![Davidlohr Bueso](/assets/img/avatar_default.png)
Currently, IPC mechanisms do security and auditing related checks under RCU. However, since security modules can free the security structure, for example, through selinux_[sem,msg_queue,shm]_free_security(), we can race if the structure is freed before other tasks are done with it, creating a use-after-free condition. Manfred illustrates this nicely, for instance with shared mem and selinux: -> do_shmat calls rcu_read_lock() -> do_shmat calls shm_object_check(). Checks that the object is still valid - but doesn't acquire any locks. Then it returns. -> do_shmat calls security_shm_shmat (e.g. selinux_shm_shmat) -> selinux_shm_shmat calls ipc_has_perm() -> ipc_has_perm accesses ipc_perms->security shm_close() -> shm_close acquires rw_mutex & shm_lock -> shm_close calls shm_destroy -> shm_destroy calls security_shm_free (e.g. selinux_shm_free_security) -> selinux_shm_free_security calls ipc_free_security(&shp->shm_perm) -> ipc_free_security calls kfree(ipc_perms->security) This patch delays the freeing of the security structures after all RCU readers are done. Furthermore it aligns the security life cycle with that of the rest of IPC - freeing them based on the reference counter. For situations where we need not free security, the current behavior is kept. Linus states: "... the old behavior was suspect for another reason too: having the security blob go away from under a user sounds like it could cause various other problems anyway, so I think the old code was at least _prone_ to bugs even if it didn't have catastrophic behavior." I have tested this patch with IPC testcases from LTP on both my quad-core laptop and on a 64 core NUMA server. In both cases selinux is enabled, and tests pass for both voluntary and forced preemption models. While the mentioned races are theoretical (at least no one as reported them), I wanted to make sure that this new logic doesn't break anything we weren't aware of. Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Davidlohr Bueso <davidlohr@hp.com> Acked-by: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1052 lines
23 KiB
C
1052 lines
23 KiB
C
/*
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* linux/ipc/msg.c
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* Copyright (C) 1992 Krishna Balasubramanian
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*
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* Removed all the remaining kerneld mess
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* Catch the -EFAULT stuff properly
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* Use GFP_KERNEL for messages as in 1.2
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* Fixed up the unchecked user space derefs
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* Copyright (C) 1998 Alan Cox & Andi Kleen
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*
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* /proc/sysvipc/msg support (c) 1999 Dragos Acostachioaie <dragos@iname.com>
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*
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* mostly rewritten, threaded and wake-one semantics added
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* MSGMAX limit removed, sysctl's added
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* (c) 1999 Manfred Spraul <manfred@colorfullife.com>
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*
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* support for audit of ipc object properties and permission changes
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* Dustin Kirkland <dustin.kirkland@us.ibm.com>
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*
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* namespaces support
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* OpenVZ, SWsoft Inc.
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* Pavel Emelianov <xemul@openvz.org>
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*/
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#include <linux/capability.h>
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#include <linux/msg.h>
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#include <linux/spinlock.h>
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#include <linux/init.h>
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#include <linux/mm.h>
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#include <linux/proc_fs.h>
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#include <linux/list.h>
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#include <linux/security.h>
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#include <linux/sched.h>
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#include <linux/syscalls.h>
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#include <linux/audit.h>
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#include <linux/seq_file.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <linux/ipc_namespace.h>
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#include <asm/current.h>
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#include <asm/uaccess.h>
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#include "util.h"
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/*
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* one msg_receiver structure for each sleeping receiver:
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*/
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struct msg_receiver {
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struct list_head r_list;
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struct task_struct *r_tsk;
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int r_mode;
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long r_msgtype;
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long r_maxsize;
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struct msg_msg *volatile r_msg;
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};
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/* one msg_sender for each sleeping sender */
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struct msg_sender {
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struct list_head list;
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struct task_struct *tsk;
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};
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#define SEARCH_ANY 1
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#define SEARCH_EQUAL 2
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#define SEARCH_NOTEQUAL 3
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#define SEARCH_LESSEQUAL 4
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#define SEARCH_NUMBER 5
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#define msg_ids(ns) ((ns)->ids[IPC_MSG_IDS])
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static void freeque(struct ipc_namespace *, struct kern_ipc_perm *);
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static int newque(struct ipc_namespace *, struct ipc_params *);
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#ifdef CONFIG_PROC_FS
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static int sysvipc_msg_proc_show(struct seq_file *s, void *it);
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#endif
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/*
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* Scale msgmni with the available lowmem size: the memory dedicated to msg
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* queues should occupy at most 1/MSG_MEM_SCALE of lowmem.
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* Also take into account the number of nsproxies created so far.
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* This should be done staying within the (MSGMNI , IPCMNI/nr_ipc_ns) range.
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*/
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void recompute_msgmni(struct ipc_namespace *ns)
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{
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struct sysinfo i;
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unsigned long allowed;
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int nb_ns;
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si_meminfo(&i);
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allowed = (((i.totalram - i.totalhigh) / MSG_MEM_SCALE) * i.mem_unit)
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/ MSGMNB;
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nb_ns = atomic_read(&nr_ipc_ns);
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allowed /= nb_ns;
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if (allowed < MSGMNI) {
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ns->msg_ctlmni = MSGMNI;
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return;
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}
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if (allowed > IPCMNI / nb_ns) {
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ns->msg_ctlmni = IPCMNI / nb_ns;
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return;
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}
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ns->msg_ctlmni = allowed;
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}
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void msg_init_ns(struct ipc_namespace *ns)
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{
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ns->msg_ctlmax = MSGMAX;
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ns->msg_ctlmnb = MSGMNB;
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recompute_msgmni(ns);
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atomic_set(&ns->msg_bytes, 0);
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atomic_set(&ns->msg_hdrs, 0);
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ipc_init_ids(&ns->ids[IPC_MSG_IDS]);
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}
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#ifdef CONFIG_IPC_NS
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void msg_exit_ns(struct ipc_namespace *ns)
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{
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free_ipcs(ns, &msg_ids(ns), freeque);
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idr_destroy(&ns->ids[IPC_MSG_IDS].ipcs_idr);
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}
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#endif
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void __init msg_init(void)
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{
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msg_init_ns(&init_ipc_ns);
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printk(KERN_INFO "msgmni has been set to %d\n",
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init_ipc_ns.msg_ctlmni);
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ipc_init_proc_interface("sysvipc/msg",
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" key msqid perms cbytes qnum lspid lrpid uid gid cuid cgid stime rtime ctime\n",
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IPC_MSG_IDS, sysvipc_msg_proc_show);
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}
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static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id)
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{
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struct kern_ipc_perm *ipcp = ipc_obtain_object(&msg_ids(ns), id);
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if (IS_ERR(ipcp))
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return ERR_CAST(ipcp);
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return container_of(ipcp, struct msg_queue, q_perm);
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}
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static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id);
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if (IS_ERR(ipcp))
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return ERR_CAST(ipcp);
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return container_of(ipcp, struct msg_queue, q_perm);
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}
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static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
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{
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ipc_rmid(&msg_ids(ns), &s->q_perm);
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}
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static void msg_rcu_free(struct rcu_head *head)
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{
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struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu);
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struct msg_queue *msq = ipc_rcu_to_struct(p);
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security_msg_queue_free(msq);
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ipc_rcu_free(head);
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}
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/**
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* newque - Create a new msg queue
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* @ns: namespace
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* @params: ptr to the structure that contains the key and msgflg
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*
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* Called with msg_ids.rwsem held (writer)
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*/
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static int newque(struct ipc_namespace *ns, struct ipc_params *params)
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{
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struct msg_queue *msq;
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int id, retval;
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key_t key = params->key;
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int msgflg = params->flg;
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msq = ipc_rcu_alloc(sizeof(*msq));
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if (!msq)
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return -ENOMEM;
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msq->q_perm.mode = msgflg & S_IRWXUGO;
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msq->q_perm.key = key;
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msq->q_perm.security = NULL;
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retval = security_msg_queue_alloc(msq);
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if (retval) {
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ipc_rcu_putref(msq, ipc_rcu_free);
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return retval;
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}
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/* ipc_addid() locks msq upon success. */
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id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni);
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if (id < 0) {
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ipc_rcu_putref(msq, msg_rcu_free);
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return id;
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}
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msq->q_stime = msq->q_rtime = 0;
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msq->q_ctime = get_seconds();
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msq->q_cbytes = msq->q_qnum = 0;
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msq->q_qbytes = ns->msg_ctlmnb;
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msq->q_lspid = msq->q_lrpid = 0;
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INIT_LIST_HEAD(&msq->q_messages);
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INIT_LIST_HEAD(&msq->q_receivers);
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INIT_LIST_HEAD(&msq->q_senders);
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ipc_unlock_object(&msq->q_perm);
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rcu_read_unlock();
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return msq->q_perm.id;
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}
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static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss)
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{
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mss->tsk = current;
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current->state = TASK_INTERRUPTIBLE;
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list_add_tail(&mss->list, &msq->q_senders);
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}
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static inline void ss_del(struct msg_sender *mss)
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{
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if (mss->list.next != NULL)
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list_del(&mss->list);
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}
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static void ss_wakeup(struct list_head *h, int kill)
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{
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struct msg_sender *mss, *t;
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list_for_each_entry_safe(mss, t, h, list) {
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if (kill)
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mss->list.next = NULL;
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wake_up_process(mss->tsk);
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}
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}
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static void expunge_all(struct msg_queue *msq, int res)
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{
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struct msg_receiver *msr, *t;
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list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) {
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msr->r_msg = NULL;
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wake_up_process(msr->r_tsk);
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smp_mb();
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msr->r_msg = ERR_PTR(res);
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}
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}
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/*
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* freeque() wakes up waiters on the sender and receiver waiting queue,
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* removes the message queue from message queue ID IDR, and cleans up all the
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* messages associated with this queue.
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*
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* msg_ids.rwsem (writer) and the spinlock for this message queue are held
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* before freeque() is called. msg_ids.rwsem remains locked on exit.
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*/
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static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp)
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{
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struct msg_msg *msg, *t;
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struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
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expunge_all(msq, -EIDRM);
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ss_wakeup(&msq->q_senders, 1);
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msg_rmid(ns, msq);
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ipc_unlock_object(&msq->q_perm);
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rcu_read_unlock();
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list_for_each_entry_safe(msg, t, &msq->q_messages, m_list) {
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atomic_dec(&ns->msg_hdrs);
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free_msg(msg);
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}
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atomic_sub(msq->q_cbytes, &ns->msg_bytes);
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ipc_rcu_putref(msq, msg_rcu_free);
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}
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/*
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* Called with msg_ids.rwsem and ipcp locked.
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*/
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static inline int msg_security(struct kern_ipc_perm *ipcp, int msgflg)
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{
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struct msg_queue *msq = container_of(ipcp, struct msg_queue, q_perm);
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return security_msg_queue_associate(msq, msgflg);
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}
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SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg)
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{
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struct ipc_namespace *ns;
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struct ipc_ops msg_ops;
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struct ipc_params msg_params;
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ns = current->nsproxy->ipc_ns;
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msg_ops.getnew = newque;
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msg_ops.associate = msg_security;
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msg_ops.more_checks = NULL;
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msg_params.key = key;
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msg_params.flg = msgflg;
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return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);
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}
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static inline unsigned long
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copy_msqid_to_user(void __user *buf, struct msqid64_ds *in, int version)
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{
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switch(version) {
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case IPC_64:
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return copy_to_user(buf, in, sizeof(*in));
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case IPC_OLD:
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{
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struct msqid_ds out;
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memset(&out, 0, sizeof(out));
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ipc64_perm_to_ipc_perm(&in->msg_perm, &out.msg_perm);
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out.msg_stime = in->msg_stime;
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out.msg_rtime = in->msg_rtime;
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out.msg_ctime = in->msg_ctime;
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if (in->msg_cbytes > USHRT_MAX)
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out.msg_cbytes = USHRT_MAX;
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else
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out.msg_cbytes = in->msg_cbytes;
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out.msg_lcbytes = in->msg_cbytes;
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if (in->msg_qnum > USHRT_MAX)
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out.msg_qnum = USHRT_MAX;
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else
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out.msg_qnum = in->msg_qnum;
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if (in->msg_qbytes > USHRT_MAX)
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out.msg_qbytes = USHRT_MAX;
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else
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out.msg_qbytes = in->msg_qbytes;
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out.msg_lqbytes = in->msg_qbytes;
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out.msg_lspid = in->msg_lspid;
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out.msg_lrpid = in->msg_lrpid;
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return copy_to_user(buf, &out, sizeof(out));
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}
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default:
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return -EINVAL;
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}
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}
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static inline unsigned long
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copy_msqid_from_user(struct msqid64_ds *out, void __user *buf, int version)
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{
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switch(version) {
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case IPC_64:
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if (copy_from_user(out, buf, sizeof(*out)))
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return -EFAULT;
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return 0;
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case IPC_OLD:
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{
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struct msqid_ds tbuf_old;
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if (copy_from_user(&tbuf_old, buf, sizeof(tbuf_old)))
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return -EFAULT;
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out->msg_perm.uid = tbuf_old.msg_perm.uid;
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out->msg_perm.gid = tbuf_old.msg_perm.gid;
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out->msg_perm.mode = tbuf_old.msg_perm.mode;
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if (tbuf_old.msg_qbytes == 0)
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out->msg_qbytes = tbuf_old.msg_lqbytes;
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else
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out->msg_qbytes = tbuf_old.msg_qbytes;
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return 0;
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}
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default:
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return -EINVAL;
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}
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}
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/*
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* This function handles some msgctl commands which require the rwsem
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* to be held in write mode.
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* NOTE: no locks must be held, the rwsem is taken inside this function.
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*/
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static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd,
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struct msqid_ds __user *buf, int version)
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{
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struct kern_ipc_perm *ipcp;
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struct msqid64_ds uninitialized_var(msqid64);
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struct msg_queue *msq;
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int err;
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if (cmd == IPC_SET) {
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if (copy_msqid_from_user(&msqid64, buf, version))
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return -EFAULT;
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}
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down_write(&msg_ids(ns).rwsem);
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rcu_read_lock();
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ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd,
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&msqid64.msg_perm, msqid64.msg_qbytes);
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if (IS_ERR(ipcp)) {
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err = PTR_ERR(ipcp);
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goto out_unlock1;
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}
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msq = container_of(ipcp, struct msg_queue, q_perm);
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err = security_msg_queue_msgctl(msq, cmd);
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if (err)
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goto out_unlock1;
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switch (cmd) {
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case IPC_RMID:
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ipc_lock_object(&msq->q_perm);
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/* freeque unlocks the ipc object and rcu */
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freeque(ns, ipcp);
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goto out_up;
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case IPC_SET:
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if (msqid64.msg_qbytes > ns->msg_ctlmnb &&
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!capable(CAP_SYS_RESOURCE)) {
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err = -EPERM;
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goto out_unlock1;
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}
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ipc_lock_object(&msq->q_perm);
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err = ipc_update_perm(&msqid64.msg_perm, ipcp);
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if (err)
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goto out_unlock0;
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msq->q_qbytes = msqid64.msg_qbytes;
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msq->q_ctime = get_seconds();
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/* sleeping receivers might be excluded by
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* stricter permissions.
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*/
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expunge_all(msq, -EAGAIN);
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/* sleeping senders might be able to send
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* due to a larger queue size.
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*/
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ss_wakeup(&msq->q_senders, 0);
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break;
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default:
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err = -EINVAL;
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goto out_unlock1;
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}
|
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|
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out_unlock0:
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ipc_unlock_object(&msq->q_perm);
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out_unlock1:
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rcu_read_unlock();
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out_up:
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up_write(&msg_ids(ns).rwsem);
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return err;
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}
|
|
|
|
static int msgctl_nolock(struct ipc_namespace *ns, int msqid,
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int cmd, int version, void __user *buf)
|
|
{
|
|
int err;
|
|
struct msg_queue *msq;
|
|
|
|
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).rwsem);
|
|
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).rwsem);
|
|
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;
|
|
|
|
memset(&tbuf, 0, sizeof(tbuf));
|
|
|
|
rcu_read_lock();
|
|
if (cmd == MSG_STAT) {
|
|
msq = msq_obtain_object(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
err = PTR_ERR(msq);
|
|
goto out_unlock;
|
|
}
|
|
success_return = msq->q_perm.id;
|
|
} else {
|
|
msq = msq_obtain_object_check(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
err = PTR_ERR(msq);
|
|
goto out_unlock;
|
|
}
|
|
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;
|
|
|
|
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;
|
|
rcu_read_unlock();
|
|
|
|
if (copy_msqid_to_user(buf, &tbuf, version))
|
|
return -EFAULT;
|
|
return success_return;
|
|
}
|
|
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
|
|
return err;
|
|
out_unlock:
|
|
rcu_read_unlock();
|
|
return err;
|
|
}
|
|
|
|
SYSCALL_DEFINE3(msgctl, int, msqid, int, cmd, struct msqid_ds __user *, buf)
|
|
{
|
|
int 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:
|
|
case MSG_STAT: /* msqid is an index rather than a msg queue id */
|
|
case IPC_STAT:
|
|
return msgctl_nolock(ns, msqid, cmd, version, buf);
|
|
case IPC_SET:
|
|
case IPC_RMID:
|
|
return msgctl_down(ns, msqid, cmd, buf, version);
|
|
default:
|
|
return -EINVAL;
|
|
}
|
|
}
|
|
|
|
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)) {
|
|
|
|
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;
|
|
|
|
return 1;
|
|
}
|
|
}
|
|
}
|
|
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;
|
|
|
|
rcu_read_lock();
|
|
msq = msq_obtain_object_check(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
err = PTR_ERR(msq);
|
|
goto out_unlock1;
|
|
}
|
|
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
for (;;) {
|
|
struct msg_sender s;
|
|
|
|
err = -EACCES;
|
|
if (ipcperms(ns, &msq->q_perm, S_IWUGO))
|
|
goto out_unlock0;
|
|
|
|
err = security_msg_queue_msgsnd(msq, msg, msgflg);
|
|
if (err)
|
|
goto out_unlock0;
|
|
|
|
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_unlock0;
|
|
}
|
|
|
|
ss_add(msq, &s);
|
|
|
|
if (!ipc_rcu_getref(msq)) {
|
|
err = -EIDRM;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
rcu_read_unlock();
|
|
schedule();
|
|
|
|
rcu_read_lock();
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
ipc_rcu_putref(msq, ipc_rcu_free);
|
|
if (msq->q_perm.deleted) {
|
|
err = -EIDRM;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ss_del(&s);
|
|
|
|
if (signal_pending(current)) {
|
|
err = -ERESTARTNOHAND;
|
|
goto out_unlock0;
|
|
}
|
|
|
|
}
|
|
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_unlock0:
|
|
ipc_unlock_object(&msq->q_perm);
|
|
out_unlock1:
|
|
rcu_read_unlock();
|
|
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, *found = NULL;
|
|
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;
|
|
found = msg;
|
|
} else if (mode == SEARCH_NUMBER) {
|
|
if (*msgtyp == count)
|
|
return msg;
|
|
} else
|
|
return msg;
|
|
count++;
|
|
}
|
|
}
|
|
|
|
return found ?: 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))
|
|
{
|
|
int mode;
|
|
struct msg_queue *msq;
|
|
struct ipc_namespace *ns;
|
|
struct msg_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);
|
|
|
|
rcu_read_lock();
|
|
msq = msq_obtain_object_check(ns, msqid);
|
|
if (IS_ERR(msq)) {
|
|
rcu_read_unlock();
|
|
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_unlock1;
|
|
|
|
ipc_lock_object(&msq->q_perm);
|
|
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_unlock0;
|
|
}
|
|
/*
|
|
* 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_unlock0;
|
|
}
|
|
|
|
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);
|
|
|
|
goto out_unlock0;
|
|
}
|
|
|
|
/* No message waiting. Wait for a message */
|
|
if (msgflg & IPC_NOWAIT) {
|
|
msg = ERR_PTR(-ENOMSG);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
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;
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
rcu_read_unlock();
|
|
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 acquiring the q_perm.lock in ipc_lock_object().
|
|
*/
|
|
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))
|
|
goto out_unlock1;
|
|
|
|
/* Lockless receive, part 3:
|
|
* Acquire the queue spinlock.
|
|
*/
|
|
ipc_lock_object(&msq->q_perm);
|
|
|
|
/* 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_unlock0;
|
|
|
|
list_del(&msr_d.r_list);
|
|
if (signal_pending(current)) {
|
|
msg = ERR_PTR(-ERESTARTNOHAND);
|
|
goto out_unlock0;
|
|
}
|
|
|
|
ipc_unlock_object(&msq->q_perm);
|
|
}
|
|
|
|
out_unlock0:
|
|
ipc_unlock_object(&msq->q_perm);
|
|
out_unlock1:
|
|
rcu_read_unlock();
|
|
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
|