[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;
diff --git a/security/selinux/include/av_perm_to_string.h b/security/selinux/include/av_perm_to_string.h
index bc020bd..e777578 100644
--- a/security/selinux/include/av_perm_to_string.h
+++ b/security/selinux/include/av_perm_to_string.h
@@ -72,6 +72,7 @@
S_(SECCLASS_PROCESS, PROCESS__EXECMEM, "execmem")
S_(SECCLASS_PROCESS, PROCESS__EXECSTACK, "execstack")
S_(SECCLASS_PROCESS, PROCESS__EXECHEAP, "execheap")
+ S_(SECCLASS_PROCESS, PROCESS__SETKEYCREATE, "setkeycreate")
S_(SECCLASS_MSGQ, MSGQ__ENQUEUE, "enqueue")
S_(SECCLASS_MSG, MSG__SEND, "send")
S_(SECCLASS_MSG, MSG__RECEIVE, "receive")
@@ -248,3 +249,4 @@
S_(SECCLASS_KEY, KEY__SEARCH, "search")
S_(SECCLASS_KEY, KEY__LINK, "link")
S_(SECCLASS_KEY, KEY__SETATTR, "setattr")
+ S_(SECCLASS_KEY, KEY__CREATE, "create")
diff --git a/security/selinux/include/av_permissions.h b/security/selinux/include/av_permissions.h
index 1205227..1e16780 100644
--- a/security/selinux/include/av_permissions.h
+++ b/security/selinux/include/av_permissions.h
@@ -467,6 +467,7 @@
#define PROCESS__EXECMEM 0x02000000UL
#define PROCESS__EXECSTACK 0x04000000UL
#define PROCESS__EXECHEAP 0x08000000UL
+#define PROCESS__SETKEYCREATE 0x10000000UL
#define IPC__CREATE 0x00000001UL
#define IPC__DESTROY 0x00000002UL
@@ -966,4 +967,4 @@
#define KEY__SEARCH 0x00000008UL
#define KEY__LINK 0x00000010UL
#define KEY__SETATTR 0x00000020UL
-
+#define KEY__CREATE 0x00000040UL
diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 8f5547a..191b3e4 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -32,6 +32,7 @@
u32 sid; /* current SID */
u32 exec_sid; /* exec SID */
u32 create_sid; /* fscreate SID */
+ u32 keycreate_sid; /* keycreate SID */
u32 ptrace_sid; /* SID of ptrace parent */
};