Merge tag 'tags/upstream-4.20-rc1' of git://git.infradead.org/linux-ubifs

Pull UBIFS updates from Richard Weinberger:

 - Full filesystem authentication feature, UBIFS is now able to have the
   whole filesystem structure authenticated plus user data encrypted and
   authenticated.

 - Minor cleanups

* tag 'tags/upstream-4.20-rc1' of git://git.infradead.org/linux-ubifs: (26 commits)
  ubifs: Remove unneeded semicolon
  Documentation: ubifs: Add authentication whitepaper
  ubifs: Enable authentication support
  ubifs: Do not update inode size in-place in authenticated mode
  ubifs: Add hashes and HMACs to default filesystem
  ubifs: authentication: Authenticate super block node
  ubifs: Create hash for default LPT
  ubfis: authentication: Authenticate master node
  ubifs: authentication: Authenticate LPT
  ubifs: Authenticate replayed journal
  ubifs: Add auth nodes to garbage collector journal head
  ubifs: Add authentication nodes to journal
  ubifs: authentication: Add hashes to index nodes
  ubifs: Add hashes to the tree node cache
  ubifs: Create functions to embed a HMAC in a node
  ubifs: Add helper functions for authentication support
  ubifs: Add separate functions to init/crc a node
  ubifs: Format changes for authentication support
  ubifs: Store read superblock node
  ubifs: Drop write_node
  ...

1 files changed, 58 insertions, 6 deletions

diff --git a/fs/ubifs/master.c b/fs/ubifs/master.c
index 9df4a41bba52..5ea51bbd14c7 100644
--- a/fs/ubifs/master.c
+++ b/fs/ubifs/master.c
@@ -25,6 +25,42 @@
 #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:
@@ -305,6 +352,8 @@ int ubifs_read_master(struct ubifs_info *c)
 	c->lst.total_dead  = le64_to_cpu(c->mst_node->total_dead);
 	c->lst.total_dark  = le64_to_cpu(c->mst_node->total_dark);
 
+	ubifs_copy_hash(c, c->mst_node->hash_root_idx, c->zroot.hash);
+
 	c->calc_idx_sz = c->bi.old_idx_sz;
 
 	if (c->mst_node->flags & cpu_to_le32(UBIFS_MST_NO_ORPHS))
@@ -378,7 +427,9 @@ int ubifs_write_master(struct ubifs_info *c)
 	c->mst_offs = offs;
 	c->mst_node->highest_inum = cpu_to_le64(c->highest_inum);
 
-	err = ubifs_write_node(c, c->mst_node, len, lnum, offs);
+	ubifs_copy_hash(c, c->zroot.hash, c->mst_node->hash_root_idx);
+	err = ubifs_write_node_hmac(c, c->mst_node, len, lnum, offs,
+				    offsetof(struct ubifs_mst_node, hmac));
 	if (err)
 		return err;
 
@@ -389,7 +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;
 }