linux/ipc/shm.c
Davidlohr Bueso 82061c57ce ipc: drop ipc_lock()
ipc/util.c contains multiple functions to get the ipc object pointer given
an id number.

There are two sets of function: One set verifies the sequence counter part
of the id number, other functions do not check the sequence counter.

The standard for function names in ipc/util.c is
- ..._check() functions verify the sequence counter
- ..._idr() functions do not verify the sequence counter

ipc_lock() is an exception: It does not verify the sequence counter value,
but this is not obvious from the function name.

Furthermore, shm.c is the only user of this helper.  Thus, we can simply
move the logic into shm_lock() and get rid of the function altogether.

[manfred@colorfullife.com: most of changelog]
Link: http://lkml.kernel.org/r/20180712185241.4017-7-manfred@colorfullife.com
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Kees Cook <keescook@chromium.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-08-22 10:52:52 -07:00

1754 lines
42 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* 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>
*
* Better ipc lock (kern_ipc_perm.lock) handling
* Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
*/
#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 <linux/rhashtable.h>
#include <linux/uaccess.h>
#include "util.h"
struct shmid_kernel /* private to the kernel */
{
struct kern_ipc_perm shm_perm;
struct file *shm_file;
unsigned long shm_nattch;
unsigned long shm_segsz;
time64_t shm_atim;
time64_t shm_dtim;
time64_t shm_ctim;
struct pid *shm_cprid;
struct pid *shm_lprid;
struct user_struct *mlock_user;
/* The task created the shm object. NULL if the task is dead. */
struct task_struct *shm_creator;
struct list_head shm_clist; /* list by creator */
} __randomize_layout;
/* shm_mode upper byte flags */
#define SHM_DEST 01000 /* segment will be destroyed on last detach */
#define SHM_LOCKED 02000 /* segment will not be swapped */
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 const 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
int shm_init_ns(struct ipc_namespace *ns)
{
ns->shm_ctlmax = SHMMAX;
ns->shm_ctlall = SHMALL;
ns->shm_ctlmni = SHMMNI;
ns->shm_rmid_forced = 0;
ns->shm_tot = 0;
return ipc_init_ids(&shm_ids(ns));
}
/*
* Called with shm_ids.rwsem (writer) and the shp structure locked.
* Only shm_ids.rwsem 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 */
ipc_set_key_private(&shm_ids(ns), &shp->shm_perm);
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);
idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
rhashtable_destroy(&ns->ids[IPC_SHM_IDS].key_ht);
}
#endif
static int __init ipc_ns_init(void)
{
const int err = shm_init_ns(&init_ipc_ns);
WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err);
return err;
}
pure_initcall(ipc_ns_init);
void __init shm_init(void)
{
ipc_init_proc_interface("sysvipc/shm",
#if BITS_PER_LONG <= 32
" key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n",
#else
" key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n",
#endif
IPC_SHM_IDS, sysvipc_shm_proc_show);
}
static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
if (IS_ERR(ipcp))
return ERR_CAST(ipcp);
return container_of(ipcp, struct shmid_kernel, shm_perm);
}
static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&shm_ids(ns), id);
if (IS_ERR(ipcp))
return ERR_CAST(ipcp);
return container_of(ipcp, struct shmid_kernel, shm_perm);
}
/*
* shm_lock_(check_) routines are called in the paths where the rwsem
* is not necessarily held.
*/
static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
{
struct kern_ipc_perm *ipcp;
rcu_read_lock();
ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
if (IS_ERR(ipcp))
goto err;
ipc_lock_object(ipcp);
/*
* ipc_rmid() may have already freed the ID while ipc_lock_object()
* was spinning: here verify that the structure is still valid.
* Upon races with RMID, return -EIDRM, thus indicating that
* the ID points to a removed identifier.
*/
if (ipc_valid_object(ipcp)) {
/* return a locked ipc object upon success */
return container_of(ipcp, struct shmid_kernel, shm_perm);
}
ipc_unlock_object(ipcp);
err:
rcu_read_unlock();
/*
* Callers of shm_lock() must validate the status of the returned ipc
* object pointer and error out as appropriate.
*/
return (void *)ipcp;
}
static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
{
rcu_read_lock();
ipc_lock_object(&ipcp->shm_perm);
}
static void shm_rcu_free(struct rcu_head *head)
{
struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm,
rcu);
struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel,
shm_perm);
security_shm_free(&shp->shm_perm);
kvfree(shp);
}
static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
{
list_del(&s->shm_clist);
ipc_rmid(&shm_ids(ns), &s->shm_perm);
}
static int __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);
if (IS_ERR(shp))
return PTR_ERR(shp);
if (shp->shm_file != sfd->file) {
/* ID was reused */
shm_unlock(shp);
return -EINVAL;
}
shp->shm_atim = ktime_get_real_seconds();
ipc_update_pid(&shp->shm_lprid, task_tgid(current));
shp->shm_nattch++;
shm_unlock(shp);
return 0;
}
/* This is called by fork, once for every shm attach. */
static void shm_open(struct vm_area_struct *vma)
{
int err = __shm_open(vma);
/*
* We raced in the idr lookup or with shm_destroy().
* Either way, the ID is busted.
*/
WARN_ON_ONCE(err);
}
/*
* shm_destroy - free the struct shmid_kernel
*
* @ns: namespace
* @shp: struct to free
*
* It has to be called with shp and shm_ids.rwsem (writer) locked,
* but returns with shp unlocked and freed.
*/
static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
struct file *shm_file;
shm_file = shp->shm_file;
shp->shm_file = NULL;
ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
shm_rmid(ns, shp);
shm_unlock(shp);
if (!is_file_hugepages(shm_file))
shmem_lock(shm_file, 0, shp->mlock_user);
else if (shp->mlock_user)
user_shm_unlock(i_size_read(file_inode(shm_file)),
shp->mlock_user);
fput(shm_file);
ipc_update_pid(&shp->shm_cprid, NULL);
ipc_update_pid(&shp->shm_lprid, NULL);
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
}
/*
* shm_may_destroy - identifies whether shm segment should be destroyed now
*
* Returns true if and only if there are no active users of the segment and
* one of the following is true:
*
* 1) shmctl(id, IPC_RMID, NULL) was called for this shp
*
* 2) sysctl kernel.shm_rmid_forced is set to 1.
*/
static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
return (shp->shm_nattch == 0) &&
(ns->shm_rmid_forced ||
(shp->shm_perm.mode & SHM_DEST));
}
/*
* 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).rwsem);
/* remove from the list of attaches of the shm segment */
shp = shm_lock(ns, sfd->id);
/*
* We raced in the idr lookup or with shm_destroy().
* Either way, the ID is busted.
*/
if (WARN_ON_ONCE(IS_ERR(shp)))
goto done; /* no-op */
ipc_update_pid(&shp->shm_lprid, task_tgid(current));
shp->shm_dtim = ktime_get_real_seconds();
shp->shm_nattch--;
if (shm_may_destroy(ns, shp))
shm_destroy(ns, shp);
else
shm_unlock(shp);
done:
up_write(&shm_ids(ns).rwsem);
}
/* Called with ns->shm_ids(ns).rwsem locked */
static int shm_try_destroy_orphaned(int id, void *p, void *data)
{
struct ipc_namespace *ns = data;
struct kern_ipc_perm *ipcp = p;
struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
/*
* We want to destroy segments without users and with already
* exit'ed originating process.
*
* As shp->* are changed under rwsem, it's safe to skip shp locking.
*/
if (shp->shm_creator != NULL)
return 0;
if (shm_may_destroy(ns, shp)) {
shm_lock_by_ptr(shp);
shm_destroy(ns, shp);
}
return 0;
}
void shm_destroy_orphaned(struct ipc_namespace *ns)
{
down_write(&shm_ids(ns).rwsem);
if (shm_ids(ns).in_use)
idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
up_write(&shm_ids(ns).rwsem);
}
/* Locking assumes this will only be called with task == current */
void exit_shm(struct task_struct *task)
{
struct ipc_namespace *ns = task->nsproxy->ipc_ns;
struct shmid_kernel *shp, *n;
if (list_empty(&task->sysvshm.shm_clist))
return;
/*
* If kernel.shm_rmid_forced is not set then only keep track of
* which shmids are orphaned, so that a later set of the sysctl
* can clean them up.
*/
if (!ns->shm_rmid_forced) {
down_read(&shm_ids(ns).rwsem);
list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
shp->shm_creator = NULL;
/*
* Only under read lock but we are only called on current
* so no entry on the list will be shared.
*/
list_del(&task->sysvshm.shm_clist);
up_read(&shm_ids(ns).rwsem);
return;
}
/*
* Destroy all already created segments, that were not yet mapped,
* and mark any mapped as orphan to cover the sysctl toggling.
* Destroy is skipped if shm_may_destroy() returns false.
*/
down_write(&shm_ids(ns).rwsem);
list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
shp->shm_creator = NULL;
if (shm_may_destroy(ns, shp)) {
shm_lock_by_ptr(shp);
shm_destroy(ns, shp);
}
}
/* Remove the list head from any segments still attached. */
list_del(&task->sysvshm.shm_clist);
up_write(&shm_ids(ns).rwsem);
}
static vm_fault_t shm_fault(struct vm_fault *vmf)
{
struct file *file = vmf->vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
return sfd->vm_ops->fault(vmf);
}
static int shm_split(struct vm_area_struct *vma, unsigned long addr)
{
struct file *file = vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
if (sfd->vm_ops->split)
return sfd->vm_ops->split(vma, addr);
return 0;
}
static unsigned long shm_pagesize(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
if (sfd->vm_ops->pagesize)
return sfd->vm_ops->pagesize(vma);
return PAGE_SIZE;
}
#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;
/*
* In case of remap_file_pages() emulation, the file can represent an
* IPC ID that was removed, and possibly even reused by another shm
* segment already. Propagate this case as an error to caller.
*/
ret = __shm_open(vma);
if (ret)
return ret;
ret = call_mmap(sfd->file, vma);
if (ret) {
shm_close(vma);
return ret;
}
sfd->vm_ops = vma->vm_ops;
#ifdef CONFIG_MMU
WARN_ON(!sfd->vm_ops->fault);
#endif
vma->vm_ops = &shm_vm_ops;
return 0;
}
static int shm_release(struct inode *ino, struct file *file)
{
struct shm_file_data *sfd = shm_file_data(file);
put_ipc_ns(sfd->ns);
fput(sfd->file);
shm_file_data(file) = NULL;
kfree(sfd);
return 0;
}
static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
struct shm_file_data *sfd = shm_file_data(file);
if (!sfd->file->f_op->fsync)
return -EINVAL;
return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
}
static long shm_fallocate(struct file *file, int mode, loff_t offset,
loff_t len)
{
struct shm_file_data *sfd = shm_file_data(file);
if (!sfd->file->f_op->fallocate)
return -EOPNOTSUPP;
return sfd->file->f_op->fallocate(file, mode, offset, len);
}
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 sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
pgoff, flags);
}
static const struct file_operations shm_file_operations = {
.mmap = shm_mmap,
.fsync = shm_fsync,
.release = shm_release,
.get_unmapped_area = shm_get_unmapped_area,
.llseek = noop_llseek,
.fallocate = shm_fallocate,
};
/*
* shm_file_operations_huge is now identical to shm_file_operations,
* but we keep it distinct for the sake of is_file_shm_hugepages().
*/
static const struct file_operations shm_file_operations_huge = {
.mmap = shm_mmap,
.fsync = shm_fsync,
.release = shm_release,
.get_unmapped_area = shm_get_unmapped_area,
.llseek = noop_llseek,
.fallocate = shm_fallocate,
};
bool is_file_shm_hugepages(struct file *file)
{
return file->f_op == &shm_file_operations_huge;
}
static const 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,
.split = shm_split,
.pagesize = shm_pagesize,
#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.rwsem 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;
size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
struct file *file;
char name[13];
vm_flags_t acctflag = 0;
if (size < SHMMIN || size > ns->shm_ctlmax)
return -EINVAL;
if (numpages << PAGE_SHIFT < size)
return -ENOSPC;
if (ns->shm_tot + numpages < ns->shm_tot ||
ns->shm_tot + numpages > ns->shm_ctlall)
return -ENOSPC;
shp = kvmalloc(sizeof(*shp), GFP_KERNEL);
if (unlikely(!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->shm_perm);
if (error) {
kvfree(shp);
return error;
}
sprintf(name, "SYSV%08x", key);
if (shmflg & SHM_HUGETLB) {
struct hstate *hs;
size_t hugesize;
hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
if (!hs) {
error = -EINVAL;
goto no_file;
}
hugesize = ALIGN(size, huge_page_size(hs));
/* hugetlb_file_setup applies strict accounting */
if (shmflg & SHM_NORESERVE)
acctflag = VM_NORESERVE;
file = hugetlb_file_setup(name, hugesize, acctflag,
&shp->mlock_user, HUGETLB_SHMFS_INODE,
(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
} else {
/*
* Do not allow no accounting for OVERCOMMIT_NEVER, even
* if it's asked for.
*/
if ((shmflg & SHM_NORESERVE) &&
sysctl_overcommit_memory != OVERCOMMIT_NEVER)
acctflag = VM_NORESERVE;
file = shmem_kernel_file_setup(name, size, acctflag);
}
error = PTR_ERR(file);
if (IS_ERR(file))
goto no_file;
shp->shm_cprid = get_pid(task_tgid(current));
shp->shm_lprid = NULL;
shp->shm_atim = shp->shm_dtim = 0;
shp->shm_ctim = ktime_get_real_seconds();
shp->shm_segsz = size;
shp->shm_nattch = 0;
shp->shm_file = file;
shp->shm_creator = current;
/* ipc_addid() locks shp upon success. */
error = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
if (error < 0)
goto no_id;
list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
/*
* shmid gets reported as "inode#" in /proc/pid/maps.
* proc-ps tools use this. Changing this will break them.
*/
file_inode(file)->i_ino = shp->shm_perm.id;
ns->shm_tot += numpages;
error = shp->shm_perm.id;
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();
return error;
no_id:
ipc_update_pid(&shp->shm_cprid, NULL);
ipc_update_pid(&shp->shm_lprid, NULL);
if (is_file_hugepages(file) && shp->mlock_user)
user_shm_unlock(size, shp->mlock_user);
fput(file);
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
return error;
no_file:
call_rcu(&shp->shm_perm.rcu, shm_rcu_free);
return error;
}
/*
* Called with shm_ids.rwsem 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;
}
long ksys_shmget(key_t key, size_t size, int shmflg)
{
struct ipc_namespace *ns;
static const struct ipc_ops shm_ops = {
.getnew = newseg,
.associate = security_shm_associate,
.more_checks = shm_more_checks,
};
struct ipc_params shm_params;
ns = current->nsproxy->ipc_ns;
shm_params.key = key;
shm_params.flg = shmflg;
shm_params.u.size = size;
return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
}
SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
{
return ksys_shmget(key, size, shmflg);
}
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;
memset(&out, 0, sizeof(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;
}
}
/*
* Calculate and add used RSS and swap pages of a shm.
* Called with shm_ids.rwsem held as a reader
*/
static void shm_add_rss_swap(struct shmid_kernel *shp,
unsigned long *rss_add, unsigned long *swp_add)
{
struct inode *inode;
inode = file_inode(shp->shm_file);
if (is_file_hugepages(shp->shm_file)) {
struct address_space *mapping = inode->i_mapping;
struct hstate *h = hstate_file(shp->shm_file);
*rss_add += pages_per_huge_page(h) * mapping->nrpages;
} else {
#ifdef CONFIG_SHMEM
struct shmem_inode_info *info = SHMEM_I(inode);
spin_lock_irq(&info->lock);
*rss_add += inode->i_mapping->nrpages;
*swp_add += info->swapped;
spin_unlock_irq(&info->lock);
#else
*rss_add += inode->i_mapping->nrpages;
#endif
}
}
/*
* Called with shm_ids.rwsem 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 kern_ipc_perm *ipc;
struct shmid_kernel *shp;
ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
if (ipc == NULL)
continue;
shp = container_of(ipc, struct shmid_kernel, shm_perm);
shm_add_rss_swap(shp, rss, swp);
total++;
}
}
/*
* This function handles some shmctl commands which require the rwsem
* to be held in write mode.
* NOTE: no locks must be held, the rwsem is taken inside this function.
*/
static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
struct shmid64_ds *shmid64)
{
struct kern_ipc_perm *ipcp;
struct shmid_kernel *shp;
int err;
down_write(&shm_ids(ns).rwsem);
rcu_read_lock();
ipcp = ipcctl_obtain_check(ns, &shm_ids(ns), shmid, cmd,
&shmid64->shm_perm, 0);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
goto out_unlock1;
}
shp = container_of(ipcp, struct shmid_kernel, shm_perm);
err = security_shm_shmctl(&shp->shm_perm, cmd);
if (err)
goto out_unlock1;
switch (cmd) {
case IPC_RMID:
ipc_lock_object(&shp->shm_perm);
/* do_shm_rmid unlocks the ipc object and rcu */
do_shm_rmid(ns, ipcp);
goto out_up;
case IPC_SET:
ipc_lock_object(&shp->shm_perm);
err = ipc_update_perm(&shmid64->shm_perm, ipcp);
if (err)
goto out_unlock0;
shp->shm_ctim = ktime_get_real_seconds();
break;
default:
err = -EINVAL;
goto out_unlock1;
}
out_unlock0:
ipc_unlock_object(&shp->shm_perm);
out_unlock1:
rcu_read_unlock();
out_up:
up_write(&shm_ids(ns).rwsem);
return err;
}
static int shmctl_ipc_info(struct ipc_namespace *ns,
struct shminfo64 *shminfo)
{
int err = security_shm_shmctl(NULL, IPC_INFO);
if (!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;
down_read(&shm_ids(ns).rwsem);
err = ipc_get_maxid(&shm_ids(ns));
up_read(&shm_ids(ns).rwsem);
if (err < 0)
err = 0;
}
return err;
}
static int shmctl_shm_info(struct ipc_namespace *ns,
struct shm_info *shm_info)
{
int err = security_shm_shmctl(NULL, SHM_INFO);
if (!err) {
memset(shm_info, 0, sizeof(*shm_info));
down_read(&shm_ids(ns).rwsem);
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).rwsem);
if (err < 0)
err = 0;
}
return err;
}
static int shmctl_stat(struct ipc_namespace *ns, int shmid,
int cmd, struct shmid64_ds *tbuf)
{
struct shmid_kernel *shp;
int err;
memset(tbuf, 0, sizeof(*tbuf));
rcu_read_lock();
if (cmd == SHM_STAT || cmd == SHM_STAT_ANY) {
shp = shm_obtain_object(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
goto out_unlock;
}
} else { /* IPC_STAT */
shp = shm_obtain_object_check(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
goto out_unlock;
}
}
/*
* Semantically SHM_STAT_ANY ought to be identical to
* that functionality provided by the /proc/sysvipc/
* interface. As such, only audit these calls and
* do not do traditional S_IRUGO permission checks on
* the ipc object.
*/
if (cmd == SHM_STAT_ANY)
audit_ipc_obj(&shp->shm_perm);
else {
err = -EACCES;
if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
goto out_unlock;
}
err = security_shm_shmctl(&shp->shm_perm, cmd);
if (err)
goto out_unlock;
ipc_lock_object(&shp->shm_perm);
if (!ipc_valid_object(&shp->shm_perm)) {
ipc_unlock_object(&shp->shm_perm);
err = -EIDRM;
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;
#ifndef CONFIG_64BIT
tbuf->shm_atime_high = shp->shm_atim >> 32;
tbuf->shm_dtime_high = shp->shm_dtim >> 32;
tbuf->shm_ctime_high = shp->shm_ctim >> 32;
#endif
tbuf->shm_cpid = pid_vnr(shp->shm_cprid);
tbuf->shm_lpid = pid_vnr(shp->shm_lprid);
tbuf->shm_nattch = shp->shm_nattch;
if (cmd == IPC_STAT) {
/*
* As defined in SUS:
* Return 0 on success
*/
err = 0;
} else {
/*
* SHM_STAT and SHM_STAT_ANY (both Linux specific)
* Return the full id, including the sequence number
*/
err = shp->shm_perm.id;
}
ipc_unlock_object(&shp->shm_perm);
out_unlock:
rcu_read_unlock();
return err;
}
static int shmctl_do_lock(struct ipc_namespace *ns, int shmid, int cmd)
{
struct shmid_kernel *shp;
struct file *shm_file;
int err;
rcu_read_lock();
shp = shm_obtain_object_check(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
goto out_unlock1;
}
audit_ipc_obj(&(shp->shm_perm));
err = security_shm_shmctl(&shp->shm_perm, cmd);
if (err)
goto out_unlock1;
ipc_lock_object(&shp->shm_perm);
/* check if shm_destroy() is tearing down shp */
if (!ipc_valid_object(&shp->shm_perm)) {
err = -EIDRM;
goto out_unlock0;
}
if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
kuid_t euid = current_euid();
if (!uid_eq(euid, shp->shm_perm.uid) &&
!uid_eq(euid, shp->shm_perm.cuid)) {
err = -EPERM;
goto out_unlock0;
}
if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
err = -EPERM;
goto out_unlock0;
}
}
shm_file = shp->shm_file;
if (is_file_hugepages(shm_file))
goto out_unlock0;
if (cmd == SHM_LOCK) {
struct user_struct *user = current_user();
err = shmem_lock(shm_file, 1, user);
if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
shp->shm_perm.mode |= SHM_LOCKED;
shp->mlock_user = user;
}
goto out_unlock0;
}
/* SHM_UNLOCK */
if (!(shp->shm_perm.mode & SHM_LOCKED))
goto out_unlock0;
shmem_lock(shm_file, 0, shp->mlock_user);
shp->shm_perm.mode &= ~SHM_LOCKED;
shp->mlock_user = NULL;
get_file(shm_file);
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();
shmem_unlock_mapping(shm_file->f_mapping);
fput(shm_file);
return err;
out_unlock0:
ipc_unlock_object(&shp->shm_perm);
out_unlock1:
rcu_read_unlock();
return err;
}
long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
{
int err, version;
struct ipc_namespace *ns;
struct shmid64_ds sem64;
if (cmd < 0 || shmid < 0)
return -EINVAL;
version = ipc_parse_version(&cmd);
ns = current->nsproxy->ipc_ns;
switch (cmd) {
case IPC_INFO: {
struct shminfo64 shminfo;
err = shmctl_ipc_info(ns, &shminfo);
if (err < 0)
return err;
if (copy_shminfo_to_user(buf, &shminfo, version))
err = -EFAULT;
return err;
}
case SHM_INFO: {
struct shm_info shm_info;
err = shmctl_shm_info(ns, &shm_info);
if (err < 0)
return err;
if (copy_to_user(buf, &shm_info, sizeof(shm_info)))
err = -EFAULT;
return err;
}
case SHM_STAT:
case SHM_STAT_ANY:
case IPC_STAT: {
err = shmctl_stat(ns, shmid, cmd, &sem64);
if (err < 0)
return err;
if (copy_shmid_to_user(buf, &sem64, version))
err = -EFAULT;
return err;
}
case IPC_SET:
if (copy_shmid_from_user(&sem64, buf, version))
return -EFAULT;
/* fallthru */
case IPC_RMID:
return shmctl_down(ns, shmid, cmd, &sem64);
case SHM_LOCK:
case SHM_UNLOCK:
return shmctl_do_lock(ns, shmid, cmd);
default:
return -EINVAL;
}
}
SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
{
return ksys_shmctl(shmid, cmd, buf);
}
#ifdef CONFIG_COMPAT
struct compat_shmid_ds {
struct compat_ipc_perm shm_perm;
int shm_segsz;
compat_time_t shm_atime;
compat_time_t shm_dtime;
compat_time_t shm_ctime;
compat_ipc_pid_t shm_cpid;
compat_ipc_pid_t shm_lpid;
unsigned short shm_nattch;
unsigned short shm_unused;
compat_uptr_t shm_unused2;
compat_uptr_t shm_unused3;
};
struct compat_shminfo64 {
compat_ulong_t shmmax;
compat_ulong_t shmmin;
compat_ulong_t shmmni;
compat_ulong_t shmseg;
compat_ulong_t shmall;
compat_ulong_t __unused1;
compat_ulong_t __unused2;
compat_ulong_t __unused3;
compat_ulong_t __unused4;
};
struct compat_shm_info {
compat_int_t used_ids;
compat_ulong_t shm_tot, shm_rss, shm_swp;
compat_ulong_t swap_attempts, swap_successes;
};
static int copy_compat_shminfo_to_user(void __user *buf, struct shminfo64 *in,
int version)
{
if (in->shmmax > INT_MAX)
in->shmmax = INT_MAX;
if (version == IPC_64) {
struct compat_shminfo64 info;
memset(&info, 0, sizeof(info));
info.shmmax = in->shmmax;
info.shmmin = in->shmmin;
info.shmmni = in->shmmni;
info.shmseg = in->shmseg;
info.shmall = in->shmall;
return copy_to_user(buf, &info, sizeof(info));
} else {
struct shminfo info;
memset(&info, 0, sizeof(info));
info.shmmax = in->shmmax;
info.shmmin = in->shmmin;
info.shmmni = in->shmmni;
info.shmseg = in->shmseg;
info.shmall = in->shmall;
return copy_to_user(buf, &info, sizeof(info));
}
}
static int put_compat_shm_info(struct shm_info *ip,
struct compat_shm_info __user *uip)
{
struct compat_shm_info info;
memset(&info, 0, sizeof(info));
info.used_ids = ip->used_ids;
info.shm_tot = ip->shm_tot;
info.shm_rss = ip->shm_rss;
info.shm_swp = ip->shm_swp;
info.swap_attempts = ip->swap_attempts;
info.swap_successes = ip->swap_successes;
return copy_to_user(uip, &info, sizeof(info));
}
static int copy_compat_shmid_to_user(void __user *buf, struct shmid64_ds *in,
int version)
{
if (version == IPC_64) {
struct compat_shmid64_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc64_perm(&v.shm_perm, &in->shm_perm);
v.shm_atime = lower_32_bits(in->shm_atime);
v.shm_atime_high = upper_32_bits(in->shm_atime);
v.shm_dtime = lower_32_bits(in->shm_dtime);
v.shm_dtime_high = upper_32_bits(in->shm_dtime);
v.shm_ctime = lower_32_bits(in->shm_ctime);
v.shm_ctime_high = upper_32_bits(in->shm_ctime);
v.shm_segsz = in->shm_segsz;
v.shm_nattch = in->shm_nattch;
v.shm_cpid = in->shm_cpid;
v.shm_lpid = in->shm_lpid;
return copy_to_user(buf, &v, sizeof(v));
} else {
struct compat_shmid_ds v;
memset(&v, 0, sizeof(v));
to_compat_ipc_perm(&v.shm_perm, &in->shm_perm);
v.shm_perm.key = in->shm_perm.key;
v.shm_atime = in->shm_atime;
v.shm_dtime = in->shm_dtime;
v.shm_ctime = in->shm_ctime;
v.shm_segsz = in->shm_segsz;
v.shm_nattch = in->shm_nattch;
v.shm_cpid = in->shm_cpid;
v.shm_lpid = in->shm_lpid;
return copy_to_user(buf, &v, sizeof(v));
}
}
static int copy_compat_shmid_from_user(struct shmid64_ds *out, void __user *buf,
int version)
{
memset(out, 0, sizeof(*out));
if (version == IPC_64) {
struct compat_shmid64_ds __user *p = buf;
return get_compat_ipc64_perm(&out->shm_perm, &p->shm_perm);
} else {
struct compat_shmid_ds __user *p = buf;
return get_compat_ipc_perm(&out->shm_perm, &p->shm_perm);
}
}
long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr)
{
struct ipc_namespace *ns;
struct shmid64_ds sem64;
int version = compat_ipc_parse_version(&cmd);
int err;
ns = current->nsproxy->ipc_ns;
if (cmd < 0 || shmid < 0)
return -EINVAL;
switch (cmd) {
case IPC_INFO: {
struct shminfo64 shminfo;
err = shmctl_ipc_info(ns, &shminfo);
if (err < 0)
return err;
if (copy_compat_shminfo_to_user(uptr, &shminfo, version))
err = -EFAULT;
return err;
}
case SHM_INFO: {
struct shm_info shm_info;
err = shmctl_shm_info(ns, &shm_info);
if (err < 0)
return err;
if (put_compat_shm_info(&shm_info, uptr))
err = -EFAULT;
return err;
}
case IPC_STAT:
case SHM_STAT_ANY:
case SHM_STAT:
err = shmctl_stat(ns, shmid, cmd, &sem64);
if (err < 0)
return err;
if (copy_compat_shmid_to_user(uptr, &sem64, version))
err = -EFAULT;
return err;
case IPC_SET:
if (copy_compat_shmid_from_user(&sem64, uptr, version))
return -EFAULT;
/* fallthru */
case IPC_RMID:
return shmctl_down(ns, shmid, cmd, &sem64);
case SHM_LOCK:
case SHM_UNLOCK:
return shmctl_do_lock(ns, shmid, cmd);
break;
default:
return -EINVAL;
}
return err;
}
COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
{
return compat_ksys_shmctl(shmid, cmd, uptr);
}
#endif
/*
* 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, unsigned long shmlba)
{
struct shmid_kernel *shp;
unsigned long addr = (unsigned long)shmaddr;
unsigned long size;
struct file *file, *base;
int err;
unsigned long flags = MAP_SHARED;
unsigned long prot;
int acc_mode;
struct ipc_namespace *ns;
struct shm_file_data *sfd;
int f_flags;
unsigned long populate = 0;
err = -EINVAL;
if (shmid < 0)
goto out;
if (addr) {
if (addr & (shmlba - 1)) {
if (shmflg & SHM_RND) {
addr &= ~(shmlba - 1); /* round down */
/*
* Ensure that the round-down is non-nil
* when remapping. This can happen for
* cases when addr < shmlba.
*/
if (!addr && (shmflg & SHM_REMAP))
goto out;
} else
#ifndef __ARCH_FORCE_SHMLBA
if (addr & ~PAGE_MASK)
#endif
goto out;
}
flags |= MAP_FIXED;
} else if ((shmflg & SHM_REMAP))
goto out;
if (shmflg & SHM_RDONLY) {
prot = PROT_READ;
acc_mode = S_IRUGO;
f_flags = O_RDONLY;
} else {
prot = PROT_READ | PROT_WRITE;
acc_mode = S_IRUGO | S_IWUGO;
f_flags = O_RDWR;
}
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;
rcu_read_lock();
shp = shm_obtain_object_check(ns, shmid);
if (IS_ERR(shp)) {
err = PTR_ERR(shp);
goto out_unlock;
}
err = -EACCES;
if (ipcperms(ns, &shp->shm_perm, acc_mode))
goto out_unlock;
err = security_shm_shmat(&shp->shm_perm, shmaddr, shmflg);
if (err)
goto out_unlock;
ipc_lock_object(&shp->shm_perm);
/* check if shm_destroy() is tearing down shp */
if (!ipc_valid_object(&shp->shm_perm)) {
ipc_unlock_object(&shp->shm_perm);
err = -EIDRM;
goto out_unlock;
}
/*
* We need to take a reference to the real shm file to prevent the
* pointer from becoming stale in cases where the lifetime of the outer
* file extends beyond that of the shm segment. It's not usually
* possible, but it can happen during remap_file_pages() emulation as
* that unmaps the memory, then does ->mmap() via file reference only.
* We'll deny the ->mmap() if the shm segment was since removed, but to
* detect shm ID reuse we need to compare the file pointers.
*/
base = get_file(shp->shm_file);
shp->shm_nattch++;
size = i_size_read(file_inode(base));
ipc_unlock_object(&shp->shm_perm);
rcu_read_unlock();
err = -ENOMEM;
sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
if (!sfd) {
fput(base);
goto out_nattch;
}
file = alloc_file_clone(base, f_flags,
is_file_hugepages(base) ?
&shm_file_operations_huge :
&shm_file_operations);
err = PTR_ERR(file);
if (IS_ERR(file)) {
kfree(sfd);
fput(base);
goto out_nattch;
}
sfd->id = shp->shm_perm.id;
sfd->ns = get_ipc_ns(ns);
sfd->file = base;
sfd->vm_ops = NULL;
file->private_data = sfd;
err = security_mmap_file(file, prot, flags);
if (err)
goto out_fput;
if (down_write_killable(&current->mm->mmap_sem)) {
err = -EINTR;
goto out_fput;
}
if (addr && !(shmflg & SHM_REMAP)) {
err = -EINVAL;
if (addr + size < addr)
goto invalid;
if (find_vma_intersection(current->mm, addr, addr + size))
goto invalid;
}
addr = do_mmap_pgoff(file, addr, size, prot, flags, 0, &populate, NULL);
*raddr = addr;
err = 0;
if (IS_ERR_VALUE(addr))
err = (long)addr;
invalid:
up_write(&current->mm->mmap_sem);
if (populate)
mm_populate(addr, populate);
out_fput:
fput(file);
out_nattch:
down_write(&shm_ids(ns).rwsem);
shp = shm_lock(ns, shmid);
shp->shm_nattch--;
if (shm_may_destroy(ns, shp))
shm_destroy(ns, shp);
else
shm_unlock(shp);
up_write(&shm_ids(ns).rwsem);
return err;
out_unlock:
rcu_read_unlock();
out:
return err;
}
SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
{
unsigned long ret;
long err;
err = do_shmat(shmid, shmaddr, shmflg, &ret, SHMLBA);
if (err)
return err;
force_successful_syscall_return();
return (long)ret;
}
#ifdef CONFIG_COMPAT
#ifndef COMPAT_SHMLBA
#define COMPAT_SHMLBA SHMLBA
#endif
COMPAT_SYSCALL_DEFINE3(shmat, int, shmid, compat_uptr_t, shmaddr, int, shmflg)
{
unsigned long ret;
long err;
err = do_shmat(shmid, compat_ptr(shmaddr), shmflg, &ret, COMPAT_SHMLBA);
if (err)
return err;
force_successful_syscall_return();
return (long)ret;
}
#endif
/*
* detach and kill segment if marked destroyed.
* The work is done in shm_close.
*/
long ksys_shmdt(char __user *shmaddr)
{
struct mm_struct *mm = current->mm;
struct vm_area_struct *vma;
unsigned long addr = (unsigned long)shmaddr;
int retval = -EINVAL;
#ifdef CONFIG_MMU
loff_t size = 0;
struct file *file;
struct vm_area_struct *next;
#endif
if (addr & ~PAGE_MASK)
return retval;
if (down_write_killable(&mm->mmap_sem))
return -EINTR;
/*
* 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 and that are from the
* same shm segment from which we determined the 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);
#ifdef CONFIG_MMU
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) {
/*
* Record the file of the shm segment being
* unmapped. With mremap(), someone could place
* page from another segment but with equal offsets
* in the range we are unmapping.
*/
file = vma->vm_file;
size = i_size_read(file_inode(vma->vm_file));
do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
/*
* 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 comparisons 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) &&
(vma->vm_file == file))
do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
vma = next;
}
#else /* CONFIG_MMU */
/* under NOMMU conditions, the exact address to be destroyed must be
* given
*/
if (vma && vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start, NULL);
retval = 0;
}
#endif
up_write(&mm->mmap_sem);
return retval;
}
SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
{
return ksys_shmdt(shmaddr);
}
#ifdef CONFIG_PROC_FS
static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
{
struct pid_namespace *pid_ns = ipc_seq_pid_ns(s);
struct user_namespace *user_ns = seq_user_ns(s);
struct kern_ipc_perm *ipcp = it;
struct shmid_kernel *shp;
unsigned long rss = 0, swp = 0;
shp = container_of(ipcp, struct shmid_kernel, shm_perm);
shm_add_rss_swap(shp, &rss, &swp);
#if BITS_PER_LONG <= 32
#define SIZE_SPEC "%10lu"
#else
#define SIZE_SPEC "%21lu"
#endif
seq_printf(s,
"%10d %10d %4o " SIZE_SPEC " %5u %5u "
"%5lu %5u %5u %5u %5u %10llu %10llu %10llu "
SIZE_SPEC " " SIZE_SPEC "\n",
shp->shm_perm.key,
shp->shm_perm.id,
shp->shm_perm.mode,
shp->shm_segsz,
pid_nr_ns(shp->shm_cprid, pid_ns),
pid_nr_ns(shp->shm_lprid, pid_ns),
shp->shm_nattch,
from_kuid_munged(user_ns, shp->shm_perm.uid),
from_kgid_munged(user_ns, shp->shm_perm.gid),
from_kuid_munged(user_ns, shp->shm_perm.cuid),
from_kgid_munged(user_ns, shp->shm_perm.cgid),
shp->shm_atim,
shp->shm_dtim,
shp->shm_ctim,
rss * PAGE_SIZE,
swp * PAGE_SIZE);
return 0;
}
#endif