[PATCH v2 14/15] selinux: allow setxattr on rootfs so initramfs code can set them

Taras Kondratiuk takondra at cisco.com
Thu Jan 25 03:27:54 UTC 2018

From: Victor Kamensky <kamensky at cisco.com>

initramfs code supporting extended cpio format have ability to
fill extended attributes from cpio archive, but if SELinux enabled
and security server is not initialized yet, selinux callback would
refuse setxattr made by initramfs code.

Solution enable SBLABEL_MNT on rootfs even if secrurity server is
not initialized yet.

Signed-off-by: Victor Kamensky <kamensky at cisco.com>
 security/selinux/hooks.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 8644d864e3c1..f3fe65589f02 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -706,6 +706,18 @@ static int selinux_set_mnt_opts(struct super_block *sb,
 	if (!ss_initialized) {
 		if (!num_opts) {
+			/*
+			 * Special handling for rootfs. Is genfs but supports
+			 * setting SELinux context on in-core inodes.
+			 *
+			 * Chicken and egg problem: policy may reside in rootfs
+			 * but for initramfs code to fill in attributes, it
+			 * needs selinux to allow that.
+			 */
+			if (!strncmp(sb->s_type->name, "rootfs",
+				     sizeof("rootfs")))
+				sbsec->flags |= SBLABEL_MNT;
 			/* Defer initialization until selinux_complete_init,
 			   after the initial policy is loaded and the security
 			   server is ready to handle calls. */

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