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[PATCH v4 6/9] ipc: add new SEM_SET command for sys_semctl() call [message #47483] Mon, 13 August 2012 12:32
Stanislav Kinsbursky is currently offline  Stanislav Kinsbursky
Messages: 683
Registered: October 2011
Senior Member
From: *parallels.com
New SEM_SET command will be interpreted exactly as IPC_SET, but also will
update key, cuid and cgid values. IOW, it allows to change existent key value.
The fact, that key is not used is checked before update. Otherwise -EEXIST is
returned.

Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com>
Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
---
include/linux/sem.h | 1 +
ipc/compat.c | 1 +
ipc/sem.c | 10 ++++++++--
security/selinux/hooks.c | 1 +
security/smack/smack_lsm.c | 1 +
5 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/include/linux/sem.h b/include/linux/sem.h
index 10d6b22..c74b9b5 100644
--- a/include/linux/sem.h
+++ b/include/linux/sem.h
@@ -18,6 +18,7 @@
/* ipcs ctl cmds */
#define SEM_STAT 18
#define SEM_INFO 19
+#define SEM_SET 20

/* Obsolete, used only for backwards compatibility and libc5 compiles */
struct semid_ds {
diff --git a/ipc/compat.c b/ipc/compat.c
index da4f5c6..7cfdb5b 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -290,6 +290,7 @@ static long do_compat_semctl(int first, int second, int third, u32 pad)
break;

case IPC_SET:
+ case SEM_SET:
if (version == IPC_64) {
err = get_compat_semid64_ds(&s64, compat_ptr(pad));
} else {
diff --git a/ipc/sem.c b/ipc/sem.c
index 845c912..d9024d5 100644
--- a/ipc/sem.c
+++ b/ipc/sem.c
@@ -1084,12 +1084,13 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
struct semid64_ds semid64;
struct kern_ipc_perm *ipcp;

- if(cmd == IPC_SET) {
+ if (cmd == IPC_SET || cmd == SEM_SET) {
if (copy_semid_from_user(&semid64, arg.buf, version))
return -EFAULT;
}

- ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid, cmd,
+ ipcp = ipcctl_pre_down(ns, &sem_ids(ns), semid,
+ (cmd != SEM_SET) ? : IPC_SET,
&semid64.sem_perm, 0);
if (IS_ERR(ipcp))
return PTR_ERR(ipcp);
@@ -1104,6 +1105,10 @@ static int semctl_down(struct ipc_namespace *ns, int semid,
case IPC_RMID:
freeary(ns, ipcp);
goto out_up;
+ case SEM_SET:
+ err = ipc_update_key(&sem_ids(ns), &semid64.sem_perm, ipcp);
+ if (err)
+ break;
case IPC_SET:
ipc_update_perm(&semid64.sem_perm, ipcp);
sma->sem_ctime = get_seconds();
@@ -1149,6 +1154,7 @@ SYSCALL_DEFINE(semctl)(int semid, int semnum, int cmd, union semun arg)
return err;
case IPC_RMID:
case IPC_SET:
+ case SEM_SET:
err = semctl_down(ns, semid, cmd, version, arg);
return err;
default:
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 622e020..704391b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5160,6 +5160,7 @@ static int selinux_sem_semctl(struct sem_array *sma, int cmd)
perms = SEM__DESTROY;
break;
case IPC_SET:
+ case SEM_SET:
perms = SEM__SETATTR;
break;
case IPC_STAT:
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 62826b1..1116076 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2277,6 +2277,7 @@ static int smack_sem_semctl(struct sem_array *sma, int cmd)
case SETALL:
case IPC_RMID:
case IPC_SET:
+ case SEM_SET:
may = MAY_READWRITE;
break;
case IPC_INFO:
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