shm.c 29.2 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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 */

#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 <asm/uaccess.h>

#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.rw_mutex (writer) and the shp structure locked.
 * Only shm_ids.rw_mutex 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){
		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);

void __init shm_init (void)
{
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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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/*
 * shm_lock_(check_) routines are called in the paths where the rw_mutex
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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();
	spin_lock(&ipcp->shm_perm.lock);
}

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static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
						int id)
{
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	struct kern_ipc_perm *ipcp = ipc_lock_check(&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_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
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{
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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.rw_mutex (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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	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);
	if (!is_file_hugepages(shp->shm_file))
		shmem_lock(shp->shm_file, 0, shp->mlock_user);
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	else if (shp->mlock_user)
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		user_shm_unlock(shp->shm_file->f_path.dentry->d_inode->i_size,
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						shp->mlock_user);
	fput (shp->shm_file);
	security_shm_free(shp);
	ipc_rcu_putref(shp);
}

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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;
	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).rw_mutex);
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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);
	up_write(&shm_ids(ns).rw_mutex);
}

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/* Called with ns->shm_ids(ns).rw_mutex locked */
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static int shm_try_destroy_current(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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	if (shp->shm_creator != current)
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		return 0;

	/*
	 * Mark it as orphaned to destroy the segment when
	 * kernel.shm_rmid_forced is changed.
	 * It is noop if the following shm_may_destroy() returns true.
	 */
	shp->shm_creator = NULL;

	/*
	 * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
	 * is not set, it shouldn't be deleted here.
	 */
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	if (!ns->shm_rmid_forced)
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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;
}

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/* Called with ns->shm_ids(ns).rw_mutex 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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	 *
	 * As shp->* are changed under rw_mutex, 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)
{
	down_write(&shm_ids(ns).rw_mutex);
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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).rw_mutex);
}


void exit_shm(struct task_struct *task)
{
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	struct ipc_namespace *ns = task->nsproxy->ipc_ns;
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	if (shm_ids(ns).in_use == 0)
		return;

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	/* Destroy all already created segments, but not mapped yet */
	down_write(&shm_ids(ns).rw_mutex);
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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_current, ns);
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	up_write(&shm_ids(ns).rw_mutex);
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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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	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 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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};

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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};

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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.rw_mutex 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;
	int numpages = (size + PAGE_SIZE -1) >> PAGE_SHIFT;
	struct file * file;
	char name[13];
	int id;
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	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 (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;
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	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) {
		ipc_rcu_putref(shp);
		return error;
	}

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	sprintf (name, "SYSV%08x", key);
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	if (shmflg & SHM_HUGETLB) {
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		/* hugetlb_file_setup applies strict accounting */
		if (shmflg & SHM_NORESERVE)
			acctflag = VM_NORESERVE;
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		file = hugetlb_file_setup(name, 0, size, acctflag,
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					&shp->mlock_user, HUGETLB_SHMFS_INODE);
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	} else {
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		/*
		 * Do not allow no accounting for OVERCOMMIT_NEVER, even
	 	 * if it's asked for.
		 */
		if  ((shmflg & SHM_NORESERVE) &&
				sysctl_overcommit_memory != OVERCOMMIT_NEVER)
494
			acctflag = VM_NORESERVE;
495
		file = shmem_file_setup(name, size, acctflag);
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	}
	error = PTR_ERR(file);
	if (IS_ERR(file))
		goto no_file;

501
	id = ipc_addid(&shm_ids(ns), &shp->shm_perm, ns->shm_ctlmni);
502 503
	if (id < 0) {
		error = id;
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		goto no_id;
505
	}
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506

507
	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;
514
	shp->shm_creator = current;
515 516 517 518
	/*
	 * shmid gets reported as "inode#" in /proc/pid/maps.
	 * proc-ps tools use this. Changing this will break them.
	 */
N
Nadia Derbey 已提交
519
	file->f_dentry->d_inode->i_ino = shp->shm_perm.id;
520

K
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521
	ns->shm_tot += numpages;
N
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522
	error = shp->shm_perm.id;
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523
	shm_unlock(shp);
N
Nadia Derbey 已提交
524
	return error;
L
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no_id:
527
	if (is_file_hugepages(file) && shp->mlock_user)
528
		user_shm_unlock(size, shp->mlock_user);
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	fput(file);
no_file:
	security_shm_free(shp);
	ipc_rcu_putref(shp);
	return error;
}

N
Nadia Derbey 已提交
536
/*
N
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537
 * Called with shm_ids.rw_mutex and ipcp locked.
N
Nadia Derbey 已提交
538
 */
N
Nadia Derbey 已提交
539
static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
N
Nadia Derbey 已提交
540
{
N
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541 542 543 544
	struct shmid_kernel *shp;

	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
	return security_shm_associate(shp, shmflg);
N
Nadia Derbey 已提交
545 546
}

N
Nadia Derbey 已提交
547
/*
N
Nadia Derbey 已提交
548
 * Called with shm_ids.rw_mutex and ipcp locked.
N
Nadia Derbey 已提交
549
 */
N
Nadia Derbey 已提交
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static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
				struct ipc_params *params)
N
Nadia Derbey 已提交
552
{
N
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553 554 555 556
	struct shmid_kernel *shp;

	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
	if (shp->shm_segsz < params->u.size)
N
Nadia Derbey 已提交
557 558 559 560 561
		return -EINVAL;

	return 0;
}

562
SYSCALL_DEFINE3(shmget, key_t, key, size_t, size, int, shmflg)
L
Linus Torvalds 已提交
563
{
K
Kirill Korotaev 已提交
564
	struct ipc_namespace *ns;
N
Nadia Derbey 已提交
565 566
	struct ipc_ops shm_ops;
	struct ipc_params shm_params;
K
Kirill Korotaev 已提交
567 568

	ns = current->nsproxy->ipc_ns;
L
Linus Torvalds 已提交
569

N
Nadia Derbey 已提交
570 571 572
	shm_ops.getnew = newseg;
	shm_ops.associate = shm_security;
	shm_ops.more_checks = shm_more_checks;
N
Nadia Derbey 已提交
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N
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	shm_params.key = key;
	shm_params.flg = shmflg;
	shm_params.u.size = size;
L
Linus Torvalds 已提交
577

N
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578
	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)
{
	switch(version) {
	case IPC_64:
		return copy_to_user(buf, in, sizeof(*in));
	case IPC_OLD:
	    {
		struct shmid_ds out;

590
		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;
	}
}

607 608
static inline unsigned long
copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
L
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{
	switch(version) {
	case IPC_64:
612
		if (copy_from_user(out, buf, sizeof(*out)))
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613 614 615 616 617 618 619 620 621
			return -EFAULT;
		return 0;
	case IPC_OLD:
	    {
		struct shmid_ds tbuf_old;

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

622 623 624
		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)
{
	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;
	}
}

659 660 661 662 663 664 665 666 667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686
/*
 * Calculate and add used RSS and swap pages of a shm.
 * Called with shm_ids.rw_mutex 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 = shp->shm_file->f_path.dentry->d_inode;

	if (is_file_hugepages(shp->shm_file)) {
		struct address_space *mapping = inode->i_mapping;
		struct hstate *h = hstate_file(shp->shm_file);
		*rss_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
	}
}

N
Nadia Derbey 已提交
687
/*
N
Nadia Derbey 已提交
688
 * Called with shm_ids.rw_mutex held as a reader
N
Nadia Derbey 已提交
689
 */
K
Kirill Korotaev 已提交
690 691
static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
		unsigned long *swp)
L
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692
{
N
Nadia Derbey 已提交
693 694
	int next_id;
	int total, in_use;
L
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695 696 697 698

	*rss = 0;
	*swp = 0;

N
Nadia Derbey 已提交
699 700 701
	in_use = shm_ids(ns).in_use;

	for (total = 0, next_id = 0; total < in_use; next_id++) {
702
		struct kern_ipc_perm *ipc;
L
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		struct shmid_kernel *shp;

705 706
		ipc = idr_find(&shm_ids(ns).ipcs_idr, next_id);
		if (ipc == NULL)
L
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707
			continue;
708
		shp = container_of(ipc, struct shmid_kernel, shm_perm);
L
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709

710
		shm_add_rss_swap(shp, rss, swp);
N
Nadia Derbey 已提交
711 712

		total++;
L
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713 714 715
	}
}

716 717 718 719 720 721 722
/*
 * This function handles some shmctl commands which require the rw_mutex
 * to be held in write mode.
 * NOTE: no locks must be held, the rw_mutex is taken inside this function.
 */
static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
		       struct shmid_ds __user *buf, int version)
L
Linus Torvalds 已提交
723
{
724
	struct kern_ipc_perm *ipcp;
725
	struct shmid64_ds shmid64;
726 727 728 729
	struct shmid_kernel *shp;
	int err;

	if (cmd == IPC_SET) {
730
		if (copy_shmid_from_user(&shmid64, buf, version))
731 732 733
			return -EFAULT;
	}

734 735
	ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
			       &shmid64.shm_perm, 0);
736 737
	if (IS_ERR(ipcp))
		return PTR_ERR(ipcp);
738

739
	shp = container_of(ipcp, struct shmid_kernel, shm_perm);
740 741 742 743 744 745 746 747 748

	err = security_shm_shmctl(shp, cmd);
	if (err)
		goto out_unlock;
	switch (cmd) {
	case IPC_RMID:
		do_shm_rmid(ns, ipcp);
		goto out_up;
	case IPC_SET:
749
		ipc_update_perm(&shmid64.shm_perm, ipcp);
750 751 752 753 754 755 756 757 758 759 760 761
		shp->shm_ctim = get_seconds();
		break;
	default:
		err = -EINVAL;
	}
out_unlock:
	shm_unlock(shp);
out_up:
	up_write(&shm_ids(ns).rw_mutex);
	return err;
}

762
SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
763
{
L
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	struct shmid_kernel *shp;
	int err, version;
K
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	struct ipc_namespace *ns;
L
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767 768 769 770 771 772 773

	if (cmd < 0 || shmid < 0) {
		err = -EINVAL;
		goto out;
	}

	version = ipc_parse_version(&cmd);
K
Kirill Korotaev 已提交
774
	ns = current->nsproxy->ipc_ns;
L
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775 776 777 778 779 780 781 782 783 784

	switch (cmd) { /* replace with proc interface ? */
	case IPC_INFO:
	{
		struct shminfo64 shminfo;

		err = security_shm_shmctl(NULL, cmd);
		if (err)
			return err;

W
WANG Cong 已提交
785
		memset(&shminfo, 0, sizeof(shminfo));
K
Kirill Korotaev 已提交
786 787 788
		shminfo.shmmni = shminfo.shmseg = ns->shm_ctlmni;
		shminfo.shmmax = ns->shm_ctlmax;
		shminfo.shmall = ns->shm_ctlall;
L
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789 790 791 792

		shminfo.shmmin = SHMMIN;
		if(copy_shminfo_to_user (buf, &shminfo, version))
			return -EFAULT;
N
Nadia Derbey 已提交
793

N
Nadia Derbey 已提交
794
		down_read(&shm_ids(ns).rw_mutex);
N
Nadia Derbey 已提交
795
		err = ipc_get_maxid(&shm_ids(ns));
N
Nadia Derbey 已提交
796
		up_read(&shm_ids(ns).rw_mutex);
N
Nadia Derbey 已提交
797

L
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798 799 800 801 802 803 804 805 806 807 808 809
		if(err<0)
			err = 0;
		goto out;
	}
	case SHM_INFO:
	{
		struct shm_info shm_info;

		err = security_shm_shmctl(NULL, cmd);
		if (err)
			return err;

W
WANG Cong 已提交
810
		memset(&shm_info, 0, sizeof(shm_info));
N
Nadia Derbey 已提交
811
		down_read(&shm_ids(ns).rw_mutex);
K
Kirill Korotaev 已提交
812 813 814
		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;
L
Linus Torvalds 已提交
815 816
		shm_info.swap_attempts = 0;
		shm_info.swap_successes = 0;
N
Nadia Derbey 已提交
817
		err = ipc_get_maxid(&shm_ids(ns));
N
Nadia Derbey 已提交
818
		up_read(&shm_ids(ns).rw_mutex);
W
WANG Cong 已提交
819
		if (copy_to_user(buf, &shm_info, sizeof(shm_info))) {
L
Linus Torvalds 已提交
820 821 822 823 824 825 826 827 828 829 830 831
			err = -EFAULT;
			goto out;
		}

		err = err < 0 ? 0 : err;
		goto out;
	}
	case SHM_STAT:
	case IPC_STAT:
	{
		struct shmid64_ds tbuf;
		int result;
832 833 834 835 836 837 838

		if (cmd == SHM_STAT) {
			shp = shm_lock(ns, shmid);
			if (IS_ERR(shp)) {
				err = PTR_ERR(shp);
				goto out;
			}
N
Nadia Derbey 已提交
839
			result = shp->shm_perm.id;
L
Linus Torvalds 已提交
840
		} else {
841 842 843 844 845
			shp = shm_lock_check(ns, shmid);
			if (IS_ERR(shp)) {
				err = PTR_ERR(shp);
				goto out;
			}
L
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846 847
			result = 0;
		}
W
WANG Cong 已提交
848
		err = -EACCES;
849
		if (ipcperms(ns, &shp->shm_perm, S_IRUGO))
L
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850 851 852 853
			goto out_unlock;
		err = security_shm_shmctl(shp, cmd);
		if (err)
			goto out_unlock;
854
		memset(&tbuf, 0, sizeof(tbuf));
L
Linus Torvalds 已提交
855 856 857 858 859 860 861
		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;
862
		tbuf.shm_nattch	= shp->shm_nattch;
L
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863 864 865 866 867 868 869 870 871 872
		shm_unlock(shp);
		if(copy_shmid_to_user (buf, &tbuf, version))
			err = -EFAULT;
		else
			err = result;
		goto out;
	}
	case SHM_LOCK:
	case SHM_UNLOCK:
	{
873
		struct file *shm_file;
874

875 876 877
		shp = shm_lock_check(ns, shmid);
		if (IS_ERR(shp)) {
			err = PTR_ERR(shp);
L
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878 879 880
			goto out;
		}

A
Al Viro 已提交
881
		audit_ipc_obj(&(shp->shm_perm));
S
Steve Grubb 已提交
882

883
		if (!ns_capable(ns->user_ns, CAP_IPC_LOCK)) {
884
			uid_t euid = current_euid();
L
Linus Torvalds 已提交
885
			err = -EPERM;
886 887
			if (euid != shp->shm_perm.uid &&
			    euid != shp->shm_perm.cuid)
L
Linus Torvalds 已提交
888
				goto out_unlock;
J
Jiri Slaby 已提交
889
			if (cmd == SHM_LOCK && !rlimit(RLIMIT_MEMLOCK))
L
Linus Torvalds 已提交
890 891 892 893 894 895
				goto out_unlock;
		}

		err = security_shm_shmctl(shp, cmd);
		if (err)
			goto out_unlock;
896 897 898 899 900 901

		shm_file = shp->shm_file;
		if (is_file_hugepages(shm_file))
			goto out_unlock;

		if (cmd == SHM_LOCK) {
902
			struct user_struct *user = current_user();
903 904 905 906
			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;
L
Linus Torvalds 已提交
907
			}
908
			goto out_unlock;
L
Linus Torvalds 已提交
909
		}
910 911 912 913 914 915 916 917

		/* SHM_UNLOCK */
		if (!(shp->shm_perm.mode & SHM_LOCKED))
			goto out_unlock;
		shmem_lock(shm_file, 0, shp->mlock_user);
		shp->shm_perm.mode &= ~SHM_LOCKED;
		shp->mlock_user = NULL;
		get_file(shm_file);
L
Linus Torvalds 已提交
918
		shm_unlock(shp);
919
		shmem_unlock_mapping(shm_file->f_mapping);
920
		fput(shm_file);
L
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921 922 923 924
		goto out;
	}
	case IPC_RMID:
	case IPC_SET:
925 926
		err = shmctl_down(ns, shmid, cmd, buf, version);
		return err;
L
Linus Torvalds 已提交
927
	default:
928
		return -EINVAL;
L
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929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953
	}

out_unlock:
	shm_unlock(shp);
out:
	return err;
}

/*
 * Fix shmaddr, allocate descriptor, map shm, add attach descriptor to lists.
 *
 * NOTE! Despite the name, this is NOT a direct system call entrypoint. The
 * "raddr" thing points to kernel space, and there has to be a wrapper around
 * this.
 */
long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr)
{
	struct shmid_kernel *shp;
	unsigned long addr;
	unsigned long size;
	struct file * file;
	int    err;
	unsigned long flags;
	unsigned long prot;
	int acc_mode;
954
	unsigned long user_addr;
K
Kirill Korotaev 已提交
955
	struct ipc_namespace *ns;
956 957
	struct shm_file_data *sfd;
	struct path path;
958
	fmode_t f_mode;
L
Linus Torvalds 已提交
959

960 961
	err = -EINVAL;
	if (shmid < 0)
L
Linus Torvalds 已提交
962
		goto out;
963
	else if ((addr = (ulong)shmaddr)) {
L
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964 965 966 967 968 969 970
		if (addr & (SHMLBA-1)) {
			if (shmflg & SHM_RND)
				addr &= ~(SHMLBA-1);	   /* round down */
			else
#ifndef __ARCH_FORCE_SHMLBA
				if (addr & ~PAGE_MASK)
#endif
971
					goto out;
L
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972 973 974 975
		}
		flags = MAP_SHARED | MAP_FIXED;
	} else {
		if ((shmflg & SHM_REMAP))
976
			goto out;
L
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977 978 979 980 981 982 983

		flags = MAP_SHARED;
	}

	if (shmflg & SHM_RDONLY) {
		prot = PROT_READ;
		acc_mode = S_IRUGO;
984
		f_mode = FMODE_READ;
L
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985 986 987
	} else {
		prot = PROT_READ | PROT_WRITE;
		acc_mode = S_IRUGO | S_IWUGO;
988
		f_mode = FMODE_READ | FMODE_WRITE;
L
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989 990 991 992 993 994 995 996 997 998
	}
	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...
	 */
K
Kirill Korotaev 已提交
999
	ns = current->nsproxy->ipc_ns;
1000 1001 1002
	shp = shm_lock_check(ns, shmid);
	if (IS_ERR(shp)) {
		err = PTR_ERR(shp);
L
Linus Torvalds 已提交
1003
		goto out;
1004
	}
1005 1006

	err = -EACCES;
1007
	if (ipcperms(ns, &shp->shm_perm, acc_mode))
1008
		goto out_unlock;
L
Linus Torvalds 已提交
1009 1010

	err = security_shm_shmat(shp, shmaddr, shmflg);
1011 1012 1013
	if (err)
		goto out_unlock;

1014 1015
	path = shp->shm_file->f_path;
	path_get(&path);
L
Linus Torvalds 已提交
1016
	shp->shm_nattch++;
1017
	size = i_size_read(path.dentry->d_inode);
L
Linus Torvalds 已提交
1018 1019
	shm_unlock(shp);

1020 1021 1022
	err = -ENOMEM;
	sfd = kzalloc(sizeof(*sfd), GFP_KERNEL);
	if (!sfd)
1023
		goto out_put_dentry;
1024

1025 1026
	file = alloc_file(&path, f_mode,
			  is_file_hugepages(shp->shm_file) ?
1027 1028
				&shm_file_operations_huge :
				&shm_file_operations);
1029 1030 1031 1032 1033
	if (!file)
		goto out_free;

	file->private_data = sfd;
	file->f_mapping = shp->shm_file->f_mapping;
N
Nadia Derbey 已提交
1034
	sfd->id = shp->shm_perm.id;
1035 1036 1037 1038
	sfd->ns = get_ipc_ns(ns);
	sfd->file = shp->shm_file;
	sfd->vm_ops = NULL;

L
Linus Torvalds 已提交
1039 1040
	down_write(&current->mm->mmap_sem);
	if (addr && !(shmflg & SHM_REMAP)) {
1041
		err = -EINVAL;
L
Linus Torvalds 已提交
1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052
		if (find_vma_intersection(current->mm, addr, addr + size))
			goto invalid;
		/*
		 * If shm segment goes below stack, make sure there is some
		 * space left for the stack to grow (at least 4 pages).
		 */
		if (addr < current->mm->start_stack &&
		    addr > current->mm->start_stack - size - PAGE_SIZE * 5)
			goto invalid;
	}
		
1053 1054 1055 1056 1057
	user_addr = do_mmap (file, addr, size, prot, flags, 0);
	*raddr = user_addr;
	err = 0;
	if (IS_ERR_VALUE(user_addr))
		err = (long)user_addr;
L
Linus Torvalds 已提交
1058 1059 1060
invalid:
	up_write(&current->mm->mmap_sem);

1061 1062 1063
	fput(file);

out_nattch:
N
Nadia Derbey 已提交
1064
	down_write(&shm_ids(ns).rw_mutex);
N
Nadia Derbey 已提交
1065
	shp = shm_lock(ns, shmid);
1066
	BUG_ON(IS_ERR(shp));
L
Linus Torvalds 已提交
1067
	shp->shm_nattch--;
1068
	if (shm_may_destroy(ns, shp))
K
Kirill Korotaev 已提交
1069
		shm_destroy(ns, shp);
L
Linus Torvalds 已提交
1070 1071
	else
		shm_unlock(shp);
N
Nadia Derbey 已提交
1072
	up_write(&shm_ids(ns).rw_mutex);
L
Linus Torvalds 已提交
1073 1074 1075

out:
	return err;
1076 1077 1078 1079 1080 1081 1082

out_unlock:
	shm_unlock(shp);
	goto out;

out_free:
	kfree(sfd);
1083
out_put_dentry:
1084
	path_put(&path);
1085
	goto out_nattch;
L
Linus Torvalds 已提交
1086 1087
}

1088
SYSCALL_DEFINE3(shmat, int, shmid, char __user *, shmaddr, int, shmflg)
S
Stephen Rothwell 已提交
1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
{
	unsigned long ret;
	long err;

	err = do_shmat(shmid, shmaddr, shmflg, &ret);
	if (err)
		return err;
	force_successful_syscall_return();
	return (long)ret;
}

L
Linus Torvalds 已提交
1100 1101 1102 1103
/*
 * detach and kill segment if marked destroyed.
 * The work is done in shm_close.
 */
1104
SYSCALL_DEFINE1(shmdt, char __user *, shmaddr)
L
Linus Torvalds 已提交
1105 1106
{
	struct mm_struct *mm = current->mm;
1107
	struct vm_area_struct *vma;
L
Linus Torvalds 已提交
1108 1109
	unsigned long addr = (unsigned long)shmaddr;
	int retval = -EINVAL;
1110 1111 1112 1113
#ifdef CONFIG_MMU
	loff_t size = 0;
	struct vm_area_struct *next;
#endif
L
Linus Torvalds 已提交
1114

1115 1116 1117
	if (addr & ~PAGE_MASK)
		return retval;

L
Linus Torvalds 已提交
1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134 1135 1136 1137 1138 1139 1140 1141
	down_write(&mm->mmap_sem);

	/*
	 * This function tries to be smart and unmap shm segments that
	 * were modified by partial mlock or munmap calls:
	 * - It first determines the size of the shm segment that should be
	 *   unmapped: It searches for a vma that is backed by shm and that
	 *   started at address shmaddr. It records it's size and then unmaps
	 *   it.
	 * - Then it unmaps all shm vmas that started at shmaddr and that
	 *   are within the initially determined size.
	 * Errors from do_munmap are ignored: the function only fails if
	 * it's called with invalid parameters or if it's called to unmap
	 * a part of a vma. Both calls in this function are for full vmas,
	 * the parameters are directly copied from the vma itself and always
	 * valid - therefore do_munmap cannot fail. (famous last words?)
	 */
	/*
	 * If it had been mremap()'d, the starting address would not
	 * match the usual checks anyway. So assume all vma's are
	 * above the starting address given.
	 */
	vma = find_vma(mm, addr);

1142
#ifdef CONFIG_MMU
L
Linus Torvalds 已提交
1143 1144 1145 1146 1147 1148 1149 1150
	while (vma) {
		next = vma->vm_next;

		/*
		 * Check if the starting address would match, i.e. it's
		 * a fragment created by mprotect() and/or munmap(), or it
		 * otherwise it starts at this address with no hassles.
		 */
1151
		if ((vma->vm_ops == &shm_vm_ops) &&
L
Linus Torvalds 已提交
1152 1153 1154
			(vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) {


J
Josef Sipek 已提交
1155
			size = vma->vm_file->f_path.dentry->d_inode->i_size;
L
Linus Torvalds 已提交
1156 1157 1158 1159 1160 1161 1162 1163 1164 1165 1166 1167 1168 1169 1170 1171 1172
			do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
			/*
			 * We discovered the size of the shm segment, so
			 * break out of here and fall through to the next
			 * loop that uses the size information to stop
			 * searching for matching vma's.
			 */
			retval = 0;
			vma = next;
			break;
		}
		vma = next;
	}

	/*
	 * We need look no further than the maximum address a fragment
	 * could possibly have landed at. Also cast things to loff_t to
L
Lucas De Marchi 已提交
1173
	 * prevent overflows and make comparisons vs. equal-width types.
L
Linus Torvalds 已提交
1174
	 */
1175
	size = PAGE_ALIGN(size);
L
Linus Torvalds 已提交
1176 1177 1178 1179
	while (vma && (loff_t)(vma->vm_end - addr) <= size) {
		next = vma->vm_next;

		/* finding a matching vma now does not alter retval */
1180
		if ((vma->vm_ops == &shm_vm_ops) &&
L
Linus Torvalds 已提交
1181 1182 1183 1184 1185 1186
			(vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff)

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

1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197
#else /* CONFIG_MMU */
	/* under NOMMU conditions, the exact address to be destroyed must be
	 * given */
	retval = -EINVAL;
	if (vma->vm_start == addr && vma->vm_ops == &shm_vm_ops) {
		do_munmap(mm, vma->vm_start, vma->vm_end - vma->vm_start);
		retval = 0;
	}

#endif

L
Linus Torvalds 已提交
1198 1199 1200 1201 1202
	up_write(&mm->mmap_sem);
	return retval;
}

#ifdef CONFIG_PROC_FS
1203
static int sysvipc_shm_proc_show(struct seq_file *s, void *it)
L
Linus Torvalds 已提交
1204
{
1205
	struct shmid_kernel *shp = it;
1206 1207 1208
	unsigned long rss = 0, swp = 0;

	shm_add_rss_swap(shp, &rss, &swp);
L
Linus Torvalds 已提交
1209

1210 1211 1212 1213 1214
#if BITS_PER_LONG <= 32
#define SIZE_SPEC "%10lu"
#else
#define SIZE_SPEC "%21lu"
#endif
L
Linus Torvalds 已提交
1215

1216 1217
	return seq_printf(s,
			  "%10d %10d  %4o " SIZE_SPEC " %5u %5u  "
1218 1219
			  "%5lu %5u %5u %5u %5u %10lu %10lu %10lu "
			  SIZE_SPEC " " SIZE_SPEC "\n",
1220
			  shp->shm_perm.key,
N
Nadia Derbey 已提交
1221
			  shp->shm_perm.id,
A
Andrew Morton 已提交
1222
			  shp->shm_perm.mode,
1223 1224 1225
			  shp->shm_segsz,
			  shp->shm_cprid,
			  shp->shm_lprid,
1226
			  shp->shm_nattch,
1227 1228 1229 1230 1231 1232
			  shp->shm_perm.uid,
			  shp->shm_perm.gid,
			  shp->shm_perm.cuid,
			  shp->shm_perm.cgid,
			  shp->shm_atim,
			  shp->shm_dtim,
1233 1234 1235
			  shp->shm_ctim,
			  rss * PAGE_SIZE,
			  swp * PAGE_SIZE);
L
Linus Torvalds 已提交
1236 1237
}
#endif