v4.19.13 snapshot.
diff --git a/ipc/util.c b/ipc/util.c
new file mode 100644
index 0000000..0af0575
--- /dev/null
+++ b/ipc/util.c
@@ -0,0 +1,864 @@
+// 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, <chris@ferret.lmh.ox.ac.uk>
+ * Nov 1999 - ipc helper functions, unified SMP locking
+ * Manfred Spraul <manfred@colorfullife.com>
+ * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
+ * Mingming Cao <cmm@us.ibm.com>
+ * Mar 2006 - support for audit of ipc object properties
+ * Dustin Kirkland <dustin.kirkland@us.ibm.com>
+ * Jun 2006 - namespaces ssupport
+ * OpenVZ, SWsoft Inc.
+ * Pavel Emelianov <xemul@openvz.org>
+ *
+ * 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 <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 = FIELD_SIZEOF(struct kern_ipc_perm, key),
+ .locks_mul = 1,
+ .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 IPCMNI) 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;
+#ifdef CONFIG_CHECKPOINT_RESTORE
+ ids->next_id = -1;
+#endif
+}
+
+#ifdef CONFIG_PROC_FS
+static const struct file_operations sysvipc_proc_fops;
+/**
+ * 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_fops,
+ 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.
+ */
+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 */
+ new->seq = ids->seq++;
+ if (ids->seq > IPCID_SEQ_MAX)
+ ids->seq = 0;
+ idx = idr_alloc(&ids->ipcs_idr, new, 0, 0, GFP_NOWAIT);
+ } 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 = SEQ_MULTIPLIER * new->seq + 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 > IPCMNI)
+ limit = IPCMNI;
+
+ 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)
+ rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode,
+ ipc_kht_params);
+}
+
+/**
+ * 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);
+
+ idr_remove(&ids->ipcs_idr, idx);
+ ipc_kht_remove(ids, ipcp);
+ ids->in_use--;
+ ipcp->deleted = true;
+
+ if (unlikely(idx == ids->max_idx)) {
+ do {
+ idx--;
+ if (idx == -1)
+ break;
+ } while (!idr_find(&ids->ipcs_idr, 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;
+}
+
+/*
+ * This routine locks the ipc structure found at least at position pos.
+ */
+static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
+ loff_t *new_pos)
+{
+ struct kern_ipc_perm *ipc;
+ int total, id;
+
+ total = 0;
+ for (id = 0; id < pos && total < ids->in_use; id++) {
+ ipc = idr_find(&ids->ipcs_idr, id);
+ if (ipc != NULL)
+ total++;
+ }
+
+ if (total >= ids->in_use)
+ return NULL;
+
+ for (; pos < IPCMNI; pos++) {
+ ipc = idr_find(&ids->ipcs_idr, pos);
+ if (ipc != NULL) {
+ *new_pos = pos + 1;
+ rcu_read_lock();
+ ipc_lock_object(ipc);
+ return ipc;
+ }
+ }
+
+ /* Out of range - return NULL to terminate iteration */
+ return NULL;
+}
+
+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);
+
+ return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);
+}
+
+/*
+ * File positions: pos 0 -> header, pos n -> ipc id = 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;
+
+ /* Find the (pos-1)th ipc */
+ return sysvipc_find_ipc(ids, *pos - 1, 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 file_operations sysvipc_proc_fops = {
+ .open = sysvipc_proc_open,
+ .read = seq_read,
+ .llseek = seq_lseek,
+ .release = sysvipc_proc_release,
+};
+#endif /* CONFIG_PROC_FS */