// SPDX-License-Identifier: GPL-2.0/* * 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/wake_q.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 <linux/uaccess.h>#include "util.h" /* one msq_queue structure for each present queue on the system */struct msg_queue { struct kern_ipc_perm q_perm; time64_t q_stime; /* last msgsnd time */ time64_t q_rtime; /* last msgrcv time */ time64_t q_ctime; /* last change time */ unsigned long q_cbytes; /* current number of bytes on queue */ unsigned long q_qnum; /* number of messages in queue */ unsigned long q_qbytes; /* max number of bytes on queue */ struct pid *q_lspid; /* pid of last msgsnd */ struct pid *q_lrpid; /* last receive pid */ struct list_head q_messages; struct list_head q_receivers; struct list_head q_senders;} __randomize_layout; /* 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 *r_msg;}; /* one msg_sender for each sleeping sender */struct msg_sender { struct list_head list; struct task_struct *tsk; size_t msgsz;}; #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]) static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id){ struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id); if (IS_ERR(ipcp)) return ERR_CAST(ipcp); return container_of(ipcp, struct msg_queue, q_perm);} static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, int id){ struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); if (IS_ERR(ipcp)) return ERR_CAST(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);} static void msg_rcu_free(struct rcu_head *head){ struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu); struct msg_queue *msq = container_of(p, struct msg_queue, q_perm); security_msg_queue_free(&msq->q_perm); kvfree(msq);} /** * newque - Create a new msg queue * @ns: namespace * @params: ptr to the structure that contains the key and msgflg * * Called with msg_ids.rwsem held (writer) */static int newque(struct ipc_namespace *ns, struct ipc_params *params){ struct msg_queue *msq; int retval; key_t key = params->key; int msgflg = params->flg; msq = kvmalloc(sizeof(*msq), GFP_KERNEL); if (unlikely(!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->q_perm); if (retval) { kvfree(msq); return retval; } msq->q_stime = msq->q_rtime = 0; msq->q_ctime = ktime_get_real_seconds(); msq->q_cbytes = msq->q_qnum = 0; msq->q_qbytes = ns->msg_ctlmnb; msq->q_lspid = msq->q_lrpid = NULL; INIT_LIST_HEAD(&msq->q_messages); INIT_LIST_HEAD(&msq->q_receivers); INIT_LIST_HEAD(&msq->q_senders); /* ipc_addid() locks msq upon success. */ retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); if (retval < 0) { call_rcu(&msq->q_perm.rcu, msg_rcu_free); return retval; } ipc_unlock_object(&msq->q_perm); rcu_read_unlock(); return msq->q_perm.id;} static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz){ return msgsz + msq->q_cbytes <= msq->q_qbytes && 1 + msq->q_qnum <= msq->q_qbytes;} static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss, size_t msgsz){ mss->tsk = current; mss->msgsz = msgsz; __set_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) list_del(&mss->list);} static void ss_wakeup(struct msg_queue *msq, struct wake_q_head *wake_q, bool kill){ struct msg_sender *mss, *t; struct task_struct *stop_tsk = NULL; struct list_head *h = &msq->q_senders; list_for_each_entry_safe(mss, t, h, list) { if (kill) mss->list.next = NULL; /* * Stop at the first task we don't wakeup, * we've already iterated the original * sender queue. */ else if (stop_tsk == mss->tsk) break; /* * We are not in an EIDRM scenario here, therefore * verify that we really need to wakeup the task. * To maintain current semantics and wakeup order, * move the sender to the tail on behalf of the * blocked task. */ else if (!msg_fits_inqueue(msq, mss->msgsz)) { if (!stop_tsk) stop_tsk = mss->tsk; list_move_tail(&mss->list, &msq->q_senders); continue; } wake_q_add(wake_q, mss->tsk); }} static void expunge_all(struct msg_queue *msq, int res, struct wake_q_head *wake_q){ struct msg_receiver *msr, *t; list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { wake_q_add(wake_q, msr->r_tsk); WRITE_ONCE(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 IDR, and cleans up all the * messages associated with this queue. * * msg_ids.rwsem (writer) and the spinlock for this message queue are held * before freeque() is called. msg_ids.rwsem 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); DEFINE_WAKE_Q(wake_q); expunge_all(msq, -EIDRM, &wake_q); ss_wakeup(msq, &wake_q, true); msg_rmid(ns, msq); ipc_unlock_object(&msq->q_perm); wake_up_q(&wake_q); rcu_read_unlock(); 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); ipc_update_pid(&msq->q_lspid, NULL); ipc_update_pid(&msq->q_lrpid, NULL); ipc_rcu_putref(&msq->q_perm, msg_rcu_free);} long ksys_msgget(key_t key, int msgflg){ struct ipc_namespace *ns; static const struct ipc_ops msg_ops = { .getnew = newque, .associate = security_msg_queue_associate, }; struct ipc_params msg_params; ns = current->nsproxy->ipc_ns; msg_params.key = key; msg_params.flg = msgflg; return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params);} SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg){ return ksys_msgget(key, msgflg);} static inline unsigned longcopy_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 longcopy_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 rwsem * to be held in write mode. * NOTE: no locks must be held, the rwsem is taken inside this function. */static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, struct msqid64_ds *msqid64){ struct kern_ipc_perm *ipcp; struct msg_queue *msq; int err; down_write(&msg_ids(ns).rwsem); rcu_read_lock(); ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd, &msqid64->msg_perm, msqid64->msg_qbytes); if (IS_ERR(ipcp)) { err = PTR_ERR(ipcp); goto out_unlock1; } msq = container_of(ipcp, struct msg_queue, q_perm); err = security_msg_queue_msgctl(&msq->q_perm, cmd); if (err) goto out_unlock1; switch (cmd) { case IPC_RMID: ipc_lock_object(&msq->q_perm); /* freeque unlocks the ipc object and rcu */ freeque(ns, ipcp); goto out_up; case IPC_SET: { DEFINE_WAKE_Q(wake_q); if (msqid64->msg_qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) { err = -EPERM; goto out_unlock1; } ipc_lock_object(&msq->q_perm); err = ipc_update_perm(&msqid64->msg_perm, ipcp); if (err) goto out_unlock0; msq->q_qbytes = msqid64->msg_qbytes; msq->q_ctime = ktime_get_real_seconds(); /* * Sleeping receivers might be excluded by * stricter permissions. */ expunge_all(msq, -EAGAIN, &wake_q); /* * Sleeping senders might be able to send * due to a larger queue size. */ ss_wakeup(msq, &wake_q, false); ipc_unlock_object(&msq->q_perm); wake_up_q(&wake_q); goto out_unlock1; } default: err = -EINVAL; goto out_unlock1; } out_unlock0: ipc_unlock_object(&msq->q_perm);out_unlock1: rcu_read_unlock();out_up: up_write(&msg_ids(ns).rwsem); return err;} static int msgctl_info(struct ipc_namespace *ns, int msqid, int cmd, struct msginfo *msginfo){ int err; int max_id; /* * 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); return (max_id < 0) ? 0 : max_id;} static int msgctl_stat(struct ipc_namespace *ns, int msqid, int cmd, struct msqid64_ds *p){ struct msg_queue *msq; int id = 0; int err; memset(p, 0, sizeof(*p)); rcu_read_lock(); if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {Lines 1–500 of 1288. 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// SPDX-License-Identifier: GPL-2.0 /* * 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/wake_q.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 <linux/uaccess.h> #include "util.h" /* one msq_queue structure for each present queue on the system */ struct msg_queue { struct kern_ipc_perm q_perm; time64_t q_stime; /* last msgsnd time */ time64_t q_rtime; /* last msgrcv time */ time64_t q_ctime; /* last change time */ unsigned long q_cbytes; /* current number of bytes on queue */ unsigned long q_qnum; /* number of messages in queue */ unsigned long q_qbytes; /* max number of bytes on queue */ struct pid *q_lspid; /* pid of last msgsnd */ struct pid *q_lrpid; /* last receive pid */ struct list_head q_messages; struct list_head q_receivers; struct list_head q_senders; } __randomize_layout; /* 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 *r_msg; }; /* one msg_sender for each sleeping sender */ struct msg_sender { struct list_head list; struct task_struct *tsk; size_t msgsz; }; #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]) static inline struct msg_queue *msq_obtain_object(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_obtain_object_idr(&msg_ids(ns), id); if (IS_ERR(ipcp)) return ERR_CAST(ipcp); return container_of(ipcp, struct msg_queue, q_perm); } static inline struct msg_queue *msq_obtain_object_check(struct ipc_namespace *ns, int id) { struct kern_ipc_perm *ipcp = ipc_obtain_object_check(&msg_ids(ns), id); if (IS_ERR(ipcp)) return ERR_CAST(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); } static void msg_rcu_free(struct rcu_head *head) { struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu); struct msg_queue *msq = container_of(p, struct msg_queue, q_perm); security_msg_queue_free(&msq->q_perm); kvfree(msq); } /** * newque - Create a new msg queue * @ns: namespace * @params: ptr to the structure that contains the key and msgflg * * Called with msg_ids.rwsem held (writer) */ static int newque(struct ipc_namespace *ns, struct ipc_params *params) { struct msg_queue *msq; int retval; key_t key = params->key; int msgflg = params->flg; msq = kvmalloc(sizeof(*msq), GFP_KERNEL); if (unlikely(!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->q_perm); if (retval) { kvfree(msq); return retval; } msq->q_stime = msq->q_rtime = 0; msq->q_ctime = ktime_get_real_seconds(); msq->q_cbytes = msq->q_qnum = 0; msq->q_qbytes = ns->msg_ctlmnb; msq->q_lspid = msq->q_lrpid = NULL; INIT_LIST_HEAD(&msq->q_messages); INIT_LIST_HEAD(&msq->q_receivers); INIT_LIST_HEAD(&msq->q_senders); /* ipc_addid() locks msq upon success. */ retval = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); if (retval < 0) { call_rcu(&msq->q_perm.rcu, msg_rcu_free); return retval; } ipc_unlock_object(&msq->q_perm); rcu_read_unlock(); return msq->q_perm.id; } static inline bool msg_fits_inqueue(struct msg_queue *msq, size_t msgsz) { return msgsz + msq->q_cbytes <= msq->q_qbytes && 1 + msq->q_qnum <= msq->q_qbytes; } static inline void ss_add(struct msg_queue *msq, struct msg_sender *mss, size_t msgsz) { mss->tsk = current; mss->msgsz = msgsz; __set_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) list_del(&mss->list); } static void ss_wakeup(struct msg_queue *msq, struct wake_q_head *wake_q, bool kill) { struct msg_sender *mss, *t; struct task_struct *stop_tsk = NULL; struct list_head *h = &msq->q_senders; list_for_each_entry_safe(mss, t, h, list) { if (kill) mss->list.next = NULL; /* * Stop at the first task we don't wakeup, * we've already iterated the original * sender queue. */ else if (stop_tsk == mss->tsk) break; /* * We are not in an EIDRM scenario here, therefore * verify that we really need to wakeup the task. * To maintain current semantics and wakeup order, * move the sender to the tail on behalf of the * blocked task. */ else if (!msg_fits_inqueue(msq, mss->msgsz)) { if (!stop_tsk) stop_tsk = mss->tsk; list_move_tail(&mss->list, &msq->q_senders); continue; } wake_q_add(wake_q, mss->tsk); } } static void expunge_all(struct msg_queue *msq, int res, struct wake_q_head *wake_q) { struct msg_receiver *msr, *t; list_for_each_entry_safe(msr, t, &msq->q_receivers, r_list) { wake_q_add(wake_q, msr->r_tsk); WRITE_ONCE(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 IDR, and cleans up all the * messages associated with this queue. * * msg_ids.rwsem (writer) and the spinlock for this message queue are held * before freeque() is called. msg_ids.rwsem 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); DEFINE_WAKE_Q(wake_q); expunge_all(msq, -EIDRM, &wake_q); ss_wakeup(msq, &wake_q, true); msg_rmid(ns, msq); ipc_unlock_object(&msq->q_perm); wake_up_q(&wake_q); rcu_read_unlock(); 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); ipc_update_pid(&msq->q_lspid, NULL); ipc_update_pid(&msq->q_lrpid, NULL); ipc_rcu_putref(&msq->q_perm, msg_rcu_free); } long ksys_msgget(key_t key, int msgflg) { struct ipc_namespace *ns; static const struct ipc_ops msg_ops = { .getnew = newque, .associate = security_msg_queue_associate, }; struct ipc_params msg_params; ns = current->nsproxy->ipc_ns; msg_params.key = key; msg_params.flg = msgflg; return ipcget(ns, &msg_ids(ns), &msg_ops, &msg_params); } SYSCALL_DEFINE2(msgget, key_t, key, int, msgflg) { return ksys_msgget(key, msgflg); } 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 rwsem * to be held in write mode. * NOTE: no locks must be held, the rwsem is taken inside this function. */ static int msgctl_down(struct ipc_namespace *ns, int msqid, int cmd, struct msqid64_ds *msqid64) { struct kern_ipc_perm *ipcp; struct msg_queue *msq; int err; down_write(&msg_ids(ns).rwsem); rcu_read_lock(); ipcp = ipcctl_pre_down_nolock(ns, &msg_ids(ns), msqid, cmd, &msqid64->msg_perm, msqid64->msg_qbytes); if (IS_ERR(ipcp)) { err = PTR_ERR(ipcp); goto out_unlock1; } msq = container_of(ipcp, struct msg_queue, q_perm); err = security_msg_queue_msgctl(&msq->q_perm, cmd); if (err) goto out_unlock1; switch (cmd) { case IPC_RMID: ipc_lock_object(&msq->q_perm); /* freeque unlocks the ipc object and rcu */ freeque(ns, ipcp); goto out_up; case IPC_SET: { DEFINE_WAKE_Q(wake_q); if (msqid64->msg_qbytes > ns->msg_ctlmnb && !capable(CAP_SYS_RESOURCE)) { err = -EPERM; goto out_unlock1; } ipc_lock_object(&msq->q_perm); err = ipc_update_perm(&msqid64->msg_perm, ipcp); if (err) goto out_unlock0; msq->q_qbytes = msqid64->msg_qbytes; msq->q_ctime = ktime_get_real_seconds(); /* * Sleeping receivers might be excluded by * stricter permissions. */ expunge_all(msq, -EAGAIN, &wake_q); /* * Sleeping senders might be able to send * due to a larger queue size. */ ss_wakeup(msq, &wake_q, false); ipc_unlock_object(&msq->q_perm); wake_up_q(&wake_q); goto out_unlock1; } default: err = -EINVAL; goto out_unlock1; } out_unlock0: ipc_unlock_object(&msq->q_perm); out_unlock1: rcu_read_unlock(); out_up: up_write(&msg_ids(ns).rwsem); return err; } static int msgctl_info(struct ipc_namespace *ns, int msqid, int cmd, struct msginfo *msginfo) { int err; int max_id; /* * 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); return (max_id < 0) ? 0 : max_id; } static int msgctl_stat(struct ipc_namespace *ns, int msqid, int cmd, struct msqid64_ds *p) { struct msg_queue *msq; int id = 0; int err; memset(p, 0, sizeof(*p)); rcu_read_lock(); if (cmd == MSG_STAT || cmd == MSG_STAT_ANY) {