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fix idr_find() locking
This is a patch that fixes the way idr_find() used to be called in ipc_lock():
in all the paths that don't imply an update of the ipcs idr, it was called
without the idr tree being locked.
The changes are:
. in ipc_ids, the mutex has been changed into a reader/writer semaphore.
. ipc_lock() now takes the mutex as a reader during the idr_find().
. a new routine ipc_lock_down() has been defined: it doesn't take the
mutex, assuming that it is being held by the caller. This is the routine
that is now called in all the update paths.
Signed-off-by: Nadia Derbey <Nadia.Derbey@bull.net>
Acked-by: Jarek Poplawski <jarkao2@o2.pl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Nadia Derbey
Linus Torvalds
parent
f4566f0485
commit
3e148c7993
41
ipc/msg.c
41
ipc/msg.c
@ -34,7 +34,7 @@
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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/mutex.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <asm/current.h>
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@ -110,7 +110,7 @@ void msg_exit_ns(struct ipc_namespace *ns)
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int next_id;
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int total, in_use;
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mutex_lock(&msg_ids(ns).mutex);
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down_write(&msg_ids(ns).rw_mutex);
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in_use = msg_ids(ns).in_use;
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@ -122,7 +122,8 @@ void msg_exit_ns(struct ipc_namespace *ns)
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freeque(ns, msq);
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total++;
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}
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mutex_unlock(&msg_ids(ns).mutex);
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up_write(&msg_ids(ns).rw_mutex);
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kfree(ns->ids[IPC_MSG_IDS]);
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ns->ids[IPC_MSG_IDS] = NULL;
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@ -136,6 +137,22 @@ void __init msg_init(void)
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IPC_MSG_IDS, sysvipc_msg_proc_show);
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}
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/*
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* This routine is called in the paths where the rw_mutex is held to protect
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* access to the idr tree.
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*/
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static inline struct msg_queue *msg_lock_check_down(struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock_check_down(&msg_ids(ns), id);
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return container_of(ipcp, struct msg_queue, q_perm);
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}
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/*
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* msg_lock_(check_) routines are called in the paths where the rw_mutex
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* is not held.
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*/
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static inline struct msg_queue *msg_lock(struct ipc_namespace *ns, int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock(&msg_ids(ns), id);
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@ -161,7 +178,7 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s)
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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.mutex held
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* Called with msg_ids.rw_mutex 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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@ -260,8 +277,8 @@ static void expunge_all(struct msg_queue *msq, int res)
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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.mutex and the spinlock for this message queue are held
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* before freeque() is called. msg_ids.mutex remains locked on exit.
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* msg_ids.rw_mutex (writer) and the spinlock for this message queue are held
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* before freeque() is called. msg_ids.rw_mutex remains locked on exit.
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*/
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static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
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{
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@ -286,7 +303,7 @@ static void freeque(struct ipc_namespace *ns, struct msg_queue *msq)
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}
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/*
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* Called with msg_ids.mutex and ipcp locked.
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* Called with msg_ids.rw_mutex 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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@ -444,7 +461,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
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msginfo.msgmnb = ns->msg_ctlmnb;
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msginfo.msgssz = MSGSSZ;
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msginfo.msgseg = MSGSEG;
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mutex_lock(&msg_ids(ns).mutex);
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down_read(&msg_ids(ns).rw_mutex);
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if (cmd == MSG_INFO) {
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msginfo.msgpool = msg_ids(ns).in_use;
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msginfo.msgmap = atomic_read(&msg_hdrs);
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@ -455,7 +472,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
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msginfo.msgtql = MSGTQL;
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}
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max_id = ipc_get_maxid(&msg_ids(ns));
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mutex_unlock(&msg_ids(ns).mutex);
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up_read(&msg_ids(ns).rw_mutex);
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if (copy_to_user(buf, &msginfo, sizeof(struct msginfo)))
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return -EFAULT;
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return (max_id < 0) ? 0 : max_id;
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@ -516,8 +533,8 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
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return -EINVAL;
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}
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mutex_lock(&msg_ids(ns).mutex);
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msq = msg_lock_check(ns, msqid);
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down_write(&msg_ids(ns).rw_mutex);
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msq = msg_lock_check_down(ns, msqid);
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if (IS_ERR(msq)) {
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err = PTR_ERR(msq);
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goto out_up;
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@ -576,7 +593,7 @@ asmlinkage long sys_msgctl(int msqid, int cmd, struct msqid_ds __user *buf)
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}
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err = 0;
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out_up:
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mutex_unlock(&msg_ids(ns).mutex);
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up_write(&msg_ids(ns).rw_mutex);
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return err;
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out_unlock_up:
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msg_unlock(msq);
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44
ipc/sem.c
44
ipc/sem.c
@ -80,7 +80,7 @@
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#include <linux/audit.h>
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#include <linux/capability.h>
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#include <linux/seq_file.h>
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#include <linux/mutex.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <asm/uaccess.h>
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@ -148,7 +148,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
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int next_id;
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int total, in_use;
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mutex_lock(&sem_ids(ns).mutex);
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down_write(&sem_ids(ns).rw_mutex);
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in_use = sem_ids(ns).in_use;
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@ -160,7 +160,7 @@ void sem_exit_ns(struct ipc_namespace *ns)
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freeary(ns, sma);
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total++;
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}
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mutex_unlock(&sem_ids(ns).mutex);
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up_write(&sem_ids(ns).rw_mutex);
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kfree(ns->ids[IPC_SEM_IDS]);
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ns->ids[IPC_SEM_IDS] = NULL;
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@ -174,6 +174,22 @@ void __init sem_init (void)
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IPC_SEM_IDS, sysvipc_sem_proc_show);
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}
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/*
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* This routine is called in the paths where the rw_mutex is held to protect
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* access to the idr tree.
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*/
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static inline struct sem_array *sem_lock_check_down(struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock_check_down(&sem_ids(ns), id);
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return container_of(ipcp, struct sem_array, sem_perm);
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}
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/*
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* sem_lock_(check_) routines are called in the paths where the rw_mutex
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* is not held.
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*/
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static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id);
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@ -233,7 +249,7 @@ static inline void sem_rmid(struct ipc_namespace *ns, struct sem_array *s)
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* @ns: namespace
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* @params: ptr to the structure that contains key, semflg and nsems
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*
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* Called with sem_ids.mutex held
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* Called with sem_ids.rw_mutex held (as a writer)
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*/
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static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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@ -290,7 +306,7 @@ static int newary(struct ipc_namespace *ns, struct ipc_params *params)
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/*
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* Called with sem_ids.mutex and ipcp locked.
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* Called with sem_ids.rw_mutex and ipcp locked.
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*/
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static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
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{
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@ -301,7 +317,7 @@ static inline int sem_security(struct kern_ipc_perm *ipcp, int semflg)
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}
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/*
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* Called with sem_ids.mutex and ipcp locked.
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* Called with sem_ids.rw_mutex and ipcp locked.
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*/
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static inline int sem_more_checks(struct kern_ipc_perm *ipcp,
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struct ipc_params *params)
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@ -528,9 +544,9 @@ static int count_semzcnt (struct sem_array * sma, ushort semnum)
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return semzcnt;
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}
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/* Free a semaphore set. freeary() is called with sem_ids.mutex locked and
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* the spinlock for this semaphore set hold. sem_ids.mutex remains locked
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* on exit.
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/* Free a semaphore set. freeary() is called with sem_ids.rw_mutex locked
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* as a writer and the spinlock for this semaphore set hold. sem_ids.rw_mutex
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* remains locked on exit.
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*/
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static void freeary(struct ipc_namespace *ns, struct sem_array *sma)
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{
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@ -615,7 +631,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
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seminfo.semmnu = SEMMNU;
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seminfo.semmap = SEMMAP;
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seminfo.semume = SEMUME;
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mutex_lock(&sem_ids(ns).mutex);
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down_read(&sem_ids(ns).rw_mutex);
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if (cmd == SEM_INFO) {
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seminfo.semusz = sem_ids(ns).in_use;
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seminfo.semaem = ns->used_sems;
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@ -624,7 +640,7 @@ static int semctl_nolock(struct ipc_namespace *ns, int semid, int semnum,
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seminfo.semaem = SEMAEM;
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}
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max_id = ipc_get_maxid(&sem_ids(ns));
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mutex_unlock(&sem_ids(ns).mutex);
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up_read(&sem_ids(ns).rw_mutex);
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if (copy_to_user (arg.__buf, &seminfo, sizeof(struct seminfo)))
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return -EFAULT;
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return (max_id < 0) ? 0: max_id;
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@ -895,7 +911,7 @@ static int semctl_down(struct ipc_namespace *ns, int semid, int semnum,
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if(copy_semid_from_user (&setbuf, arg.buf, version))
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return -EFAULT;
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}
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sma = sem_lock_check(ns, semid);
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sma = sem_lock_check_down(ns, semid);
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if (IS_ERR(sma))
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return PTR_ERR(sma);
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@ -976,9 +992,9 @@ asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
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return err;
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case IPC_RMID:
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case IPC_SET:
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mutex_lock(&sem_ids(ns).mutex);
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down_write(&sem_ids(ns).rw_mutex);
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err = semctl_down(ns,semid,semnum,cmd,version,arg);
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mutex_unlock(&sem_ids(ns).mutex);
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up_write(&sem_ids(ns).rw_mutex);
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return err;
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default:
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return -EINVAL;
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77
ipc/shm.c
77
ipc/shm.c
@ -35,7 +35,7 @@
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#include <linux/capability.h>
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#include <linux/ptrace.h>
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#include <linux/seq_file.h>
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#include <linux/mutex.h>
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#include <linux/rwsem.h>
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#include <linux/nsproxy.h>
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#include <linux/mount.h>
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@ -83,8 +83,8 @@ static void __shm_init_ns(struct ipc_namespace *ns, struct ipc_ids *ids)
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}
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/*
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* Called with shm_ids.mutex and the shp structure locked.
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* Only shm_ids.mutex remains locked on exit.
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* Called with shm_ids.rw_mutex (writer) and the shp structure locked.
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* Only shm_ids.rw_mutex remains locked on exit.
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*/
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static void do_shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *shp)
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{
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@ -115,7 +115,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
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int next_id;
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int total, in_use;
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mutex_lock(&shm_ids(ns).mutex);
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down_write(&shm_ids(ns).rw_mutex);
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in_use = shm_ids(ns).in_use;
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@ -127,7 +127,7 @@ void shm_exit_ns(struct ipc_namespace *ns)
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do_shm_rmid(ns, shp);
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total++;
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}
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mutex_unlock(&shm_ids(ns).mutex);
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up_write(&shm_ids(ns).rw_mutex);
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kfree(ns->ids[IPC_SHM_IDS]);
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ns->ids[IPC_SHM_IDS] = NULL;
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@ -141,6 +141,31 @@ void __init shm_init (void)
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IPC_SHM_IDS, sysvipc_shm_proc_show);
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}
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/*
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* shm_lock_(check_)down routines are called in the paths where the rw_mutex
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* is held to protect access to the idr tree.
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*/
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static inline struct shmid_kernel *shm_lock_down(struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock_down(&shm_ids(ns), id);
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return container_of(ipcp, struct shmid_kernel, shm_perm);
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}
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static inline struct shmid_kernel *shm_lock_check_down(
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struct ipc_namespace *ns,
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int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock_check_down(&shm_ids(ns), id);
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return container_of(ipcp, struct shmid_kernel, shm_perm);
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}
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/*
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* shm_lock_(check_) routines are called in the paths where the rw_mutex
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* is not held.
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*/
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static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
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{
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struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
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@ -189,7 +214,7 @@ static void shm_open(struct vm_area_struct *vma)
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* @ns: namespace
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* @shp: struct to free
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*
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* It has to be called with shp and shm_ids.mutex locked,
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* It has to be called with shp and shm_ids.rw_mutex (writer) locked,
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* but returns with shp unlocked and freed.
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*/
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static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp)
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@ -220,9 +245,9 @@ static void shm_close(struct vm_area_struct *vma)
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struct shmid_kernel *shp;
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struct ipc_namespace *ns = sfd->ns;
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mutex_lock(&shm_ids(ns).mutex);
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down_write(&shm_ids(ns).rw_mutex);
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/* remove from the list of attaches of the shm segment */
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shp = shm_lock(ns, sfd->id);
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shp = shm_lock_down(ns, sfd->id);
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BUG_ON(IS_ERR(shp));
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shp->shm_lprid = task_tgid_vnr(current);
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shp->shm_dtim = get_seconds();
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@ -232,7 +257,7 @@ static void shm_close(struct vm_area_struct *vma)
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shm_destroy(ns, shp);
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else
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shm_unlock(shp);
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mutex_unlock(&shm_ids(ns).mutex);
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up_write(&shm_ids(ns).rw_mutex);
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}
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static int shm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
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@ -353,7 +378,7 @@ static struct vm_operations_struct shm_vm_ops = {
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* @ns: namespace
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* @params: ptr to the structure that contains key, size and shmflg
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*
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* Called with shm_ids.mutex held
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* Called with shm_ids.rw_mutex held as a writer.
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*/
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static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
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@ -442,7 +467,7 @@ no_file:
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}
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/*
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* Called with shm_ids.mutex and ipcp locked.
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* Called with shm_ids.rw_mutex and ipcp locked.
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*/
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static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
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{
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@ -453,7 +478,7 @@ static inline int shm_security(struct kern_ipc_perm *ipcp, int shmflg)
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}
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/*
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* Called with shm_ids.mutex and ipcp locked.
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* Called with shm_ids.rw_mutex and ipcp locked.
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*/
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static inline int shm_more_checks(struct kern_ipc_perm *ipcp,
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struct ipc_params *params)
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@ -578,7 +603,7 @@ static inline unsigned long copy_shminfo_to_user(void __user *buf, struct shminf
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}
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/*
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* Called with shm_ids.mutex held
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* Called with shm_ids.rw_mutex held as a reader
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*/
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static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss,
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unsigned long *swp)
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@ -649,9 +674,9 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
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if(copy_shminfo_to_user (buf, &shminfo, version))
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return -EFAULT;
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mutex_lock(&shm_ids(ns).mutex);
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down_read(&shm_ids(ns).rw_mutex);
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err = ipc_get_maxid(&shm_ids(ns));
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mutex_unlock(&shm_ids(ns).mutex);
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up_read(&shm_ids(ns).rw_mutex);
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if(err<0)
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err = 0;
|
||||
@ -666,14 +691,14 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
|
||||
return err;
|
||||
|
||||
memset(&shm_info,0,sizeof(shm_info));
|
||||
mutex_lock(&shm_ids(ns).mutex);
|
||||
down_read(&shm_ids(ns).rw_mutex);
|
||||
shm_info.used_ids = shm_ids(ns).in_use;
|
||||
shm_get_stat (ns, &shm_info.shm_rss, &shm_info.shm_swp);
|
||||
shm_info.shm_tot = ns->shm_tot;
|
||||
shm_info.swap_attempts = 0;
|
||||
shm_info.swap_successes = 0;
|
||||
err = ipc_get_maxid(&shm_ids(ns));
|
||||
mutex_unlock(&shm_ids(ns).mutex);
|
||||
up_read(&shm_ids(ns).rw_mutex);
|
||||
if(copy_to_user (buf, &shm_info, sizeof(shm_info))) {
|
||||
err = -EFAULT;
|
||||
goto out;
|
||||
@ -786,8 +811,8 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
|
||||
* Instead we set a destroyed flag, and then blow
|
||||
* the name away when the usage hits zero.
|
||||
*/
|
||||
mutex_lock(&shm_ids(ns).mutex);
|
||||
shp = shm_lock_check(ns, shmid);
|
||||
down_write(&shm_ids(ns).rw_mutex);
|
||||
shp = shm_lock_check_down(ns, shmid);
|
||||
if (IS_ERR(shp)) {
|
||||
err = PTR_ERR(shp);
|
||||
goto out_up;
|
||||
@ -809,7 +834,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
|
||||
goto out_unlock_up;
|
||||
|
||||
do_shm_rmid(ns, shp);
|
||||
mutex_unlock(&shm_ids(ns).mutex);
|
||||
up_write(&shm_ids(ns).rw_mutex);
|
||||
goto out;
|
||||
}
|
||||
|
||||
@ -824,8 +849,8 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
|
||||
err = -EFAULT;
|
||||
goto out;
|
||||
}
|
||||
mutex_lock(&shm_ids(ns).mutex);
|
||||
shp = shm_lock_check(ns, shmid);
|
||||
down_write(&shm_ids(ns).rw_mutex);
|
||||
shp = shm_lock_check_down(ns, shmid);
|
||||
if (IS_ERR(shp)) {
|
||||
err = PTR_ERR(shp);
|
||||
goto out_up;
|
||||
@ -864,7 +889,7 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf)
|
||||
out_unlock_up:
|
||||
shm_unlock(shp);
|
||||
out_up:
|
||||
mutex_unlock(&shm_ids(ns).mutex);
|
||||
up_write(&shm_ids(ns).rw_mutex);
|
||||
goto out;
|
||||
out_unlock:
|
||||
shm_unlock(shp);
|
||||
@ -998,8 +1023,8 @@ invalid:
|
||||
fput(file);
|
||||
|
||||
out_nattch:
|
||||
mutex_lock(&shm_ids(ns).mutex);
|
||||
shp = shm_lock(ns, shmid);
|
||||
down_write(&shm_ids(ns).rw_mutex);
|
||||
shp = shm_lock_down(ns, shmid);
|
||||
BUG_ON(IS_ERR(shp));
|
||||
shp->shm_nattch--;
|
||||
if(shp->shm_nattch == 0 &&
|
||||
@ -1007,7 +1032,7 @@ out_nattch:
|
||||
shm_destroy(ns, shp);
|
||||
else
|
||||
shm_unlock(shp);
|
||||
mutex_unlock(&shm_ids(ns).mutex);
|
||||
up_write(&shm_ids(ns).rw_mutex);
|
||||
|
||||
out:
|
||||
return err;
|
||||
|
||||
78
ipc/util.c
78
ipc/util.c
@ -32,6 +32,7 @@
|
||||
#include <linux/proc_fs.h>
|
||||
#include <linux/audit.h>
|
||||
#include <linux/nsproxy.h>
|
||||
#include <linux/rwsem.h>
|
||||
|
||||
#include <asm/unistd.h>
|
||||
|
||||
@ -136,7 +137,7 @@ __initcall(ipc_init);
|
||||
|
||||
void ipc_init_ids(struct ipc_ids *ids)
|
||||
{
|
||||
mutex_init(&ids->mutex);
|
||||
init_rwsem(&ids->rw_mutex);
|
||||
|
||||
ids->in_use = 0;
|
||||
ids->seq = 0;
|
||||
@ -191,7 +192,7 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
|
||||
* @ids: Identifier set
|
||||
* @key: The key to find
|
||||
*
|
||||
* Requires ipc_ids.mutex locked.
|
||||
* Requires ipc_ids.rw_mutex locked.
|
||||
* Returns the LOCKED pointer to the ipc structure if found or NULL
|
||||
* if not.
|
||||
* If key is found ipc points to the owning ipc structure
|
||||
@ -225,7 +226,7 @@ static struct kern_ipc_perm *ipc_findkey(struct ipc_ids *ids, key_t key)
|
||||
* ipc_get_maxid - get the last assigned id
|
||||
* @ids: IPC identifier set
|
||||
*
|
||||
* Called with ipc_ids.mutex held.
|
||||
* Called with ipc_ids.rw_mutex held.
|
||||
*/
|
||||
|
||||
int ipc_get_maxid(struct ipc_ids *ids)
|
||||
@ -263,7 +264,7 @@ int ipc_get_maxid(struct ipc_ids *ids)
|
||||
* is returned. The 'new' entry is returned in a locked state on success.
|
||||
* On failure the entry is not locked and -1 is returned.
|
||||
*
|
||||
* Called with ipc_ids.mutex held.
|
||||
* Called with ipc_ids.rw_mutex held as a writer.
|
||||
*/
|
||||
|
||||
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
|
||||
@ -316,9 +317,9 @@ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
|
||||
if (!err)
|
||||
return -ENOMEM;
|
||||
|
||||
mutex_lock(&ids->mutex);
|
||||
down_write(&ids->rw_mutex);
|
||||
err = ops->getnew(ns, params);
|
||||
mutex_unlock(&ids->mutex);
|
||||
up_write(&ids->rw_mutex);
|
||||
|
||||
return err;
|
||||
}
|
||||
@ -335,7 +336,7 @@ int ipcget_new(struct ipc_namespace *ns, struct ipc_ids *ids,
|
||||
*
|
||||
* On success, the IPC id is returned.
|
||||
*
|
||||
* It is called with ipc_ids.mutex and ipcp->lock held.
|
||||
* It is called with ipc_ids.rw_mutex and ipcp->lock held.
|
||||
*/
|
||||
static int ipc_check_perms(struct kern_ipc_perm *ipcp, struct ipc_ops *ops,
|
||||
struct ipc_params *params)
|
||||
@ -376,7 +377,11 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
|
||||
|
||||
err = idr_pre_get(&ids->ipcs_idr, GFP_KERNEL);
|
||||
|
||||
mutex_lock(&ids->mutex);
|
||||
/*
|
||||
* Take the lock as a writer since we are potentially going to add
|
||||
* a new entry + read locks are not "upgradable"
|
||||
*/
|
||||
down_write(&ids->rw_mutex);
|
||||
ipcp = ipc_findkey(ids, params->key);
|
||||
if (ipcp == NULL) {
|
||||
/* key not used */
|
||||
@ -404,7 +409,7 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
|
||||
}
|
||||
ipc_unlock(ipcp);
|
||||
}
|
||||
mutex_unlock(&ids->mutex);
|
||||
up_write(&ids->rw_mutex);
|
||||
|
||||
return err;
|
||||
}
|
||||
@ -415,8 +420,8 @@ int ipcget_public(struct ipc_namespace *ns, struct ipc_ids *ids,
|
||||
* @ids: IPC identifier set
|
||||
* @ipcp: ipc perm structure containing the identifier to remove
|
||||
*
|
||||
* ipc_ids.mutex and the spinlock for this ID are held before this
|
||||
* function is called, and remain locked on the exit.
|
||||
* ipc_ids.rw_mutex (as a writer) and the spinlock for this ID are held
|
||||
* before this function is called, and remain locked on the exit.
|
||||
*/
|
||||
|
||||
void ipc_rmid(struct ipc_ids *ids, struct kern_ipc_perm *ipcp)
|
||||
@ -680,15 +685,17 @@ void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
|
||||
}
|
||||
|
||||
/**
|
||||
* ipc_lock - Lock an ipc structure
|
||||
* ipc_lock - Lock an ipc structure without rw_mutex held
|
||||
* @ids: IPC identifier set
|
||||
* @id: ipc id to look for
|
||||
*
|
||||
* Look for an id in the ipc ids idr and lock the associated ipc object.
|
||||
*
|
||||
* ipc_ids.mutex is not necessarily held before this function is called,
|
||||
* that's why we enter a RCU read section.
|
||||
* The ipc object is locked on exit.
|
||||
*
|
||||
* This is the routine that should be called when the rw_mutex is not already
|
||||
* held, i.e. idr tree not protected: it protects the idr tree in read mode
|
||||
* during the idr_find().
|
||||
*/
|
||||
|
||||
struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
|
||||
@ -696,13 +703,18 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
|
||||
struct kern_ipc_perm *out;
|
||||
int lid = ipcid_to_idx(id);
|
||||
|
||||
down_read(&ids->rw_mutex);
|
||||
|
||||
rcu_read_lock();
|
||||
out = idr_find(&ids->ipcs_idr, lid);
|
||||
if (out == NULL) {
|
||||
rcu_read_unlock();
|
||||
up_read(&ids->rw_mutex);
|
||||
return ERR_PTR(-EINVAL);
|
||||
}
|
||||
|
||||
up_read(&ids->rw_mutex);
|
||||
|
||||
spin_lock(&out->lock);
|
||||
|
||||
/* ipc_rmid() may have already freed the ID while ipc_lock
|
||||
@ -717,6 +729,40 @@ struct kern_ipc_perm *ipc_lock(struct ipc_ids *ids, int id)
|
||||
return out;
|
||||
}
|
||||
|
||||
/**
|
||||
* ipc_lock_down - Lock an ipc structure with rw_sem held
|
||||
* @ids: IPC identifier set
|
||||
* @id: ipc id to look for
|
||||
*
|
||||
* Look for an id in the ipc ids idr and lock the associated ipc object.
|
||||
*
|
||||
* The ipc object is locked on exit.
|
||||
*
|
||||
* This is the routine that should be called when the rw_mutex is already
|
||||
* held, i.e. idr tree protected.
|
||||
*/
|
||||
|
||||
struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *ids, int id)
|
||||
{
|
||||
struct kern_ipc_perm *out;
|
||||
int lid = ipcid_to_idx(id);
|
||||
|
||||
rcu_read_lock();
|
||||
out = idr_find(&ids->ipcs_idr, lid);
|
||||
if (out == NULL) {
|
||||
rcu_read_unlock();
|
||||
return ERR_PTR(-EINVAL);
|
||||
}
|
||||
|
||||
spin_lock(&out->lock);
|
||||
|
||||
/*
|
||||
* No need to verify that the structure is still valid since the
|
||||
* rw_mutex is held.
|
||||
*/
|
||||
return out;
|
||||
}
|
||||
|
||||
#ifdef __ARCH_WANT_IPC_PARSE_VERSION
|
||||
|
||||
|
||||
@ -808,7 +854,7 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
|
||||
* Take the lock - this will be released by the corresponding
|
||||
* call to stop().
|
||||
*/
|
||||
mutex_lock(&ids->mutex);
|
||||
down_read(&ids->rw_mutex);
|
||||
|
||||
/* pos < 0 is invalid */
|
||||
if (*pos < 0)
|
||||
@ -835,7 +881,7 @@ static void sysvipc_proc_stop(struct seq_file *s, void *it)
|
||||
|
||||
ids = iter->ns->ids[iface->ids];
|
||||
/* Release the lock we took in start() */
|
||||
mutex_unlock(&ids->mutex);
|
||||
up_read(&ids->rw_mutex);
|
||||
}
|
||||
|
||||
static int sysvipc_proc_show(struct seq_file *s, void *it)
|
||||
|
||||
28
ipc/util.h
28
ipc/util.h
@ -32,7 +32,7 @@ struct ipc_ids {
|
||||
int in_use;
|
||||
unsigned short seq;
|
||||
unsigned short seq_max;
|
||||
struct mutex mutex;
|
||||
struct rw_semaphore rw_mutex;
|
||||
struct idr ipcs_idr;
|
||||
};
|
||||
|
||||
@ -81,8 +81,10 @@ void __init ipc_init_proc_interface(const char *path, const char *header,
|
||||
|
||||
#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
|
||||
|
||||
/* must be called with ids->mutex acquired.*/
|
||||
/* must be called with ids->rw_mutex acquired for writing */
|
||||
int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
|
||||
|
||||
/* must be called with ids->rw_mutex acquired for reading */
|
||||
int ipc_get_maxid(struct ipc_ids *);
|
||||
|
||||
/* must be called with both locks acquired. */
|
||||
@ -107,6 +109,11 @@ void* ipc_rcu_alloc(int size);
|
||||
void ipc_rcu_getref(void *ptr);
|
||||
void ipc_rcu_putref(void *ptr);
|
||||
|
||||
/*
|
||||
* ipc_lock_down: called with rw_mutex held
|
||||
* ipc_lock: called without that lock held
|
||||
*/
|
||||
struct kern_ipc_perm *ipc_lock_down(struct ipc_ids *, int);
|
||||
struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
|
||||
|
||||
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
|
||||
@ -155,6 +162,23 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
|
||||
rcu_read_unlock();
|
||||
}
|
||||
|
||||
static inline struct kern_ipc_perm *ipc_lock_check_down(struct ipc_ids *ids,
|
||||
int id)
|
||||
{
|
||||
struct kern_ipc_perm *out;
|
||||
|
||||
out = ipc_lock_down(ids, id);
|
||||
if (IS_ERR(out))
|
||||
return out;
|
||||
|
||||
if (ipc_checkid(ids, out, id)) {
|
||||
ipc_unlock(out);
|
||||
return ERR_PTR(-EIDRM);
|
||||
}
|
||||
|
||||
return out;
|
||||
}
|
||||
|
||||
static inline struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids,
|
||||
int id)
|
||||
{
|
||||
|
||||
Loading…
Reference in New Issue
Block a user