[PATCH] keys: add a way to store the appropriate context for newly-created keys
Add a /proc/<pid>/attr/keycreate entry that stores the appropriate context for
newly-created keys. Modify the selinux_key_alloc hook to make use of the new
entry. Update the flask headers to include a new "setkeycreate" permission
for processes. Update the flask headers to include a new "create" permission
for keys. Use the create permission to restrict which SIDs each task can
assign to newly-created keys. Add a new parameter to the security hook
"security_key_alloc" to indicate whether it is being invoked by the kernel, or
from userspace. If it is being invoked by the kernel, the security hook
should never fail. Update the documentation to reflect these changes.
Signed-off-by: Michael LeMay <mdlemay@epoch.ncsc.mil>
Signed-off-by: James Morris <jmorris@namei.org>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 13384fe..0d8b275 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -1099,6 +1099,17 @@
FILESYSTEM__ASSOCIATE, &ad);
}
+/* Check whether a task can create a key. */
+static int may_create_key(u32 ksid,
+ struct task_struct *ctx)
+{
+ struct task_security_struct *tsec;
+
+ tsec = ctx->security;
+
+ return avc_has_perm(tsec->sid, ksid, SECCLASS_KEY, KEY__CREATE, NULL);
+}
+
#define MAY_LINK 0
#define MAY_UNLINK 1
#define MAY_RMDIR 2
@@ -4150,6 +4161,8 @@
sid = tsec->exec_sid;
else if (!strcmp(name, "fscreate"))
sid = tsec->create_sid;
+ else if (!strcmp(name, "keycreate"))
+ sid = tsec->keycreate_sid;
else
return -EINVAL;
@@ -4182,6 +4195,8 @@
error = task_has_perm(current, p, PROCESS__SETEXEC);
else if (!strcmp(name, "fscreate"))
error = task_has_perm(current, p, PROCESS__SETFSCREATE);
+ else if (!strcmp(name, "keycreate"))
+ error = task_has_perm(current, p, PROCESS__SETKEYCREATE);
else if (!strcmp(name, "current"))
error = task_has_perm(current, p, PROCESS__SETCURRENT);
else
@@ -4211,7 +4226,12 @@
tsec->exec_sid = sid;
else if (!strcmp(name, "fscreate"))
tsec->create_sid = sid;
- else if (!strcmp(name, "current")) {
+ else if (!strcmp(name, "keycreate")) {
+ error = may_create_key(sid, p);
+ if (error)
+ return error;
+ tsec->keycreate_sid = sid;
+ } else if (!strcmp(name, "current")) {
struct av_decision avd;
if (sid == 0)
@@ -4275,7 +4295,10 @@
return -ENOMEM;
ksec->obj = k;
- ksec->sid = tsec->sid;
+ if (tsec->keycreate_sid)
+ ksec->sid = tsec->keycreate_sid;
+ else
+ ksec->sid = tsec->sid;
k->security = ksec;
return 0;
@@ -4514,10 +4537,10 @@
#ifdef CONFIG_KEYS
/* Add security information to initial keyrings */
- security_key_alloc(&root_user_keyring, current,
- KEY_ALLOC_NOT_IN_QUOTA);
- security_key_alloc(&root_session_keyring, current,
- KEY_ALLOC_NOT_IN_QUOTA);
+ selinux_key_alloc(&root_user_keyring, current,
+ KEY_ALLOC_NOT_IN_QUOTA);
+ selinux_key_alloc(&root_session_keyring, current,
+ KEY_ALLOC_NOT_IN_QUOTA);
#endif
return 0;