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[PATCH v7 04/10] ipc: add new SHM_SET command for sys_shmctl() call [message #48469] Thu, 18 October 2012 10:22
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>
---
include/uapi/linux/shm.h | 1 +
ipc/compat.c | 1 +
ipc/shm.c | 14 ++++++++++++--
security/selinux/hooks.c | 1 +
security/smack/smack_lsm.c | 1 +
5 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/include/uapi/linux/shm.h b/include/uapi/linux/shm.h
index ec36fa1..d7413fd 100644
--- a/include/uapi/linux/shm.h
+++ b/include/uapi/linux/shm.h
@@ -56,6 +56,7 @@ 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 af30d13..35c750d 100644
--- a/ipc/compat.c
+++ b/ipc/compat.c
@@ -692,6 +692,7 @@ 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 80b0046..650911e 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -636,6 +636,9 @@ 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;
}
@@ -740,12 +743,13 @@ 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) ? cmd : IPC_SET,
&shmid64.shm_perm, 0);
if (IS_ERR(ipcp))
return PTR_ERR(ipcp);
@@ -759,6 +763,11 @@ 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;
+ /* fall through */
case IPC_SET:
err = ipc_update_perm(&shmid64.shm_perm, ipcp);
if (err)
@@ -938,6 +947,7 @@ 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 24ab414..62b2447 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -5027,6 +5027,7 @@ 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 38be92c..c7eabc9 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -2121,6 +2121,7 @@ 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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