/* * 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> */ #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/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 <asm/unistd.h> #include "util.h" struct ipc_proc_iface { const char *path; const char *header; int ids; int (*show)(struct seq_file *, void *); }; struct ipc_namespace init_ipc_ns = { .kref = { .refcount = ATOMIC_INIT(2), }, }; static struct ipc_namespace *clone_ipc_ns(struct ipc_namespace *old_ns) { int err; struct ipc_namespace *ns; err = -ENOMEM; ns = kmalloc(sizeof(struct ipc_namespace), GFP_KERNEL); if (ns == NULL) goto err_mem; err = sem_init_ns(ns); if (err) goto err_sem; err = msg_init_ns(ns); if (err) goto err_msg; err = shm_init_ns(ns); if (err) goto err_shm; kref_init(&ns->kref); return ns; err_shm: msg_exit_ns(ns); err_msg: sem_exit_ns(ns); err_sem: kfree(ns); err_mem: return ERR_PTR(err); } struct ipc_namespace *copy_ipcs(unsigned long flags, struct ipc_namespace *ns) { struct ipc_namespace *new_ns; BUG_ON(!ns); get_ipc_ns(ns); if (!(flags & CLONE_NEWIPC)) return ns; new_ns = clone_ipc_ns(ns); put_ipc_ns(ns); return new_ns; } void free_ipc_ns(struct kref *kref) { struct ipc_namespace *ns; ns = container_of(kref, struct ipc_namespace, kref); sem_exit_ns(ns); msg_exit_ns(ns); shm_exit_ns(ns); kfree(ns); } /** * ipc_init - initialise IPC subsystem * * The various system5 IPC resources (semaphores, messages and shared * memory) are initialised */ static int __init ipc_init(void) { sem_init(); msg_init(); shm_init(); return 0; } __initcall(ipc_init); /** * ipc_init_ids - initialise IPC identifiers * @ids: Identifier set * * Set up the sequence range to use for the ipc identifier range (limited * below IPCMNI) then initialise the ids idr. */ void ipc_init_ids(struct ipc_ids *ids) { mutex_init(&ids->mutex); ids->in_use = 0; ids->seq = 0; { int seq_limit = INT_MAX/SEQ_MULTIPLIER; if(seq_limit > USHRT_MAX) ids->seq_max = USHRT_MAX; else ids->seq_max = seq_limit; } idr_init(&ids->ipcs_idr); } #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 = create_proc_entry(path, S_IRUGO, /* world readable */ NULL /* parent dir */); if (pde) { pde->data = iface; pde->proc_fops = &sysvipc_proc_fops; } else { kfree(iface); } } #endif /** * ipc_findkey - find a key in an ipc identifier set * @ids: Identifier set * @key: The key to find * * Requires ipc_ids.mutex locked. * Returns the LOCKED pointer to the ipc structure if found or NULL * if not. * If key is found ipc contains its ipc structure */ 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; } ipc_lock_by_ptr(ipc); return ipc; } return NULL; } /** * ipc_get_maxid - get the last assigned id * @ids: IPC identifier set * * Called with ipc_ids.mutex held. */ int ipc_get_maxid(struct ipc_ids *ids) { struct kern_ipc_perm *ipc; int max_id = -1; int total, id; if (ids->in_use == 0) return -1; if (ids->in_use == IPCMNI) return IPCMNI - 1; /* 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++; } } return max_id; } /** * ipc_addid - add an IPC identifier * @ids: IPC identifier set * @new: new IPC permission set * @size: limit for the number of used ids * * Add an entry 'new' to the IPC idr. The permissions object is * initialised and the first free entry is set up and the id assigned * is returned. The list is returned in a locked state on success. * On failure the list is not locked and -1 is returned. * * Called with ipc_ids.mutex held. */ int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) { int id, err; /* * rcu_dereference()() is not needed here since * ipc_ids.mutex is held */ if (size > IPCMNI) size = IPCMNI; if (ids->in_use >= size) return -1; err = idr_get_new(&ids->ipcs_idr, new, &id); if (err) return -1; ids->in_use++; new->cuid = new->uid = current->euid; new->gid = new->cgid = current->egid; new->seq = ids->seq++; if(ids->seq > ids->seq_max) ids->seq = 0; spin_lock_init(&new->lock); new->deleted = 0; rcu_read_lock(); spin_lock(&new->lock); return id; } /** * ipcget_new - create a new ipc object * @ns: namespace * @ids: identifer set * @ops: the actual creation routine to call * @params: its parameters * * This routine is called sys_msgget, sys_semget() and sys_shmget() when * the key is IPC_PRIVATE */ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, struct ipc_ops *ops, struct ipc_params *params) { int err; err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); if (!err) return -ENOMEM; mutex_lock(&ids->mutex); err = ops->getnew(ns, params); mutex_unlock(&ids->mutex); return err; } /** * ipc_check_perms - check security and permissions for an IPC * @ipcp: ipc permission set * @ids: identifer set * @ops: the actual security routine to call * @params: its parameters */ static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops, struct ipc_params *params) { int err; if (ipcperms(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: namespace * @ids: identifer set * @ops: the actual creation routine to call * @params: its parameters * * This routine is called sys_msgget, sys_semget() and sys_shmget() when * the key is not IPC_PRIVATE */ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids, struct ipc_ops *ops, struct ipc_params *params) { struct kern_ipc_perm *ipcp; int flg = params->flg; int err; err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); mutex_lock(&ids->mutex); ipcp = ipc_findkey(ids, params->key); if (ipcp == NULL) { /* key not used */ if (!(flg & IPC_CREAT)) err = -ENOENT; else if (!err) err = -ENOMEM; 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) err = ipc_check_perms(ipcp, ops, params); } ipc_unlock(ipcp); } mutex_unlock(&ids->mutex); return err; } /** * ipc_rmid - remove an IPC identifier * @ids: identifier set * @id: ipc perm structure containing the identifier to remove * * The identifier must be valid, and in use. The kernel will panic if * fed an invalid identifier. The entry is removed and internal * variables recomputed. * ipc_ids.mutex 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 lid = ipcp->id % SEQ_MULTIPLIER; idr_remove(&ids->ipcs_idr, lid); ids->in_use--; ipcp->deleted = 1; return; } /** * ipc_alloc - allocate ipc space * @size: size desired * * Allocate memory from the appropriate pools and return a pointer to it. * NULL is returned if the allocation fails */ void* ipc_alloc(int size) { void* out; if(size > PAGE_SIZE) out = vmalloc(size); else out = kmalloc(size, GFP_KERNEL); return out; } /** * 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. */ void ipc_free(void* ptr, int size) { if(size > PAGE_SIZE) vfree(ptr); else kfree(ptr); } /* * rcu allocations: * There are three headers that are prepended to the actual allocation: * - during use: ipc_rcu_hdr. * - during the rcu grace period: ipc_rcu_grace. * - [only if vmalloc]: ipc_rcu_sched. * Their lifetime doesn't overlap, thus the headers share the same memory. * Unlike a normal union, they are right-aligned, thus some container_of * forward/backward casting is necessary: */ struct ipc_rcu_hdr { int refcount; int is_vmalloc; void *data[0]; }; struct ipc_rcu_grace { struct rcu_head rcu; /* "void *" makes sure alignment of following data is sane. */ void *data[0]; }; struct ipc_rcu_sched { struct work_struct work; /* "void *" makes sure alignment of following data is sane. */ void *data[0]; }; #define HDRLEN_KMALLOC (sizeof(struct ipc_rcu_grace) > sizeof(struct ipc_rcu_hdr) ? \ sizeof(struct ipc_rcu_grace) : sizeof(struct ipc_rcu_hdr)) #define HDRLEN_VMALLOC (sizeof(struct ipc_rcu_sched) > HDRLEN_KMALLOC ? \ sizeof(struct ipc_rcu_sched) : HDRLEN_KMALLOC) static inline int rcu_use_vmalloc(int size) { /* Too big for a single page? */ if (HDRLEN_KMALLOC + size > PAGE_SIZE) return 1; return 0; } /** * ipc_rcu_alloc - allocate ipc and rcu space * @size: size desired * * Allocate memory for the rcu header structure + the object. * Returns the pointer to the object. * NULL is returned if the allocation fails. */ void* ipc_rcu_alloc(int size) { void* out; /* * We prepend the allocation with the rcu struct, and * workqueue if necessary (for vmalloc). */ if (rcu_use_vmalloc(size)) { out = vmalloc(HDRLEN_VMALLOC + size); if (out) { out += HDRLEN_VMALLOC; container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 1; container_of(out, struct ipc_rcu_hdr, data)->refcount = 1; } } else { out = kmalloc(HDRLEN_KMALLOC + size, GFP_KERNEL); if (out) { out += HDRLEN_KMALLOC; container_of(out, struct ipc_rcu_hdr, data)->is_vmalloc = 0; container_of(out, struct ipc_rcu_hdr, data)->refcount = 1; } } return out; } void ipc_rcu_getref(void *ptr) { container_of(ptr, struct ipc_rcu_hdr, data)->refcount++; } static void ipc_do_vfree(struct work_struct *work) { vfree(container_of(work, struct ipc_rcu_sched, work)); } /** * ipc_schedule_free - free ipc + rcu space * @head: RCU callback structure for queued work * * Since RCU callback function is called in bh, * we need to defer the vfree to schedule_work(). */ static void ipc_schedule_free(struct rcu_head *head) { struct ipc_rcu_grace *grace = container_of(head, struct ipc_rcu_grace, rcu); struct ipc_rcu_sched *sched = container_of(&(grace->data[0]), struct ipc_rcu_sched, data[0]); INIT_WORK(&sched->work, ipc_do_vfree); schedule_work(&sched->work); } /** * ipc_immediate_free - free ipc + rcu space * @head: RCU callback structure that contains pointer to be freed * * Free from the RCU callback context. */ static void ipc_immediate_free(struct rcu_head *head) { struct ipc_rcu_grace *free = container_of(head, struct ipc_rcu_grace, rcu); kfree(free); } void ipc_rcu_putref(void *ptr) { if (--container_of(ptr, struct ipc_rcu_hdr, data)->refcount > 0) return; if (container_of(ptr, struct ipc_rcu_hdr, data)->is_vmalloc) { call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu, ipc_schedule_free); } else { call_rcu(&container_of(ptr, struct ipc_rcu_grace, data)->rcu, ipc_immediate_free); } } /** * ipcperms - check IPC permissions * @ipcp: IPC permission set * @flag: desired permission set. * * Check user, group, other permissions for access * to ipc resources. return 0 if allowed */ int ipcperms (struct kern_ipc_perm *ipcp, short flag) { /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */ int requested_mode, granted_mode, err; if (unlikely((err = audit_ipc_obj(ipcp)))) return err; requested_mode = (flag >> 6) | (flag >> 3) | flag; granted_mode = ipcp->mode; if (current->euid == ipcp->cuid || current->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) && !capable(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 = in->uid; out->gid = in->gid; out->cuid = in->cuid; out->cgid = in->cgid; out->mode = in->mode; out->seq = in->seq; } /** * ipc64_perm_to_ipc_perm - convert old ipc permissions to new * @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; } struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) { struct kern_ipc_perm *out; int lid = id % SEQ_MULTIPLIER; rcu_read_lock(); out = idr_find(&ids->ipcs_idr, lid); if (out == NULL) { rcu_read_unlock(); return ERR_PTR(-EINVAL); } 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) { spin_unlock(&out->lock); rcu_read_unlock(); return ERR_PTR(-EINVAL); } return out; } int ipc_buildid(struct ipc_ids* ids, int id, int seq) { return SEQ_MULTIPLIER*seq + id; } #ifdef __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 /* __ARCH_WANT_IPC_PARSE_VERSION */ #ifdef CONFIG_PROC_FS struct ipc_proc_iter { struct ipc_namespace *ns; struct ipc_proc_iface *iface; }; /* * This routine locks the ipc structure found at least at position pos. */ 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; ipc_lock_by_ptr(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 + 1. * SeqFile iterator: iterator value locked shp 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(). */ mutex_lock(&ids->mutex); /* 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 segment, release it */ if (ipc && ipc != SEQ_START_TOKEN) ipc_unlock(ipc); ids = iter->ns->ids[iface->ids]; /* Release the lock we took in start() */ mutex_unlock(&ids->mutex); } 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); return iface->show(s, it); } static 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) { int ret; struct seq_file *seq; struct ipc_proc_iter *iter; ret = -ENOMEM; iter = kmalloc(sizeof(*iter), GFP_KERNEL); if (!iter) goto out; ret = seq_open(file, &sysvipc_proc_seqops); if (ret) goto out_kfree; seq = file->private_data; seq->private = iter; iter->iface = PDE(inode)->data; iter->ns = get_ipc_ns(current->nsproxy->ipc_ns); out: return ret; out_kfree: kfree(iter); goto out; } 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); 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 */