From: Amir Goldstein <amir73il@xxxxxxxxx> commit a9ffe682c58aaff643764547f5420e978b6e0830 upstream. When inode has no listxattr op of its own (e.g. squashfs) vfs_listxattr calls the LSM inode_listsecurity hooks to list the xattrs that LSMs will intercept in inode_getxattr hooks. When selinux LSM is installed but not initialized, it will list the security.selinux xattr in inode_listsecurity, but will not intercept it in inode_getxattr. This results in -ENODATA for a getxattr call for an xattr returned by listxattr. This situation was manifested as overlayfs failure to copy up lower files from squashfs when selinux is built-in but not initialized, because ovl_copy_xattr() iterates the lower inode xattrs by vfs_listxattr() and vfs_getxattr(). Match the logic of inode_listsecurity to that of inode_getxattr and do not list the security.selinux xattr if selinux is not initialized. Reported-by: Michael Labriola <michael.d.labriola@xxxxxxxxx> Tested-by: Michael Labriola <michael.d.labriola@xxxxxxxxx> Link: https://lore.kernel.org/linux-unionfs/2nv9d47zt7.fsf@xxxxxxxxxxxxxxxxxxxxxxxxx/ Fixes: c8e222616c7e ("selinux: allow reading labels before policy is loaded") Cc: stable@xxxxxxxxxxxxxxx#v5.9+ Signed-off-by: Amir Goldstein <amir73il@xxxxxxxxx> Reviewed-by: Ondrej Mosnacek <omosnace@xxxxxxxxxx> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- security/selinux/hooks.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -3414,6 +3414,10 @@ static int selinux_inode_setsecurity(str static int selinux_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer_size) { const int len = sizeof(XATTR_NAME_SELINUX); + + if (!selinux_initialized(&selinux_state)) + return 0; + if (buffer && len <= buffer_size) memcpy(buffer, XATTR_NAME_SELINUX, len); return len;
