• NeilBrown's avatar
    security: make inode_follow_link RCU-walk aware · bda0be7a
    NeilBrown authored
    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: default avatarNeilBrown <neilb@suse.de>
    Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
    bda0be7a
capability.c 25.1 KB