm_area_struct *vma, *next;
         unsigned long addr = (unsigned long)shmaddr;
         loff_t size = 0;
         int retval = -EINVAL;
 
         if (addr & ~PAGE_MASK)
                 return retval;
 
         down_write(&mm->mmap_sem);
 
         /*
          * This function tries to be smart and unmap shm segments that
          * were modified by partial mlock or munmap calls:
          * - It first determines the size of the shm segment that should be
          *   unmapped: It searches for a vma that is backed by shm and that
          *   started at address shmaddr. It records it's size and then unmaps
          *   it.
          * - Then it unmaps all shm vmas that started at shmaddr and that
          *   are within the initially determined size.
          * Errors from do_munmap are ignored: the function only fails if
          * it's called with invalid parameters or if it's called to unmap
          * a part of a vma. Both calls in this function are for full vmas,
          * the parameters are directly copied from the vma itself and always
          * valid - therefore do_munmap cannot fail. (famous last words?)
          */
         /*
          * If it had been mremap()'d, the starting address would not
          * match the usual checks anyway. So assume all vma's are
          * above the starting address given.
          */
         vma = find_vma(mm, addr);
 
         while (vma) {
                next = vma->vm_next;

                /*
                 * Check if the starting address would match, i.e. it's
                 * a fragment created by mprotect() and/or munmap(), or it
                 * otherwise it starts at this address with no hassles.
                 */
                if ((vma->vm_ops == &shm_vm_ops) &&
                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {


                        size = vma->vm_file->f_path.dentry->d_inode->i_size;
                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
                        /*
                         * We discovered the size of the shm segment, so
                         * break out of here and fall through to the next
                         * loop that uses the size information to stop
                         * searching for matching vma's.
                         */
                        retval = 0;
                        vma = next;
                        break;
                }
                vma = next;
        }

        /*
         * We need look no further than the maximum address a fragment
         * could possibly have landed at. Also cast things to loff_t to
         * prevent overflows and make comparisions vs. equal-width types.
         */
        size = PAGE_ALIGN(size);
        while (vma && (loff_t)(vma->vm_end - addr) <= size) {
                next = vma->vm_next;

                /* finding a matching vma now does not alter retval */
                if ((vma->vm_ops == &shm_vm_ops) &&
                        (vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)

                        do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
                vma = next;
        }

        up_write(&mm->mmap_sem);
        return retval;
}

#ifdef CONFIG_PROC_FS
static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
{
        struct shmid_kernel *shp = it;

#if BITS_PER_LONG <= 32
#define SIZE_SPEC "%10lu"
#else
#define SIZE_SPEC "%21lu"
#endif

        return seq_printf(s,
                          "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
                          "%5lu %5u %5u %5u %5u %10lu %10lu %10lu\n",
                          shp->shm_perm.key,
                          shp->shm_perm.id,
                          shp->shm_perm.mode,
                          shp->shm_segsz,
                          shp->shm_cprid,
                          shp->shm_lprid,
                          shp->shm_nattch,
                          shp->shm_perm.uid,
                          shp->shm_perm.gid,
                          shp->shm_perm.cuid,
                          shp->shm_perm.cgid,
                          shp->shm_atim,
                          shp->shm_dtim,
                          shp->shm_ctim);
}
#endif