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OpenCloudOS-Kernel/ipc/shm.c

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/*
* 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/mutex.h>
#include <linux/nsproxy.h>
#include <asm/uaccess.h>
#include "util.h"
static struct file_operations shm_file_operations;
static struct vm_operations_struct shm_vm_ops;
static struct ipc_ids init_shm_ids;
#define shm_ids(ns) (*((ns)->ids[IPC_SHM_IDS]))
#define shm_lock(ns, id) \
((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
#define shm_unlock(shp) \
ipc_unlock(&(shp)->shm_perm)
#define shm_get(ns, id) \
((struct shmid_kernel*)ipc_get(&shm_ids(ns),id))
#define shm_buildid(ns, id, seq) \
ipc_buildid(&shm_ids(ns), id, seq)
static int newseg (struct ipc_namespace *ns, key_t key,
int shmflg, size_t size);
static void shm_open (struct vm_area_struct *shmd);
static void shm_close (struct vm_area_struct *shmd);
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
static void __ipc_init __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
{
ns->ids[IPC_SHM_IDS] = ids;
ns->shm_ctlmax = SHMMAX;
ns->shm_ctlall = SHMALL;
ns->shm_ctlmni = SHMMNI;
ns->shm_tot = 0;
ipc_init_ids(ids, 1);
}
static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
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
int shm_init_ns(struct ipc_namespace *ns)
{
struct ipc_ids *ids;
ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
if (ids == NULL)
return -ENOMEM;
__shm_init_ns(ns, ids);
return 0;
}
void shm_exit_ns(struct ipc_namespace *ns)
{
int i;
struct shmid_kernel *shp;
mutex_lock(&shm_ids(ns).mutex);
for (i = 0; i <= shm_ids(ns).max_id; i++) {
shp = shm_lock(ns, i);
if (shp == NULL)
continue;
do_shm_rmid(ns, shp);
}
mutex_unlock(&shm_ids(ns).mutex);
ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
kfree(ns->ids[IPC_SHM_IDS]);
ns->ids[IPC_SHM_IDS] = NULL;
}
#endif
void __init shm_init (void)
{
__shm_init_ns(&init_ipc_ns, &init_shm_ids);
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);
}
static inline int shm_checkid(struct ipc_namespace *ns,
struct shmid_kernel *s, int id)
{
if (ipc_checkid(&shm_ids(ns), &s->shm_perm, id))
return -EIDRM;
return 0;
}
static inline struct shmid_kernel *shm_rmid(struct ipc_namespace *ns, int id)
{
return (struct shmid_kernel *)ipc_rmid(&shm_ids(ns), id);
}
static inline int shm_addid(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
return ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
}
static inline void shm_inc(struct ipc_namespace *ns, int id)
{
struct shmid_kernel *shp;
shp = shm_lock(ns, id);
BUG_ON(!shp);
shp->shm_atim = get_seconds();
shp->shm_lprid = current->tgid;
shp->shm_nattch++;
shm_unlock(shp);
}
#define shm_file_ns(file) (*((struct ipc_namespace **)&(file)->private_data))
/* This is called by fork, once for every shm attach. */
static void shm_open(struct vm_area_struct *shmd)
{
shm_inc(shm_file_ns(shmd->vm_file),
shmd->vm_file->f_dentry->d_inode->i_ino);
}
/*
* shm_destroy - free the struct shmid_kernel
*
* @shp: struct to free
*
* It has to be called with shp and shm_ids.mutex 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->id);
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_dentry->d_inode->i_size,
shp->mlock_user);
fput (shp->shm_file);
security_shm_free(shp);
ipc_rcu_putref(shp);
}
/*
* remove the attach descriptor shmd.
* 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 *shmd)
{
struct file * file = shmd->vm_file;
int id = file->f_dentry->d_inode->i_ino;
struct shmid_kernel *shp;
struct ipc_namespace *ns;
ns = shm_file_ns(file);
mutex_lock(&shm_ids(ns).mutex);
/* remove from the list of attaches of the shm segment */
shp = shm_lock(ns, id);
BUG_ON(!shp);
shp->shm_lprid = current->tgid;
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);
mutex_unlock(&shm_ids(ns).mutex);
}
static int shm_mmap(struct file * file, struct vm_area_struct * vma)
{
int ret;
ret = shmem_mmap(file, vma);
if (ret == 0) {
vma->vm_ops = &shm_vm_ops;
if (!(vma->vm_flags & VM_WRITE))
vma->vm_flags &= ~VM_MAYWRITE;
shm_inc(shm_file_ns(file), file->f_dentry->d_inode->i_ino);
}
return ret;
}
static int shm_release(struct inode *ino, struct file *file)
{
struct ipc_namespace *ns;
ns = shm_file_ns(file);
put_ipc_ns(ns);
shm_file_ns(file) = NULL;
return 0;
}
static struct file_operations shm_file_operations = {
.mmap = shm_mmap,
.release = shm_release,
#ifndef CONFIG_MMU
.get_unmapped_area = shmem_get_unmapped_area,
#endif
};
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 */
.nopage = shmem_nopage,
#if defined(CONFIG_NUMA) && defined(CONFIG_SHMEM)
.set_policy = shmem_set_policy,
.get_policy = shmem_get_policy,
#endif
};
static int newseg (struct ipc_namespace *ns, key_t key, int shmflg, size_t 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;
}
if (shmflg & SHM_HUGETLB) {
/* hugetlb_zero_setup takes care of mlock user accounting */
file = hugetlb_zero_setup(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;
sprintf (name, "SYSV%08x", key);
file = shmem_file_setup(name, size, acctflag);
}
error = PTR_ERR(file);
if (IS_ERR(file))
goto no_file;
error = -ENOSPC;
id = shm_addid(ns, shp);
if(id == -1)
goto no_id;
shp->shm_cprid = current->tgid;
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->id = shm_buildid(ns, id, shp->shm_perm.seq);
shp->shm_file = file;
file->f_dentry->d_inode->i_ino = shp->id;
shm_file_ns(file) = get_ipc_ns(ns);
/* Hugetlb ops would have already been assigned. */
if (!(shmflg & SHM_HUGETLB))
file->f_op = &shm_file_operations;
ns->shm_tot += numpages;
shm_unlock(shp);
return shp->id;
no_id:
fput(file);
no_file:
security_shm_free(shp);
ipc_rcu_putref(shp);
return error;
}
asmlinkage long sys_shmget (key_t key, size_t size, int shmflg)
{
struct shmid_kernel *shp;
int err, id = 0;
struct ipc_namespace *ns;
ns = current->nsproxy->ipc_ns;
mutex_lock(&shm_ids(ns).mutex);
if (key == IPC_PRIVATE) {
err = newseg(ns, key, shmflg, size);
} else if ((id = ipc_findkey(&shm_ids(ns), key)) == -1) {
if (!(shmflg & IPC_CREAT))
err = -ENOENT;
else
err = newseg(ns, key, shmflg, size);
} else if ((shmflg & IPC_CREAT) && (shmflg & IPC_EXCL)) {
err = -EEXIST;
} else {
shp = shm_lock(ns, id);
BUG_ON(shp==NULL);
if (shp->shm_segsz < size)
err = -EINVAL;
else if (ipcperms(&shp->shm_perm, shmflg))
err = -EACCES;
else {
int shmid = shm_buildid(ns, id, shp->shm_perm.seq);
err = security_shm_associate(shp, shmflg);
if (!err)
err = shmid;
}
shm_unlock(shp);
}
mutex_unlock(&shm_ids(ns).mutex);
return err;
}
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;
}
}
struct shm_setbuf {
uid_t uid;
gid_t gid;
mode_t mode;
};
static inline unsigned long copy_shmid_from_user(struct shm_setbuf *out, void __user *buf, int version)
{
switch(version) {
case IPC_64:
{
struct shmid64_ds tbuf;
if (copy_from_user(&tbuf, buf, sizeof(tbuf)))
return -EFAULT;
out->uid = tbuf.shm_perm.uid;
out->gid = tbuf.shm_perm.gid;
out->mode = tbuf.shm_perm.mode;
return 0;
}
case IPC_OLD:
{
struct shmid_ds tbuf_old;
if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
return -EFAULT;
out->uid = tbuf_old.shm_perm.uid;
out->gid = tbuf_old.shm_perm.gid;
out->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;
}
}
static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
unsigned long *swp)
{
int i;
*rss = 0;
*swp = 0;
for (i = 0; i <= shm_ids(ns).max_id; i++) {
struct shmid_kernel *shp;
struct inode *inode;
shp = shm_get(ns, i);
if(!shp)
continue;
inode = shp->shm_file->f_dentry->d_inode;
if (is_file_hugepages(shp->shm_file)) {
struct address_space *mapping = inode->i_mapping;
*rss += (HPAGE_SIZE/PAGE_SIZE)*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);
}
}
}
asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
{
struct shm_setbuf setbuf;
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;
/* reading a integer is always atomic */
err= shm_ids(ns).max_id;
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));
mutex_lock(&shm_ids(ns).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 = shm_ids(ns).max_id;
mutex_unlock(&shm_ids(ns).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;
memset(&tbuf, 0, sizeof(tbuf));
shp = shm_lock(ns, shmid);
if(shp==NULL) {
err = -EINVAL;
goto out;
} else if(cmd==SHM_STAT) {
err = -EINVAL;
if (shmid > shm_ids(ns).max_id)
goto out_unlock;
result = shm_buildid(ns, shmid, shp->shm_perm.seq);
} else {
err = shm_checkid(ns, shp,shmid);
if(err)
goto out_unlock;
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;
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;
if (!is_file_hugepages(shp->shm_file))
tbuf.shm_nattch = shp->shm_nattch;
else
tbuf.shm_nattch = file_count(shp->shm_file) - 1;
shm_unlock(shp);
if(copy_shmid_to_user (buf, &tbuf, version))
err = -EFAULT;
else
err = result;
goto out;
}
case SHM_LOCK:
case SHM_UNLOCK:
{
shp = shm_lock(ns, shmid);
if(shp==NULL) {
err = -EINVAL;
goto out;
}
err = shm_checkid(ns, shp,shmid);
if(err)
goto out_unlock;
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->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:
{
/*
* We cannot simply remove the file. The SVID states
* that the block remains until the last person
* detaches from it, then is deleted. A shmat() on
* an RMID segment is legal in older Linux and if
* we change it apps break...
*
* Instead we set a destroyed flag, and then blow
* the name away when the usage hits zero.
*/
mutex_lock(&shm_ids(ns).mutex);
shp = shm_lock(ns, shmid);
err = -EINVAL;
if (shp == NULL)
goto out_up;
err = shm_checkid(ns, shp, shmid);
if(err)
goto out_unlock_up;
err = audit_ipc_obj(&(shp->shm_perm));
if (err)
goto out_unlock_up;
if (current->euid != shp->shm_perm.uid &&
current->euid != shp->shm_perm.cuid &&
!capable(CAP_SYS_ADMIN)) {
err=-EPERM;
goto out_unlock_up;
}
err = security_shm_shmctl(shp, cmd);
if (err)
goto out_unlock_up;
do_shm_rmid(ns, shp);
mutex_unlock(&shm_ids(ns).mutex);
goto out;
}
case IPC_SET:
{
if (copy_shmid_from_user (&setbuf, buf, version)) {
err = -EFAULT;
goto out;
}
mutex_lock(&shm_ids(ns).mutex);
shp = shm_lock(ns, shmid);
err=-EINVAL;
if(shp==NULL)
goto out_up;
err = shm_checkid(ns, shp,shmid);
if(err)
goto out_unlock_up;
err = audit_ipc_obj(&(shp->shm_perm));
if (err)
goto out_unlock_up;
err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode);
if (err)
goto out_unlock_up;
err=-EPERM;
if (current->euid != shp->shm_perm.uid &&
current->euid != shp->shm_perm.cuid &&
!capable(CAP_SYS_ADMIN)) {
goto out_unlock_up;
}
err = security_shm_shmctl(shp, cmd);
if (err)
goto out_unlock_up;
shp->shm_perm.uid = setbuf.uid;
shp->shm_perm.gid = setbuf.gid;
shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO)
| (setbuf.mode & S_IRWXUGO);
shp->shm_ctim = get_seconds();
break;
}
default:
err = -EINVAL;
goto out;
}
err = 0;
out_unlock_up:
shm_unlock(shp);
out_up:
mutex_unlock(&shm_ids(ns).mutex);
goto out;
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;
void *user_addr;
struct ipc_namespace *ns;
if (shmid < 0) {
err = -EINVAL;
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
return -EINVAL;
}
flags = MAP_SHARED | MAP_FIXED;
} else {
if ((shmflg & SHM_REMAP))
return -EINVAL;
flags = MAP_SHARED;
}
if (shmflg & SHM_RDONLY) {
prot = PROT_READ;
acc_mode = S_IRUGO;
} else {
prot = PROT_READ | PROT_WRITE;
acc_mode = S_IRUGO | S_IWUGO;
}
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(ns, shmid);
if(shp == NULL) {
err = -EINVAL;
goto out;
}
err = shm_checkid(ns, shp,shmid);
if (err) {
shm_unlock(shp);
goto out;
}
if (ipcperms(&shp->shm_perm, acc_mode)) {
shm_unlock(shp);
err = -EACCES;
goto out;
}
err = security_shm_shmat(shp, shmaddr, shmflg);
if (err) {
shm_unlock(shp);
return err;
}
file = shp->shm_file;
size = i_size_read(file->f_dentry->d_inode);
shp->shm_nattch++;
shm_unlock(shp);
down_write(&current->mm->mmap_sem);
if (addr && !(shmflg & SHM_REMAP)) {
user_addr = ERR_PTR(-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 = (void*) do_mmap (file, addr, size, prot, flags, 0);
invalid:
up_write(&current->mm->mmap_sem);
mutex_lock(&shm_ids(ns).mutex);
shp = shm_lock(ns, shmid);
BUG_ON(!shp);
shp->shm_nattch--;
if(shp->shm_nattch == 0 &&
shp->shm_perm.mode & SHM_DEST)
shm_destroy(ns, shp);
else
shm_unlock(shp);
mutex_unlock(&shm_ids(ns).mutex);
*raddr = (unsigned long) user_addr;
err = 0;
if (IS_ERR(user_addr))
err = PTR_ERR(user_addr);
out:
return err;
}
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 || is_vm_hugetlb_page(vma)) &&
(vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {
size = vma->vm_file->f_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 || is_vm_hugetlb_page(vma)) &&
(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;
char *format;
#define SMALL_STRING "%10d %10d %4o %10u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
#define BIG_STRING "%10d %10d %4o %21u %5u %5u %5d %5u %5u %5u %5u %10lu %10lu %10lu\n"
if (sizeof(size_t) <= sizeof(int))
format = SMALL_STRING;
else
format = BIG_STRING;
return seq_printf(s, format,
shp->shm_perm.key,
shp->id,
shp->shm_perm.mode,
shp->shm_segsz,
shp->shm_cprid,
shp->shm_lprid,
is_file_hugepages(shp->shm_file) ? (file_count(shp->shm_file) - 1) : 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
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