path: root/ipc/shm.c

/*
 * linux/ipc/shm.c
 * Copyright (C) 1992, 1993 Krishna Balasubramanian
 *	 Many improvements/fixes by Bruno Haible.
 * Replaced `struct shm_desc' by `struct vm_area_struct', July 1994.
 * Fixed the shm swap deallocation (shm_unuse()), August 1998 Andrea Arcangeli.
 *
 * /proc/sysvipc/shm support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
 * BIGMEM support, Andrea Arcangeli <andrea@suse.de>
 * SMP thread shm, Jean-Luc Boyard <jean-luc.boyard@siemens.fr>
 * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
 * Make shmmax, shmall, shmmni sysctl'able, Christoph Rohland <cr@sap.com>
 * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
 * Move the mm functionality over to mm/shmem.c, Christoph Rohland <cr@sap.com>
 *
 * support for audit of ipc object properties and permission changes
 * Dustin Kirkland <dustin.kirkland@us.ibm.com>
 *
 * namespaces support
 * OpenVZ, SWsoft Inc.
 * Pavel Emelianov <xemul@openvz.org>
 */

#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
#include <linux/shm.h>
#include <linux/init.h>
#include <linux/file.h>
#include <linux/mman.h>
#include <linux/shmem_fs.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/audit.h>
#include <linux/capability.h>
#include <linux/ptrace.h>
#include <linux/seq_file.h>
#include <linux/mutex.h>
#include <linux/nsproxy.h>
#include <linux/mount.h>

#include <asm/uaccess.h>

#include "util.h"

struct shm_file_data {
	int id;
	struct ipc_namespace *ns;
	struct file *file;
	const struct vm_operations_struct *vm_ops;
};

#define shm_file_data(file) (*((struct shm_file_data **)&(file)->private_data))

static const struct file_operations shm_file_operations;
static struct vm_operations_struct shm_vm_ops;

static struct ipc_ids init_shm_ids;

#define shm_ids(ns)	(*((ns)->ids[IPC_SHM_IDS]))

#define shm_lock(ns, id)		\
	((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id))
#define shm_unlock(shp)			\
	ipc_unlock(&(shp)->shm_perm)
#define shm_get(ns, id)			\
	((struct shmid_kernel*)ipc_get(&shm_ids(ns),id))
#define shm_buildid(ns, id, seq)	\
	ipc_buildid(&shm_ids(ns), id, seq)

static int newseg (struct ipc_namespace *ns, key_t key,
		int shmflg, size_t size);
static void shm_open(struct vm_area_struct *vma);
static void shm_close(struct vm_area_struct *vma);
static void shm_destroy (struct ipc_namespace *ns, struct shmid_kernel *shp);
#ifdef CONFIG_PROC_FS
static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
#endif

static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
{
	ns->ids[IPC_SHM_IDS] = ids;
	ns->shm_ctlmax = SHMMAX;
	ns->shm_ctlall = SHMALL;
	ns->shm_ctlmni = SHMMNI;
	ns->shm_tot = 0;
	ipc_init_ids(ids, 1);
}

static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
{
	if (shp->shm_nattch){
		shp->shm_perm.mode |= SHM_DEST;
		/* Do not find it any more */
		shp->shm_perm.key = IPC_PRIVATE;
		shm_unlock(shp);
	} else
		shm_destroy(ns, shp);
}

int shm_init_ns(struct ipc_namespace *ns)
{
	struct ipc_ids *ids;

	ids = kmalloc(sizeof(struct ipc_ids), GFP_KERNEL);
	if (ids == NULL)
		return -ENOMEM;

	__shm_init_ns(ns, ids);
	return 0;
}

void shm_exit_ns(struct ipc_namespace *ns)
{
	int i;
	struct shmid_kernel *shp;

	mutex_lock(&shm_ids(ns).mutex);
	for (i = 0; i <= shm_ids(ns).max_id; i++) {
		shp = shm_lock(ns, i);
		if (shp == NULL)
			continue;

		do_shm_rmid(ns, shp);
	}
	mutex_unlock(&shm_ids(ns).mutex);

	ipc_fini_ids(ns->ids[IPC_SHM_IDS]);
	kfree(ns->ids[IPC_SHM_IDS]);
	ns->ids[IPC_SHM_IDS] = NULL;
}

void __init shm_init (void)
{
	__shm_init_ns(&init_ipc_ns, &init_shm_ids);
	ipc_init_proc_interface("sysvipc/shm",
				"       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime\n",
				IPC_SHM_IDS, sysvipc_shm_proc_show);
}

static inline int shm_checkid(struct ipc_namespace *ns