From 0188d5c025ca8fe756ba3193bd7d150139af5a88 Mon Sep 17 00:00:00 2001 From: Stephen Smalley Date: Fri, 22 Nov 2019 12:22:45 -0500 Subject: selinux: fall back to ref-walk if audit is required commit bda0be7ad994 ("security: make inode_follow_link RCU-walk aware") passed down the rcu flag to the SELinux AVC, but failed to adjust the test in slow_avc_audit() to also return -ECHILD on LSM_AUDIT_DATA_DENTRY. Previously, we only returned -ECHILD if generating an audit record with LSM_AUDIT_DATA_INODE since this was only relevant from inode_permission. Move the handling of MAY_NOT_BLOCK to avc_audit() and its inlined equivalent in selinux_inode_permission() immediately after we determine that audit is required, and always fall back to ref-walk in this case. Fixes: bda0be7ad994 ("security: make inode_follow_link RCU-walk aware") Reported-by: Will Deacon Suggested-by: Al Viro Signed-off-by: Stephen Smalley Signed-off-by: Paul Moore --- security/selinux/hooks.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) (limited to 'security/selinux/hooks.c') diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index ed64cb4cd4c5..328d455ec293 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3011,8 +3011,7 @@ static int selinux_inode_follow_link(struct dentry *dentry, struct inode *inode, static noinline int audit_inode_permission(struct inode *inode, u32 perms, u32 audited, u32 denied, - int result, - unsigned flags) + int result) { struct common_audit_data ad; struct inode_security_struct *isec = selinux_inode(inode); @@ -3023,7 +3022,7 @@ static noinline int audit_inode_permission(struct inode *inode, rc = slow_avc_audit(&selinux_state, current_sid(), isec->sid, isec->sclass, perms, - audited, denied, result, &ad, flags); + audited, denied, result, &ad); if (rc) return rc; return 0; @@ -3070,7 +3069,11 @@ static int selinux_inode_permission(struct inode *inode, int mask) if (likely(!audited)) return rc; - rc2 = audit_inode_permission(inode, perms, audited, denied, rc, flags); + /* fall back to ref-walk if we have to generate audit */ + if (flags & MAY_NOT_BLOCK) + return -ECHILD; + + rc2 = audit_inode_permission(inode, perms, audited, denied, rc); if (rc2) return rc2; return rc; -- cgit v1.2.3