From e4e55b47ed9ae2c05ff062601ff6dacbe9dc4775 Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Fri, 24 Mar 2017 20:46:33 +0900 Subject: LSM: Revive security_task_alloc() hook and per "struct task_struct" security blob. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit We switched from "struct task_struct"->security to "struct cred"->security in Linux 2.6.29. But not all LSM modules were happy with that change. TOMOYO LSM module is an example which want to use per "struct task_struct" security blob, for TOMOYO's security context is defined based on "struct task_struct" rather than "struct cred". AppArmor LSM module is another example which want to use it, for AppArmor is currently abusing the cred a little bit to store the change_hat and setexeccon info. Although security_task_free() hook was revived in Linux 3.4 because Yama LSM module wanted to release per "struct task_struct" security blob, security_task_alloc() hook and "struct task_struct"->security field were not revived. Nowadays, we are getting proposals of lightweight LSM modules which want to use per "struct task_struct" security blob. We are already allowing multiple concurrent LSM modules (up to one fully armored module which uses "struct cred"->security field or exclusive hooks like security_xfrm_state_pol_flow_match(), plus unlimited number of lightweight modules which do not use "struct cred"->security nor exclusive hooks) as long as they are built into the kernel. But this patch does not implement variable length "struct task_struct"->security field which will become needed when multiple LSM modules want to use "struct task_struct"-> security field. Although it won't be difficult to implement variable length "struct task_struct"->security field, let's think about it after we merged this patch. Signed-off-by: Tetsuo Handa Acked-by: John Johansen Acked-by: Serge Hallyn Acked-by: Casey Schaufler Tested-by: Djalal Harouni Acked-by: José Bollo Cc: Paul Moore Cc: Stephen Smalley Cc: Eric Paris Cc: Kees Cook Cc: James Morris Cc: José Bollo Signed-off-by: James Morris --- kernel/fork.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) (limited to 'kernel/fork.c') diff --git a/kernel/fork.c b/kernel/fork.c index 6c463c80e93d..3d32513d6c73 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -1679,9 +1679,12 @@ static __latent_entropy struct task_struct *copy_process( goto bad_fork_cleanup_perf; /* copy all the process information */ shm_init_task(p); - retval = copy_semundo(clone_flags, p); + retval = security_task_alloc(p, clone_flags); if (retval) goto bad_fork_cleanup_audit; + retval = copy_semundo(clone_flags, p); + if (retval) + goto bad_fork_cleanup_security; retval = copy_files(clone_flags, p); if (retval) goto bad_fork_cleanup_semundo; @@ -1903,6 +1906,8 @@ bad_fork_cleanup_files: exit_files(p); /* blocking */ bad_fork_cleanup_semundo: exit_sem(p); +bad_fork_cleanup_security: + security_task_free(p); bad_fork_cleanup_audit: audit_free(p); bad_fork_cleanup_perf: -- cgit v1.2.3