diff options
Diffstat (limited to 'ipc')
| -rw-r--r-- | ipc/ipc_sysctl.c | 36 | ||||
| -rw-r--r-- | ipc/shm.c | 97 |
2 files changed, 129 insertions, 4 deletions
diff --git a/ipc/ipc_sysctl.c b/ipc/ipc_sysctl.c index 56410fa..00fba2b 100644 --- a/ipc/ipc_sysctl.c +++ b/ipc/ipc_sysctl.c @@ -31,12 +31,37 @@ static int proc_ipc_dointvec(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { struct ctl_table ipc_table; + memcpy(&ipc_table, table, sizeof(ipc_table)); ipc_table.data = get_ipc(table); return proc_dointvec(&ipc_table, write, buffer, lenp, ppos); } +static int proc_ipc_dointvec_minmax(ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + struct ctl_table ipc_table; + + memcpy(&ipc_table, table, sizeof(ipc_table)); + ipc_table.data = get_ipc(table); + + return proc_dointvec_minmax(&ipc_table, write, buffer, lenp, ppos); +} + +static int proc_ipc_dointvec_minmax_orphans(ctl_table *table, int write, + void __user *buffer, size_t *lenp, loff_t *ppos) +{ + struct ipc_namespace *ns = current->nsproxy->ipc_ns; + int err = proc_ipc_dointvec_minmax(table, write, buffer, lenp, ppos); + + if (err < 0) + return err; + if (ns->shm_rmid_forced) + shm_destroy_orphaned(ns); + return err; +} + static int proc_ipc_callback_dointvec(ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) { @@ -125,6 +150,8 @@ static int proc_ipcauto_dointvec_minmax(ctl_table *table, int write, #else #define proc_ipc_doulongvec_minmax NULL #define proc_ipc_dointvec NULL +#define proc_ipc_dointvec_minmax NULL +#define proc_ipc_dointvec_minmax_orphans NULL #define proc_ipc_callback_dointvec NULL #define proc_ipcauto_dointvec_minmax NULL #endif @@ -155,6 +182,15 @@ static struct ctl_table ipc_kern_table[] = { .proc_handler = proc_ipc_dointvec, }, { + .procname = "shm_rmid_forced", + .data = &init_ipc_ns.shm_rmid_forced, + .maxlen = sizeof(init_ipc_ns.shm_rmid_forced), + .mode = 0644, + .proc_handler = proc_ipc_dointvec_minmax_orphans, + .extra1 = &zero, + .extra2 = &one, + }, + { .procname = "msgmax", .data = &init_ipc_ns.msg_ctlmax, .maxlen = sizeof (init_ipc_ns.msg_ctlmax), @@ -74,6 +74,7 @@ void shm_init_ns(struct ipc_namespace *ns) ns->shm_ctlmax = SHMMAX; ns->shm_ctlall = SHMALL; ns->shm_ctlmni = SHMMNI; + ns->shm_rmid_forced = 0; ns->shm_tot = 0; ipc_init_ids(&shm_ids(ns)); } @@ -187,6 +188,23 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) } /* + * shm_may_destroy - identifies whether shm segment should be destroyed now + * + * Returns true if and only if there are no active users of the segment and + * one of the following is true: + * + * 1) shmctl(id, IPC_RMID, NULL) was called for this shp + * + * 2) sysctl kernel.shm_rmid_forced is set to 1. + */ +static bool shm_may_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) +{ + return (shp->shm_nattch == 0) && + (ns->shm_rmid_forced || + (shp->shm_perm.mode & SHM_DEST)); +} + +/* * remove the attach descriptor vma. * free memory for segment if it is marked destroyed. * The descriptor has already been removed from the current->mm->mmap list @@ -206,11 +224,83 @@ static void shm_close(struct vm_area_struct *vma) shp->shm_lprid = task_tgid_vnr(current); shp->shm_dtim = get_seconds(); shp->shm_nattch--; - if(shp->shm_nattch == 0 && - shp->shm_perm.mode & SHM_DEST) + if (shm_may_destroy(ns, shp)) + shm_destroy(ns, shp); + else + shm_unlock(shp); + up_write(&shm_ids(ns).rw_mutex); +} + +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); + + if (IS_ERR(shp)) + return 0; + + if (shp->shm_cprid != task_tgid_vnr(current)) { + shm_unlock(shp); + return 0; + } + + if (shm_may_destroy(ns, shp)) + shm_destroy(ns, shp); + else + shm_unlock(shp); + return 0; +} + +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; + + /* + * We want to destroy segments without users and with already + * exit'ed originating process. + * + * XXX: the originating process may exist in another pid namespace. + */ + task = find_task_by_vpid(shp->shm_cprid); + if (task != NULL) { + shm_unlock(shp); + return 0; + } + + if (shm_may_destroy(ns, 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); + up_write(&shm_ids(ns).rw_mutex); +} + + +void exit_shm(struct task_struct *task) +{ + struct nsproxy *nsp = task->nsproxy; + struct ipc_namespace *ns; + + if (!nsp) + return; + ns = nsp->ipc_ns; + if (!ns || !ns->shm_rmid_forced) + 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); up_write(&shm_ids(ns).rw_mutex); } @@ -950,8 +1040,7 @@ out_nattch: shp = shm_lock(ns, shmid); BUG_ON(IS_ERR(shp)); shp->shm_nattch--; - if(shp->shm_nattch == 0 && - shp->shm_perm.mode & SHM_DEST) + if (shm_may_destroy(ns, shp)) shm_destroy(ns, shp); else shm_unlock(shp); 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