diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 78 |
1 files changed, 48 insertions, 30 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index 3f5b14365f33..02ecf2c078fc 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -105,9 +105,16 @@ void shm_exit_ns(struct ipc_namespace *ns) } #endif -void __init shm_init (void) +static int __init ipc_ns_init(void) { shm_init_ns(&init_ipc_ns); + return 0; +} + +pure_initcall(ipc_ns_init); + +void __init shm_init (void) +{ ipc_init_proc_interface("sysvipc/shm", #if BITS_PER_LONG <= 32 " key shmid perms size cpid lpid nattch uid gid cuid cgid atime dtime ctime rss swap\n", @@ -131,6 +138,12 @@ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id) return container_of(ipcp, struct shmid_kernel, shm_perm); } +static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp) +{ + rcu_read_lock(); + spin_lock(&ipcp->shm_perm.lock); +} + static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns, int id) { @@ -231,76 +244,80 @@ static void shm_close(struct vm_area_struct *vma) up_write(&shm_ids(ns).rw_mutex); } +/* Called with ns->shm_ids(ns).rw_mutex locked */ static int shm_try_destroy_current(int id, void *p, void *data) { struct ipc_namespace *ns = data; - struct shmid_kernel *shp = shm_lock(ns, id); + struct kern_ipc_perm *ipcp = p; + struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm); - if (IS_ERR(shp)) + if (shp->shm_creator != current) return 0; - if (shp->shm_cprid != task_tgid_vnr(current)) { - shm_unlock(shp); + /* + * Mark it as orphaned to destroy the segment when + * kernel.shm_rmid_forced is changed. + * It is noop if the following shm_may_destroy() returns true. + */ + shp->shm_creator = NULL; + + /* + * Don't even try to destroy it. If shm_rmid_forced=0 and IPC_RMID + * is not set, it shouldn't be deleted here. + */ + if (!ns->shm_rmid_forced) return 0; - } - if (shm_may_destroy(ns, shp)) + if (shm_may_destroy(ns, shp)) { + shm_lock_by_ptr(shp); shm_destroy(ns, shp); - else - shm_unlock(shp); + } return 0; } +/* Called with ns->shm_ids(ns).rw_mutex locked */ static int shm_try_destroy_orphaned(int id, void *p, void *data) { struct ipc_namespace *ns = data; - struct shmid_kernel *shp = shm_lock(ns, id); - struct task_struct *task; - - if (IS_ERR(shp)) - return 0; + struct kern_ipc_perm *ipcp = p; + struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm); /* * We want to destroy segments without users and with already * exit'ed originating process. * - * XXX: the originating process may exist in another pid namespace. + * As shp->* are changed under rw_mutex, it's safe to skip shp locking. */ - task = find_task_by_vpid(shp->shm_cprid); - if (task != NULL) { - shm_unlock(shp); + if (shp->shm_creator != NULL) return 0; - } - if (shm_may_destroy(ns, shp)) + if (shm_may_destroy(ns, shp)) { + shm_lock_by_ptr(shp); shm_destroy(ns, shp); - else - shm_unlock(shp); + } return 0; } void shm_destroy_orphaned(struct ipc_namespace *ns) { down_write(&shm_ids(ns).rw_mutex); - idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns); + if (shm_ids(ns).in_use) + idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns); up_write(&shm_ids(ns).rw_mutex); } void exit_shm(struct task_struct *task) { - struct nsproxy *nsp = task->nsproxy; - struct ipc_namespace *ns; + struct ipc_namespace *ns = task->nsproxy->ipc_ns; - if (!nsp) - return; - ns = nsp->ipc_ns; - if (!ns || !ns->shm_rmid_forced) + if (shm_ids(ns).in_use == 0) return; /* Destroy all already created segments, but not mapped yet */ down_write(&shm_ids(ns).rw_mutex); - idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns); + if (shm_ids(ns).in_use) + idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns); up_write(&shm_ids(ns).rw_mutex); } @@ -494,6 +511,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) shp->shm_segsz = size; shp->shm_nattch = 0; shp->shm_file = file; + shp->shm_creator = current; /* * shmid gets reported as "inode#" in /proc/pid/maps. * proc-ps tools use this. Changing this will break them. |