shm.c 32.4 KB
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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>
 *
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 * support for audit of ipc object properties and permission changes
 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
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 *
 * namespaces support
 * OpenVZ, SWsoft Inc.
 * Pavel Emelianov <xemul@openvz.org>
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 *
 * Better ipc lock (kern_ipc_perm.lock) handling
 * Davidlohr Bueso <davidlohr.bueso@hp.com>, June 2013.
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 */

#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>
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#include <linux/capability.h>
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#include <linux/ptrace.h>
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#include <linux/seq_file.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <linux/mount.h>
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#include <linux/ipc_namespace.h>
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#include <linux/uaccess.h>
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#include "util.h"

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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))

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static const struct file_operations shm_file_operations;
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static const struct vm_operations_struct shm_vm_ops;
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#define shm_ids(ns)	((ns)->ids[IPC_SHM_IDS])
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#define shm_unlock(shp)			\
	ipc_unlock(&(shp)->shm_perm)
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static int newseg(struct ipc_namespace *, struct ipc_params *);
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static void shm_open(struct vm_area_struct *vma);
static void shm_close(struct vm_area_struct *vma);
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static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
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#ifdef CONFIG_PROC_FS
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static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
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#endif

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void shm_init_ns(struct ipc_namespace *ns)
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{
	ns->shm_ctlmax = SHMMAX;
	ns->shm_ctlall = SHMALL;
	ns->shm_ctlmni = SHMMNI;
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	ns->shm_rmid_forced = 0;
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	ns->shm_tot = 0;
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	ipc_init_ids(&shm_ids(ns));
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}

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/*
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 * Called with shm_ids.rwsem (writer) and the shp structure locked.
 * Only shm_ids.rwsem remains locked on exit.
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 */
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static void do_shm_rmid(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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{
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	struct shmid_kernel *shp;
	shp = container_of(ipcp, struct shmid_kernel, shm_perm);

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	if (shp->shm_nattch) {
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		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);
}

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#ifdef CONFIG_IPC_NS
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void shm_exit_ns(struct ipc_namespace *ns)
{
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	free_ipcs(ns, &shm_ids(ns), do_shm_rmid);
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	idr_destroy(&ns->ids[IPC_SHM_IDS].ipcs_idr);
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}
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#endif
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static int __init ipc_ns_init(void)
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{
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	shm_init_ns(&init_ipc_ns);
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	return 0;
}

pure_initcall(ipc_ns_init);

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void __init shm_init(void)
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{
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	ipc_init_proc_interface("sysvipc/shm",
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#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
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				IPC_SHM_IDS, sysvipc_shm_proc_show);
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}

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static inline struct shmid_kernel *shm_obtain_object(struct ipc_namespace *ns, int id)
{
	struct kern_ipc_perm *ipcp = ipc_obtain_object(&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);
}

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/*
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 * shm_lock_(check_) routines are called in the paths where the rwsem
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 * is not necessarily held.
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 */
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static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
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{
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	struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);

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	if (IS_ERR(ipcp))
		return (struct shmid_kernel *)ipcp;

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	return container_of(ipcp, struct shmid_kernel, shm_perm);
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}

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static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
{
	rcu_read_lock();
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	ipc_lock_object(&ipcp->shm_perm);
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}

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static void shm_rcu_free(struct rcu_head *head)
{
	struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
	struct shmid_kernel *shp = ipc_rcu_to_struct(p);

	security_shm_free(shp);
	ipc_rcu_free(head);
}

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static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
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{
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	list_del(&s->shm_clist);
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	ipc_rmid(&shm_ids(ns), &s->shm_perm);
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}


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/* This is called by fork, once for every shm attach. */
static void shm_open(struct vm_area_struct *vma)
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{
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	struct file *file = vma->vm_file;
	struct shm_file_data *sfd = shm_file_data(file);
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	struct shmid_kernel *shp;

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	shp = shm_lock(sfd->ns, sfd->id);
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	BUG_ON(IS_ERR(shp));
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	shp->shm_atim = get_seconds();
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	shp->shm_lprid = task_tgid_vnr(current);
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	shp->shm_nattch++;
	shm_unlock(shp);
}

/*
 * shm_destroy - free the struct shmid_kernel
 *
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 * @ns: namespace
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 * @shp: struct to free
 *
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 * It has to be called with shp and shm_ids.rwsem (writer) locked,
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 * but returns with shp unlocked and freed.
 */
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static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
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{
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	struct file *shm_file;

	shm_file = shp->shm_file;
	shp->shm_file = NULL;
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	ns->shm_tot -= (shp->shm_segsz + PAGE_SIZE - 1) >> PAGE_SHIFT;
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	shm_rmid(ns, shp);
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	shm_unlock(shp);
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	if (!is_file_hugepages(shm_file))
		shmem_lock(shm_file, 0, shp->mlock_user);
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	else if (shp->mlock_user)
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		user_shm_unlock(file_inode(shm_file)->i_size, shp->mlock_user);
	fput(shm_file);
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	ipc_rcu_putref(shp, shm_rcu_free);
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}

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/*
 * 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));
}

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/*
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 * remove the attach descriptor vma.
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 * 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.
 */
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static void shm_close(struct vm_area_struct *vma)
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{
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	struct file *file = vma->vm_file;
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	struct shm_file_data *sfd = shm_file_data(file);
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	struct shmid_kernel *shp;
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	struct ipc_namespace *ns = sfd->ns;
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	down_write(&shm_ids(ns).rwsem);
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	/* remove from the list of attaches of the shm segment */
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	shp = shm_lock(ns, sfd->id);
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	BUG_ON(IS_ERR(shp));
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	shp->shm_lprid = task_tgid_vnr(current);
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	shp->shm_dtim = get_seconds();
	shp->shm_nattch--;
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	if (shm_may_destroy(ns, shp))
		shm_destroy(ns, shp);
	else
		shm_unlock(shp);
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	up_write(&shm_ids(ns).rwsem);
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}

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/* Called with ns->shm_ids(ns).rwsem locked */
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static int shm_try_destroy_orphaned(int id, void *p, void *data)
{
	struct ipc_namespace *ns = data;
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	struct kern_ipc_perm *ipcp = p;
	struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
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	/*
	 * We want to destroy segments without users and with already
	 * exit'ed originating process.
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	 *
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	 * As shp->* are changed under rwsem, it's safe to skip shp locking.
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	 */
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	if (shp->shm_creator != NULL)
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		return 0;

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	if (shm_may_destroy(ns, shp)) {
		shm_lock_by_ptr(shp);
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		shm_destroy(ns, shp);
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	}
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	return 0;
}

void shm_destroy_orphaned(struct ipc_namespace *ns)
{
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	down_write(&shm_ids(ns).rwsem);
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	if (shm_ids(ns).in_use)
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		idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
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	up_write(&shm_ids(ns).rwsem);
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}

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/* Locking assumes this will only be called with task == current */
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void exit_shm(struct task_struct *task)
{
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	struct ipc_namespace *ns = task->nsproxy->ipc_ns;
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	struct shmid_kernel *shp, *n;
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	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);
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		return;
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	}
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	/*
	 * 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.
	 */
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	down_write(&shm_ids(ns).rwsem);
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	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. */
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	list_del(&task->sysvshm.shm_clist);
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	up_write(&shm_ids(ns).rwsem);
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}

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static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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{
	struct file *file = vma->vm_file;
	struct shm_file_data *sfd = shm_file_data(file);

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	return sfd->vm_ops->fault(vma, vmf);
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}

#ifdef CONFIG_NUMA
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static int shm_set_policy(struct vm_area_struct *vma, struct mempolicy *new)
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{
	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;
}

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static struct mempolicy *shm_get_policy(struct vm_area_struct *vma,
					unsigned long addr)
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{
	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);
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	else if (vma->vm_policy)
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		pol = vma->vm_policy;
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	return pol;
}
#endif

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static int shm_mmap(struct file *file, struct vm_area_struct *vma)
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{
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	struct shm_file_data *sfd = shm_file_data(file);
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	int ret;

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	ret = sfd->file->f_op->mmap(sfd->file, vma);
	if (ret != 0)
		return ret;
	sfd->vm_ops = vma->vm_ops;
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#ifdef CONFIG_MMU
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	BUG_ON(!sfd->vm_ops->fault);
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#endif
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	vma->vm_ops = &shm_vm_ops;
	shm_open(vma);
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	return ret;
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}

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static int shm_release(struct inode *ino, struct file *file)
{
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	struct shm_file_data *sfd = shm_file_data(file);
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	put_ipc_ns(sfd->ns);
	shm_file_data(file) = NULL;
	kfree(sfd);
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	return 0;
}

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static int shm_fsync(struct file *file, loff_t start, loff_t end, int datasync)
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{
	struct shm_file_data *sfd = shm_file_data(file);

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	if (!sfd->file->f_op->fsync)
		return -EINVAL;
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	return sfd->file->f_op->fsync(sfd->file, start, end, datasync);
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}

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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);
}

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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);
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	return sfd->file->f_op->get_unmapped_area(sfd->file, addr, len,
						pgoff, flags);
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}

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static const struct file_operations shm_file_operations = {
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	.mmap		= shm_mmap,
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	.fsync		= shm_fsync,
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	.release	= shm_release,
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#ifndef CONFIG_MMU
	.get_unmapped_area	= shm_get_unmapped_area,
#endif
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	.llseek		= noop_llseek,
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	.fallocate	= shm_fallocate,
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};

static const struct file_operations shm_file_operations_huge = {
	.mmap		= shm_mmap,
	.fsync		= shm_fsync,
	.release	= shm_release,
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	.get_unmapped_area	= shm_get_unmapped_area,
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	.llseek		= noop_llseek,
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	.fallocate	= shm_fallocate,
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};

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int is_file_shm_hugepages(struct file *file)
{
	return file->f_op == &shm_file_operations_huge;
}

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static const struct vm_operations_struct shm_vm_ops = {
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	.open	= shm_open,	/* callback for a new vm-area open */
	.close	= shm_close,	/* callback for when the vm-area is released */
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	.fault	= shm_fault,
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#if defined(CONFIG_NUMA)
	.set_policy = shm_set_policy,
	.get_policy = shm_get_policy,
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#endif
};

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/**
 * newseg - Create a new shared memory segment
 * @ns: namespace
 * @params: ptr to the structure that contains key, size and shmflg
 *
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 * Called with shm_ids.rwsem held as a writer.
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 */
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static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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{
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	key_t key = params->key;
	int shmflg = params->flg;
	size_t size = params->u.size;
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	int error;
	struct shmid_kernel *shp;
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	size_t numpages = (size + PAGE_SIZE - 1) >> PAGE_SHIFT;
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	struct file *file;
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	char name[13];
	int id;
493
	vm_flags_t acctflag = 0;
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	if (size < SHMMIN || size > ns->shm_ctlmax)
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		return -EINVAL;

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	if (numpages << PAGE_SHIFT < size)
		return -ENOSPC;

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	if (ns->shm_tot + numpages < ns->shm_tot ||
			ns->shm_tot + numpages > ns->shm_ctlall)
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		return -ENOSPC;

	shp = ipc_rcu_alloc(sizeof(*shp));
	if (!shp)
		return -ENOMEM;

	shp->shm_perm.key = key;
510
	shp->shm_perm.mode = (shmflg & S_IRWXUGO);
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	shp->mlock_user = NULL;

	shp->shm_perm.security = NULL;
	error = security_shm_alloc(shp);
	if (error) {
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		ipc_rcu_putref(shp, ipc_rcu_free);
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		return error;
	}

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	sprintf(name, "SYSV%08x", key);
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	if (shmflg & SHM_HUGETLB) {
522
		struct hstate *hs;
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		size_t hugesize;

525
		hs = hstate_sizelog((shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
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		if (!hs) {
			error = -EINVAL;
			goto no_file;
		}
		hugesize = ALIGN(size, huge_page_size(hs));
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		/* hugetlb_file_setup applies strict accounting */
		if (shmflg & SHM_NORESERVE)
			acctflag = VM_NORESERVE;
535
		file = hugetlb_file_setup(name, hugesize, acctflag,
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				  &shp->mlock_user, HUGETLB_SHMFS_INODE,
				(shmflg >> SHM_HUGE_SHIFT) & SHM_HUGE_MASK);
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	} else {
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		/*
		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
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		 * if it's asked for.
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		 */
		if  ((shmflg & SHM_NORESERVE) &&
				sysctl_overcommit_memory != OVERCOMMIT_NEVER)
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			acctflag = VM_NORESERVE;
546
		file = shmem_file_setup(name, size, acctflag);
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	}
	error = PTR_ERR(file);
	if (IS_ERR(file))
		goto no_file;

552
	id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
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	if (id < 0) {
		error = id;
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		goto no_id;
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	}
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	shp->shm_cprid = task_tgid_vnr(current);
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	shp->shm_lprid = 0;
	shp->shm_atim = shp->shm_dtim = 0;
	shp->shm_ctim = get_seconds();
	shp->shm_segsz = size;
	shp->shm_nattch = 0;
	shp->shm_file = file;
565
	shp->shm_creator = current;
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	list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
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	/*
	 * shmid gets reported as "inode#" in /proc/pid/maps.
	 * proc-ps tools use this. Changing this will break them.
	 */
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	file_inode(file)->i_ino = shp->shm_perm.id;
573

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	ns->shm_tot += numpages;
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	error = shp->shm_perm.id;
576

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	ipc_unlock_object(&shp->shm_perm);
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	rcu_read_unlock();
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	return error;
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no_id:
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	if (is_file_hugepages(file) && shp->mlock_user)
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		user_shm_unlock(size, shp->mlock_user);
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	fput(file);
no_file:
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	ipc_rcu_putref(shp, shm_rcu_free);
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	return error;
}

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/*
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 * Called with shm_ids.rwsem and ipcp locked.
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 */
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static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
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{
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	struct shmid_kernel *shp;

	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
	return security_shm_associate(shp, shmflg);
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}

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/*
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 * Called with shm_ids.rwsem and ipcp locked.
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 */
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static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
				struct ipc_params *params)
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{
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	struct shmid_kernel *shp;

	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
	if (shp->shm_segsz < params->u.size)
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		return -EINVAL;

	return 0;
}

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SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
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{
618
	struct ipc_namespace *ns;
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	static const struct ipc_ops shm_ops = {
		.getnew = newseg,
		.associate = shm_security,
		.more_checks = shm_more_checks,
	};
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	struct ipc_params shm_params;
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	ns = current->nsproxy->ipc_ns;
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	shm_params.key = key;
	shm_params.flg = shmflg;
	shm_params.u.size = size;
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	return ipcget(ns, &shm_ids(ns), &shm_ops, &shm_params);
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}

static inline unsigned long copy_shmid_to_user(void __user *buf, struct shmid64_ds *in, int version)
{
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	switch (version) {
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	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	    {
		struct shmid_ds out;

644
		memset(&out, 0, sizeof(out));
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		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;
	}
}

661 662
static inline unsigned long
copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
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{
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	switch (version) {
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	case IPC_64:
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		if (copy_from_user(out, buf, sizeof(*out)))
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			return -EFAULT;
		return 0;
	case IPC_OLD:
	    {
		struct shmid_ds tbuf_old;

		if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
			return -EFAULT;

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		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;
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		return 0;
	    }
	default:
		return -EINVAL;
	}
}

static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminfo64 *in, int version)
{
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	switch (version) {
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	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	    {
		struct shminfo out;

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		if (in->shmmax > INT_MAX)
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			out.shmmax = INT_MAX;
		else
			out.shmmax = (int)in->shmmax;

		out.shmmin	= in->shmmin;
		out.shmmni	= in->shmmni;
		out.shmseg	= in->shmseg;
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		out.shmall	= in->shmall;
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		return copy_to_user(buf, &out, sizeof(out));
	    }
	default:
		return -EINVAL;
	}
}

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/*
 * Calculate and add used RSS and swap pages of a shm.
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 * Called with shm_ids.rwsem held as a reader
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 */
static void shm_add_rss_swap(struct shmid_kernel *shp,
	unsigned long *rss_add, unsigned long *swp_add)
{
	struct inode *inode;

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	inode = file_inode(shp->shm_file);
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	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(&info->lock);
		*rss_add += inode->i_mapping->nrpages;
		*swp_add += info->swapped;
		spin_unlock(&info->lock);
#else
		*rss_add += inode->i_mapping->nrpages;
#endif
	}
}

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/*
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 * Called with shm_ids.rwsem held as a reader
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 */
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static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
		unsigned long *swp)
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{
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	int next_id;
	int total, in_use;
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	*rss = 0;
	*swp = 0;

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	in_use = shm_ids(ns).in_use;

	for (total = 0, next_id = 0; total < in_use; next_id++) {
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		struct kern_ipc_perm *ipc;
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		struct shmid_kernel *shp;

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		ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
		if (ipc == NULL)
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			continue;
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		shp = container_of(ipc, struct shmid_kernel, shm_perm);
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764
		shm_add_rss_swap(shp, rss, swp);
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		total++;
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	}
}

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/*
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 * This function handles some shmctl commands which require the rwsem
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 * to be held in write mode.
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 * NOTE: no locks must be held, the rwsem is taken inside this function.
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 */
static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
		       struct shmid_ds __user *buf, int version)
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{
778
	struct kern_ipc_perm *ipcp;
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	struct shmid64_ds shmid64;
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	struct shmid_kernel *shp;
	int err;

	if (cmd == IPC_SET) {
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		if (copy_shmid_from_user(&shmid64, buf, version))
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			return -EFAULT;
	}

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	down_write(&shm_ids(ns).rwsem);
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	rcu_read_lock();

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	ipcp = ipcctl_pre_down_nolock(ns, &shm_ids(ns), shmid, cmd,
				      &shmid64.shm_perm, 0);
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	if (IS_ERR(ipcp)) {
		err = PTR_ERR(ipcp);
		goto out_unlock1;
	}
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798
	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
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	err = security_shm_shmctl(shp, cmd);
	if (err)
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		goto out_unlock1;
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	switch (cmd) {
	case IPC_RMID:
806
		ipc_lock_object(&shp->shm_perm);
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		/* do_shm_rmid unlocks the ipc object and rcu */
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		do_shm_rmid(ns, ipcp);
		goto out_up;
	case IPC_SET:
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		ipc_lock_object(&shp->shm_perm);
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		err = ipc_update_perm(&shmid64.shm_perm, ipcp);
		if (err)
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			goto out_unlock0;
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		shp->shm_ctim = get_seconds();
		break;
	default:
		err = -EINVAL;
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		goto out_unlock1;
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	}
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out_unlock0:
	ipc_unlock_object(&shp->shm_perm);
out_unlock1:
	rcu_read_unlock();
826
out_up:
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	up_write(&shm_ids(ns).rwsem);
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	return err;
}

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static int shmctl_nolock(struct ipc_namespace *ns, int shmid,
			 int cmd, int version, void __user *buf)
833
{
834
	int err;
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	struct shmid_kernel *shp;

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	/* preliminary security checks for *_INFO */
	if (cmd == IPC_INFO || cmd == SHM_INFO) {
		err = security_shm_shmctl(NULL, cmd);
		if (err)
			return err;
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	}

844
	switch (cmd) {
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	case IPC_INFO:
	{
		struct shminfo64 shminfo;

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		memset(&shminfo, 0, sizeof(shminfo));
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		shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
		shminfo.shmmax = ns->shm_ctlmax;
		shminfo.shmall = ns->shm_ctlall;
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		shminfo.shmmin = SHMMIN;
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		if (copy_shminfo_to_user(buf, &shminfo, version))
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			return -EFAULT;
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		down_read(&shm_ids(ns).rwsem);
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		err = ipc_get_maxid(&shm_ids(ns));
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		up_read(&shm_ids(ns).rwsem);
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		if (err < 0)
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			err = 0;
		goto out;
	}
	case SHM_INFO:
	{
		struct shm_info shm_info;

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		memset(&shm_info, 0, sizeof(shm_info));
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		down_read(&shm_ids(ns).rwsem);
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		shm_info.used_ids = shm_ids(ns).in_use;
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		shm_get_stat(ns, &shm_info.shm_rss, &shm_info.shm_swp);
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		shm_info.shm_tot = ns->shm_tot;
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		shm_info.swap_attempts = 0;
		shm_info.swap_successes = 0;
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		err = ipc_get_maxid(&shm_ids(ns));
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		up_read(&shm_ids(ns).rwsem);
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		if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
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			err = -EFAULT;
			goto out;
		}

		err = err < 0 ? 0 : err;
		goto out;
	}
	case SHM_STAT:
	case IPC_STAT:
	{
		struct shmid64_ds tbuf;
		int result;
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893
		rcu_read_lock();
894
		if (cmd == SHM_STAT) {
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			shp = shm_obtain_object(ns, shmid);
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			if (IS_ERR(shp)) {
				err = PTR_ERR(shp);
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				goto out_unlock;
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			}
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			result = shp->shm_perm.id;
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		} else {
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			shp = shm_obtain_object_check(ns, shmid);
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			if (IS_ERR(shp)) {
				err = PTR_ERR(shp);
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				goto out_unlock;
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			}
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			result = 0;
		}
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		err = -EACCES;
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		if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
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			goto out_unlock;
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		err = security_shm_shmctl(shp, cmd);
		if (err)
			goto out_unlock;
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		memset(&tbuf, 0, sizeof(tbuf));
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		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;
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		tbuf.shm_nattch	= shp->shm_nattch;
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		rcu_read_unlock();

		if (copy_shmid_to_user(buf, &tbuf, version))
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			err = -EFAULT;
		else
			err = result;
		goto out;
	}
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	default:
		return -EINVAL;
	}

out_unlock:
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	rcu_read_unlock();
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out:
	return err;
}

SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
{
	struct shmid_kernel *shp;
	int err, version;
	struct ipc_namespace *ns;

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	if (cmd < 0 || shmid < 0)
		return -EINVAL;
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	version = ipc_parse_version(&cmd);
	ns = current->nsproxy->ipc_ns;

	switch (cmd) {
	case IPC_INFO:
	case SHM_INFO:
	case SHM_STAT:
	case IPC_STAT:
		return shmctl_nolock(ns, shmid, cmd, version, buf);
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	case IPC_RMID:
	case IPC_SET:
		return shmctl_down(ns, shmid, cmd, buf, version);
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	case SHM_LOCK:
	case SHM_UNLOCK:
	{
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		struct file *shm_file;
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		rcu_read_lock();
		shp = shm_obtain_object_check(ns, shmid);
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		if (IS_ERR(shp)) {
			err = PTR_ERR(shp);
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			goto out_unlock1;
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		}

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		audit_ipc_obj(&(shp->shm_perm));
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		err = security_shm_shmctl(shp, cmd);
		if (err)
			goto out_unlock1;
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		ipc_lock_object(&shp->shm_perm);
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		/* check if shm_destroy() is tearing down shp */
		if (!ipc_valid_object(&shp->shm_perm)) {
			err = -EIDRM;
			goto out_unlock0;
		}

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		if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
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			kuid_t euid = current_euid();
			if (!uid_eq(euid, shp->shm_perm.uid) &&
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			    !uid_eq(euid, shp->shm_perm.cuid)) {
				err = -EPERM;
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				goto out_unlock0;
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			}
			if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK)) {
				err = -EPERM;
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				goto out_unlock0;
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			}
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		}

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		shm_file = shp->shm_file;
		if (is_file_hugepages(shm_file))
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			goto out_unlock0;
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		if (cmd == SHM_LOCK) {
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			struct user_struct *user = current_user();
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			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;
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			}
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			goto out_unlock0;
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		}
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		/* SHM_UNLOCK */
		if (!(shp->shm_perm.mode & SHM_LOCKED))
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			goto out_unlock0;
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		shmem_lock(shm_file, 0, shp->mlock_user);
		shp->shm_perm.mode &= ~SHM_LOCKED;
		shp->mlock_user = NULL;
		get_file(shm_file);
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		ipc_unlock_object(&shp->shm_perm);
		rcu_read_unlock();
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		shmem_unlock_mapping(shm_file->f_mapping);
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		fput(shm_file);
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		return err;
1031
	}
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	default:
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		return -EINVAL;
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	}

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out_unlock0:
	ipc_unlock_object(&shp->shm_perm);
out_unlock1:
	rcu_read_unlock();
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	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.
 */
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long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr,
	      unsigned long shmlba)
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{
	struct shmid_kernel *shp;
	unsigned long addr;
	unsigned long size;
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	struct file *file;
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	int    err;
	unsigned long flags;
	unsigned long prot;
	int acc_mode;
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	struct ipc_namespace *ns;
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	struct shm_file_data *sfd;
	struct path path;
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	fmode_t f_mode;
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	unsigned long populate = 0;
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	err = -EINVAL;
	if (shmid < 0)
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		goto out;
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	else if ((addr = (ulong)shmaddr)) {
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		if (addr & (shmlba - 1)) {
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			if (shmflg & SHM_RND)
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				addr &= ~(shmlba - 1);	   /* round down */
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			else
#ifndef __ARCH_FORCE_SHMLBA
				if (addr & ~PAGE_MASK)
#endif
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					goto out;
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		}
		flags = MAP_SHARED | MAP_FIXED;
	} else {
		if ((shmflg & SHM_REMAP))
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			goto out;
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		flags = MAP_SHARED;
	}

	if (shmflg & SHM_RDONLY) {
		prot = PROT_READ;
		acc_mode = S_IRUGO;
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		f_mode = FMODE_READ;
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	} else {
		prot = PROT_READ | PROT_WRITE;
		acc_mode = S_IRUGO | S_IWUGO;