diff options
Diffstat (limited to 'ipc/util.c')
| -rw-r--r-- | ipc/util.c | 51 |
1 files changed, 51 insertions, 0 deletions
diff --git a/ipc/util.c b/ipc/util.c index dc8943aa9719..c4f1d33b89e4 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -824,6 +824,57 @@ void ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out) | (in->mode & S_IRWXUGO); } +/** + * ipcctl_pre_down - retrieve an ipc and check permissions for some IPC_XXX cmd + * @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_ids *ids, int id, int cmd, + struct ipc64_perm *perm, int extra_perm) +{ + struct kern_ipc_perm *ipcp; + int err; + + down_write(&ids->rw_mutex); + ipcp = ipc_lock_check_down(ids, id); + if (IS_ERR(ipcp)) { + err = PTR_ERR(ipcp); + goto out_up; + } + + err = audit_ipc_obj(ipcp); + if (err) + goto out_unlock; + + if (cmd == IPC_SET) { + err = audit_ipc_set_perm(extra_perm, perm->uid, + perm->gid, perm->mode); + if (err) + goto out_unlock; + } + if (current->euid == ipcp->cuid || + current->euid == ipcp->uid || capable(CAP_SYS_ADMIN)) + return ipcp; + + err = -EPERM; +out_unlock: + ipc_unlock(ipcp); +out_up: + up_write(&ids->rw_mutex); + return ERR_PTR(err); +} + #ifdef __ARCH_WANT_IPC_PARSE_VERSION |