From: NeilBrown Date: Mon, 23 Mar 2015 02:37:39 +0000 (+1100) Subject: security: make inode_follow_link RCU-walk aware X-Git-Tag: omap-for-v4.2/fixes-rc1^2~184^2~33 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=bda0be7ad994812960e9f8f2d2757f72cb4a96cb;p=pandora-kernel.git security: make inode_follow_link RCU-walk aware inode_follow_link now takes an inode and rcu flag as well as the dentry. inode is used in preference to d_backing_inode(dentry), particularly in RCU-walk mode. selinux_inode_follow_link() gets dentry_has_perm() and inode_has_perm() open-coded into it so that it can call avc_has_perm_flags() in way that is safe if LOOKUP_RCU is set. Calling avc_has_perm_flags() with rcu_read_lock() held means that when avc_has_perm_noaudit calls avc_compute_av(), the attempt to rcu_read_unlock() before calling security_compute_av() will not actually drop the RCU read-lock. However as security_compute_av() is completely in a read_lock()ed region, it should be safe with the RCU read-lock held. Signed-off-by: NeilBrown Signed-off-by: Al Viro --- Reading git-diff-tree failed