/* * linux/ipc/msg.c * Copyright (C) 1992 Krishna Balasubramanian * * Removed all the remaining kerneld mess * Catch the -EFAULT stuff properly * Use GFP_KERNEL for messages as in 1.2 * Fixed up the unchecked user space derefs * Copyright (C) 1998 Alan Cox & Andi Kleen * * /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com> * * mostly rewritten, threaded and wake-one semantics added * MSGMAX limit removed, sysctl's added * (c) 1999 Manfred Spraul <manfred@colorfullife.com> * * support for audit of ipc object properties and permission changes * Dustin Kirkland <dustin.kirkland@us.ibm.com> */ #include <linux/capability.h> #include <linux/slab.h> #include <linux/msg.h> #include <linux/spinlock.h> #include <linux/init.h> #include <linux/proc_fs.h> #include <linux/list.h> #include <linux/security.h> #include <linux/sched.h> #include <linux/syscalls.h> #include <linux/audit.h> #include <linux/seq_file.h> #include <linux/mutex.h> #include <asm/current.h> #include <asm/uaccess.h> #include "util.h" /* sysctl: */ int msg_ctlmax = MSGMAX; int msg_ctlmnb = MSGMNB; int msg_ctlmni = MSGMNI; /* * one msg_receiver structure for each sleeping receiver: */ struct msg_receiver { struct list_head r_list; struct task_struct *r_tsk; int r_mode; long r_msgtype; long r_maxsize; volatile struct msg_msg *r_msg; }; /* one msg_sender for each sleeping sender */ struct msg_sender { struct list_head list; struct task_struct *tsk; }; #define SEARCH_ANY 1 #define SEARCH_EQUAL 2 #define SEARCH_NOTEQUAL 3 #define SEARCH_LESSEQUAL 4 static atomic_t msg_bytes = ATOMIC_INIT(0); static atomic_t msg_hdrs = ATOMIC_INIT(0); static struct ipc_ids msg_ids; #define msg_lock(id) ((struct msg_queue *)ipc_lock(&msg_ids, id)) #define msg_unlock(msq) ipc_unlock(&(msq)->q_perm) #define msg_rmid(id) ((struct msg_queue *)ipc_rmid(&msg_ids, id)) #define msg_checkid(msq, msgid) ipc_checkid(&msg_ids, &msq->q_perm, msgid) #define msg_buildid(id, seq) ipc_buildid(&msg_ids, id, seq) static void freeque(struct msg_queue *msq, int id); static int newque(key_t key, int msgflg); #ifdef CONFIG_PROC_FS static int sysvipc_msg_proc_show(struct seq_file *s, void *it); #endif void __init msg_init(void) { ipc_init_ids(&msg_ids, msg_ctlmni); ipc_init_proc_interface("sysvipc/msg", " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", &msg_ids, sysvipc_msg_proc_show); } static int newque(key_t key, int msgflg) { struct msg_queue *msq; int id, retval; msq = ipc_rcu_alloc(sizeof(*msq)); if (!msq) return -ENOMEM; msq->q_perm.mode = msgflg & S_IRWXUGO; msq->q_perm.key = key; msq->q_perm.security = NULL; retval = security_msg_queue_alloc(msq); if (retval) { ipc_rcu_putref(msq); return retval; } id = ipc_addid(&msg_ids, &msq->q_perm, msg_ctlmni); if (id == -1) { security_msg_queue_free(msq); ipc_rcu_putref(msq); return -ENOSPC; } msq->q_id = msg_buildid(id, msq->q_perm.seq); msq->q_stime = msq->q_rtime = 0; msq->q_ctime = get_seconds(); msq->q_cbytes = msq->q_qnum = 0; msq->q_qbytes = msg_ctlmnb; msq->q_lspid = msq->q_lrpid = 0; INIT_LIST_HEAD(&msq->q_messages); INIT_LIST_HEAD(&msq->q_receivers); INIT_LIST_HEAD(&msq->q_senders); msg_unlock(msq); return msq->q_id; } static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss) { mss->tsk = current; current->state = TASK_INTERRUPTIBLE; list_add_tail(&mss->list, &msq->q_senders); } static inline void ss_del(struct msg_sender *mss) { if (mss->list.next != NULL) list_del(&mss->list); } static void ss_wakeup(struct list_head *h, int kill) { struct list_head *tmp; tmp = h->next; while (tmp != h) { struct msg_sender *mss; mss = list_entry(tmp, struct msg_sender, list); tmp = tmp->next; if (kill) mss->list.next = NULL; wake_up_process(mss->tsk); } } static void expunge_all(struct msg_queue *msq, int res) { struct list_head *tmp; tmp = msq->q_receivers.next; while (tmp != &msq->q_receivers) { struct msg_receiver *msr; msr = list_entry(tmp, struct msg_receiver, r_list); tmp = tmp->next; msr->r_msg = NULL; wake_up_process(msr->r_tsk); smp_mb(); msr->r_msg = ERR_PTR(res); } } /* * freeque() wakes up waiters on the sender and receiver waiting queue, * removes the message queue from message queue ID * array, and cleans up all the messages associated with this queue. * * msg_ids.mutex and the spinlock for this message queue is hold * before freeque() is called. msg_ids.mutex remains locked on exit. */ static void freeque(struct msg_queue *msq, int id) { struct list_head *tmp; expunge_all(msq, -EIDRM); ss_wakeup(&msq->q_senders, 1); msq = msg_rmid(id); msg_unlock(msq); tmp = msq->q_messages.next; while (tmp != &msq->q_messages) { struct msg_msg *msg = list_entry(tmp, struct msg_msg, m_list); tmp = tmp->next; atomic_dec(&msg_hdrs); free_msg(msg); } atomic_sub(msq->q_cbytes, &msg_bytes); security_msg_queue_free(msq); ipc_rcu_putref(msq); } asmlinkage long sys_msgget(key_t key, int msgflg) { struct msg_queue *msq; int id, ret = -EPERM; mutex_lock(&msg_ids.mutex); if (key == IPC_PRIVATE) ret = newque(key, msgflg); else if ((id = ipc_findkey(&msg_ids, key)) == -1) { /* key not used */ if (!(msgflg & IPC_CREAT)) ret = -ENOENT; else ret = newque(key, msgflg); } else if (msgflg & IPC_CREAT && msgflg & IPC_EXCL) { ret = -EEXIST; } else { msq = msg_lock(id); BUG_ON(msq == NULL); if (ipcperms(&msq->q_perm, msgflg)) ret = -EACCES; else { int qid = msg_buildid(id, msq->q_perm.seq); ret = security_msg_queue_associate(msq, msgflg); if (!ret) ret = qid; } msg_unlock(msq); } mutex_unlock(&msg_ids.mutex); return ret; } static inline unsigned long copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version) { switch(version) { case IPC_64: return copy_to_user(buf, in, sizeof(*in)); case IPC_OLD: { struct msqid_ds out; memset(&out, 0, sizeof(out)); ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm); out.msg_stime = in->msg_stime; out.msg_rtime = in->msg_rtime; out.msg_ctime = in->msg_ctime; if (in->msg_cbytes > USHRT_MAX) out.msg_cbytes = USHRT_MAX; else out.msg_cbytes = in->msg_cbytes; out.msg_lcbytes = in->msg_cbytes; if (in->msg_qnum > USHRT_MAX) out.msg_qnum = USHRT_MAX; else out.msg_qnum = in->msg_qnum; if (in->msg_qbytes > USHRT_MAX) out.msg_qbytes = USHRT_MAX; else out.msg_qbytes = in->msg_qbytes; out.msg_lqbytes = in->msg_qbytes; out.msg_lspid = in->msg_lspid; out.msg_lrpid = in->msg_lrpid; return copy_to_user(buf, &out, sizeof(out)); } default: return -EINVAL; } } struct msq_setbuf { unsigned long qbytes; uid_t uid; gid_t gid; mode_t mode; }; static inline unsigned long copy_msqid_from_user(struct msq_setbuf *out, void __user *buf, int version) { switch(version) { case IPC_64: { struct msqid64_ds tbuf; if (copy_from_user(&tbuf, buf, sizeof(tbuf))) return -EFAULT; out->qbytes = tbuf.msg_qbytes; out->uid = tbuf.msg_perm.uid; out->gid = tbuf.msg_perm.gid; out->mode = tbuf.msg_perm.mode; return 0; } case IPC_OLD: { struct msqid_ds tbuf_old; if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) return -EFAULT; out->uid = tbuf_old.msg_perm.uid; out->gid = tbuf_old.msg_perm.gid; out->mode = tbuf_old.msg_perm.mode; if (tbuf_old.msg_qbytes == 0) out->qbytes = tbuf_old.msg_lqbytes; else out->qbytes = tbuf_old.msg_qbytes; return 0; } default: return -EINVAL; } } asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf) { struct kern_ipc_perm *ipcp; struct msq_setbuf setbuf; struct msg_queue *msq; int err, version; if (msqid < 0 || cmd < 0) return -EINVAL; version = ipc_parse_version(&cmd); switch (cmd) { case IPC_INFO: case MSG_INFO: { struct msginfo msginfo; int max_id; if (!buf) return -EFAULT; /* * We must not return kernel stack data. * due to padding, it's not enough * to set all member fields. */ err = security_msg_queue_msgctl(NULL, cmd); if (err) return err; memset(&msginfo, 0, sizeof(msginfo)); msginfo.msgmni = msg_ctlmni; msginfo.msgmax = msg_ctlmax; msginfo.msgmnb = msg_ctlmnb; msginfo.msgssz = MSGSSZ; msginfo.msgseg = MSGSEG; mutex_lock(&msg_ids.mutex); if (cmd == MSG_INFO) { msginfo.msgpool = msg_ids.in_use; msginfo.msgmap = atomic_read(&msg_hdrs); msginfo.msgtql = atomic_read(&msg_bytes); } else { msginfo.msgmap = MSGMAP; msginfo.msgpool = MSGPOOL; msginfo.msgtql = MSGTQL; } max_id = msg_ids.max_id; mutex_unlock(&msg_ids.mutex); if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) return -EFAULT; return (max_id < 0) ? 0 : max_id; } case MSG_STAT: case IPC_STAT: { struct msqid64_ds tbuf; int success_return; if (!buf) return -EFAULT; if (cmd == MSG_STAT && msqid >= msg_ids.entries->size) return -EINVAL; memset(&tbuf, 0, sizeof(tbuf)); msq = msg_lock(msqid); if (msq == NULL) return -EINVAL; if (cmd == MSG_STAT) { success_return = msg_buildid(msqid, msq->q_perm.seq); } else { err = -EIDRM; if (msg_checkid(msq, msqid)) goto out_unlock; success_return = 0; } err = -EACCES; if (ipcperms(&msq->q_perm, S_IRUGO)) goto out_unlock; err = security_msg_queue_msgctl(msq, cmd); if (err) goto out_unlock; kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); tbuf.msg_stime = msq->q_stime; tbuf.msg_rtime = msq->q_rtime; tbuf.msg_ctime = msq->q_ctime; tbuf.msg_cbytes = msq->q_cbytes; tbuf.msg_qnum = msq->q_qnum; tbuf.msg_qbytes = msq->q_qbytes; tbuf.msg_lspid = msq->q_lspid; tbuf.msg_lrpid = msq->q_lrpid; msg_unlock(msq); if (copy_msqid_to_user(buf, &tbuf, version)) return -EFAULT; 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; default: return -EINVAL; } mutex_lock(&msg_ids.mutex); msq = msg_lock(msqid); err = -EINVAL; if (msq == NULL) goto out_up; err = -EIDRM; if (msg_checkid(msq, msqid)) goto out_unlock_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 > 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(msq, msqid); break; } err = 0; out_up: mutex_unlock(&msg_ids.mutex); return err; out_unlock_up: msg_unlock(msq); goto out_up; out_unlock: msg_unlock(msq); return err; } static int testmsg(struct msg_msg *msg, long type, int mode) { switch(mode) { case SEARCH_ANY: return 1; case SEARCH_LESSEQUAL: if (msg->m_type <=type) return 1; break; case SEARCH_EQUAL: if (msg->m_type == type) return 1; break; case SEARCH_NOTEQUAL: if (msg->m_type != type) return 1; break; } return 0; } static inline int pipelined_send(struct msg_queue *msq, struct msg_msg *msg) { struct list_head *tmp; tmp = msq->q_receivers.next; while (tmp != &msq->q_receivers) { struct msg_receiver *msr; msr = list_entry(tmp, struct msg_receiver, r_list); tmp = tmp->next; if (testmsg(msg, msr->r_msgtype, msr->r_mode) && !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, msr->r_msgtype, msr->r_mode)) { list_del(&msr->r_list); if (msr->r_maxsize < msg->m_ts) { msr->r_msg = NULL; wake_up_process(msr->r_tsk); smp_mb(); msr->r_msg = ERR_PTR(-E2BIG); } else { msr->r_msg = NULL; msq->q_lrpid = msr->r_tsk->pid; msq->q_rtime = get_seconds(); wake_up_process(msr->r_tsk); smp_mb(); msr->r_msg = msg; return 1; } } } return 0; } asmlinkage long sys_msgsnd(int msqid, struct msgbuf __user *msgp, size_t msgsz, int msgflg) { struct msg_queue *msq; struct msg_msg *msg; long mtype; int err; if (msgsz > msg_ctlmax || (long) msgsz < 0 || msqid < 0) return -EINVAL; if (get_user(mtype, &msgp->mtype)) return -EFAULT; if (mtype < 1) return -EINVAL; msg = load_msg(msgp->mtext, msgsz); if (IS_ERR(msg)) return PTR_ERR(msg); msg->m_type = mtype; msg->m_ts = msgsz; msq = msg_lock(msqid); err = -EINVAL; if (msq == NULL) goto out_free; err= -EIDRM; if (msg_checkid(msq, msqid)) goto out_unlock_free; for (;;) { struct msg_sender s; err = -EACCES; if (ipcperms(&msq->q_perm, S_IWUGO)) goto out_unlock_free; err = security_msg_queue_msgsnd(msq, msg, msgflg); if (err) goto out_unlock_free; if (msgsz + msq->q_cbytes <= msq->q_qbytes && 1 + msq->q_qnum <= msq->q_qbytes) { break; } /* queue full, wait: */ if (msgflg & IPC_NOWAIT) { err = -EAGAIN; goto out_unlock_free; } ss_add(msq, &s); ipc_rcu_getref(msq); msg_unlock(msq); schedule(); ipc_lock_by_ptr(&msq->q_perm); ipc_rcu_putref(msq); if (msq->q_perm.deleted) { err = -EIDRM; goto out_unlock_free; } ss_del(&s); if (signal_pending(current)) { err = -ERESTARTNOHAND; goto out_unlock_free; } } msq->q_lspid = current->tgid; msq->q_stime = get_seconds(); if (!pipelined_send(msq, msg)) { /* noone is waiting for this message, enqueue it */ list_add_tail(&msg->m_list, &msq->q_messages); msq->q_cbytes += msgsz; msq->q_qnum++; atomic_add(msgsz, &msg_bytes); atomic_inc(&msg_hdrs); } err = 0; msg = NULL; out_unlock_free: msg_unlock(msq); out_free: if (msg != NULL) free_msg(msg); return err; } static inline int convert_mode(long *msgtyp, int msgflg) { /* * find message of correct type. * msgtyp = 0 => get first. * msgtyp > 0 => get first message of matching type. * msgtyp < 0 => get message with least type must be < abs(msgtype). */ if (*msgtyp == 0) return SEARCH_ANY; if (*msgtyp < 0) { *msgtyp = -*msgtyp; return SEARCH_LESSEQUAL; } if (msgflg & MSG_EXCEPT) return SEARCH_NOTEQUAL; return SEARCH_EQUAL; } asmlinkage long sys_msgrcv(int msqid, struct msgbuf __user *msgp, size_t msgsz, long msgtyp, int msgflg) { struct msg_queue *msq; struct msg_msg *msg; int mode; if (msqid < 0 || (long) msgsz < 0) return -EINVAL; mode = convert_mode(&msgtyp, msgflg); msq = msg_lock(msqid); if (msq == NULL) return -EINVAL; msg = ERR_PTR(-EIDRM); if (msg_checkid(msq, msqid)) goto out_unlock; for (;;) { struct msg_receiver msr_d; struct list_head *tmp; msg = ERR_PTR(-EACCES); if (ipcperms(&msq->q_perm, S_IRUGO)) goto out_unlock; msg = ERR_PTR(-EAGAIN); tmp = msq->q_messages.next; while (tmp != &msq->q_messages) { struct msg_msg *walk_msg; walk_msg = list_entry(tmp, struct msg_msg, m_list); if (testmsg(walk_msg, msgtyp, mode) && !security_msg_queue_msgrcv(msq, walk_msg, current, msgtyp, mode)) { msg = walk_msg; if (mode == SEARCH_LESSEQUAL && walk_msg->m_type != 1) { msg = walk_msg; msgtyp = walk_msg->m_type - 1; } else { msg = walk_msg; break; } } tmp = tmp->next; } if (!IS_ERR(msg)) { /* * Found a suitable message. * Unlink it from the queue. */ if ((msgsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { msg = ERR_PTR(-E2BIG); goto out_unlock; } list_del(&msg->m_list); msq->q_qnum--; msq->q_rtime = get_seconds(); msq->q_lrpid = current->tgid; msq->q_cbytes -= msg->m_ts; atomic_sub(msg->m_ts, &msg_bytes); atomic_dec(&msg_hdrs); ss_wakeup(&msq->q_senders, 0); msg_unlock(msq); break; } /* No message waiting. Wait for a message */ if (msgflg & IPC_NOWAIT) { msg = ERR_PTR(-ENOMSG); goto out_unlock; } list_add_tail(&msr_d.r_list, &msq->q_receivers); msr_d.r_tsk = current; msr_d.r_msgtype = msgtyp; msr_d.r_mode = mode; if (msgflg & MSG_NOERROR) msr_d.r_maxsize = INT_MAX; else msr_d.r_maxsize = msgsz; msr_d.r_msg = ERR_PTR(-EAGAIN); current->state = TASK_INTERRUPTIBLE; msg_unlock(msq); schedule(); /* Lockless receive, part 1: * Disable preemption. We don't hold a reference to the queue * and getting a reference would defeat the idea of a lockless * operation, thus the code relies on rcu to guarantee the * existance of msq: * Prior to destruction, expunge_all(-EIRDM) changes r_msg. * Thus if r_msg is -EAGAIN, then the queue not yet destroyed. * rcu_read_lock() prevents preemption between reading r_msg * and the spin_lock() inside ipc_lock_by_ptr(). */ rcu_read_lock(); /* Lockless receive, part 2: * Wait until pipelined_send or expunge_all are outside of * wake_up_process(). There is a race with exit(), see * ipc/mqueue.c for the details. */ msg = (struct msg_msg*)msr_d.r_msg; while (msg == NULL) { cpu_relax(); msg = (struct msg_msg *)msr_d.r_msg; } /* Lockless receive, part 3: * If there is a message or an error then accept it without * locking. */ if (msg != ERR_PTR(-EAGAIN)) { rcu_read_unlock(); break; } /* Lockless receive, part 3: * Acquire the queue spinlock. */ ipc_lock_by_ptr(&msq->q_perm); rcu_read_unlock(); /* Lockless receive, part 4: * Repeat test after acquiring the spinlock. */ msg = (struct msg_msg*)msr_d.r_msg; if (msg != ERR_PTR(-EAGAIN)) goto out_unlock; list_del(&msr_d.r_list); if (signal_pending(current)) { msg = ERR_PTR(-ERESTARTNOHAND); out_unlock: msg_unlock(msq); break; } } if (IS_ERR(msg)) return PTR_ERR(msg); msgsz = (msgsz > msg->m_ts) ? msg->m_ts : msgsz; if (put_user (msg->m_type, &msgp->mtype) || store_msg(msgp->mtext, msg, msgsz)) { msgsz = -EFAULT; } free_msg(msg); return msgsz; } #ifdef CONFIG_PROC_FS static int sysvipc_msg_proc_show(struct seq_file *s, void *it) { struct msg_queue *msq = it; return seq_printf(s, "%10d %10d %4o %10lu %10lu %5u %5u %5u %5u %5u %5u %10lu %10lu %10lu\n", msq->q_perm.key, msq->q_id, msq->q_perm.mode, msq->q_cbytes, msq->q_qnum, msq->q_lspid, msq->q_lrpid, msq->q_perm.uid, msq->q_perm.gid, msq->q_perm.cuid, msq->q_perm.cgid, msq->q_stime, msq->q_rtime, msq->q_ctime); } #endif