Commit 625700cc authored by Sascha Hauer's avatar Sascha Hauer Committed by Richard Weinberger
Browse files

ubfis: authentication: Authenticate master node 



The master node contains hashes over the root index node and the LPT.
This patch adds a HMAC to authenticate the master node itself.

Signed-off-by: default avatarSascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: default avatarRichard Weinberger <richard@nod.at>
parent a1dc5814

fs/ubifs/master.c

+55 −6
Original line number Diff line number Diff line
@@ -24,6 +24,42 @@ 


#include "ubifs.h"



/**

 * ubifs_compare_master_node - compare two UBIFS master nodes

 * @c: UBIFS file-system description object

 * @m1: the first node

 * @m2: the second node

 *

 * This function compares two UBIFS master nodes. Returns 0 if they are equal

 * and nonzero if not.

 */

int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)

{

	int ret;

	int behind;

	int hmac_offs = offsetof(struct ubifs_mst_node, hmac);



	/*

	 * Do not compare the common node header since the sequence number and

	 * hence the CRC are different.

	 */

	ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,

		     hmac_offs - UBIFS_CH_SZ);

	if (ret)

		return ret;



	/*

	 * Do not compare the embedded HMAC aswell which also must be different

	 * due to the different common node header.

	 */

	behind = hmac_offs + UBIFS_MAX_HMAC_LEN;



	if (UBIFS_MST_NODE_SZ > behind)

		return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);



	return 0;

}



/**

 * scan_for_master - search the valid master node.

 * @c: UBIFS file-system description object
@@ -37,7 +73,7 @@ static int scan_for_master(struct ubifs_info *c) 
{

	struct ubifs_scan_leb *sleb;

	struct ubifs_scan_node *snod;

	int lnum, offs = 0, nodes_cnt;

	int lnum, offs = 0, nodes_cnt, err;



	lnum = UBIFS_MST_LNUM;
@@ -69,12 +105,23 @@ static int scan_for_master(struct ubifs_info *c) 
		goto out_dump;

	if (snod->offs != offs)

		goto out;

	if (memcmp((void *)c->mst_node + UBIFS_CH_SZ,

		   (void *)snod->node + UBIFS_CH_SZ,

		   UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))

	if (ubifs_compare_master_node(c, c->mst_node, snod->node))

		goto out;



	c->mst_offs = offs;

	ubifs_scan_destroy(sleb);



	if (!ubifs_authenticated(c))

		return 0;



	err = ubifs_node_verify_hmac(c, c->mst_node,

				     sizeof(struct ubifs_mst_node),

				     offsetof(struct ubifs_mst_node, hmac));

	if (err) {

		ubifs_err(c, "Failed to verify master node HMAC");

		return -EPERM;

	}



	return 0;



out:
@@ -381,7 +428,8 @@ int ubifs_write_master(struct ubifs_info *c) 
	c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);



	ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);

	err = ubifs_write_node(c, c->mst_node, len, lnum, offs);

	err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,

				    offsetof(struct ubifs_mst_node, hmac));

	if (err)

		return err;
@@ -392,7 +440,8 @@ int ubifs_write_master(struct ubifs_info *c) 
		if (err)

			return err;

	}

	err = ubifs_write_node(c, c->mst_node, len, lnum, offs);

	err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,

				    offsetof(struct ubifs_mst_node, hmac));



	return err;

}

fs/ubifs/recovery.c

+5 −4
Original line number Diff line number Diff line
@@ -212,7 +212,10 @@ static int write_rcvrd_mst_node(struct ubifs_info *c, 
	save_flags = mst->flags;

	mst->flags |= cpu_to_le32(UBIFS_MST_RCVRY);



	ubifs_prepare_node(c, mst, UBIFS_MST_NODE_SZ, 1);

	err = ubifs_prepare_node_hmac(c, mst, UBIFS_MST_NODE_SZ,

				      offsetof(struct ubifs_mst_node, hmac), 1);

	if (err)

		goto out;

	err = ubifs_leb_change(c, lnum, mst, sz);

	if (err)

		goto out;
@@ -264,9 +267,7 @@ int ubifs_recover_master_node(struct ubifs_info *c) 
			offs2 = (void *)mst2 - buf2;

			if (offs1 == offs2) {

				/* Same offset, so must be the same */

				if (memcmp((void *)mst1 + UBIFS_CH_SZ,

					   (void *)mst2 + UBIFS_CH_SZ,

					   UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))

				if (ubifs_compare_master_node(c, mst1, mst2))

					goto out_err;

				mst = mst1;

			} else if (offs2 + sz == offs1) {

fs/ubifs/ubifs.h

+1 −0
Original line number Diff line number Diff line
@@ -1900,6 +1900,7 @@ int ubifs_gc_should_commit(struct ubifs_info *c); 
void ubifs_wait_for_commit(struct ubifs_info *c);



/* master.c */

int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2);

int ubifs_read_master(struct ubifs_info *c);

int ubifs_write_master(struct ubifs_info *c);