diff options
| -rw-r--r-- | ipc/msg.c | 162 |
1 files changed, 89 insertions, 73 deletions
@@ -436,10 +436,95 @@ copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version) } } -asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) +/* + * This function handles some msgctl commands which require the rw_mutex + * to be held in write mode. + * NOTE: no locks must be held, the rw_mutex is taken inside this function. + */ +static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, + struct msqid_ds __user *buf, int version) { struct kern_ipc_perm *ipcp; - struct msq_setbuf uninitialized_var(setbuf); + struct msq_setbuf setbuf; + struct msg_queue *msq; + int err; + + if (cmd == IPC_SET) { + if (copy_msqid_from_user(&setbuf, buf, version)) + return -EFAULT; + } + + down_write(&msg_ids(ns).rw_mutex); + msq = msg_lock_check_down(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_up; + } + + ipcp = &msq->q_perm; + + err = audit_ipc_obj(ipcp); + if (err) + goto out_unlock; + + if (cmd == IPC_SET) { + err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid, + setbuf.mode); + if (err) + goto out_unlock; + } + + if (current->euid != ipcp->cuid && + current->euid != ipcp->uid && + !capable(CAP_SYS_ADMIN)) { + /* We _could_ check for CAP_CHOWN above, but we don't */ + err = -EPERM; + goto out_unlock; + } + + err = security_msg_queue_msgctl(msq, cmd); + if (err) + goto out_unlock; + + switch (cmd) { + case IPC_RMID: + freeque(ns, ipcp); + goto out_up; + case IPC_SET: + if (setbuf.qbytes > ns->msg_ctlmnb && + !capable(CAP_SYS_RESOURCE)) { + err = -EPERM; + goto out_unlock; + } + + msq->q_qbytes = setbuf.qbytes; + + ipcp->uid = setbuf.uid; + ipcp->gid = setbuf.gid; + ipcp->mode = (ipcp->mode & ~S_IRWXUGO) | + (S_IRWXUGO & setbuf.mode); + msq->q_ctime = get_seconds(); + /* sleeping receivers might be excluded by + * stricter permissions. + */ + expunge_all(msq, -EAGAIN); + /* sleeping senders might be able to send + * due to a larger queue size. + */ + ss_wakeup(&msq->q_senders, 0); + break; + default: + err = -EINVAL; + } +out_unlock: + msg_unlock(msq); +out_up: + up_write(&msg_ids(ns).rw_mutex); + return err; +} + +asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) +{ struct msg_queue *msq; int err, version; struct ipc_namespace *ns; @@ -535,82 +620,13 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) return success_return; } case IPC_SET: - if (!buf) - return -EFAULT; - if (copy_msqid_from_user(&setbuf, buf, version)) - return -EFAULT; - break; case IPC_RMID: - break; + err = msgctl_down(ns, msqid, cmd, buf, version); + return err; default: return -EINVAL; } - down_write(&msg_ids(ns).rw_mutex); - msq = msg_lock_check_down(ns, msqid); - if (IS_ERR(msq)) { - err = PTR_ERR(msq); - goto out_up; - } - - ipcp = &msq->q_perm; - - err = audit_ipc_obj(ipcp); - if (err) - goto out_unlock_up; - if (cmd == IPC_SET) { - err = audit_ipc_set_perm(setbuf.qbytes, setbuf.uid, setbuf.gid, - setbuf.mode); - if (err) - goto out_unlock_up; - } - - err = -EPERM; - if (current->euid != ipcp->cuid && - current->euid != ipcp->uid && !capable(CAP_SYS_ADMIN)) - /* We _could_ check for CAP_CHOWN above, but we don't */ - goto out_unlock_up; - - err = security_msg_queue_msgctl(msq, cmd); - if (err) - goto out_unlock_up; - - switch (cmd) { - case IPC_SET: - { - err = -EPERM; - if (setbuf.qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) - goto out_unlock_up; - - msq->q_qbytes = setbuf.qbytes; - - ipcp->uid = setbuf.uid; - ipcp->gid = setbuf.gid; - ipcp->mode = (ipcp->mode & ~S_IRWXUGO) | - (S_IRWXUGO & setbuf.mode); - msq->q_ctime = get_seconds(); - /* sleeping receivers might be excluded by - * stricter permissions. - */ - expunge_all(msq, -EAGAIN); - /* sleeping senders might be able to send - * due to a larger queue size. - */ - ss_wakeup(&msq->q_senders, 0); - msg_unlock(msq); - break; - } - case IPC_RMID: - freeque(ns, &msq->q_perm); - break; - } - err = 0; -out_up: - up_write(&msg_ids(ns).rw_mutex); - return err; -out_unlock_up: - msg_unlock(msq); - goto out_up; out_unlock: msg_unlock(msq); return err; |