diff options
author | Pierre Peiffer <pierre.peiffer@bull.net> | 2008-04-29 01:00:47 -0700 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-29 08:06:13 -0700 |
commit | 8d4cc8b5c5e5bac526618ee704f3cfdcad954e0c (patch) | |
tree | 21258b10175f63703ace0a88402e513c6046d2d8 /ipc | |
parent | 6ff3797218ef41c248c83184101ce1aedc227333 (diff) | |
download | kernel_samsung_smdk4412-8d4cc8b5c5e5bac526618ee704f3cfdcad954e0c.zip kernel_samsung_smdk4412-8d4cc8b5c5e5bac526618ee704f3cfdcad954e0c.tar.gz kernel_samsung_smdk4412-8d4cc8b5c5e5bac526618ee704f3cfdcad954e0c.tar.bz2 |
IPC/shared memory: introduce shmctl_down
Currently, the way the different commands are handled in sys_shmctl introduces
some duplicated code.
This patch introduces the shmctl_down function to handle all the commands
requiring the rwmutex to be taken in write mode (ie IPC_SET and IPC_RMID for
now). It is the equivalent function of semctl_down for shared memory.
This removes some duplicated code for handling these both commands and
harmonizes the way they are handled among all IPCs.
Signed-off-by: Pierre Peiffer <pierre.peiffer@bull.net>
Acked-by: Serge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc')
-rw-r--r-- | ipc/shm.c | 160 |
1 files changed, 72 insertions, 88 deletions
@@ -616,10 +616,78 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss, } } -asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) +/* + * This function handles some shmctl commands which require the rw_mutex + * to be held in write mode. + * NOTE: no locks must be held, the rw_mutex is taken inside this function. + */ +static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd, + struct shmid_ds __user *buf, int version) { + struct kern_ipc_perm *ipcp; struct shm_setbuf setbuf; struct shmid_kernel *shp; + int err; + + if (cmd == IPC_SET) { + if (copy_shmid_from_user(&setbuf, buf, version)) + return -EFAULT; + } + + 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; + } + + ipcp = &shp->shm_perm; + + err = audit_ipc_obj(ipcp); + if (err) + goto out_unlock; + + if (cmd == IPC_SET) { + err = audit_ipc_set_perm(0, setbuf.uid, + setbuf.gid, setbuf.mode); + if (err) + goto out_unlock; + } + + if (current->euid != ipcp->uid && + current->euid != ipcp->cuid && + !capable(CAP_SYS_ADMIN)) { + err = -EPERM; + goto out_unlock; + } + + err = security_shm_shmctl(shp, cmd); + if (err) + goto out_unlock; + switch (cmd) { + case IPC_RMID: + do_shm_rmid(ns, ipcp); + goto out_up; + case IPC_SET: + ipcp->uid = setbuf.uid; + ipcp->gid = setbuf.gid; + ipcp->mode = (ipcp->mode & ~S_IRWXUGO) + | (setbuf.mode & S_IRWXUGO); + shp->shm_ctim = get_seconds(); + break; + default: + err = -EINVAL; + } +out_unlock: + shm_unlock(shp); +out_up: + up_write(&shm_ids(ns).rw_mutex); + return err; +} + +asmlinkage long sys_shmctl(int shmid, int cmd, struct shmid_ds __user *buf) +{ + struct shmid_kernel *shp; int err, version; struct ipc_namespace *ns; @@ -775,97 +843,13 @@ asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds __user *buf) goto out; } case IPC_RMID: - { - /* - * We cannot simply remove the file. The SVID states - * that the block remains until the last person - * detaches from it, then is deleted. A shmat() on - * an RMID segment is legal in older Linux and if - * we change it apps break... - * - * Instead we set a destroyed flag, and then blow - * the name away when the usage hits zero. - */ - 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; - } - - err = audit_ipc_obj(&(shp->shm_perm)); - if (err) - goto out_unlock_up; - - if (current->euid != shp->shm_perm.uid && - current->euid != shp->shm_perm.cuid && - !capable(CAP_SYS_ADMIN)) { - err=-EPERM; - goto out_unlock_up; - } - - err = security_shm_shmctl(shp, cmd); - if (err) - goto out_unlock_up; - - do_shm_rmid(ns, &shp->shm_perm); - up_write(&shm_ids(ns).rw_mutex); - goto out; - } - case IPC_SET: - { - if (!buf) { - err = -EFAULT; - goto out; - } - - if (copy_shmid_from_user (&setbuf, buf, version)) { - err = -EFAULT; - goto out; - } - 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; - } - err = audit_ipc_obj(&(shp->shm_perm)); - if (err) - goto out_unlock_up; - err = audit_ipc_set_perm(0, setbuf.uid, setbuf.gid, setbuf.mode); - if (err) - goto out_unlock_up; - err=-EPERM; - if (current->euid != shp->shm_perm.uid && - current->euid != shp->shm_perm.cuid && - !capable(CAP_SYS_ADMIN)) { - goto out_unlock_up; - } - - err = security_shm_shmctl(shp, cmd); - if (err) - goto out_unlock_up; - - shp->shm_perm.uid = setbuf.uid; - shp->shm_perm.gid = setbuf.gid; - shp->shm_perm.mode = (shp->shm_perm.mode & ~S_IRWXUGO) - | (setbuf.mode & S_IRWXUGO); - shp->shm_ctim = get_seconds(); - break; - } - + err = shmctl_down(ns, shmid, cmd, buf, version); + return err; default: - err = -EINVAL; - goto out; + return -EINVAL; } - err = 0; -out_unlock_up: - shm_unlock(shp); -out_up: - up_write(&shm_ids(ns).rw_mutex); - goto out; out_unlock: shm_unlock(shp); out: |