aboutsummaryrefslogtreecommitdiffstats
path: root/security/security.c
diff options
context:
space:
mode:
authorDavid Howells <dhowells@redhat.com>2009-09-02 04:14:21 -0400
committerJames Morris <jmorris@namei.org>2009-09-02 07:29:22 -0400
commitee18d64c1f632043a02e6f5ba5e045bb26a5465f (patch)
tree80b5a4d530ec7d5fd69799920f0db7b78aba6b9d /security/security.c
parentd0420c83f39f79afb82010c2d2cafd150eef651b (diff)
KEYS: Add a keyctl to install a process's session keyring on its parent [try #6]
Add a keyctl to install a process's session keyring onto its parent. This replaces the parent's session keyring. Because the COW credential code does not permit one process to change another process's credentials directly, the change is deferred until userspace next starts executing again. Normally this will be after a wait*() syscall. To support this, three new security hooks have been provided: cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in the blank security creds and key_session_to_parent() - which asks the LSM if the process may replace its parent's session keyring. The replacement may only happen if the process has the same ownership details as its parent, and the process has LINK permission on the session keyring, and the session keyring is owned by the process, and the LSM permits it. Note that this requires alteration to each architecture's notify_resume path. This has been done for all arches barring blackfin, m68k* and xtensa, all of which need assembly alteration to support TIF_NOTIFY_RESUME. This allows the replacement to be performed at the point the parent process resumes userspace execution. This allows the userspace AFS pioctl emulation to fully emulate newpag() and the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to alter the parent process's PAG membership. However, since kAFS doesn't use PAGs per se, but rather dumps the keys into the session keyring, the session keyring of the parent must be replaced if, for example, VIOCSETTOK is passed the newpag flag. This can be tested with the following program: #include <stdio.h> #include <stdlib.h> #include <keyutils.h> #define KEYCTL_SESSION_TO_PARENT 18 #define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0) int main(int argc, char **argv) { key_serial_t keyring, key; long ret; keyring = keyctl_join_session_keyring(argv[1]); OSERROR(keyring, "keyctl_join_session_keyring"); key = add_key("user", "a", "b", 1, keyring); OSERROR(key, "add_key"); ret = keyctl(KEYCTL_SESSION_TO_PARENT); OSERROR(ret, "KEYCTL_SESSION_TO_PARENT"); return 0; } Compiled and linked with -lkeyutils, you should see something like: [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 355907932 --alswrv 4043 -1 \_ keyring: _uid.4043 [dhowells@andromeda ~]$ /tmp/newpag [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: _ses 1055658746 --alswrv 4043 4043 \_ user: a [dhowells@andromeda ~]$ /tmp/newpag hello [dhowells@andromeda ~]$ keyctl show Session Keyring -3 --alswrv 4043 4043 keyring: hello 340417692 --alswrv 4043 4043 \_ user: a Where the test program creates a new session keyring, sticks a user key named 'a' into it and then installs it on its parent. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: James Morris <jmorris@namei.org>
Diffstat (limited to 'security/security.c')
-rw-r--r--security/security.c17
1 files changed, 17 insertions, 0 deletions
diff --git a/security/security.c b/security/security.c
index f88eaf6b14cc..d8b727637f02 100644
--- a/security/security.c
+++ b/security/security.c
@@ -684,6 +684,11 @@ int security_task_create(unsigned long clone_flags)
684 return security_ops->task_create(clone_flags); 684 return security_ops->task_create(clone_flags);
685} 685}
686 686
687int security_cred_alloc_blank(struct cred *cred, gfp_t gfp)
688{
689 return security_ops->cred_alloc_blank(cred, gfp);
690}
691
687void security_cred_free(struct cred *cred) 692void security_cred_free(struct cred *cred)
688{ 693{
689 security_ops->cred_free(cred); 694 security_ops->cred_free(cred);
@@ -699,6 +704,11 @@ void security_commit_creds(struct cred *new, const struct cred *old)
699 security_ops->cred_commit(new, old); 704 security_ops->cred_commit(new, old);
700} 705}
701 706
707void security_transfer_creds(struct cred *new, const struct cred *old)
708{
709 security_ops->cred_transfer(new, old);
710}
711
702int security_kernel_act_as(struct cred *new, u32 secid) 712int security_kernel_act_as(struct cred *new, u32 secid)
703{ 713{
704 return security_ops->kernel_act_as(new, secid); 714 return security_ops->kernel_act_as(new, secid);
@@ -1241,6 +1251,13 @@ int security_key_getsecurity(struct key *key, char **_buffer)
1241 return security_ops->key_getsecurity(key, _buffer); 1251 return security_ops->key_getsecurity(key, _buffer);
1242} 1252}
1243 1253
1254int security_key_session_to_parent(const struct cred *cred,
1255 const struct cred *parent_cred,
1256 struct key *key)
1257{
1258 return security_ops->key_session_to_parent(cred, parent_cred, key);
1259}
1260
1244#endif /* CONFIG_KEYS */ 1261#endif /* CONFIG_KEYS */
1245 1262
1246#ifdef CONFIG_AUDIT 1263#ifdef CONFIG_AUDIT