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[PATCH v4 4/9] ipc: add new SHM_SET command for sys_shmctl() call [message #47486] Mon, 13 August 2012 12:31
Stanislav Kinsbursky is currently offline  Stanislav Kinsbursky
Messages: 683
Registered: October 2011
Senior Member
From: *parallels.com
New SHM_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/shm.h | 1 +
ipc/compat.c | 1 +
ipc/shm.c | 13 +++++++++++--
security/selinux/hooks.c | 1 +
security/smack/smack_lsm.c | 1 +
5 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/include/linux/shm.h b/include/linux/shm.h
index 92808b8..6fc5447 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -63,6 +63,7 @@ struct shmid_ds {
/* ipcs ctl commands */
#define SHM_STAT 13
#define SHM_INFO 14
+#define SHM_SET 15

/* Obsolete, used only for backwards compatibility */
struct shminfo {
diff --git a/ipc/compat.c b/ipc/compat.c
index aa88515..e7d4af7 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -688,6 +688,7 @@ long compat_sys_shmctl(int first, int second, void __user *uptr)


case IPC_SET:
+ case SHM_SET:
if (version == IPC_64) {
err = get_compat_shmid64_ds(&s64, uptr);
} else {
diff --git a/ipc/shm.c b/ipc/shm.c
index d4c0a9e..677b9f6 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -635,6 +635,9 @@ copy_shmid_from_user(struct shmid64_ds *out, void __user *buf, int version)
out->shm_perm.uid = tbuf_old.shm_perm.uid;
out->shm_perm.gid = tbuf_old.shm_perm.gid;
out->shm_perm.mode = tbuf_old.shm_perm.mode;
+ out->shm_perm.cuid = tbuf_old.shm_perm.cuid;
+ out->shm_perm.cgid = tbuf_old.shm_perm.cgid;
+ out->shm_perm.key = tbuf_old.shm_perm.key;

return 0;
}
@@ -739,12 +742,13 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
struct shmid_kernel *shp;
int err;

- if (cmd == IPC_SET) {
+ if (cmd == IPC_SET || cmd == SHM_SET) {
if (copy_shmid_from_user(&shmid64, buf, version))
return -EFAULT;
}

- ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid, cmd,
+ ipcp = ipcctl_pre_down(ns, &shm_ids(ns), shmid,
+ (cmd != SHM_SET) ? : IPC_SET,
&shmid64.shm_perm, 0);
if (IS_ERR(ipcp))
return PTR_ERR(ipcp);
@@ -758,6 +762,10 @@ static int shmctl_down(struct ipc_namespace *ns, int shmid, int cmd,
case IPC_RMID:
do_shm_rmid(ns, ipcp);
goto out_up;
+ case SHM_SET:
+ err = ipc_update_key(&shm_ids(ns), &shmid64.shm_perm, ipcp);
+ if (err)
+ break;
case IPC_SET:
ipc_update_perm(&shmid64.shm_perm, ipcp);
shp->shm_ctim = get_seconds();
@@ -935,6 +943,7 @@ SYSCALL_DEFINE3(shmctl, int, shmid, int, cmd, struct shmid_ds __user *, buf)
}
case IPC_RMID:
case IPC_SET:
+ case SHM_SET:
err = shmctl_down(ns, shmid, cmd, buf, version);
return err;
default:
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6c56ebf..9e07e22 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5054,6 +5054,7 @@ static int selinux_shm_shmctl(struct shmid_kernel *shp, int cmd)
perms = SHM__GETATTR | SHM__ASSOCIATE;
break;
case IPC_SET:
+ case SHM_SET:
perms = SHM__SETATTR;
break;
case SHM_LOCK:
diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index ee0bb57..a25dfd1 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2145,6 +2145,7 @@ static int smack_shm_shmctl(struct shmid_kernel *shp, int cmd)
may = MAY_READ;
break;
case IPC_SET:
+ case SHM_SET:
case SHM_LOCK:
case SHM_UNLOCK:
case IPC_RMID:
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