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2024-10-12 a5969cabbb4660eab42b6ef0412cbbd1200cf14d 
 kernel/fs/ubifs/master.c
....@@ -1,20 +1,8 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
12 /*
23  * This file is part of UBIFS.
34  *
45  * Copyright (C) 2006-2008 Nokia Corporation.
5
- *
6
- * This program is free software; you can redistribute it and/or modify it
7
- * under the terms of the GNU General Public License version 2 as published by
8
- * the Free Software Foundation.
9
- *
10
- * This program is distributed in the hope that it will be useful, but WITHOUT
11
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
13
- * more details.
14
- *
15
- * You should have received a copy of the GNU General Public License along with
16
- * this program; if not, write to the Free Software Foundation, Inc., 51
17
- * Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
186  *
197  * Authors: Artem Bityutskiy (Битюцкий Артём)
208  *          Adrian Hunter
....@@ -23,6 +11,72 @@
2311 /* This file implements reading and writing the master node */
2412 
2513 #include "ubifs.h"
14
+
15
+/**
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+ * ubifs_compare_master_node - compare two UBIFS master nodes
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+ * @c: UBIFS file-system description object
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+ * @m1: the first node
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+ * @m2: the second node
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+ *
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+ * This function compares two UBIFS master nodes. Returns 0 if they are equal
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+ * and nonzero if not.
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+ */
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+int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
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+{
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+	int ret;
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+	int behind;
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+	int hmac_offs = offsetof(struct ubifs_mst_node, hmac);
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+
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+	/*
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+	 * Do not compare the common node header since the sequence number and
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+	 * hence the CRC are different.
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+	 */
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+	ret = memcmp(m1 + UBIFS_CH_SZ, m2 + UBIFS_CH_SZ,
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+		     hmac_offs - UBIFS_CH_SZ);
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+	if (ret)
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+		return ret;
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+
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+	/*
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+	 * Do not compare the embedded HMAC aswell which also must be different
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+	 * due to the different common node header.
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+	 */
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+	behind = hmac_offs + UBIFS_MAX_HMAC_LEN;
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+
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+	if (UBIFS_MST_NODE_SZ > behind)
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+		return memcmp(m1 + behind, m2 + behind, UBIFS_MST_NODE_SZ - behind);
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+
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+	return 0;
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+}
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+
51
+/* mst_node_check_hash - Check hash of a master node
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+ * @c: UBIFS file-system description object
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+ * @mst: The master node
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+ * @expected: The expected hash of the master node
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+ *
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+ * This checks the hash of a master node against a given expected hash.
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+ * Note that we have two master nodes on a UBIFS image which have different
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+ * sequence numbers and consequently different CRCs. To be able to match
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+ * both master nodes we exclude the common node header containing the sequence
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+ * number and CRC from the hash.
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+ *
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+ * Returns 0 if the hashes are equal, a negative error code otherwise.
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+ */
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+static int mst_node_check_hash(const struct ubifs_info *c,
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+			       const struct ubifs_mst_node *mst,
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+			       const u8 *expected)
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+{
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+	u8 calc[UBIFS_MAX_HASH_LEN];
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+	const void *node = mst;
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+
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+	crypto_shash_tfm_digest(c->hash_tfm, node + sizeof(struct ubifs_ch),
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+				UBIFS_MST_NODE_SZ - sizeof(struct ubifs_ch),
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+				calc);
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+
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+	if (ubifs_check_hash(c, expected, calc))
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+		return -EPERM;
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+
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+	return 0;
79
+}
2680 
2781 /**
2882  * scan_for_master - search the valid master node.
....@@ -37,7 +91,7 @@
3791 {
3892 	struct ubifs_scan_leb *sleb;
3993 	struct ubifs_scan_node *snod;
40
-	int lnum, offs = 0, nodes_cnt;
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+	int lnum, offs = 0, nodes_cnt, err;
4195 
4296 	lnum = UBIFS_MST_LNUM;
4397 
....@@ -69,12 +123,31 @@
69123 		goto out_dump;
70124 	if (snod->offs != offs)
71125 		goto out;
72
-	if (memcmp((void *)c->mst_node + UBIFS_CH_SZ,
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-		   (void *)snod->node + UBIFS_CH_SZ,
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-		   UBIFS_MST_NODE_SZ - UBIFS_CH_SZ))
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+	if (ubifs_compare_master_node(c, c->mst_node, snod->node))
75127 		goto out;
128
+
76129 	c->mst_offs = offs;
77130 	ubifs_scan_destroy(sleb);
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+
132
+	if (!ubifs_authenticated(c))
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+		return 0;
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+
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+	if (ubifs_hmac_zero(c, c->mst_node->hmac)) {
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+		err = mst_node_check_hash(c, c->mst_node,
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+					  c->sup_node->hash_mst);
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+		if (err)
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+			ubifs_err(c, "Failed to verify master node hash");
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+	} else {
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+		err = ubifs_node_verify_hmac(c, c->mst_node,
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+					sizeof(struct ubifs_mst_node),
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+					offsetof(struct ubifs_mst_node, hmac));
144
+		if (err)
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+			ubifs_err(c, "Failed to verify master node HMAC");
146
+	}
147
+
148
+	if (err)
149
+		return -EPERM;
150
+
78151 	return 0;
79152 
80153 out:
....@@ -305,6 +378,8 @@
305378 	c->lst.total_dead  = le64_to_cpu(c->mst_node->total_dead);
306379 	c->lst.total_dark  = le64_to_cpu(c->mst_node->total_dark);
307380 
381
+	ubifs_copy_hash(c, c->mst_node->hash_root_idx, c->zroot.hash);
382
+
308383 	c->calc_idx_sz = c->bi.old_idx_sz;
309384 
310385 	if (c->mst_node->flags & cpu_to_le32(UBIFS_MST_NO_ORPHS))
....@@ -378,7 +453,9 @@
378453 	c->mst_offs = offs;
379454 	c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);
380455 
381
-	err = ubifs_write_node(c, c->mst_node, len, lnum, offs);
456
+	ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
457
+	err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
458
+				    offsetof(struct ubifs_mst_node, hmac));
382459 	if (err)
383460 		return err;
384461 
....@@ -389,7 +466,8 @@
389466 		if (err)
390467 			return err;
391468 	}
392
-	err = ubifs_write_node(c, c->mst_node, len, lnum, offs);
469
+	err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
470
+				    offsetof(struct ubifs_mst_node, hmac));
393471 
394472 	return err;
395473 }