From e0e817392b9acf2c98d3be80c233dddb1b52003d Mon Sep 17 00:00:00 2001 From: David Howells Date: Wed, 2 Sep 2009 09:13:40 +0100 Subject: CRED: Add some configurable debugging [try #6] Add a config option (CONFIG_DEBUG_CREDENTIALS) to turn on some debug checking for credential management. The additional code keeps track of the number of pointers from task_structs to any given cred struct, and checks to see that this number never exceeds the usage count of the cred struct (which includes all references, not just those from task_structs). Furthermore, if SELinux is enabled, the code also checks that the security pointer in the cred struct is never seen to be invalid. This attempts to catch the bug whereby inode_has_perm() faults in an nfsd kernel thread on seeing cred->security be a NULL pointer (it appears that the credential struct has been previously released): http://www.kerneloops.org/oops.php?number=252883 Signed-off-by: David Howells Signed-off-by: James Morris --- security/selinux/hooks.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) (limited to 'security/selinux/hooks.c') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 27b4c552735..c3bb31ecc5a 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -1531,6 +1531,8 @@ static int inode_has_perm(const struct cred *cred, struct common_audit_data ad; u32 sid; + validate_creds(cred); + if (unlikely(IS_PRIVATE(inode))) return 0; @@ -3236,7 +3238,9 @@ static int selinux_task_create(unsigned long clone_flags) static void selinux_cred_free(struct cred *cred) { struct task_security_struct *tsec = cred->security; - cred->security = NULL; + + BUG_ON((unsigned long) cred->security < PAGE_SIZE); + cred->security = (void *) 0x7UL; kfree(tsec); } -- cgit v1.2.3