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Diffstat (limited to 'ipc/util.c')
| -rw-r--r-- | ipc/util.c | 987 |
1 files changed, 987 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c new file mode 100644 index 00000000..75261a31 --- /dev/null +++ b/ipc/util.c @@ -0,0 +1,987 @@ +/* + * 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 <linux/rwsem.h> +#include <linux/memory.h> +#include <linux/ipc_namespace.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 *); +}; + +#ifdef CONFIG_MEMORY_HOTPLUG + +static void ipc_memory_notifier(struct work_struct *work) +{ + ipcns_notify(IPCNS_MEMCHANGED); +} + +static DECLARE_WORK(ipc_memory_wq, ipc_memory_notifier); + + +static int ipc_memory_callback(struct notifier_block *self, + unsigned long action, void *arg) +{ + 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; +} + +#endif /* CONFIG_MEMORY_HOTPLUG */ + +/** + * ipc_init - initialise IPC subsystem + * + * 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. + */ + +static int __init ipc_init(void) +{ + sem_init(); + msg_init(); + shm_init(); + hotplug_memory_notifier(ipc_memory_callback, IPC_CALLBACK_PRI); + register_ipcns_notifier(&init_ipc_ns); + 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) +{ + init_rwsem(&ids->rw_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 = 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: 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 + */ + +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.rw_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 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. + * + * Called with ipc_ids.rw_mutex held as a writer. + */ + +int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size) +{ + uid_t euid; + gid_t egid; + int id, err; + + if (size > IPCMNI) + size = IPCMNI; + + if (ids->in_use >= size) + return -ENOSPC; + + spin_lock_init(&new->lock); + new->deleted = 0; + rcu_read_lock(); + spin_lock(&new->lock); + + err = idr_get_new(&ids->ipcs_idr, new, &id); + if (err) { + spin_unlock(&new->lock); + rcu_read_unlock(); + return err; + } + + ids->in_use++; + + current_euid_egid(&euid, &egid); + new->cuid = new->uid = euid; + new->gid = new->cgid = egid; + + new->seq = ids->seq++; + if(ids->seq > ids->seq_max) + ids->seq = 0; + + new->id = ipc_buildid(id, new->seq); + return id; +} + +/** + * 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. + */ +static int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids, + struct ipc_ops *ops, struct ipc_params *params) +{ + int err; +retry: + err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); + + if (!err) + return -ENOMEM; + + down_write(&ids->rw_mutex); + err = ops->getnew(ns, params); + up_write(&ids->rw_mutex); + + if (err == -EAGAIN) + goto retry; + + 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 + * + * 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. + * + * On success, the IPC id is returned. + * + * It is called with ipc_ids.rw_mutex and ipcp->lock held. + */ +static int ipc_check_perms(struct ipc_namespace *ns, + struct kern_ipc_perm *ipcp, + 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: 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. + */ +static 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; +retry: + err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL); + + /* + * 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); + 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) + /* + * ipc_check_perms returns the IPC id on + * success + */ + err = ipc_check_perms(ns, ipcp, ops, params); + } + ipc_unlock(ipcp); + } + up_write(&ids->rw_mutex); + + if (err == -EAGAIN) + goto retry; + + return err; +} + + +/** + * ipc_rmid - remove an IPC identifier + * @ids: IPC identifier set + * @ipcp: ipc perm structure containing the identifier 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. + */ + +void ipc_rmid(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; +} + +/** + * 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; + struct ipc_rcu_sched *sched; + + grace = container_of(head, struct ipc_rcu_grace, rcu); + sched = container_of(&(grace->data[0]), struct ipc_rcu_sched, + data[0]); + + INIT_WORK(&sched->work, ipc_do_vfree); + schedule_work(&sched->work); +} + +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 { + kfree_rcu(container_of(ptr, struct ipc_rcu_grace, data), rcu); + } +} + +/** + * 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) +{ + uid_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 (euid == ipcp->cuid || + 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 = 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 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_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 exit. + */ + +struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id) +{ + struct kern_ipc_perm *out; + int lid = ipcid_to_idx(id); + + 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; +} + +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. + * + * 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) +{ + 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. + * @in: the permission given as input. + * @out: the permission of the ipc to set. + */ +void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) +{ + out->uid = in->uid; + out->gid = in->gid; + out->mode = (out->mode & ~S_IRWXUGO) + | (in->mode & S_IRWXUGO); +} + +/** + * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd + * @ns: the 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 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 both ipc and rw_mutex locks held in case of success + * or an err-code without any lock held otherwise. + */ +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; + uid_t euid; + int err; + + down_write(&ids->rw_mutex); + ipcp = ipc_lock_check(ids, id); + if (IS_ERR(ipcp)) { + err = PTR_ERR(ipcp); + goto out_up; + } + + audit_ipc_obj(ipcp); + if (cmd == IPC_SET) + audit_ipc_set_perm(extra_perm, perm->uid, + perm->gid, perm->mode); + + euid = current_euid(); + if (euid == ipcp->cuid || euid == ipcp->uid || + ns_capable(ns->user_ns, CAP_SYS_ADMIN)) + return ipcp; + + err = -EPERM; + ipc_unlock(ipcp); +out_up: + up_write(&ids->rw_mutex); + return ERR_PTR(err); +} + +#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. + */ +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; + 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 = 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->rw_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 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->rw_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 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) +{ + 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 */ |