1 files changed, 144 insertions, 2 deletions

diff --git a/fs/ubifs/replay.c b/fs/ubifs/replay.c
index db489d93439c..75f961c4c044 100644
--- a/fs/ubifs/replay.c
+++ b/fs/ubifs/replay.c
@@ -34,6 +34,8 @@
 
 #include "ubifs.h"
 #include <linux/list_sort.h>
+#include <crypto/hash.h>
+#include <crypto/algapi.h>
 
 /**
  * struct replay_entry - replay list entry.
@@ -532,6 +534,105 @@ static int is_last_bud(struct ubifs_info *c, struct ubifs_bud *bud)
 }
 
 /**
+ * authenticate_sleb - authenticate one scan LEB
+ * @c: UBIFS file-system description object
+ * @sleb: the scan LEB to authenticate
+ * @log_hash:
+ * @is_last: if true, this is is the last LEB
+ *
+ * This function iterates over the buds of a single LEB authenticating all buds
+ * with the authentication nodes on this LEB. Authentication nodes are written
+ * after some buds and contain a HMAC covering the authentication node itself
+ * and the buds between the last authentication node and the current
+ * authentication node. It can happen that the last buds cannot be authenticated
+ * because a powercut happened when some nodes were written but not the
+ * corresponding authentication node. This function returns the number of nodes
+ * that could be authenticated or a negative error code.
+ */
+static int authenticate_sleb(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
+			     struct shash_desc *log_hash, int is_last)
+{
+	int n_not_auth = 0;
+	struct ubifs_scan_node *snod;
+	int n_nodes = 0;
+	int err;
+	u8 *hash, *hmac;
+
+	if (!ubifs_authenticated(c))
+		return sleb->nodes_cnt;
+
+	hash = kmalloc(crypto_shash_descsize(c->hash_tfm), GFP_NOFS);
+	hmac = kmalloc(c->hmac_desc_len, GFP_NOFS);
+	if (!hash || !hmac) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	list_for_each_entry(snod, &sleb->nodes, list) {
+
+		n_nodes++;
+
+		if (snod->type == UBIFS_AUTH_NODE) {
+			struct ubifs_auth_node *auth = snod->node;
+			SHASH_DESC_ON_STACK(hash_desc, c->hash_tfm);
+			SHASH_DESC_ON_STACK(hmac_desc, c->hmac_tfm);
+
+			hash_desc->tfm = c->hash_tfm;
+			hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+
+			ubifs_shash_copy_state(c, log_hash, hash_desc);
+			err = crypto_shash_final(hash_desc, hash);
+			if (err)
+				goto out;
+
+			hmac_desc->tfm = c->hmac_tfm;
+			hmac_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+			err = crypto_shash_digest(hmac_desc, hash, c->hash_len,
+						  hmac);
+			if (err)
+				goto out;
+
+			err = ubifs_check_hmac(c, auth->hmac, hmac);
+			if (err) {
+				err = -EPERM;
+				goto out;
+			}
+			n_not_auth = 0;
+		} else {
+			err = crypto_shash_update(log_hash, snod->node,
+						  snod->len);
+			if (err)
+				goto out;
+			n_not_auth++;
+		}
+	}
+
+	/*
+	 * A powercut can happen when some nodes were written, but not yet
+	 * the corresponding authentication node. This may only happen on
+	 * the last bud though.
+	 */
+	if (n_not_auth) {
+		if (is_last) {
+			dbg_mnt("%d unauthenticated nodes found on LEB %d, Ignoring them",
+				n_not_auth, sleb->lnum);
+			err = 0;
+		} else {
+			dbg_mnt("%d unauthenticated nodes found on non-last LEB %d",
+				n_not_auth, sleb->lnum);
+			err = -EPERM;
+		}
+	} else {
+		err = 0;
+	}
+out:
+	kfree(hash);
+	kfree(hmac);
+
+	return err ? err : n_nodes - n_not_auth;
+}
+
+/**
  * replay_bud - replay a bud logical eraseblock.
  * @c: UBIFS file-system description object
  * @b: bud entry which describes the bud
@@ -544,6 +645,7 @@ static int replay_bud(struct ubifs_info *c, struct bud_entry *b)
 {
 	int is_last = is_last_bud(c, b->bud);
 	int err = 0, used = 0, lnum = b->bud->lnum, offs = b->bud->start;
+	int n_nodes, n = 0;
 	struct ubifs_scan_leb *sleb;
 	struct ubifs_scan_node *snod;
 
@@ -563,6 +665,15 @@ static int replay_bud(struct ubifs_info *c, struct bud_entry *b)
 	if (IS_ERR(sleb))
 		return PTR_ERR(sleb);
 
+	n_nodes = authenticate_sleb(c, sleb, b->bud->log_hash, is_last);
+	if (n_nodes < 0) {
+		err = n_nodes;
+		goto out;
+	}
+
+	ubifs_shash_copy_state(c, b->bud->log_hash,
+			       c->jheads[b->bud->jhead].log_hash);
+
 	/*
 	 * The bud does not have to start from offset zero - the beginning of
 	 * the 'lnum' LEB may contain previously committed data. One of the
@@ -676,6 +787,10 @@ static int replay_bud(struct ubifs_info *c, struct bud_entry *b)
 		}
 		if (err)
 			goto out;
+
+		n++;
+		if (n == n_nodes)
+			break;
 	}
 
 	ubifs_assert(c, ubifs_search_bud(c, lnum));
@@ -754,6 +869,7 @@ static int add_replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
 {
 	struct ubifs_bud *bud;
 	struct bud_entry *b;
+	int err;
 
 	dbg_mnt("add replay bud LEB %d:%d, head %d", lnum, offs, jhead);
 
@@ -763,13 +879,21 @@ static int add_replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
 
 	b = kmalloc(sizeof(struct bud_entry), GFP_KERNEL);
 	if (!b) {
-		kfree(bud);
-		return -ENOMEM;
+		err = -ENOMEM;
+		goto out;
 	}
 
 	bud->lnum = lnum;
 	bud->start = offs;
 	bud->jhead = jhead;
+	bud->log_hash = ubifs_hash_get_desc(c);
+	if (IS_ERR(bud->log_hash)) {
+		err = PTR_ERR(bud->log_hash);
+		goto out;
+	}
+
+	ubifs_shash_copy_state(c, c->log_hash, bud->log_hash);
+
 	ubifs_add_bud(c, bud);
 
 	b->bud = bud;
@@ -777,6 +901,11 @@ static int add_replay_bud(struct ubifs_info *c, int lnum, int offs, int jhead,
 	list_add_tail(&b->list, &c->replay_buds);
 
 	return 0;
+out:
+	kfree(bud);
+	kfree(b);
+
+	return err;
 }
 
 /**
@@ -882,6 +1011,14 @@ static int replay_log_leb(struct ubifs_info *c, int lnum, int offs, void *sbuf)
 
 		c->cs_sqnum = le64_to_cpu(node->ch.sqnum);
 		dbg_mnt("commit start sqnum %llu", c->cs_sqnum);
+
+		err = ubifs_shash_init(c, c->log_hash);
+		if (err)
+			goto out;
+
+		err = ubifs_shash_update(c, c->log_hash, node, UBIFS_CS_NODE_SZ);
+		if (err < 0)
+			goto out;
 	}
 
 	if (snod->sqnum < c->cs_sqnum) {
@@ -929,6 +1066,11 @@ static int replay_log_leb(struct ubifs_info *c, int lnum, int offs, void *sbuf)
 			if (err)
 				goto out_dump;
 
+			err = ubifs_shash_update(c, c->log_hash, ref,
+						 UBIFS_REF_NODE_SZ);
+			if (err)
+				goto out;
+
 			err = add_replay_bud(c, le32_to_cpu(ref->lnum),
 					     le32_to_cpu(ref->offs),
 					     le32_to_cpu(ref->jhead),