selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link
commit bda0be7ad9948 ("security: make inode_follow_link RCU-walk aware")
switched selinux_inode_follow_link() to use avc_has_perm_flags() and
pass down the MAY_NOT_BLOCK flag if called during RCU walk. However,
the only test of MAY_NOT_BLOCK occurs during slow_avc_audit()
and only if passing an inode as audit data (LSM_AUDIT_DATA_INODE). Since
selinux_inode_follow_link() passes a dentry directly, passing MAY_NOT_BLOCK
here serves no purpose. Switch selinux_inode_follow_link() to use
avc_has_perm() and drop avc_has_perm_flags() since there are no other
users.
Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 7f60684..f08a0f2 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2925,9 +2925,8 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode,
if (IS_ERR(isec))
return PTR_ERR(isec);
- return avc_has_perm_flags(&selinux_state,
- sid, isec->sid, isec->sclass, FILE__READ, &ad,
- rcu ? MAY_NOT_BLOCK : 0);
+ return avc_has_perm(&selinux_state,
+ sid, isec->sid, isec->sclass, FILE__READ, &ad);
}
static noinline int audit_inode_permission(struct inode *inode,