// SPDX-License-Identifier: GPL-2.0
/*
* linux/ipc/util.c
* Copyright (C) 1992 Krishna Balasubramanian
*
* Sep 1997 - Call suser() last after "normal" permission checks so we
* get BSD style process accounting right.
* Occurs in several places in the IPC code.
* Chris Evans, <[email protected]>
* Nov 1999 - ipc helper functions, unified SMP locking
* Manfred Spraul <[email protected]>
* Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
* Mingming Cao <[email protected]>
* Mar 2006 - support for audit of ipc object properties
* Dustin Kirkland <[email protected]>
* Jun 2006 - namespaces ssupport
* OpenVZ, SWsoft Inc.
* Pavel Emelianov <[email protected]>
*
* General sysv ipc locking scheme:
* rcu_read_lock()
* obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
* tree.
* - perform initial checks (capabilities, auditing and permission,
* etc).
* - perform read-only operations, such as INFO command, that
* do not demand atomicity
* acquire the ipc lock (kern_ipc_perm.lock) through
* ipc_lock_object()
* - perform read-only operations that demand atomicity,
* such as STAT command.
* - perform data updates, such as SET, RMID commands and
* mechanism-specific operations (semop/semtimedop,
* msgsnd/msgrcv, shmat/shmdt).
* drop the ipc lock, through ipc_unlock_object().
* rcu_read_unlock()
*
* The ids->rwsem must be taken when:
* - creating, removing and iterating the existing entries in ipc
* identifier sets.
* - iterating through files under /proc/sysvipc/
*
* Note that sems have a special fast path that avoids kern_ipc_perm.lock -
* see sem_lock().
*/
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/init.h>
#include <linux/msg.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/notifier.h>
#include <linux/capability.h>
#include <linux/highuid.h>
#include <linux/security.h>
#include <linux/rcupdate.h>
#include <linux/workqueue.h>
#include <linux/seq_file.h>
#include <linux/proc_fs.h>
#include <linux/audit.h>
#include <linux/nsproxy.h>
#include <linux/rwsem.h>
#include <linux/memory.h>
#include <linux/ipc_namespace.h>
#include <linux/rhashtable.h>
#include <linux/log2.h>
#include <asm/unistd.h>
#include "util.h"
struct ipc_proc_iface {
const char *path;
const char *header;
int ids;
int (*show)(struct seq_file *, void *);
};
/**
* ipc_init - initialise ipc subsystem
*
* The various sysv ipc resources (semaphores, messages and shared
* memory) are initialised.
*
* A callback routine is registered into the memory hotplug notifier
* chain: since msgmni scales to lowmem this callback routine will be
* called upon successful memory add / remove to recompute msmgni.
*/
static int __init ipc_init(void)
{
proc_mkdir("sysvipc", NULL);
sem_init();
msg_init();
shm_init();
return 0;
}
device_initcall(ipc_init);
static const struct rhashtable_params ipc_kht_params = {
.head_offset = offsetof(struct kern_ipc_perm, khtnode),
.key_offset = offsetof(struct kern_ipc_perm, key),
.key_len = sizeof_field(struct kern_ipc_perm, key),
.automatic_shrinking = true,
};
/**
* ipc_init_ids - initialise ipc identifiers
* @ids: ipc identifier set
*
* Set up the sequence range to use for the ipc identifier range (limited
* below ipc_mni) then initialise the keys hashtable and ids idr.
*/
void ipc_init_ids(struct ipc_ids *ids)
{
ids->in_use = 0;
ids->seq = 0;
init_rwsem(&ids->rwsem);
rhashtable_init(&ids->key_ht, &ipc_kht_params);
idr_init(&ids->ipcs_idr);
ids->max_idx = -1;
ids->last_idx = -1;
#ifdef CONFIG_CHECKPOINT_RESTORE
ids->next_id = -1;
#endif
}
#ifdef CONFIG_PROC_FS
static const struct proc_ops sysvipc_proc_ops;
/**
* ipc_init_proc_interface - create a proc interface for sysipc types using a seq_file interface.
* @path: Path in procfs
* @header: Banner to be printed at the beginning of the file.
* @ids: ipc id table to iterate.
* @show: show routine.
*/
void __init ipc_init_proc_interface(const char *path, const char *header,
int ids, int (*show)(struct seq_file *, void *))
{
struct proc_dir_entry *pde;
struct ipc_proc_iface *iface;
iface = kmalloc(sizeof(*iface), GFP_KERNEL);
if (!iface)
return;
iface->path = path;
iface->header = header;
iface->ids = ids;
iface->show = show;
pde = proc_create_data(path,
S_IRUGO, /* world readable */
NULL, /* parent dir */
&sysvipc_proc_ops,
iface);
if (!pde)
kfree(iface);
}
#endif
/**
* ipc_findkey - find a key in an ipc identifier set
* @ids: ipc identifier set
* @key: key to find
*
* Returns the locked pointer to the ipc structure if found or NULL
* otherwise. If key is found ipc points to the owning ipc structure
*
* Called with writer ipc_ids.rwsem held.
*/
static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
{
struct kern_ipc_perm *ipcp;
ipcp = rhashtable_lookup_fast(&ids->key_ht, &key,
ipc_kht_params);
if (!ipcp)
return NULL;
rcu_read_lock();
ipc_lock_object(ipcp);
return ipcp;
}
/*
* Insert new IPC object into idr tree, and set sequence number and id
* in the correct order.
* Especially:
* - the sequence number must be set before inserting the object into the idr,
* because the sequence number is accessed without a lock.
* - the id can/must be set after inserting the object into the idr.
* All accesses must be done after getting kern_ipc_perm.lock.
*
* The caller must own kern_ipc_perm.lock.of the new object.
* On error, the function returns a (negative) error code.
*
* To conserve sequence number space, especially with extended ipc_mni,
* the sequence number is incremented only when the returned ID is less than
* the last one.
*/
static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new)
{
int idx, next_id = -1;
#ifdef CONFIG_CHECKPOINT_RESTORE
next_id = ids->next_id;
ids->next_id = -1;
#endif
/*
* As soon as a new object is inserted into the idr,
* ipc_obtain_object_idr() or ipc_obtain_object_check() can find it,
* and the lockless preparations for ipc operations can start.
* This means especially: permission checks, audit calls, allocation
* of undo structures, ...
*
* Thus the object must be fully initialized, and if something fails,
* then the full tear-down sequence must be followed.
* (i.e.: set new->deleted, reduce refcount, call_rcu())
*/
if (next_id < 0) { /* !CHECKPOINT_RESTORE or next_id is unset */
int max_idx;
max_idx = max(ids->in_use*3/2, ipc_min_cycle);
max_idx = min(max_idx, ipc_mni);
/* allocate the idx, with a NULL struct kern_ipc_perm */
idx = idr_alloc_cyclic(&ids->ipcs_idr, NULL, 0, max_idx,
GFP_NOWAIT);
if (idx >= 0) {
/*
* idx got allocated successfully.
* Now calculate the sequence number and set the
* pointer for real.
*/
if (idx <= ids->last_idx) {
ids->seq++;
if (ids->seq >= ipcid_seq_max())
ids->seq = 0;
}
ids->last_idx = idx;
new->seq = ids->seq;
/* no need for smp_wmb(), this is done
* inside idr_replace, as part of
* rcu_assign_pointer
*/
idr_replace(&ids->ipcs_idr, new, idx);
}
} else {
new->seq = ipcid_to_seqx(next_id);
idx = idr_alloc(&ids->ipcs_idr, new, ipcid_to_idx(next_id),
0, GFP_NOWAIT);
}
if (idx >= 0)
new->id = (new->seq << ipcmni_seq_shift()) + idx;
return idx;
}
/**
* ipc_addid - add an ipc identifier
* @ids: ipc identifier set
* @new: new ipc permission set
* @limit: limit for the number of used ids
*
* Add an entry 'new' to the ipc ids idr. The permissions object is
* initialised and the first free entry is set up and the index assigned
* is returned. The 'new' entry is returned in a locked state on success.
*
* On failure the entry is not locked and a negative err-code is returned.
* The caller must use ipc_rcu_putref() to free the identifier.
*
* Called with writer ipc_ids.rwsem held.
*/
int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit)
{
kuid_t euid;
kgid_t egid;
int idx, err;
/* 1) Initialize the refcount so that ipc_rcu_putref works */
refcount_set(&new->refcount, 1);
if (limit > ipc_mni)
limit = ipc_mni;
if (ids->in_use >= limit)
return -ENOSPC;
idr_preload(GFP_KERNEL);
spin_lock_init(&new->lock);
rcu_read_lock();
spin_lock(&new->lock);
current_euid_egid(&euid, &egid);
new->cuid = new->uid = euid;
new->gid = new->cgid = egid;
new->deleted = false;
idx = ipc_idr_alloc(ids, new);
idr_preload_end();
if (idx >= 0 && new->key != IPC_PRIVATE) {
err = rhashtable_insert_fast(&ids->key_ht, &new->khtnode,
ipc_kht_params);
if (err < 0) {
idr_remove(&ids->ipcs_idr, idx);
idx = err;
}
}
if (idx < 0) {
new->deleted = true;
spin_unlock(&new->lock);
rcu_read_unlock();
return idx;
}
ids->in_use++;
if (idx > ids->max_idx)
ids->max_idx = idx;
return idx;
}
/**
* ipcget_new - create a new ipc object
* @ns: ipc namespace
* @ids: ipc identifier set
* @ops: the actual creation routine to call
* @params: its parameters
*
* This routine is called by sys_msgget, sys_semget() and sys_shmget()
* when the key is IPC_PRIVATE.
*/
static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
const struct ipc_ops *ops, struct ipc_params *params)
{
int err;
down_write(&ids->rwsem);
err = ops->getnew(ns, params);
up_write(&ids->rwsem);
return err;
}
/**
* ipc_check_perms - check security and permissions for an ipc object
* @ns: ipc namespace
* @ipcp: ipc permission set
* @ops: the actual security routine to call
* @params: its parameters
*
* This routine is called by sys_msgget(), sys_semget() and sys_shmget()
* when the key is not IPC_PRIVATE and that key already exists in the
* ds IDR.
*
* On success, the ipc id is returned.
*
* It is called with ipc_ids.rwsem and ipcp->lock held.
*/
static int ipc_check_perms(struct ipc_namespace *ns,
struct kern_ipc_perm *ipcp,
const struct ipc_ops *ops,
struct ipc_params *params)
{
int err;
if (ipcperms(ns, ipcp, params->flg))
err = -EACCES;
else {
err = ops->associate(ipcp, params->flg);
if (!err)
err = ipcp->id;
}
return err;
}
/**
* ipcget_public - get an ipc object or create a new one
* @ns: ipc namespace
* @ids: ipc identifier set
* @ops: the actual creation routine to call
* @params: its parameters
*
* This routine is called by sys_msgget, sys_semget() and sys_shmget()
* when the key is not IPC_PRIVATE.
* It adds a new entry if the key is not found and does some permission
* / security checkings if the key is found.
*
* On success, the ipc id is returned.
*/
static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
const struct ipc_ops *ops, struct ipc_params *params)
{
struct kern_ipc_perm *ipcp;
int flg = params->flg;
int err;
/*
* Take the lock as a writer since we are potentially going to add
* a new entry + read locks are not "upgradable"
*/
down_write(&ids->rwsem);
ipcp = ipc_findkey(ids, params->key);
if (ipcp == NULL) {
/* key not used */
if (!(flg & IPC_CREAT))
err = -ENOENT;
else
err = ops->getnew(ns, params);
} else {
/* ipc object has been locked by ipc_findkey() */
if (flg & IPC_CREAT && flg & IPC_EXCL)
err = -EEXIST;
else {
err = 0;
if (ops->more_checks)
err = ops->more_checks(ipcp, params);
if (!err)
/*
* ipc_check_perms returns the IPC id on
* success
*/
err = ipc_check_perms(ns, ipcp, ops, params);
}
ipc_unlock(ipcp);
}
up_write(&ids->rwsem);
return err;
}
/**
* ipc_kht_remove - remove an ipc from the key hashtable
* @ids: ipc identifier set
* @ipcp: ipc perm structure containing the key to remove
*
* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
* before this function is called, and remain locked on the exit.
*/
static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
{
if (ipcp->key != IPC_PRIVATE)
WARN_ON_ONCE(rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
ipc_kht_params));
}
/**
* ipc_search_maxidx - search for the highest assigned index
* @ids: ipc identifier set
* @limit: known upper limit for highest assigned index
*
* The function determines the highest assigned index in @ids. It is intended
* to be called when ids->max_idx needs to be updated.
* Updating ids->max_idx is necessary when the current highest index ipc
* object is deleted.
* If no ipc object is allocated, then -1 is returned.
*
* ipc_ids.rwsem needs to be held by the caller.
*/
static int ipc_search_maxidx(struct ipc_ids *ids, int limit)
{
int tmpidx;
int i;
int retval;
i = ilog2(limit+1);
retval = 0;
for (; i >= 0; i--) {
tmpidx = retval | (1<<i);
/*
* "0" is a possible index value, thus search using
* e.g. 15,7,3,1,0 instead of 16,8,4,2,1.
*/
tmpidx = tmpidx-1;
if (idr_get_next(&ids->ipcs_idr, &tmpidx))
retval |= (1<<i);
}
return retval - 1;
}
/**
* ipc_rmid - remove an ipc identifier
* @ids: ipc identifier set
* @ipcp: ipc perm structure containing the identifier to remove
*
* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
* before this function is called, and remain locked on the exit.
*/
void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
{
int idx = ipcid_to_idx(ipcp->id);
WARN_ON_ONCE(idr_remove(&ids->ipcs_idr, idx) != ipcp);
ipc_kht_remove(ids, ipcp);
ids->in_use--;
ipcp->deleted = true;
if (unlikely(idx == ids->max_idx)) {
idx = ids->max_idx-1;
if (idx >= 0)
idx = ipc_search_maxidx(ids, idx);
ids->max_idx = idx;
}
}
/**
* ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
* @ids: ipc identifier set
* @ipcp: ipc perm structure containing the key to modify
*
* ipc_ids.rwsem (as a writer) and the spinlock for this ID are held
* before this function is called, and remain locked on the exit.
*/
void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
{
ipc_kht_remove(ids, ipcp);
ipcp->key = IPC_PRIVATE;
}
bool ipc_rcu_getref(struct kern_ipc_perm *ptr)
{
return refcount_inc_not_zero(&ptr->refcount);
}
void ipc_rcu_putref(struct kern_ipc_perm *ptr,
void (*func)(struct rcu_head *head))
{
if (!refcount_dec_and_test(&ptr->refcount))
return;
call_rcu(&ptr->rcu, func);
}
/**
* ipcperms - check ipc permissions
* @ns: ipc namespace
* @ipcp: ipc permission set
* @flag: desired permission set
*
* Check user, group, other permissions for access
* to ipc resources. return 0 if allowed
*
* @flag will most probably be 0 or ``S_...UGO`` from <linux/stat.h>
*/
int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag)
{
kuid_t euid = current_euid();
int requested_mode, granted_mode;
audit_ipc_obj(ipcp);
requested_mode = (flag >> 6) | (flag >> 3) | flag;
granted_mode = ipcp->mode;
if (uid_eq(euid, ipcp->cuid) ||
uid_eq(euid, ipcp->uid))
granted_mode >>= 6;
else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
granted_mode >>= 3;
/* is there some bit set in requested_mode but not in granted_mode? */
if ((requested_mode & ~granted_mode & 0007) &&
!ns_capable(ns->user_ns, CAP_IPC_OWNER))
return -1;
return security_ipc_permission(ipcp, flag);
}
/*
* Functions to convert between the kern_ipc_perm structure and the
* old/new ipc_perm structures
*/
/**
* kernel_to_ipc64_perm - convert kernel ipc permissions to user
* @in: kernel permissions
* @out: new style ipc permissions
*
* Turn the kernel object @in into a set of permissions descriptions
* for returning to userspace (@out).
*/
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out)
{
out->key = in->key;
out->uid = from_kuid_munged(current_user_ns(), in->uid);
out->gid = from_kgid_munged(current_user_ns(), in->gid);
out->cuid = from_kuid_munged(current_user_ns(), in->cuid);
out->cgid = from_kgid_munged(current_user_ns(), in->cgid);
out->mode = in->mode;
out->seq = in->seq;
}
/**
* ipc64_perm_to_ipc_perm - convert new ipc permissions to old
* @in: new style ipc permissions
* @out: old style ipc permissions
*
* Turn the new style permissions object @in into a compatibility
* object and store it into the @out pointer.
*/
void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out)
{
out->key = in->key;
SET_UID(out->uid, in->uid);
SET_GID(out->gid, in->gid);
SET_UID(out->cuid, in->cuid);
SET_GID(out->cgid, in->cgid);
out->mode = in->mode;
out->seq = in->seq;
}
/**
* ipc_obtain_object_idr
* @ids: ipc identifier set
* @id: ipc id to look for
*
* Look for an id in the ipc ids idr and return associated ipc object.
*
* Call inside the RCU critical section.
* The ipc object is *not* locked on exit.
*/
struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id)
{
struct kern_ipc_perm *out;
int idx = ipcid_to_idx(id);
out = idr_find(&ids->ipcs_idr, idx);
if (!out)
return ERR_PTR(-EINVAL);
return out;
}
/**
* ipc_obtain_object_check
* @ids: ipc identifier set
* @id: ipc id to look for
*
* Similar to ipc_obtain_object_idr() but also checks the ipc object
* sequence number.
*
* Call inside the RCU critical section.
* The ipc object is *not* locked on exit.
*/
struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id)
{
struct kern_ipc_perm *out = ipc_obtain_object_idr(ids, id);
if (IS_ERR(out))
goto out;
if (ipc_checkid(out, id))
return ERR_PTR(-EINVAL);
out:
return out;
}
/**
* ipcget - Common sys_*get() code
* @ns: namespace
* @ids: ipc identifier set
* @ops: operations to be called on ipc object creation, permission checks
* and further checks
* @params: the parameters needed by the previous operations.
*
* Common routine called by sys_msgget(), sys_semget() and sys_shmget().
*/
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
const struct ipc_ops *ops, struct ipc_params *params)
{
if (params->key == IPC_PRIVATE)
return ipcget_new(ns, ids, ops, params);
else
return ipcget_public(ns, ids, ops, params);
}
/**
* ipc_update_perm - update the permissions of an ipc object
* @in: the permission given as input.
* @out: the permission of the ipc to set.
*/
int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out)
{
kuid_t uid = make_kuid(current_user_ns(), in->uid);
kgid_t gid = make_kgid(current_user_ns(), in->gid);
if (!uid_valid(uid) || !gid_valid(gid))
return -EINVAL;
out->uid = uid;
out->gid = gid;
out->mode = (out->mode & ~S_IRWXUGO)
| (in->mode & S_IRWXUGO);
return 0;
}
/**
* ipcctl_obtain_check - retrieve an ipc object and check permissions
* @ns: ipc namespace
* @ids: the table of ids where to look for the ipc
* @id: the id of the ipc to retrieve
* @cmd: the cmd to check
* @perm: the permission to set
* @extra_perm: one extra permission parameter used by msq
*
* This function does some common audit and permissions check for some IPC_XXX
* cmd and is called from semctl_down, shmctl_down and msgctl_down.
*
* It:
* - retrieves the ipc object with the given id in the given table.
* - performs some audit and permission check, depending on the given cmd
* - returns a pointer to the ipc object or otherwise, the corresponding
* error.
*
* Call holding the both the rwsem and the rcu read lock.
*/
struct kern_ipc_perm *ipcctl_obtain_check(struct ipc_namespace *ns,
struct ipc_ids *ids, int id, int cmd,
struct ipc64_perm *perm, int extra_perm)
{
kuid_t euid;
int err = -EPERM;
struct kern_ipc_perm *ipcp;
ipcp = ipc_obtain_object_check(ids, id);
if (IS_ERR(ipcp)) {
err = PTR_ERR(ipcp);
goto err;
}
audit_ipc_obj(ipcp);
if (cmd == IPC_SET)
audit_ipc_set_perm(extra_perm, perm->uid,
perm->gid, perm->mode);
euid = current_euid();
if (uid_eq(euid, ipcp->cuid) || uid_eq(euid, ipcp->uid) ||
ns_capable(ns->user_ns, CAP_SYS_ADMIN))
return ipcp; /* successful lookup */
err:
return ERR_PTR(err);
}
#ifdef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
/**
* ipc_parse_version - ipc call version
* @cmd: pointer to command
*
* Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
* The @cmd value is turned from an encoding command and version into
* just the command code.
*/
int ipc_parse_version(int *cmd)
{
if (*cmd & IPC_64) {
*cmd ^= IPC_64;
return IPC_64;
} else {
return IPC_OLD;
}
}
#endif /* CONFIG_ARCH_WANT_IPC_PARSE_VERSION */
#ifdef CONFIG_PROC_FS
struct ipc_proc_iter {
struct ipc_namespace *ns;
struct pid_namespace *pid_ns;
struct ipc_proc_iface *iface;
};
struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s)
{
struct ipc_proc_iter *iter = s->private;
return iter->pid_ns;
}
/**
* sysvipc_find_ipc - Find and lock the ipc structure based on seq pos
* @ids: ipc identifier set
* @pos: expected position
*
* The function finds an ipc structure, based on the sequence file
* position @pos. If there is no ipc structure at position @pos, then
* the successor is selected.
* If a structure is found, then it is locked (both rcu_read_lock() and
* ipc_lock_object()) and @pos is set to the position needed to locate
* the found ipc structure.
* If nothing is found (i.e. EOF), @pos is not modified.
*
* The function returns the found ipc structure, or NULL at EOF.
*/
static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos)
{
int tmpidx;
struct kern_ipc_perm *ipc;
/* convert from position to idr index -> "-1" */
tmpidx = *pos - 1;
ipc = idr_get_next(&ids->ipcs_idr, &tmpidx);
if (ipc != NULL) {
rcu_read_lock();
ipc_lock_object(ipc);
/* convert from idr index to position -> "+1" */
*pos = tmpidx + 1;
}
return ipc;
}
static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos)
{
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct kern_ipc_perm *ipc = it;
/* If we had an ipc id locked before, unlock it */
if (ipc && ipc != SEQ_START_TOKEN)
ipc_unlock(ipc);
/* Next -> search for *pos+1 */
(*pos)++;
return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos);
}
/*
* File positions: pos 0 -> header, pos n -> ipc idx = n - 1.
* SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
*/
static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
{
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct ipc_ids *ids;
ids = &iter->ns->ids[iface->ids];
/*
* Take the lock - this will be released by the corresponding
* call to stop().
*/
down_read(&ids->rwsem);
/* pos < 0 is invalid */
if (*pos < 0)
return NULL;
/* pos == 0 means header */
if (*pos == 0)
return SEQ_START_TOKEN;
/* Otherwise return the correct ipc structure */
return sysvipc_find_ipc(ids, pos);
}
static void sysvipc_proc_stop(struct seq_file *s, void *it)
{
struct kern_ipc_perm *ipc = it;
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
struct ipc_ids *ids;
/* If we had a locked structure, release it */
if (ipc && ipc != SEQ_START_TOKEN)
ipc_unlock(ipc);
ids = &iter->ns->ids[iface->ids];
/* Release the lock we took in start() */
up_read(&ids->rwsem);
}
static int sysvipc_proc_show(struct seq_file *s, void *it)
{
struct ipc_proc_iter *iter = s->private;
struct ipc_proc_iface *iface = iter->iface;
if (it == SEQ_START_TOKEN) {
seq_puts(s, iface->header);
return 0;
}
return iface->show(s, it);
}
static const struct seq_operations sysvipc_proc_seqops = {
.start = sysvipc_proc_start,
.stop = sysvipc_proc_stop,
.next = sysvipc_proc_next,
.show = sysvipc_proc_show,
};
static int sysvipc_proc_open(struct inode *inode, struct file *file)
{
struct ipc_proc_iter *iter;
iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter));
if (!iter)
return -ENOMEM;
iter->iface = pde_data(inode);
iter->ns = get_ipc_ns(current->nsproxy->ipc_ns);
iter->pid_ns = get_pid_ns(task_active_pid_ns(current));
return 0;
}
static int sysvipc_proc_release(struct inode *inode, struct file *file)
{
struct seq_file *seq = file->private_data;
struct ipc_proc_iter *iter = seq->private;
put_ipc_ns(iter->ns);
put_pid_ns(iter->pid_ns);
return seq_release_private(inode, file);
}
static const struct proc_ops sysvipc_proc_ops = {
.proc_flags = PROC_ENTRY_PERMANENT,
.proc_open = sysvipc_proc_open,
.proc_read = seq_read,
.proc_lseek = seq_lseek,
.proc_release = sysvipc_proc_release,
};
#endif /* CONFIG_PROC_FS */
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