| /* |
| * 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> |
| * |
| * namespaces support |
| * OpenVZ, SWsoft Inc. |
| * Pavel Emelianov <xemul@openvz.org> |
| */ |
| |
| #include <linux/capability.h> |
| #include <linux/msg.h> |
| #include <linux/spinlock.h> |
| #include <linux/init.h> |
| #include <linux/mm.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/rwsem.h> |
| #include <linux/nsproxy.h> |
| #include <linux/ipc_namespace.h> |
| |
| #include <asm/current.h> |
| #include <asm/uaccess.h> |
| #include "util.h" |
| |
| /* |
| * 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; |
| |
| struct msg_msg *volatile 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 |
| #define SEARCH_NUMBER 5 |
| |
| #define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS]) |
| |
| #define msg_unlock(msq) ipc_unlock(&(msq)->q_perm) |
| |
| static void freeque(struct ipc_namespace *, struct kern_ipc_perm *); |
| static int newque(struct ipc_namespace *, struct ipc_params *); |
| #ifdef CONFIG_PROC_FS |
| static int sysvipc_msg_proc_show(struct seq_file *s, void *it); |
| #endif |
| |
| /* |
| * Scale msgmni with the available lowmem size: the memory dedicated to msg |
| * queues should occupy at most 1/MSG_MEM_SCALE of lowmem. |
| * Also take into account the number of nsproxies created so far. |
| * This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range. |
| */ |
| void recompute_msgmni(struct ipc_namespace *ns) |
| { |
| struct sysinfo i; |
| unsigned long allowed; |
| int nb_ns; |
| |
| si_meminfo(&i); |
| allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit) |
| / MSGMNB; |
| nb_ns = atomic_read(&nr_ipc_ns); |
| allowed /= nb_ns; |
| |
| if (allowed < MSGMNI) { |
| ns->msg_ctlmni = MSGMNI; |
| return; |
| } |
| |
| if (allowed > IPCMNI / nb_ns) { |
| ns->msg_ctlmni = IPCMNI / nb_ns; |
| return; |
| } |
| |
| ns->msg_ctlmni = allowed; |
| } |
| |
| void msg_init_ns(struct ipc_namespace *ns) |
| { |
| ns->msg_ctlmax = MSGMAX; |
| ns->msg_ctlmnb = MSGMNB; |
| |
| recompute_msgmni(ns); |
| |
| atomic_set(&ns->msg_bytes, 0); |
| atomic_set(&ns->msg_hdrs, 0); |
| ipc_init_ids(&ns->ids[IPC_MSG_IDS]); |
| } |
| |
| #ifdef CONFIG_IPC_NS |
| void msg_exit_ns(struct ipc_namespace *ns) |
| { |
| free_ipcs(ns, &msg_ids(ns), freeque); |
| idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr); |
| } |
| #endif |
| |
| void __init msg_init(void) |
| { |
| msg_init_ns(&init_ipc_ns); |
| |
| printk(KERN_INFO "msgmni has been set to %d\n", |
| init_ipc_ns.msg_ctlmni); |
| |
| ipc_init_proc_interface("sysvipc/msg", |
| " key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n", |
| IPC_MSG_IDS, sysvipc_msg_proc_show); |
| } |
| |
| /* |
| * msg_lock_(check_) routines are called in the paths where the rw_mutex |
| * is not held. |
| */ |
| static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id) |
| { |
| struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id); |
| |
| if (IS_ERR(ipcp)) |
| return (struct msg_queue *)ipcp; |
| |
| return container_of(ipcp, struct msg_queue, q_perm); |
| } |
| |
| static inline struct msg_queue *msg_lock_check(struct ipc_namespace *ns, |
| int id) |
| { |
| struct kern_ipc_perm *ipcp = ipc_lock_check(&msg_ids(ns), id); |
| |
| if (IS_ERR(ipcp)) |
| return (struct msg_queue *)ipcp; |
| |
| return container_of(ipcp, struct msg_queue, q_perm); |
| } |
| |
| static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) |
| { |
| ipc_rmid(&msg_ids(ns), &s->q_perm); |
| } |
| |
| /** |
| * newque - Create a new msg queue |
| * @ns: namespace |
| * @params: ptr to the structure that contains the key and msgflg |
| * |
| * Called with msg_ids.rw_mutex held (writer) |
| */ |
| static int newque(struct ipc_namespace *ns, struct ipc_params *params) |
| { |
| struct msg_queue *msq; |
| int id, retval; |
| key_t key = params->key; |
| int msgflg = params->flg; |
| |
| 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; |
| } |
| |
| /* |
| * ipc_addid() locks msq |
| */ |
| id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); |
| if (id < 0) { |
| security_msg_queue_free(msq); |
| ipc_rcu_putref(msq); |
| return id; |
| } |
| |
| msq->q_stime = msq->q_rtime = 0; |
| msq->q_ctime = get_seconds(); |
| msq->q_cbytes = msq->q_qnum = 0; |
| msq->q_qbytes = ns->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_perm.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 msg_sender *mss, *t; |
| |
| list_for_each_entry_safe(mss, t, h, list) { |
| if (kill) |
| mss->list.next = NULL; |
| wake_up_process(mss->tsk); |
| } |
| } |
| |
| static void expunge_all(struct msg_queue *msq, int res) |
| { |
| struct msg_receiver *msr, *t; |
| |
| list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
| /* |
| * Make sure that the wakeup doesnt preempt |
| * this CPU prematurely. (on PREEMPT_RT) |
| */ |
| preempt_disable_rt(); |
| |
| msr->r_msg = NULL; |
| wake_up_process(msr->r_tsk); |
| smp_mb(); |
| msr->r_msg = ERR_PTR(res); |
| |
| preempt_enable_rt(); |
| } |
| } |
| |
| /* |
| * freeque() wakes up waiters on the sender and receiver waiting queue, |
| * removes the message queue from message queue ID IDR, and cleans up all the |
| * messages associated with this queue. |
| * |
| * msg_ids.rw_mutex (writer) and the spinlock for this message queue are held |
| * before freeque() is called. msg_ids.rw_mutex remains locked on exit. |
| */ |
| static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) |
| { |
| struct msg_msg *msg, *t; |
| struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
| |
| expunge_all(msq, -EIDRM); |
| ss_wakeup(&msq->q_senders, 1); |
| msg_rmid(ns, msq); |
| msg_unlock(msq); |
| |
| list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) { |
| atomic_dec(&ns->msg_hdrs); |
| free_msg(msg); |
| } |
| atomic_sub(msq->q_cbytes, &ns->msg_bytes); |
| security_msg_queue_free(msq); |
| ipc_rcu_putref(msq); |
| } |
| |
| /* |
| * Called with msg_ids.rw_mutex and ipcp locked. |
| */ |
| static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg) |
| { |
| struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm); |
| |
| return security_msg_queue_associate(msq, msgflg); |
| } |
| |
| SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) |
| { |
| struct ipc_namespace *ns; |
| struct ipc_ops msg_ops; |
| struct ipc_params msg_params; |
| |
| ns = current->nsproxy->ipc_ns; |
| |
| msg_ops.getnew = newque; |
| msg_ops.associate = msg_security; |
| msg_ops.more_checks = NULL; |
| |
| msg_params.key = key; |
| msg_params.flg = msgflg; |
| |
| return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); |
| } |
| |
| 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; |
| } |
| } |
| |
| static inline unsigned long |
| copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version) |
| { |
| switch(version) { |
| case IPC_64: |
| if (copy_from_user(out, buf, sizeof(*out))) |
| return -EFAULT; |
| return 0; |
| case IPC_OLD: |
| { |
| struct msqid_ds tbuf_old; |
| |
| if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old))) |
| return -EFAULT; |
| |
| out->msg_perm.uid = tbuf_old.msg_perm.uid; |
| out->msg_perm.gid = tbuf_old.msg_perm.gid; |
| out->msg_perm.mode = tbuf_old.msg_perm.mode; |
| |
| if (tbuf_old.msg_qbytes == 0) |
| out->msg_qbytes = tbuf_old.msg_lqbytes; |
| else |
| out->msg_qbytes = tbuf_old.msg_qbytes; |
| |
| return 0; |
| } |
| default: |
| return -EINVAL; |
| } |
| } |
| |
| /* |
| * 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 msqid64_ds uninitialized_var(msqid64); |
| struct msg_queue *msq; |
| int err; |
| |
| if (cmd == IPC_SET) { |
| if (copy_msqid_from_user(&msqid64, buf, version)) |
| return -EFAULT; |
| } |
| |
| ipcp = ipcctl_pre_down(ns, &msg_ids(ns), msqid, cmd, |
| &msqid64.msg_perm, msqid64.msg_qbytes); |
| if (IS_ERR(ipcp)) |
| return PTR_ERR(ipcp); |
| |
| msq = container_of(ipcp, struct msg_queue, q_perm); |
| |
| 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 (msqid64.msg_qbytes > ns->msg_ctlmnb && |
| !capable(CAP_SYS_RESOURCE)) { |
| err = -EPERM; |
| goto out_unlock; |
| } |
| |
| err = ipc_update_perm(&msqid64.msg_perm, ipcp); |
| if (err) |
| goto out_unlock; |
| |
| msq->q_qbytes = msqid64.msg_qbytes; |
| |
| 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; |
| } |
| |
| SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf) |
| { |
| struct msg_queue *msq; |
| int err, version; |
| struct ipc_namespace *ns; |
| |
| if (msqid < 0 || cmd < 0) |
| return -EINVAL; |
| |
| version = ipc_parse_version(&cmd); |
| ns = current->nsproxy->ipc_ns; |
| |
| 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 = ns->msg_ctlmni; |
| msginfo.msgmax = ns->msg_ctlmax; |
| msginfo.msgmnb = ns->msg_ctlmnb; |
| msginfo.msgssz = MSGSSZ; |
| msginfo.msgseg = MSGSEG; |
| down_read(&msg_ids(ns).rw_mutex); |
| if (cmd == MSG_INFO) { |
| msginfo.msgpool = msg_ids(ns).in_use; |
| msginfo.msgmap = atomic_read(&ns->msg_hdrs); |
| msginfo.msgtql = atomic_read(&ns->msg_bytes); |
| } else { |
| msginfo.msgmap = MSGMAP; |
| msginfo.msgpool = MSGPOOL; |
| msginfo.msgtql = MSGTQL; |
| } |
| max_id = ipc_get_maxid(&msg_ids(ns)); |
| up_read(&msg_ids(ns).rw_mutex); |
| if (copy_to_user(buf, &msginfo, sizeof(struct msginfo))) |
| return -EFAULT; |
| return (max_id < 0) ? 0 : max_id; |
| } |
| case MSG_STAT: /* msqid is an index rather than a msg queue id */ |
| case IPC_STAT: |
| { |
| struct msqid64_ds tbuf; |
| int success_return; |
| |
| if (!buf) |
| return -EFAULT; |
| |
| if (cmd == MSG_STAT) { |
| msq = msg_lock(ns, msqid); |
| if (IS_ERR(msq)) |
| return PTR_ERR(msq); |
| success_return = msq->q_perm.id; |
| } else { |
| msq = msg_lock_check(ns, msqid); |
| if (IS_ERR(msq)) |
| return PTR_ERR(msq); |
| success_return = 0; |
| } |
| err = -EACCES; |
| if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
| goto out_unlock; |
| |
| err = security_msg_queue_msgctl(msq, cmd); |
| if (err) |
| goto out_unlock; |
| |
| memset(&tbuf, 0, sizeof(tbuf)); |
| |
| 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: |
| case IPC_RMID: |
| err = msgctl_down(ns, msqid, cmd, buf, version); |
| return err; |
| default: |
| return -EINVAL; |
| } |
| |
| out_unlock: |
| msg_unlock(msq); |
| return err; |
| } |
| |
| static int testmsg(struct msg_msg *msg, long type, int mode) |
| { |
| switch(mode) |
| { |
| case SEARCH_ANY: |
| case SEARCH_NUMBER: |
| 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 msg_receiver *msr, *t; |
| |
| list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { |
| if (testmsg(msg, msr->r_msgtype, msr->r_mode) && |
| !security_msg_queue_msgrcv(msq, msg, msr->r_tsk, |
| msr->r_msgtype, msr->r_mode)) { |
| |
| /* |
| * Make sure that the wakeup doesnt preempt |
| * this CPU prematurely. (on PREEMPT_RT) |
| */ |
| preempt_disable_rt(); |
| |
| 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 = task_pid_vnr(msr->r_tsk); |
| msq->q_rtime = get_seconds(); |
| wake_up_process(msr->r_tsk); |
| smp_mb(); |
| msr->r_msg = msg; |
| preempt_enable_rt(); |
| |
| return 1; |
| } |
| preempt_enable_rt(); |
| } |
| } |
| return 0; |
| } |
| |
| long do_msgsnd(int msqid, long mtype, void __user *mtext, |
| size_t msgsz, int msgflg) |
| { |
| struct msg_queue *msq; |
| struct msg_msg *msg; |
| int err; |
| struct ipc_namespace *ns; |
| |
| ns = current->nsproxy->ipc_ns; |
| |
| if (msgsz > ns->msg_ctlmax || (long) msgsz < 0 || msqid < 0) |
| return -EINVAL; |
| if (mtype < 1) |
| return -EINVAL; |
| |
| msg = load_msg(mtext, msgsz); |
| if (IS_ERR(msg)) |
| return PTR_ERR(msg); |
| |
| msg->m_type = mtype; |
| msg->m_ts = msgsz; |
| |
| msq = msg_lock_check(ns, msqid); |
| if (IS_ERR(msq)) { |
| err = PTR_ERR(msq); |
| goto out_free; |
| } |
| |
| for (;;) { |
| struct msg_sender s; |
| |
| err = -EACCES; |
| if (ipcperms(ns, &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); |
| |
| if (!ipc_rcu_getref(msq)) { |
| err = -EIDRM; |
| goto out_unlock_free; |
| } |
| |
| 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 = task_tgid_vnr(current); |
| msq->q_stime = get_seconds(); |
| |
| if (!pipelined_send(msq, msg)) { |
| /* no one 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, &ns->msg_bytes); |
| atomic_inc(&ns->msg_hdrs); |
| } |
| |
| err = 0; |
| msg = NULL; |
| |
| out_unlock_free: |
| msg_unlock(msq); |
| out_free: |
| if (msg != NULL) |
| free_msg(msg); |
| return err; |
| } |
| |
| SYSCALL_DEFINE4(msgsnd, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
| int, msgflg) |
| { |
| long mtype; |
| |
| if (get_user(mtype, &msgp->mtype)) |
| return -EFAULT; |
| return do_msgsnd(msqid, mtype, msgp->mtext, msgsz, msgflg); |
| } |
| |
| static inline int convert_mode(long *msgtyp, int msgflg) |
| { |
| if (msgflg & MSG_COPY) |
| return SEARCH_NUMBER; |
| /* |
| * 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; |
| } |
| |
| static long do_msg_fill(void __user *dest, struct msg_msg *msg, size_t bufsz) |
| { |
| struct msgbuf __user *msgp = dest; |
| size_t msgsz; |
| |
| if (put_user(msg->m_type, &msgp->mtype)) |
| return -EFAULT; |
| |
| msgsz = (bufsz > msg->m_ts) ? msg->m_ts : bufsz; |
| if (store_msg(msgp->mtext, msg, msgsz)) |
| return -EFAULT; |
| return msgsz; |
| } |
| |
| #ifdef CONFIG_CHECKPOINT_RESTORE |
| /* |
| * This function creates new kernel message structure, large enough to store |
| * bufsz message bytes. |
| */ |
| static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
| { |
| struct msg_msg *copy; |
| |
| /* |
| * Create dummy message to copy real message to. |
| */ |
| copy = load_msg(buf, bufsz); |
| if (!IS_ERR(copy)) |
| copy->m_ts = bufsz; |
| return copy; |
| } |
| |
| static inline void free_copy(struct msg_msg *copy) |
| { |
| if (copy) |
| free_msg(copy); |
| } |
| #else |
| static inline struct msg_msg *prepare_copy(void __user *buf, size_t bufsz) |
| { |
| return ERR_PTR(-ENOSYS); |
| } |
| |
| static inline void free_copy(struct msg_msg *copy) |
| { |
| } |
| #endif |
| |
| static struct msg_msg *find_msg(struct msg_queue *msq, long *msgtyp, int mode) |
| { |
| struct msg_msg *msg; |
| long count = 0; |
| |
| list_for_each_entry(msg, &msq->q_messages, m_list) { |
| if (testmsg(msg, *msgtyp, mode) && |
| !security_msg_queue_msgrcv(msq, msg, current, |
| *msgtyp, mode)) { |
| if (mode == SEARCH_LESSEQUAL && msg->m_type != 1) { |
| *msgtyp = msg->m_type - 1; |
| } else if (mode == SEARCH_NUMBER) { |
| if (*msgtyp == count) |
| return msg; |
| } else |
| return msg; |
| count++; |
| } |
| } |
| |
| return ERR_PTR(-EAGAIN); |
| } |
| |
| |
| long do_msgrcv(int msqid, void __user *buf, size_t bufsz, long msgtyp, |
| int msgflg, |
| long (*msg_handler)(void __user *, struct msg_msg *, size_t)) |
| { |
| struct msg_queue *msq; |
| struct msg_msg *msg; |
| int mode; |
| struct ipc_namespace *ns; |
| struct msg_msg *copy = NULL; |
| |
| ns = current->nsproxy->ipc_ns; |
| |
| if (msqid < 0 || (long) bufsz < 0) |
| return -EINVAL; |
| if (msgflg & MSG_COPY) { |
| copy = prepare_copy(buf, min_t(size_t, bufsz, ns->msg_ctlmax)); |
| if (IS_ERR(copy)) |
| return PTR_ERR(copy); |
| } |
| mode = convert_mode(&msgtyp, msgflg); |
| |
| msq = msg_lock_check(ns, msqid); |
| if (IS_ERR(msq)) { |
| free_copy(copy); |
| return PTR_ERR(msq); |
| } |
| |
| for (;;) { |
| struct msg_receiver msr_d; |
| |
| msg = ERR_PTR(-EACCES); |
| if (ipcperms(ns, &msq->q_perm, S_IRUGO)) |
| goto out_unlock; |
| |
| msg = find_msg(msq, &msgtyp, mode); |
| |
| if (!IS_ERR(msg)) { |
| /* |
| * Found a suitable message. |
| * Unlink it from the queue. |
| */ |
| if ((bufsz < msg->m_ts) && !(msgflg & MSG_NOERROR)) { |
| msg = ERR_PTR(-E2BIG); |
| goto out_unlock; |
| } |
| /* |
| * If we are copying, then do not unlink message and do |
| * not update queue parameters. |
| */ |
| if (msgflg & MSG_COPY) { |
| msg = copy_msg(msg, copy); |
| goto out_unlock; |
| } |
| list_del(&msg->m_list); |
| msq->q_qnum--; |
| msq->q_rtime = get_seconds(); |
| msq->q_lrpid = task_tgid_vnr(current); |
| msq->q_cbytes -= msg->m_ts; |
| atomic_sub(msg->m_ts, &ns->msg_bytes); |
| atomic_dec(&ns->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 = bufsz; |
| 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 |
| * existence 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)) { |
| free_copy(copy); |
| return PTR_ERR(msg); |
| } |
| |
| bufsz = msg_handler(buf, msg, bufsz); |
| free_msg(msg); |
| |
| return bufsz; |
| } |
| |
| SYSCALL_DEFINE5(msgrcv, int, msqid, struct msgbuf __user *, msgp, size_t, msgsz, |
| long, msgtyp, int, msgflg) |
| { |
| return do_msgrcv(msqid, msgp, msgsz, msgtyp, msgflg, do_msg_fill); |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| static int sysvipc_msg_proc_show(struct seq_file *s, void *it) |
| { |
| struct user_namespace *user_ns = seq_user_ns(s); |
| 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_perm.id, |
| msq->q_perm.mode, |
| msq->q_cbytes, |
| msq->q_qnum, |
| msq->q_lspid, |
| msq->q_lrpid, |
| from_kuid_munged(user_ns, msq->q_perm.uid), |
| from_kgid_munged(user_ns, msq->q_perm.gid), |
| from_kuid_munged(user_ns, msq->q_perm.cuid), |
| from_kgid_munged(user_ns, msq->q_perm.cgid), |
| msq->q_stime, |
| msq->q_rtime, |
| msq->q_ctime); |
| } |
| #endif |