From 8c0637e950d68933a67f7438f779d79b049b5e5c Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 12 May 2020 15:16:29 +0100 Subject: keys: Make the KEY_NEED_* perms an enum rather than a mask Since the meaning of combining the KEY_NEED_* constants is undefined, make it so that you can't do that by turning them into an enum. The enum is also given some extra values to represent special circumstances, such as: (1) The '0' value is reserved and causes a warning to trap the parameter being unset. (2) The key is to be unlinked and we require no permissions on it, only the keyring, (this replaces the KEY_LOOKUP_FOR_UNLINK flag). (3) An override due to CAP_SYS_ADMIN. (4) An override due to an instantiation token being present. (5) The permissions check is being deferred to later key_permission() calls. The extra values give the opportunity for LSMs to audit these situations. [Note: This really needs overhauling so that lookup_user_key() tells key_task_permission() and the LSM what operation is being done and leaves it to those functions to decide how to map that onto the available permits. However, I don't really want to make these change in the middle of the notifications patchset.] Signed-off-by: David Howells cc: Jarkko Sakkinen cc: Paul Moore cc: Stephen Smalley cc: Casey Schaufler cc: keyrings@vger.kernel.org cc: selinux@vger.kernel.org --- security/selinux/hooks.c | 37 ++++++++++++++++++++++++++++++------- 1 file changed, 30 insertions(+), 7 deletions(-) (limited to 'security/selinux') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 4c037c2545c1..196acaccbfdd 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6561,20 +6561,43 @@ static void selinux_key_free(struct key *k) static int selinux_key_permission(key_ref_t key_ref, const struct cred *cred, - unsigned perm) + enum key_need_perm need_perm) { struct key *key; struct key_security_struct *ksec; - u32 sid; + u32 perm, sid; - /* if no specific permissions are requested, we skip the - permission check. No serious, additional covert channels - appear to be created. */ - if (perm == 0) + switch (need_perm) { + case KEY_NEED_VIEW: + perm = KEY__VIEW; + break; + case KEY_NEED_READ: + perm = KEY__READ; + break; + case KEY_NEED_WRITE: + perm = KEY__WRITE; + break; + case KEY_NEED_SEARCH: + perm = KEY__SEARCH; + break; + case KEY_NEED_LINK: + perm = KEY__LINK; + break; + case KEY_NEED_SETATTR: + perm = KEY__SETATTR; + break; + case KEY_NEED_UNLINK: + case KEY_SYSADMIN_OVERRIDE: + case KEY_AUTHTOKEN_OVERRIDE: + case KEY_DEFER_PERM_CHECK: return 0; + default: + WARN_ON(1); + return -EPERM; - sid = cred_sid(cred); + } + sid = cred_sid(cred); key = key_ref_to_ptr(key_ref); ksec = key->security; -- cgit v1.2.3 From 3e412ccc22e25666772094fb5ca01af056c54471 Mon Sep 17 00:00:00 2001 From: David Howells Date: Tue, 14 Jan 2020 17:07:13 +0000 Subject: selinux: Implement the watch_key security hook Implement the watch_key security hook to make sure that a key grants the caller View permission in order to set a watch on a key. For the moment, the watch_devices security hook is left unimplemented as it's not obvious what the object should be since the queue is global and didn't previously exist. Signed-off-by: David Howells Acked-by: Stephen Smalley Reviewed-by: James Morris --- security/selinux/hooks.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'security/selinux') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 196acaccbfdd..5b3191bd6130 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -6619,6 +6619,17 @@ static int selinux_key_getsecurity(struct key *key, char **_buffer) *_buffer = context; return rc; } + +#ifdef CONFIG_KEY_NOTIFICATIONS +static int selinux_watch_key(struct key *key) +{ + struct key_security_struct *ksec = key->security; + u32 sid = current_sid(); + + return avc_has_perm(&selinux_state, + sid, ksec->sid, SECCLASS_KEY, KEY__VIEW, NULL); +} +#endif #endif #ifdef CONFIG_SECURITY_INFINIBAND @@ -7134,6 +7145,9 @@ static struct security_hook_list selinux_hooks[] __lsm_ro_after_init = { LSM_HOOK_INIT(key_free, selinux_key_free), LSM_HOOK_INIT(key_permission, selinux_key_permission), LSM_HOOK_INIT(key_getsecurity, selinux_key_getsecurity), +#ifdef CONFIG_KEY_NOTIFICATIONS + LSM_HOOK_INIT(watch_key, selinux_watch_key), +#endif #endif #ifdef CONFIG_AUDIT -- cgit v1.2.3