diff options
Diffstat (limited to 'ipc/util.c')
| -rw-r--r-- | ipc/util.c | 862 |
1 files changed, 407 insertions, 455 deletions
diff --git a/ipc/util.c b/ipc/util.c index 4704223bfad4..cae60f11d9c2 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-2.0 /* * linux/ipc/util.c * Copyright (C) 1992 Krishna Balasubramanian @@ -15,6 +16,32 @@ * 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> @@ -36,6 +63,8 @@ #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> @@ -48,101 +77,63 @@ struct ipc_proc_iface { int (*show)(struct seq_file *, void *); }; -static void ipc_memory_notifier(struct work_struct *work) -{ - ipcns_notify(IPCNS_MEMCHANGED); -} - -static int ipc_memory_callback(struct notifier_block *self, - unsigned long action, void *arg) -{ - static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier); - - switch (action) { - case MEM_ONLINE: /* memory successfully brought online */ - case MEM_OFFLINE: /* or offline: it's time to recompute msgmni */ - /* - * This is done by invoking the ipcns notifier chain with the - * IPC_MEMCHANGED event. - * In order not to keep the lock on the hotplug memory chain - * for too long, queue a work item that will, when waken up, - * activate the ipcns notification chain. - * No need to keep several ipc work items on the queue. - */ - if (!work_pending(&ipc_memory_wq)) - schedule_work(&ipc_memory_wq); - break; - case MEM_GOING_ONLINE: - case MEM_GOING_OFFLINE: - case MEM_CANCEL_ONLINE: - case MEM_CANCEL_OFFLINE: - default: - break; - } - - return NOTIFY_OK; -} - -static struct notifier_block ipc_memory_nb = { - .notifier_call = ipc_memory_callback, - .priority = IPC_CALLBACK_PRI, -}; - /** - * ipc_init - initialise IPC subsystem + * ipc_init - initialise ipc subsystem + * + * The various sysv ipc resources (semaphores, messages and shared + * memory) are initialised. * - * The various system5 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. + * 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(); - register_hotmemory_notifier(&ipc_memory_nb); - register_ipcns_notifier(&init_ipc_ns); + return 0; } -__initcall(ipc_init); +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: Identifier set + * 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 ids idr. + * 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) { - init_rwsem(&ids->rw_mutex); - ids->in_use = 0; ids->seq = 0; - ids->next_id = -1; - { - int seq_limit = INT_MAX/SEQ_MULTIPLIER; - if (seq_limit > USHRT_MAX) - ids->seq_max = USHRT_MAX; - else - ids->seq_max = seq_limit; - } - + 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 file_operations sysvipc_proc_fops; +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. + * 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 *)) @@ -161,181 +152,219 @@ void __init ipc_init_proc_interface(const char *path, const char *header, pde = proc_create_data(path, S_IRUGO, /* world readable */ NULL, /* parent dir */ - &sysvipc_proc_fops, + &sysvipc_proc_ops, iface); - if (!pde) { + if (!pde) kfree(iface); - } } #endif /** - * ipc_findkey - find a key in an ipc identifier set - * @ids: Identifier set - * @key: The key to find - * - * Requires ipc_ids.rw_mutex locked. - * Returns the LOCKED pointer to the ipc structure if found or NULL - * if not. - * If key is found ipc points to the owning ipc structure + * 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 *ipc; - int next_id; - int total; - - for (total = 0, next_id = 0; total < ids->in_use; next_id++) { - ipc = idr_find(&ids->ipcs_idr, next_id); - - if (ipc == NULL) - continue; - - if (ipc->key != key) { - total++; - continue; - } + struct kern_ipc_perm *ipcp; - ipc_lock_by_ptr(ipc); - return ipc; - } + ipcp = rhashtable_lookup_fast(&ids->key_ht, &key, + ipc_kht_params); + if (!ipcp) + return NULL; - return NULL; + rcu_read_lock(); + ipc_lock_object(ipcp); + return ipcp; } -/** - * ipc_get_maxid - get the last assigned id - * @ids: IPC identifier set +/* + * 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. * - * Called with ipc_ids.rw_mutex held. + * 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. */ - -int ipc_get_maxid(struct ipc_ids *ids) +static inline int ipc_idr_alloc(struct ipc_ids *ids, struct kern_ipc_perm *new) { - struct kern_ipc_perm *ipc; - int max_id = -1; - int total, id; + int idx, next_id = -1; - if (ids->in_use == 0) - return -1; +#ifdef CONFIG_CHECKPOINT_RESTORE + next_id = ids->next_id; + ids->next_id = -1; +#endif - if (ids->in_use == IPCMNI) - return IPCMNI - 1; + /* + * 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()) + */ - /* Look for the last assigned id */ - total = 0; - for (id = 0; id < IPCMNI && total < ids->in_use; id++) { - ipc = idr_find(&ids->ipcs_idr, id); - if (ipc != NULL) { - max_id = id; - total++; + 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); } - return max_id; + 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 - * @size: limit for the number of used ids + * 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 id 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. + * 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. * - * Called with writer ipc_ids.rw_mutex held. + * 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 size) +int ipc_addid(struct ipc_ids *ids, struct kern_ipc_perm *new, int limit) { kuid_t euid; kgid_t egid; - int id; - int next_id = ids->next_id; + int idx, err; + + /* 1) Initialize the refcount so that ipc_rcu_putref works */ + refcount_set(&new->refcount, 1); - if (size > IPCMNI) - size = IPCMNI; + if (limit > ipc_mni) + limit = ipc_mni; - if (ids->in_use >= size) + if (ids->in_use >= limit) return -ENOSPC; idr_preload(GFP_KERNEL); spin_lock_init(&new->lock); - new->deleted = 0; rcu_read_lock(); spin_lock(&new->lock); - id = idr_alloc(&ids->ipcs_idr, new, - (next_id < 0) ? 0 : ipcid_to_idx(next_id), 0, - GFP_NOWAIT); - idr_preload_end(); - if (id < 0) { - spin_unlock(&new->lock); - rcu_read_unlock(); - return id; - } - - ids->in_use++; - current_euid_egid(&euid, &egid); new->cuid = new->uid = euid; new->gid = new->cgid = egid; - if (next_id < 0) { - new->seq = ids->seq++; - if (ids->seq > ids->seq_max) - ids->seq = 0; - } else { - new->seq = ipcid_to_seqx(next_id); - ids->next_id = -1; + 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; } - new->id = ipc_buildid(id, new->seq); - return id; + ids->in_use++; + if (idx > ids->max_idx) + ids->max_idx = idx; + return idx; } /** - * ipcget_new - create a new ipc object - * @ns: namespace - * @ids: IPC identifer 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. + * 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, - struct ipc_ops *ops, struct ipc_params *params) + const struct ipc_ops *ops, struct ipc_params *params) { int err; - down_write(&ids->rw_mutex); + down_write(&ids->rwsem); err = ops->getnew(ns, params); - up_write(&ids->rw_mutex); + up_write(&ids->rwsem); return err; } /** - * ipc_check_perms - check security and permissions for an IPC - * @ns: IPC namespace - * @ipcp: ipc permission set - * @ops: the actual security routine to call - * @params: its parameters + * 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 - * ids IDR. + * 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. + * On success, the ipc id is returned. * - * It is called with ipc_ids.rw_mutex and ipcp->lock held. + * 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, - struct ipc_ops *ops, + const struct ipc_ops *ops, struct ipc_params *params) { int err; @@ -352,21 +381,21 @@ static int ipc_check_perms(struct ipc_namespace *ns, } /** - * ipcget_public - get an ipc object or create a new one - * @ns: namespace - * @ids: IPC identifer 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. + * 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, - struct ipc_ops *ops, struct ipc_params *params) + const struct ipc_ops *ops, struct ipc_params *params) { struct kern_ipc_perm *ipcp; int flg = params->flg; @@ -376,7 +405,7 @@ static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, * Take the lock as a writer since we are potentially going to add * a new entry + read locks are not "upgradable" */ - down_write(&ids->rw_mutex); + down_write(&ids->rwsem); ipcp = ipc_findkey(ids, params->key); if (ipcp == NULL) { /* key not used */ @@ -402,135 +431,125 @@ static int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, } ipc_unlock(ipcp); } - up_write(&ids->rw_mutex); + up_write(&ids->rwsem); return err; } - /** - * ipc_rmid - remove an IPC identifier - * @ids: IPC identifier set - * @ipcp: ipc perm structure containing the identifier to remove + * 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.rw_mutex (as a writer) and the spinlock for this ID are held - * before this function is called, and remain locked on the exit. + * 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) +static void ipc_kht_remove(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) { - int lid = ipcid_to_idx(ipcp->id); - - idr_remove(&ids->ipcs_idr, lid); - - ids->in_use--; - - ipcp->deleted = 1; - - return; + if (ipcp->key != IPC_PRIVATE) + WARN_ON_ONCE(rhashtable_remove_fast(&ids->key_ht, &ipcp->khtnode, + ipc_kht_params)); } /** - * ipc_alloc - allocate ipc space - * @size: size desired + * ipc_search_maxidx - search for the highest assigned index + * @ids: ipc identifier set + * @limit: known upper limit for highest assigned index * - * Allocate memory from the appropriate pools and return a pointer to it. - * NULL is returned if the allocation fails + * 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. */ - -void *ipc_alloc(int size) +static int ipc_search_maxidx(struct ipc_ids *ids, int limit) { - void *out; - if(size > PAGE_SIZE) - out = vmalloc(size); - else - out = kmalloc(size, GFP_KERNEL); - return out; -} + int tmpidx; + int i; + int retval; -/** - * ipc_free - free ipc space - * @ptr: pointer returned by ipc_alloc - * @size: size of block - * - * Free a block created with ipc_alloc(). The caller must know the size - * used in the allocation call. - */ + i = ilog2(limit+1); -void ipc_free(void* ptr, int size) -{ - if(size > PAGE_SIZE) - vfree(ptr); - else - kfree(ptr); + 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; } -struct ipc_rcu { - struct rcu_head rcu; - atomic_t refcount; -} ____cacheline_aligned_in_smp; - /** - * ipc_rcu_alloc - allocate ipc and rcu space - * @size: size desired + * ipc_rmid - remove an ipc identifier + * @ids: ipc identifier set + * @ipcp: ipc perm structure containing the identifier to remove * - * Allocate memory for the rcu header structure + the object. - * Returns the pointer to the object or NULL upon failure. + * 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_rcu_alloc(int size) +void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) { - /* - * We prepend the allocation with the rcu struct - */ - struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size); - if (unlikely(!out)) - return NULL; - atomic_set(&out->refcount, 1); - return out + 1; -} + int idx = ipcid_to_idx(ipcp->id); -int ipc_rcu_getref(void *ptr) -{ - struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; + WARN_ON_ONCE(idr_remove(&ids->ipcs_idr, idx) != ipcp); + ipc_kht_remove(ids, ipcp); + ids->in_use--; + ipcp->deleted = true; - return atomic_inc_not_zero(&p->refcount); + 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_schedule_free - free ipc + rcu space - * @head: RCU callback structure for queued work + * 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. */ -static void ipc_schedule_free(struct rcu_head *head) +void ipc_set_key_private(struct ipc_ids *ids, struct kern_ipc_perm *ipcp) { - vfree(container_of(head, struct ipc_rcu, rcu)); + ipc_kht_remove(ids, ipcp); + ipcp->key = IPC_PRIVATE; } -void ipc_rcu_putref(void *ptr) +bool ipc_rcu_getref(struct kern_ipc_perm *ptr) { - struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; + return refcount_inc_not_zero(&ptr->refcount); +} - if (!atomic_dec_and_test(&p->refcount)) +void ipc_rcu_putref(struct kern_ipc_perm *ptr, + void (*func)(struct rcu_head *head)) +{ + if (!refcount_dec_and_test(&ptr->refcount)) return; - if (is_vmalloc_addr(ptr)) { - call_rcu(&p->rcu, ipc_schedule_free); - } else { - kfree_rcu(p, rcu); - } + call_rcu(&ptr->rcu, func); } /** - * ipcperms - check IPC permissions - * @ns: IPC namespace - * @ipcp: IPC permission set - * @flag: desired permission set. + * 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 + * 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> + * @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(); @@ -545,7 +564,7 @@ int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) 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) && + if ((requested_mode & ~granted_mode & 0007) && !ns_capable(ns->user_ns, CAP_IPC_OWNER)) return -1; @@ -558,16 +577,14 @@ int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flag) */ /** - * kernel_to_ipc64_perm - convert kernel ipc permissions to user - * @in: kernel permissions - * @out: new style IPC permissions + * 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). + * 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) +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); @@ -579,15 +596,14 @@ void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out) } /** - * ipc64_perm_to_ipc_perm - convert new ipc permissions to old - * @in: new style IPC permissions - * @out: old style IPC permissions + * 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. + * 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) +void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out) { out->key = in->key; SET_UID(out->uid, in->uid); @@ -599,21 +615,20 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out) } /** - * ipc_obtain_object + * ipc_obtain_object_idr - Look for an id in the ipc ids idr and + * return associated ipc object. * @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(struct ipc_ids *ids, int id) +struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id) { struct kern_ipc_perm *out; - int lid = ipcid_to_idx(id); + int idx = ipcid_to_idx(id); - out = idr_find(&ids->ipcs_idr, lid); + out = idr_find(&ids->ipcs_idr, idx); if (!out) return ERR_PTR(-EINVAL); @@ -621,90 +636,39 @@ struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id) } /** - * ipc_lock - Lock an ipc structure without rw_mutex held - * @ids: IPC identifier set - * @id: ipc id to look for - * - * Look for an id in the ipc ids idr and lock the associated ipc object. - * - * The ipc object is locked on successful exit. - */ -struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) -{ - struct kern_ipc_perm *out; - - rcu_read_lock(); - out = ipc_obtain_object(ids, id); - if (IS_ERR(out)) - goto err1; - - spin_lock(&out->lock); - - /* ipc_rmid() may have already freed the ID while ipc_lock - * was spinning: here verify that the structure is still valid - */ - if (!out->deleted) - return out; - - spin_unlock(&out->lock); - out = ERR_PTR(-EINVAL); -err1: - rcu_read_unlock(); - return out; -} - -/** - * ipc_obtain_object_check + * ipc_obtain_object_check - Similar to ipc_obtain_object_idr() but + * also checks the ipc object sequence number. * @ids: ipc identifier set * @id: ipc id to look for * - * Similar to ipc_obtain_object() but also checks - * the ipc object reference counter. - * * 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(ids, 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(-EIDRM); + return ERR_PTR(-EINVAL); out: return out; } -struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id) -{ - struct kern_ipc_perm *out; - - out = ipc_lock(ids, id); - if (IS_ERR(out)) - return out; - - if (ipc_checkid(out, id)) { - ipc_unlock(out); - return ERR_PTR(-EIDRM); - } - - return out; -} - /** * ipcget - Common sys_*get() code - * @ns : namsepace - * @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. + * @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, - struct ipc_ops *ops, struct ipc_params *params) + const struct ipc_ops *ops, struct ipc_params *params) { if (params->key == IPC_PRIVATE) return ipcget_new(ns, ids, ops, params); @@ -713,7 +677,7 @@ int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids, } /** - * ipc_update_perm - update the permissions of an IPC. + * ipc_update_perm - update the permissions of an ipc object * @in: the permission given as input. * @out: the permission of the ipc to set. */ @@ -733,8 +697,8 @@ int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) } /** - * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd - * @ns: the ipc namespace + * 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 @@ -743,32 +707,18 @@ int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) * * 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 must be called without any lock held and - * - retrieves the ipc with the given id in the given table. - * - performs some audit and permission check, depending on the given cmd - * - returns the ipc with the ipc lock held in case of success - * or an err-code without any lock held otherwise. * - * Call holding the both the rw_mutex and the rcu read lock. + * 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_pre_down(struct ipc_namespace *ns, - struct ipc_ids *ids, int id, int cmd, - struct ipc64_perm *perm, int extra_perm) -{ - struct kern_ipc_perm *ipcp; - - ipcp = ipcctl_pre_down_nolock(ns, ids, id, cmd, perm, extra_perm); - if (IS_ERR(ipcp)) - goto out; - - spin_lock(&ipcp->lock); -out: - return ipcp; -} - -struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns, - struct ipc_ids *ids, int id, int cmd, - struct ipc64_perm *perm, int extra_perm) +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; @@ -797,15 +747,14 @@ err: /** - * ipc_parse_version - IPC call version - * @cmd: pointer to command + * 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. + * 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) +int ipc_parse_version(int *cmd) { if (*cmd & IPC_64) { *cmd ^= IPC_64; @@ -820,39 +769,48 @@ int ipc_parse_version (int *cmd) #ifdef CONFIG_PROC_FS struct ipc_proc_iter { struct ipc_namespace *ns; + struct pid_namespace *pid_ns; struct ipc_proc_iface *iface; }; -/* - * This routine locks the ipc structure found at least at position pos. +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, - loff_t *new_pos) +static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos) { + int tmpidx; 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++; - } + /* convert from position to idr index -> "-1" */ + tmpidx = *pos - 1; - if (total >= ids->in_use) - return NULL; + ipc = idr_get_next(&ids->ipcs_idr, &tmpidx); + if (ipc != NULL) { + rcu_read_lock(); + ipc_lock_object(ipc); - for ( ; pos < IPCMNI; pos++) { - ipc = idr_find(&ids->ipcs_idr, pos); - if (ipc != NULL) { - *new_pos = pos + 1; - ipc_lock_by_ptr(ipc); - return ipc; - } + /* convert from idr index to position -> "+1" */ + *pos = tmpidx + 1; } - - /* Out of range - return NULL to terminate iteration */ - return NULL; + return ipc; } static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) @@ -865,11 +823,13 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) if (ipc && ipc != SEQ_START_TOKEN) ipc_unlock(ipc); - return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); + /* Next -> search for *pos+1 */ + (*pos)++; + return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos); } /* - * File positions: pos 0 -> header, pos n -> ipc id = n - 1. + * 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) @@ -884,7 +844,7 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) * Take the lock - this will be released by the corresponding * call to stop(). */ - down_read(&ids->rw_mutex); + down_read(&ids->rwsem); /* pos < 0 is invalid */ if (*pos < 0) @@ -894,8 +854,8 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) if (*pos == 0) return SEQ_START_TOKEN; - /* Find the (pos-1)th ipc */ - return sysvipc_find_ipc(ids, *pos - 1, pos); + /* Otherwise return the correct ipc structure */ + return sysvipc_find_ipc(ids, pos); } static void sysvipc_proc_stop(struct seq_file *s, void *it) @@ -911,7 +871,7 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it) ids = &iter->ns->ids[iface->ids]; /* Release the lock we took in start() */ - up_read(&ids->rw_mutex); + up_read(&ids->rwsem); } static int sysvipc_proc_show(struct seq_file *s, void *it) @@ -919,8 +879,10 @@ 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) - return seq_puts(s, iface->header); + if (it == SEQ_START_TOKEN) { + seq_puts(s, iface->header); + return 0; + } return iface->show(s, it); } @@ -934,29 +896,17 @@ static const struct seq_operations sysvipc_proc_seqops = { static int sysvipc_proc_open(struct inode *inode, struct file *file) { - int ret; - struct seq_file *seq; struct ipc_proc_iter *iter; - ret = -ENOMEM; - iter = kmalloc(sizeof(*iter), GFP_KERNEL); + iter = __seq_open_private(file, &sysvipc_proc_seqops, sizeof(*iter)); if (!iter) - goto out; + return -ENOMEM; - ret = seq_open(file, &sysvipc_proc_seqops); - if (ret) - goto out_kfree; - - seq = file->private_data; - seq->private = iter; - - iter->iface = PDE_DATA(inode); + iter->iface = pde_data(inode); iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); -out: - return ret; -out_kfree: - kfree(iter); - goto out; + iter->pid_ns = get_pid_ns(task_active_pid_ns(current)); + + return 0; } static int sysvipc_proc_release(struct inode *inode, struct file *file) @@ -964,13 +914,15 @@ 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, +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 */ |