linux-stable/ipc/shm.c
Mike Kravetz b6305049f3 ipc/shm: call underlying open/close vm_ops
Shared memory segments can be created that are backed by hugetlb pages. 
When this happens, the vmas associated with any mappings (shmat) are
marked VM_HUGETLB, yet the vm_ops for such mappings are provided by
ipc/shm (shm_vm_ops).  There is a mechanism to call the underlying hugetlb
vm_ops, and this is done for most operations.  However, it is not done for
open and close.

This was not an issue until the introduction of the hugetlb vma_lock. 
This lock structure is pointed to by vm_private_data and the open/close
vm_ops help maintain this structure.  The special hugetlb routine called
at fork took care of structure updates at fork time.  However,
vma_splitting is not properly handled for ipc shared memory mappings
backed by hugetlb pages.  This can result in a "kernel NULL pointer
dereference" BUG or use after free as two vmas point to the same lock
structure.

Update the shm open and close routines to always call the underlying open
and close routines.

Link: https://lkml.kernel.org/r/20221114210018.49346-1-mike.kravetz@oracle.com
Fixes: 8d9bfb2608 ("hugetlb: add vma based lock for pmd sharing")
Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Reported-by: Doug Nelson <doug.nelson@intel.com>
Reported-by: <syzbot+83b4134621b7c326d950@syzkaller.appspotmail.com>
Cc: Alexander Mikhalitsyn <alexander.mikhalitsyn@virtuozzo.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-22 18:50:42 -08:00

1883 lines
45 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 ucounts *mlock_ucounts;
/*
* The task created the shm object, for
* task_lock(shp->shm_creator)
*/
struct task_struct *shm_creator;
/*
* List by creator. task_lock(->shm_creator) required for read/write.
* If list_empty(), then the creator is dead already.
*/
struct list_head shm_clist;
struct ipc_namespace *ns;
} __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
void 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;
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);
WARN_ON(ns != shp->ns);
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)
{
shm_init_ns(&init_ipc_ns);
return 0;
}
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);
ipcp = ERR_PTR(-EIDRM);
err:
rcu_read_unlock();
/*
* Callers of shm_lock() must validate the status of the returned ipc
* object pointer and error out as appropriate.
*/
return ERR_CAST(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);
kfree(shp);
}
/*
* It has to be called with shp locked.
* It must be called before ipc_rmid()
*/
static inline void shm_clist_rm(struct shmid_kernel *shp)
{
struct task_struct *creator;
/* ensure that shm_creator does not disappear */
rcu_read_lock();
/*
* A concurrent exit_shm may do a list_del_init() as well.
* Just do nothing if exit_shm already did the work
*/
if (!list_empty(&shp->shm_clist)) {
/*
* shp->shm_creator is guaranteed to be valid *only*
* if shp->shm_clist is not empty.
*/
creator = shp->shm_creator;
task_lock(creator);
/*
* list_del_init() is a nop if the entry was already removed
* from the list.
*/
list_del_init(&shp->shm_clist);
task_unlock(creator);
}
rcu_read_unlock();
}
static inline void shm_rmid(struct shmid_kernel *s)
{
shm_clist_rm(s);
ipc_rmid(&shm_ids(s->ns), &s->shm_perm);
}
static int __shm_open(struct shm_file_data *sfd)
{
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)
{
struct file *file = vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
int err;
/* Always call underlying open if present */
if (sfd->vm_ops->open)
sfd->vm_ops->open(vma);
err = __shm_open(sfd);
/*
* 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(shp);
shm_unlock(shp);
if (!is_file_hugepages(shm_file))
shmem_lock(shm_file, 0, shp->mlock_ucounts);
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 shmid_kernel *shp)
{
return (shp->shm_nattch == 0) &&
(shp->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 shm_file_data *sfd)
{
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(shp))
shm_destroy(ns, shp);
else
shm_unlock(shp);
done:
up_write(&shm_ids(ns).rwsem);
}
static void shm_close(struct vm_area_struct *vma)
{
struct file *file = vma->vm_file;
struct shm_file_data *sfd = shm_file_data(file);
/* Always call underlying close if present */
if (sfd->vm_ops->close)
sfd->vm_ops->close(vma);
__shm_close(sfd);
}
/* 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 (!list_empty(&shp->shm_clist))
return 0;
if (shm_may_destroy(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)
{
for (;;) {
struct shmid_kernel *shp;
struct ipc_namespace *ns;
task_lock(task);
if (list_empty(&task->sysvshm.shm_clist)) {
task_unlock(task);
break;
}
shp = list_first_entry(&task->sysvshm.shm_clist, struct shmid_kernel,
shm_clist);
/*
* 1) Get pointer to the ipc namespace. It is worth to say
* that this pointer is guaranteed to be valid because
* shp lifetime is always shorter than namespace lifetime
* in which shp lives.
* We taken task_lock it means that shp won't be freed.
*/
ns = shp->ns;
/*
* 2) 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)
goto unlink_continue;
/*
* 3) get a reference to the namespace.
* The refcount could be already 0. If it is 0, then
* the shm objects will be free by free_ipc_work().
*/
ns = get_ipc_ns_not_zero(ns);
if (!ns) {
unlink_continue:
list_del_init(&shp->shm_clist);
task_unlock(task);
continue;
}
/*
* 4) get a reference to shp.
* This cannot fail: shm_clist_rm() is called before
* ipc_rmid(), thus the refcount cannot be 0.
*/
WARN_ON(!ipc_rcu_getref(&shp->shm_perm));
/*
* 5) unlink the shm segment from the list of segments
* created by current.
* This must be done last. After unlinking,
* only the refcounts obtained above prevent IPC_RMID
* from destroying the segment or the namespace.
*/
list_del_init(&shp->shm_clist);
task_unlock(task);
/*
* 6) we have all references
* Thus lock & if needed destroy shp.
*/
down_write(&shm_ids(ns).rwsem);
shm_lock_by_ptr(shp);
/*
* rcu_read_lock was implicitly taken in shm_lock_by_ptr, it's
* safe to call ipc_rcu_putref here
*/
ipc_rcu_putref(&shp->shm_perm, shm_rcu_free);
if (ipc_valid_object(&shp->shm_perm)) {
if (shm_may_destroy(shp))
shm_destroy(ns, shp);
else
shm_unlock(shp);
} else {
/*
* Someone else deleted the shp from namespace
* idr/kht while we have waited.
* Just unlock and continue.
*/
shm_unlock(shp);
}
up_write(&shm_ids(ns).rwsem);
put_ipc_ns(ns); /* paired with get_ipc_ns_not_zero */
}
}
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_may_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->may_split)
return sfd->vm_ops->may_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(sfd);
if (ret)
return ret;
ret = call_mmap(sfd->file, vma);
if (ret) {
__shm_close(sfd);
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,
.may_split = shm_may_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 = kmalloc(sizeof(*shp), GFP_KERNEL_ACCOUNT);
if (unlikely(!shp))
return -ENOMEM;
shp->shm_perm.key = key;
shp->shm_perm.mode = (shmflg & S_IRWXUGO);
shp->mlock_ucounts = NULL;
shp->shm_perm.security = NULL;
error = security_shm_alloc(&shp->shm_perm);
if (error) {
kfree(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,
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;
shp->ns = ns;
task_lock(current);
list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
task_unlock(current);
/*
* 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);
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 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_maxidx(&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_maxidx(&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 ucounts *ucounts = current_ucounts();
err = shmem_lock(shm_file, 1, ucounts);
if (!err && !(shp->shm_perm.mode & SHM_LOCKED)) {
shp->shm_perm.mode |= SHM_LOCKED;
shp->mlock_ucounts = ucounts;
}
goto out_unlock0;
}
/* SHM_UNLOCK */
if (!(shp->shm_perm.mode & SHM_LOCKED))
goto out_unlock0;
shmem_lock(shm_file, 0, shp->mlock_ucounts);
shp->shm_perm.mode &= ~SHM_LOCKED;
shp->mlock_ucounts = 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;
}
static long ksys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf, int version)
{
int err;
struct ipc_namespace *ns;
struct shmid64_ds sem64;
if (cmd < 0 || shmid < 0)
return -EINVAL;
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;
fallthrough;
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, IPC_64);
}
#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
long ksys_old_shmctl(int shmid, int cmd, struct shmid_ds __user *buf)
{
int version = ipc_parse_version(&cmd);
return ksys_shmctl(shmid, cmd, buf, version);
}
SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
{
return ksys_old_shmctl(shmid, cmd, buf);
}
#endif
#ifdef CONFIG_COMPAT
struct compat_shmid_ds {
struct compat_ipc_perm shm_perm;
int shm_segsz;
old_time32_t shm_atime;
old_time32_t shm_dtime;
old_time32_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);
}
}
static long compat_ksys_shmctl(int shmid, int cmd, void __user *uptr, int version)
{
struct ipc_namespace *ns;
struct shmid64_ds sem64;
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;
fallthrough;
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;
}
return err;
}
COMPAT_SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, void __user *, uptr)
{
return compat_ksys_shmctl(shmid, cmd, uptr, IPC_64);
}
#ifdef CONFIG_ARCH_WANT_COMPAT_IPC_PARSE_VERSION
long compat_ksys_old_shmctl(int shmid, int cmd, void __user *uptr)
{
int version = compat_ipc_parse_version(&cmd);
return compat_ksys_shmctl(shmid, cmd, uptr, version);
}
COMPAT_SYSCALL_DEFINE3(old_shmctl, int, shmid, int, cmd, void __user *, uptr)
{
return compat_ksys_old_shmctl(shmid, cmd, uptr);
}
#endif
#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 (mmap_write_lock_killable(current->mm)) {
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(file, addr, size, prot, flags, 0, &populate, NULL);
*raddr = addr;
err = 0;
if (IS_ERR_VALUE(addr))
err = (long)addr;
invalid:
mmap_write_unlock(current->mm);
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(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;
VMA_ITERATOR(vmi, mm, addr);
#endif
if (addr & ~PAGE_MASK)
return retval;
if (mmap_write_lock_killable(mm))
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.
*/
#ifdef CONFIG_MMU
for_each_vma(vmi, vma) {
/*
* 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);
mas_pause(&vmi.mas);
/*
* 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 = vma_next(&vmi);
break;
}
}
/*
* 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) {
/* 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);
mas_pause(&vmi.mas);
}
vma = vma_next(&vmi);
}
#else /* CONFIG_MMU */
vma = vma_lookup(mm, addr);
/* 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
mmap_write_unlock(mm);
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