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
  ...

Documentation/filesystems/ubifs.txt

@@ -91,6 +91,13 @@ chk_data_crc		do not skip checking CRCs on data nodes
 compr=none              override default compressor and set it to "none"
 compr=lzo               override default compressor and set it to "lzo"
 compr=zlib              override default compressor and set it to "zlib"
+auth_key=		specify the key used for authenticating the filesystem.
+			Passing this option makes authentication mandatory.
+			The passed key must be present in the kernel keyring
+			and must be of type 'logon'
+auth_hash_name=		The hash algorithm used for authentication. Used for
+			both hashing and for creating HMACs. Typical values
+			include "sha256" or "sha512"
 
 
 Quick usage instructions

drivers/mtd/ubi/attach.c

@@ -1072,6 +1072,7 @@ static int scan_peb(struct ubi_device *ubi, struct ubi_attach_info *ai,
 			 * be a result of power cut during erasure.
 			 */
 			ai->maybe_bad_peb_count += 1;
+		/* fall through */
 	case UBI_IO_BAD_HDR:
 			/*
 			 * If we're facing a bad VID header we have to drop *all*

drivers/mtd/ubi/build.c

@@ -1334,8 +1334,10 @@ static int bytes_str_to_int(const char *str)
 	switch (*endp) {
 	case 'G':
 		result *= 1024;
+		/* fall through */
 	case 'M':
 		result *= 1024;
+		/* fall through */
 	case 'K':
 		result *= 1024;
 		if (endp[1] == 'i' && endp[2] == 'B')

fs/ubifs/Kconfig

@@ -7,6 +7,7 @@ config UBIFS_FS
 	select CRYPTO if UBIFS_FS_ZLIB
 	select CRYPTO_LZO if UBIFS_FS_LZO
 	select CRYPTO_DEFLATE if UBIFS_FS_ZLIB
+	select CRYPTO_HASH_INFO
 	depends on MTD_UBI
 	help
 	  UBIFS is a file system for flash devices which works on top of UBI.
@@ -85,3 +86,13 @@ config UBIFS_FS_SECURITY
 	  the extended attribute support in advance.
 
 	  If you are not using a security module, say N.
+
+config UBIFS_FS_AUTHENTICATION
+	bool "UBIFS authentication support"
+	select CRYPTO_HMAC
+	help
+	  Enable authentication support for UBIFS. This feature offers protection
+	  against offline changes for both data and metadata of the filesystem.
+	  If you say yes here you should also select a hashing algorithm such as
+	  sha256, these are not selected automatically since there are many
+	  different options.

fs/ubifs/Makefile

@@ -8,3 +8,4 @@ ubifs-y += recovery.o ioctl.o lpt_commit.o tnc_misc.o debug.o
 ubifs-y += misc.o
 ubifs-$(CONFIG_UBIFS_FS_ENCRYPTION) += crypto.o
 ubifs-$(CONFIG_UBIFS_FS_XATTR) += xattr.o
+ubifs-$(CONFIG_UBIFS_FS_AUTHENTICATION) += auth.o

fs/ubifs/debug.c

@@ -165,6 +165,8 @@ const char *dbg_ntype(int type)
 		return "commit start node";
 	case UBIFS_ORPH_NODE:
 		return "orphan node";
+	case UBIFS_AUTH_NODE:
+		return "auth node";
 	default:
 		return "unknown node";
 	}
@@ -542,6 +544,10 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node)
 			       (unsigned long long)le64_to_cpu(orph->inos[i]));
 		break;
 	}
+	case UBIFS_AUTH_NODE:
+	{
+		break;
+	}
 	default:
 		pr_err("node type %d was not recognized\n",
 		       (int)ch->node_type);

fs/ubifs/gc.c

@@ -254,7 +254,8 @@ static int sort_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb,
 			     snod->type == UBIFS_DATA_NODE ||
 			     snod->type == UBIFS_DENT_NODE ||
 			     snod->type == UBIFS_XENT_NODE ||
-			     snod->type == UBIFS_TRUN_NODE);
+			     snod->type == UBIFS_TRUN_NODE ||
+			     snod->type == UBIFS_AUTH_NODE);
 
 		if (snod->type != UBIFS_INO_NODE  &&
 		    snod->type != UBIFS_DATA_NODE &&
@@ -364,12 +365,13 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
 
 	/* Write nodes to their new location. Use the first-fit strategy */
 	while (1) {
-		int avail;
+		int avail, moved = 0;
 		struct ubifs_scan_node *snod, *tmp;
 
 		/* Move data nodes */
 		list_for_each_entry_safe(snod, tmp, &sleb->nodes, list) {
-			avail = c->leb_size - wbuf->offs - wbuf->used;
+			avail = c->leb_size - wbuf->offs - wbuf->used -
+					ubifs_auth_node_sz(c);
 			if  (snod->len > avail)
 				/*
 				 * Do not skip data nodes in order to optimize
@@ -377,14 +379,21 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
 				 */
 				break;
 
+			err = ubifs_shash_update(c, c->jheads[GCHD].log_hash,
+						 snod->node, snod->len);
+			if (err)
+				goto out;
+
 			err = move_node(c, sleb, snod, wbuf);
 			if (err)
 				goto out;
+			moved = 1;
 		}
 
 		/* Move non-data nodes */
 		list_for_each_entry_safe(snod, tmp, &nondata, list) {
-			avail = c->leb_size - wbuf->offs - wbuf->used;
+			avail = c->leb_size - wbuf->offs - wbuf->used -
+					ubifs_auth_node_sz(c);
 			if (avail < min)
 				break;
 
@@ -402,9 +411,41 @@ static int move_nodes(struct ubifs_info *c, struct ubifs_scan_leb *sleb)
 				continue;
 			}
 
+			err = ubifs_shash_update(c, c->jheads[GCHD].log_hash,
+						 snod->node, snod->len);
+			if (err)
+				goto out;
+
 			err = move_node(c, sleb, snod, wbuf);
 			if (err)
 				goto out;
+			moved = 1;
+		}
+
+		if (ubifs_authenticated(c) && moved) {
+			struct ubifs_auth_node *auth;
+
+			auth = kmalloc(ubifs_auth_node_sz(c), GFP_NOFS);
+			if (!auth) {
+				err = -ENOMEM;
+				goto out;
+			}
+
+			err = ubifs_prepare_auth_node(c, auth,
+						c->jheads[GCHD].log_hash);
+			if (err) {
+				kfree(auth);
+				goto out;
+			}
+
+			err = ubifs_wbuf_write_nolock(wbuf, auth,
+						      ubifs_auth_node_sz(c));
+			if (err) {
+				kfree(auth);
+				goto out;
+			}
+
+			ubifs_add_dirt(c, wbuf->lnum, ubifs_auth_node_sz(c));
 		}
 
 		if (list_empty(&sleb->nodes) && list_empty(&nondata))

fs/ubifs/io.c

@@ -365,20 +365,8 @@ static unsigned long long next_sqnum(struct ubifs_info *c)
 	return sqnum;
 }
 
-/**
- * ubifs_prepare_node - prepare node to be written to flash.
- * @c: UBIFS file-system description object
- * @node: the node to pad
- * @len: node length
- * @pad: if the buffer has to be padded
- *
- * This function prepares node at @node to be written to the media - it
- * calculates node CRC, fills the common header, and adds proper padding up to
- * the next minimum I/O unit if @pad is not zero.
- */
-void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
+void ubifs_init_node(struct ubifs_info *c, void *node, int len, int pad)
 {
-	uint32_t crc;
 	struct ubifs_ch *ch = node;
 	unsigned long long sqnum = next_sqnum(c);
 
@@ -389,8 +377,6 @@ void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
 	ch->group_type = UBIFS_NO_NODE_GROUP;
 	ch->sqnum = cpu_to_le64(sqnum);
 	ch->padding[0] = ch->padding[1] = 0;
-	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
-	ch->crc = cpu_to_le32(crc);
 
 	if (pad) {
 		len = ALIGN(len, 8);
@@ -399,6 +385,68 @@ void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
 	}
 }
 
+void ubifs_crc_node(struct ubifs_info *c, void *node, int len)
+{
+	struct ubifs_ch *ch = node;
+	uint32_t crc;
+
+	crc = crc32(UBIFS_CRC32_INIT, node + 8, len - 8);
+	ch->crc = cpu_to_le32(crc);
+}
+
+/**
+ * ubifs_prepare_node_hmac - prepare node to be written to flash.
+ * @c: UBIFS file-system description object
+ * @node: the node to pad
+ * @len: node length
+ * @hmac_offs: offset of the HMAC in the node
+ * @pad: if the buffer has to be padded
+ *
+ * This function prepares node at @node to be written to the media - it
+ * calculates node CRC, fills the common header, and adds proper padding up to
+ * the next minimum I/O unit if @pad is not zero. if @hmac_offs is positive then
+ * a HMAC is inserted into the node at the given offset.
+ *
+ * This function returns 0 for success or a negative error code otherwise.
+ */
+int ubifs_prepare_node_hmac(struct ubifs_info *c, void *node, int len,
+			    int hmac_offs, int pad)
+{
+	int err;
+
+	ubifs_init_node(c, node, len, pad);
+
+	if (hmac_offs > 0) {
+		err = ubifs_node_insert_hmac(c, node, len, hmac_offs);
+		if (err)
+			return err;
+	}
+
+	ubifs_crc_node(c, node, len);
+
+	return 0;
+}
+
+/**
+ * ubifs_prepare_node - prepare node to be written to flash.
+ * @c: UBIFS file-system description object
+ * @node: the node to pad
+ * @len: node length
+ * @pad: if the buffer has to be padded
+ *
+ * This function prepares node at @node to be written to the media - it
+ * calculates node CRC, fills the common header, and adds proper padding up to
+ * the next minimum I/O unit if @pad is not zero.
+ */
+void ubifs_prepare_node(struct ubifs_info *c, void *node, int len, int pad)
+{
+	/*
+	 * Deliberately ignore return value since this function can only fail
+	 * when a hmac offset is given.
+	 */
+	ubifs_prepare_node_hmac(c, node, len, 0, pad);
+}
+
 /**
  * ubifs_prep_grp_node - prepare node of a group to be written to flash.
  * @c: UBIFS file-system description object
@@ -849,12 +897,13 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
 }
 
 /**
- * ubifs_write_node - write node to the media.
+ * ubifs_write_node_hmac - write node to the media.
  * @c: UBIFS file-system description object
  * @buf: the node to write
  * @len: node length
  * @lnum: logical eraseblock number
  * @offs: offset within the logical eraseblock
+ * @hmac_offs: offset of the HMAC within the node
  *
  * This function automatically fills node magic number, assigns sequence
  * number, and calculates node CRC checksum. The length of the @buf buffer has
@@ -862,8 +911,8 @@ int ubifs_wbuf_write_nolock(struct ubifs_wbuf *wbuf, void *buf, int len)
  * appends padding node and padding bytes if needed. Returns zero in case of
  * success and a negative error code in case of failure.
  */
-int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
-		     int offs)
+int ubifs_write_node_hmac(struct ubifs_info *c, void *buf, int len, int lnum,
+			  int offs, int hmac_offs)
 {
 	int err, buf_len = ALIGN(len, c->min_io_size);
 
@@ -878,7 +927,10 @@ int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
 	if (c->ro_error)
 		return -EROFS;
 
-	ubifs_prepare_node(c, buf, len, 1);
+	err = ubifs_prepare_node_hmac(c, buf, len, hmac_offs, 1);
+	if (err)
+		return err;
+
 	err = ubifs_leb_write(c, lnum, buf, offs, buf_len);
 	if (err)
 		ubifs_dump_node(c, buf);
@@ -886,6 +938,26 @@ int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
 	return err;
 }
 
+/**
+ * ubifs_write_node - write node to the media.
+ * @c: UBIFS file-system description object
+ * @buf: the node to write
+ * @len: node length
+ * @lnum: logical eraseblock number
+ * @offs: offset within the logical eraseblock
+ *
+ * This function automatically fills node magic number, assigns sequence
+ * number, and calculates node CRC checksum. The length of the @buf buffer has
+ * to be aligned to the minimal I/O unit size. This function automatically
+ * appends padding node and padding bytes if needed. Returns zero in case of
+ * success and a negative error code in case of failure.
+ */
+int ubifs_write_node(struct ubifs_info *c, void *buf, int len, int lnum,
+		     int offs)
+{
+	return ubifs_write_node_hmac(c, buf, len, lnum, offs, -1);
+}
+
 /**
  * ubifs_read_node_wbuf - read node from the media or write-buffer.
  * @wbuf: wbuf to check for un-written data

fs/ubifs/log.c

@@ -236,6 +236,7 @@ int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
 	bud->lnum = lnum;
 	bud->start = offs;
 	bud->jhead = jhead;
+	bud->log_hash = NULL;
 
 	ref->ch.node_type = UBIFS_REF_NODE;
 	ref->lnum = cpu_to_le32(bud->lnum);
@@ -275,6 +276,14 @@ int ubifs_add_bud_to_log(struct ubifs_info *c, int jhead, int lnum, int offs)
 	if (err)
 		goto out_unlock;
 
+	err = ubifs_shash_update(c, c->log_hash, ref, UBIFS_REF_NODE_SZ);
+	if (err)
+		goto out_unlock;
+
+	err = ubifs_shash_copy_state(c, c->log_hash, c->jheads[jhead].log_hash);
+	if (err)
+		goto out_unlock;
+
 	c->lhead_offs += c->ref_node_alsz;
 
 	ubifs_add_bud(c, bud);
@@ -377,6 +386,14 @@ int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
 	cs->cmt_no = cpu_to_le64(c->cmt_no);
 	ubifs_prepare_node(c, cs, UBIFS_CS_NODE_SZ, 0);
 
+	err = ubifs_shash_init(c, c->log_hash);
+	if (err)
+		goto out;
+
+	err = ubifs_shash_update(c, c->log_hash, cs, UBIFS_CS_NODE_SZ);
+	if (err < 0)
+		goto out;
+
 	/*
 	 * Note, we do not lock 'c->log_mutex' because this is the commit start
 	 * phase and we are exclusively using the log. And we do not lock
@@ -402,6 +419,12 @@ int ubifs_log_start_commit(struct ubifs_info *c, int *ltail_lnum)
 
 		ubifs_prepare_node(c, ref, UBIFS_REF_NODE_SZ, 0);
 		len += UBIFS_REF_NODE_SZ;
+
+		err = ubifs_shash_update(c, c->log_hash, ref,
+					 UBIFS_REF_NODE_SZ);
+		if (err)
+			goto out;
+		ubifs_shash_copy_state(c, c->log_hash, c->jheads[i].log_hash);
 	}
 
 	ubifs_pad(c, buf + len, ALIGN(len, c->min_io_size) - len);
@@ -516,6 +539,7 @@ int ubifs_log_post_commit(struct ubifs_info *c, int old_ltail_lnum)
 		if (err)
 			return err;
 		list_del(&bud->list);
+		kfree(bud->log_hash);
 		kfree(bud);
 	}
 	mutex_lock(&c->log_mutex);

fs/ubifs/lpt.c

@@ -604,11 +604,12 @@ static int calc_pnode_num_from_parent(const struct ubifs_info *c,
  * @lpt_first: LEB number of first LPT LEB
  * @lpt_lebs: number of LEBs for LPT is passed and returned here
  * @big_lpt: use big LPT model is passed and returned here
+ * @hash: hash of the LPT is returned here
  *
  * This function returns %0 on success and a negative error code on failure.
  */
 int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
-			  int *lpt_lebs, int *big_lpt)
+			  int *lpt_lebs, int *big_lpt, u8 *hash)
 {
 	int lnum, err = 0, node_sz, iopos, i, j, cnt, len, alen, row;
 	int blnum, boffs, bsz, bcnt;
@@ -617,6 +618,7 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 	void *buf = NULL, *p;
 	struct ubifs_lpt_lprops *ltab = NULL;
 	int *lsave = NULL;
+	struct shash_desc *desc;
 
 	err = calc_dflt_lpt_geom(c, main_lebs, big_lpt);
 	if (err)
@@ -630,6 +632,10 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 	/* Needed by 'ubifs_pack_lsave()' */
 	c->main_first = c->leb_cnt - *main_lebs;
 
+	desc = ubifs_hash_get_desc(c);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
 	lsave = kmalloc_array(c->lsave_cnt, sizeof(int), GFP_KERNEL);
 	pnode = kzalloc(sizeof(struct ubifs_pnode), GFP_KERNEL);
 	nnode = kzalloc(sizeof(struct ubifs_nnode), GFP_KERNEL);
@@ -677,6 +683,10 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 
 	/* Add first pnode */
 	ubifs_pack_pnode(c, p, pnode);
+	err = ubifs_shash_update(c, desc, p, c->pnode_sz);
+	if (err)
+		goto out;
+
 	p += c->pnode_sz;
 	len = c->pnode_sz;
 	pnode->num += 1;
@@ -711,6 +721,10 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 			len = 0;
 		}
 		ubifs_pack_pnode(c, p, pnode);
+		err = ubifs_shash_update(c, desc, p, c->pnode_sz);
+		if (err)
+			goto out;
+
 		p += c->pnode_sz;
 		len += c->pnode_sz;
 		/*
@@ -830,6 +844,10 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 	if (err)
 		goto out;
 
+	err = ubifs_shash_final(c, desc, hash);
+	if (err)
+		goto out;
+
 	c->nhead_lnum = lnum;
 	c->nhead_offs = ALIGN(len, c->min_io_size);
 
@@ -853,6 +871,7 @@ int ubifs_create_dflt_lpt(struct ubifs_info *c, int *main_lebs, int lpt_first,
 		dbg_lp("LPT lsave is at %d:%d", c->lsave_lnum, c->lsave_offs);
 out:
 	c->ltab = NULL;
+	kfree(desc);
 	kfree(lsave);
 	vfree(ltab);
 	vfree(buf);
@@ -1439,26 +1458,25 @@ struct ubifs_pnode *ubifs_get_pnode(struct ubifs_info *c,
 }
 
 /**
- * ubifs_lpt_lookup - lookup LEB properties in the LPT.
+ * ubifs_pnode_lookup - lookup a pnode in the LPT.
  * @c: UBIFS file-system description object
- * @lnum: LEB number to lookup
+ * @i: pnode number (0 to (main_lebs - 1) / UBIFS_LPT_FANOUT)
  *
- * This function returns a pointer to the LEB properties on success or a
- * negative error code on failure.
+ * This function returns a pointer to the pnode on success or a negative
+ * error code on failure.
  */
-struct ubifs_lprops *ubifs_lpt_lookup(struct ubifs_info *c, int lnum)
+struct ubifs_pnode *ubifs_pnode_lookup(struct ubifs_info *c, int i)
 {
-	int err, i, h, iip, shft;
+	int err, h, iip, shft;
 	struct ubifs_nnode *nnode;
-	struct ubifs_pnode *pnode;
 
 	if (!c->nroot) {
 		err = ubifs_read_nnode(c, NULL, 0);
 		if (err)
 			return ERR_PTR(err);
 	}
+	i <<= UBIFS_LPT_FANOUT_SHIFT;
 	nnode = c->nroot;
-	i = lnum - c->main_first;
 	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
 	for (h = 1; h < c->lpt_hght; h++) {
 		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
@@ -1468,7 +1486,24 @@ struct ubifs_lprops *ubifs_lpt_lookup(struct ubifs_info *c, int lnum)
 			return ERR_CAST(nnode);
 	}
 	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
-	pnode = ubifs_get_pnode(c, nnode, iip);
+	return ubifs_get_pnode(c, nnode, iip);
+}
+
+/**
+ * ubifs_lpt_lookup - lookup LEB properties in the LPT.
+ * @c: UBIFS file-system description object
+ * @lnum: LEB number to lookup
+ *
+ * This function returns a pointer to the LEB properties on success or a
+ * negative error code on failure.
+ */
+struct ubifs_lprops *ubifs_lpt_lookup(struct ubifs_info *c, int lnum)
+{
+	int i, iip;
+	struct ubifs_pnode *pnode;
+
+	i = lnum - c->main_first;
+	pnode = ubifs_pnode_lookup(c, i >> UBIFS_LPT_FANOUT_SHIFT);
 	if (IS_ERR(pnode))
 		return ERR_CAST(pnode);
 	iip = (i & (UBIFS_LPT_FANOUT - 1));
@@ -1619,6 +1654,131 @@ struct ubifs_lprops *ubifs_lpt_lookup_dirty(struct ubifs_info *c, int lnum)
 	return &pnode->lprops[iip];
 }
 
+/**
+ * ubifs_lpt_calc_hash - Calculate hash of the LPT pnodes
+ * @c: UBIFS file-system description object
+ * @hash: the returned hash of the LPT pnodes
+ *
+ * This function iterates over the LPT pnodes and creates a hash over them.
+ * Returns 0 for success or a negative error code otherwise.
+ */
+int ubifs_lpt_calc_hash(struct ubifs_info *c, u8 *hash)
+{
+	struct ubifs_nnode *nnode, *nn;
+	struct ubifs_cnode *cnode;
+	struct shash_desc *desc;
+	int iip = 0, i;
+	int bufsiz = max_t(int, c->nnode_sz, c->pnode_sz);
+	void *buf;
+	int err;
+
+	if (!ubifs_authenticated(c))
+		return 0;
+
+	desc = ubifs_hash_get_desc(c);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	buf = kmalloc(bufsiz, GFP_NOFS);
+	if (!buf) {
+		err = -ENOMEM;
+		goto out;
+	}
+
+	if (!c->nroot) {
+		err = ubifs_read_nnode(c, NULL, 0);
+		if (err)
+			return err;
+	}
+
+	cnode = (struct ubifs_cnode *)c->nroot;
+
+	while (cnode) {
+		nnode = cnode->parent;
+		nn = (struct ubifs_nnode *)cnode;
+		if (cnode->level > 1) {
+			while (iip < UBIFS_LPT_FANOUT) {
+				if (nn->nbranch[iip].lnum == 0) {
+					/* Go right */
+					iip++;
+					continue;
+				}
+
+				nnode = ubifs_get_nnode(c, nn, iip);
+				if (IS_ERR(nnode)) {
+					err = PTR_ERR(nnode);
+					goto out;
+				}
+
+				/* Go down */
+				iip = 0;
+				cnode = (struct ubifs_cnode *)nnode;
+				break;
+			}
+			if (iip < UBIFS_LPT_FANOUT)
+				continue;
+		} else {
+			struct ubifs_pnode *pnode;
+
+			for (i = 0; i < UBIFS_LPT_FANOUT; i++) {
+				if (nn->nbranch[i].lnum == 0)
+					continue;
+				pnode = ubifs_get_pnode(c, nn, i);
+				if (IS_ERR(pnode)) {
+					err = PTR_ERR(pnode);
+					goto out;
+				}
+
+				ubifs_pack_pnode(c, buf, pnode);
+				err = ubifs_shash_update(c, desc, buf,
+							 c->pnode_sz);
+				if (err)
+					goto out;
+			}
+		}
+		/* Go up and to the right */
+		iip = cnode->iip + 1;
+		cnode = (struct ubifs_cnode *)nnode;
+	}
+
+	err = ubifs_shash_final(c, desc, hash);
+out:
+	kfree(desc);
+	kfree(buf);
+
+	return err;
+}
+
+/**
+ * lpt_check_hash - check the hash of the LPT.
+ * @c: UBIFS file-system description object
+ *
+ * This function calculates a hash over all pnodes in the LPT and compares it with
+ * the hash stored in the master node. Returns %0 on success and a negative error
+ * code on failure.
+ */
+static int lpt_check_hash(struct ubifs_info *c)
+{
+	int err;
+	u8 hash[UBIFS_HASH_ARR_SZ];
+
+	if (!ubifs_authenticated(c))
+		return 0;
+
+	err = ubifs_lpt_calc_hash(c, hash);
+	if (err)
+		return err;
+
+	if (ubifs_check_hash(c, c->mst_node->hash_lpt, hash)) {
+		err = -EPERM;
+		ubifs_err(c, "Failed to authenticate LPT");
+	} else {
+		err = 0;
+	}
+
+	return err;
+}
+
 /**
  * lpt_init_rd - initialize the LPT for reading.
  * @c: UBIFS file-system description object
@@ -1660,6 +1820,10 @@ static int lpt_init_rd(struct ubifs_info *c)
 	if (err)
 		return err;
 
+	err = lpt_check_hash(c);
+	if (err)
+		return err;
+
 	dbg_lp("space_bits %d", c->space_bits);
 	dbg_lp("lpt_lnum_bits %d", c->lpt_lnum_bits);
 	dbg_lp("lpt_offs_bits %d", c->lpt_offs_bits);

fs/ubifs/lpt_commit.c

@@ -618,38 +618,6 @@ static struct ubifs_pnode *next_pnode_to_dirty(struct ubifs_info *c,
 	return ubifs_get_pnode(c, nnode, iip);
 }
 
-/**
- * pnode_lookup - lookup a pnode in the LPT.
- * @c: UBIFS file-system description object
- * @i: pnode number (0 to (main_lebs - 1) / UBIFS_LPT_FANOUT))
- *
- * This function returns a pointer to the pnode on success or a negative
- * error code on failure.
- */
-static struct ubifs_pnode *pnode_lookup(struct ubifs_info *c, int i)
-{
-	int err, h, iip, shft;
-	struct ubifs_nnode *nnode;
-
-	if (!c->nroot) {
-		err = ubifs_read_nnode(c, NULL, 0);
-		if (err)
-			return ERR_PTR(err);
-	}
-	i <<= UBIFS_LPT_FANOUT_SHIFT;
-	nnode = c->nroot;
-	shft = c->lpt_hght * UBIFS_LPT_FANOUT_SHIFT;
-	for (h = 1; h < c->lpt_hght; h++) {
-		iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
-		shft -= UBIFS_LPT_FANOUT_SHIFT;
-		nnode = ubifs_get_nnode(c, nnode, iip);
-		if (IS_ERR(nnode))
-			return ERR_CAST(nnode);
-	}
-	iip = ((i >> shft) & (UBIFS_LPT_FANOUT - 1));
-	return ubifs_get_pnode(c, nnode, iip);
-}
-
 /**
  * add_pnode_dirt - add dirty space to LPT LEB properties.
  * @c: UBIFS file-system description object
@@ -702,7 +670,7 @@ static int make_tree_dirty(struct ubifs_info *c)
 {
 	struct ubifs_pnode *pnode;
 
-	pnode = pnode_lookup(c, 0);
+	pnode = ubifs_pnode_lookup(c, 0);
 	if (IS_ERR(pnode))
 		return PTR_ERR(pnode);
 
@@ -956,7 +924,7 @@ static int make_pnode_dirty(struct ubifs_info *c, int node_num, int lnum,
 	struct ubifs_pnode *pnode;
 	struct ubifs_nbranch *branch;
 
-	pnode = pnode_lookup(c, node_num);
+	pnode = ubifs_pnode_lookup(c, node_num);
 	if (IS_ERR(pnode))
 		return PTR_ERR(pnode);
 	branch = &pnode->parent->nbranch[pnode->iip];
@@ -1279,6 +1247,10 @@ int ubifs_lpt_start_commit(struct ubifs_info *c)
 	if (err)
 		goto out;
 
+	err = ubifs_lpt_calc_hash(c, c->mst_node->hash_lpt);
+	if (err)
+		goto out;
+
 	/* Copy the LPT's own lprops for end commit to write */
 	memcpy(c->ltab_cmt, c->ltab,
 	       sizeof(struct ubifs_lpt_lprops) * c->lpt_lebs);
@@ -1558,7 +1530,7 @@ static int dbg_is_pnode_dirty(struct ubifs_info *c, int lnum, int offs)
 		struct ubifs_nbranch *branch;
 
 		cond_resched();
-		pnode = pnode_lookup(c, i);
+		pnode = ubifs_pnode_lookup(c, i);
 		if (IS_ERR(pnode))
 			return PTR_ERR(pnode);
 		branch = &pnode->parent->nbranch[pnode->iip];
@@ -1710,7 +1682,7 @@ int dbg_check_ltab(struct ubifs_info *c)
 	for (i = 0; i < cnt; i++) {
 		struct ubifs_pnode *pnode;
 
-		pnode = pnode_lookup(c, i);
+		pnode = ubifs_pnode_lookup(c, i);
 		if (IS_ERR(pnode))
 			return PTR_ERR(pnode);
 		cond_resched();

fs/ubifs/master.c

@@ -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:
@@ -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;
 }

fs/ubifs/misc.h

@@ -197,7 +197,8 @@ static inline int ubifs_return_leb(struct ubifs_info *c, int lnum)
  */
 static inline int ubifs_idx_node_sz(const struct ubifs_info *c, int child_cnt)
 {
-	return UBIFS_IDX_NODE_SZ + (UBIFS_BRANCH_SZ + c->key_len) * child_cnt;
+	return UBIFS_IDX_NODE_SZ + (UBIFS_BRANCH_SZ + c->key_len + c->hash_len)
+				   * child_cnt;
 }
 
 /**
@@ -212,7 +213,7 @@ struct ubifs_branch *ubifs_idx_branch(const struct ubifs_info *c,
 				      int bnum)
 {
 	return (struct ubifs_branch *)((void *)idx->branches +
-				       (UBIFS_BRANCH_SZ + c->key_len) * bnum);
+			(UBIFS_BRANCH_SZ + c->key_len + c->hash_len) * bnum);
 }
 
 /**

fs/ubifs/recovery.c

@@ -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) {
@@ -1461,16 +1462,82 @@ static int fix_size_in_place(struct ubifs_info *c, struct size_entry *e)
 	return err;
 }
 
+/**
+ * inode_fix_size - fix inode size
+ * @c: UBIFS file-system description object
+ * @e: inode size information for recovery
+ */
+static int inode_fix_size(struct ubifs_info *c, struct size_entry *e)
+{
+	struct inode *inode;
+	struct ubifs_inode *ui;
+	int err;
+
+	if (c->ro_mount)
+		ubifs_assert(c, !e->inode);
+
+	if (e->inode) {
+		/* Remounting rw, pick up inode we stored earlier */
+		inode = e->inode;
+	} else {
+		inode = ubifs_iget(c->vfs_sb, e->inum);
+		if (IS_ERR(inode))
+			return PTR_ERR(inode);
+
+		if (inode->i_size >= e->d_size) {
+			/*
+			 * The original inode in the index already has a size
+			 * big enough, nothing to do
+			 */
+			iput(inode);
+			return 0;
+		}
+
+		dbg_rcvry("ino %lu size %lld -> %lld",
+			  (unsigned long)e->inum,
+			  inode->i_size, e->d_size);
+
+		ui = ubifs_inode(inode);
+
+		inode->i_size = e->d_size;
+		ui->ui_size = e->d_size;
+		ui->synced_i_size = e->d_size;
+
+		e->inode = inode;
+	}
+
+	/*
+	 * In readonly mode just keep the inode pinned in memory until we go
+	 * readwrite. In readwrite mode write the inode to the journal with the
+	 * fixed size.
+	 */
+	if (c->ro_mount)
+		return 0;
+
+	err = ubifs_jnl_write_inode(c, inode);
+
+	iput(inode);
+
+	if (err)
+		return err;
+
+	rb_erase(&e->rb, &c->size_tree);
+	kfree(e);
+
+	return 0;
+}
+
 /**
  * ubifs_recover_size - recover inode size.
  * @c: UBIFS file-system description object
+ * @in_place: If true, do a in-place size fixup
  *
  * This function attempts to fix inode size discrepancies identified by the
  * 'ubifs_recover_size_accum()' function.
  *
  * This functions returns %0 on success and a negative error code on failure.
  */
-int ubifs_recover_size(struct ubifs_info *c)
+int ubifs_recover_size(struct ubifs_info *c, bool in_place)
 {
 	struct rb_node *this = rb_first(&c->size_tree);
 
@@ -1479,6 +1546,9 @@ int ubifs_recover_size(struct ubifs_info *c)
 		int err;
 
 		e = rb_entry(this, struct size_entry, rb);
+
+		this = rb_next(this);
+
 		if (!e->exists) {
 			union ubifs_key key;
 
@@ -1502,40 +1572,26 @@ int ubifs_recover_size(struct ubifs_info *c)
 		}
 
 		if (e->exists && e->i_size < e->d_size) {
-			if (c->ro_mount) {
-				/* Fix the inode size and pin it in memory */
-				struct inode *inode;
-				struct ubifs_inode *ui;
-
-				ubifs_assert(c, !e->inode);
-
-				inode = ubifs_iget(c->vfs_sb, e->inum);
-				if (IS_ERR(inode))
-					return PTR_ERR(inode);
-
-				ui = ubifs_inode(inode);
-				if (inode->i_size < e->d_size) {
-					dbg_rcvry("ino %lu size %lld -> %lld",
-						  (unsigned long)e->inum,
-						  inode->i_size, e->d_size);
-					inode->i_size = e->d_size;
-					ui->ui_size = e->d_size;
-					ui->synced_i_size = e->d_size;
-					e->inode = inode;
-					this = rb_next(this);
-					continue;
-				}
-				iput(inode);
-			} else {
-				/* Fix the size in place */
+			ubifs_assert(c, !(c->ro_mount && in_place));
+
+			/*
+			 * We found data that is outside the found inode size,
+			 * fixup the inode size
+			 */
+
+			if (in_place) {
 				err = fix_size_in_place(c, e);
 				if (err)
 					return err;
 				iput(e->inode);
+			} else {
+				err = inode_fix_size(c, e);
+				if (err)
+					return err;
+				continue;
 			}
 		}
 
-		this = rb_next(this);
 		rb_erase(&e->rb, &c->size_tree);
 		kfree(e);
 	}

fs/ubifs/super.c

@@ -579,6 +579,9 @@ static int init_constants_early(struct ubifs_info *c)
 	c->ranges[UBIFS_REF_NODE].len  = UBIFS_REF_NODE_SZ;
 	c->ranges[UBIFS_TRUN_NODE].len = UBIFS_TRUN_NODE_SZ;
 	c->ranges[UBIFS_CS_NODE].len   = UBIFS_CS_NODE_SZ;
+	c->ranges[UBIFS_AUTH_NODE].min_len = UBIFS_AUTH_NODE_SZ;
+	c->ranges[UBIFS_AUTH_NODE].max_len = UBIFS_AUTH_NODE_SZ +
+				UBIFS_MAX_HMAC_LEN;
 
 	c->ranges[UBIFS_INO_NODE].min_len  = UBIFS_INO_NODE_SZ;
 	c->ranges[UBIFS_INO_NODE].max_len  = UBIFS_MAX_INO_NODE_SZ;
@@ -816,6 +819,9 @@ static int alloc_wbufs(struct ubifs_info *c)
 		c->jheads[i].wbuf.sync_callback = &bud_wbuf_callback;
 		c->jheads[i].wbuf.jhead = i;
 		c->jheads[i].grouped = 1;
+		c->jheads[i].log_hash = ubifs_hash_get_desc(c);
+		if (IS_ERR(c->jheads[i].log_hash))
+			goto out;
 	}
 
 	/*
@@ -826,6 +832,12 @@ static int alloc_wbufs(struct ubifs_info *c)
 	c->jheads[GCHD].grouped = 0;
 
 	return 0;
+
+out:
+	while (i--)
+		kfree(c->jheads[i].log_hash);
+
+	return err;
 }
 
 /**
@@ -840,6 +852,7 @@ static void free_wbufs(struct ubifs_info *c)
 		for (i = 0; i < c->jhead_cnt; i++) {
 			kfree(c->jheads[i].wbuf.buf);
 			kfree(c->jheads[i].wbuf.inodes);
+			kfree(c->jheads[i].log_hash);
 		}
 		kfree(c->jheads);
 		c->jheads = NULL;
@@ -924,6 +937,8 @@ static int check_volume_empty(struct ubifs_info *c)
  * Opt_no_chk_data_crc: do not check CRCs when reading data nodes
  * Opt_override_compr: override default compressor
  * Opt_assert: set ubifs_assert() action
+ * Opt_auth_key: The key name used for authentication
+ * Opt_auth_hash_name: The hash type used for authentication
  * Opt_err: just end of array marker
  */
 enum {
@@ -935,6 +950,8 @@ enum {
 	Opt_no_chk_data_crc,
 	Opt_override_compr,
 	Opt_assert,
+	Opt_auth_key,
+	Opt_auth_hash_name,
 	Opt_ignore,
 	Opt_err,
 };
@@ -947,6 +964,8 @@ static const match_table_t tokens = {
 	{Opt_chk_data_crc, "chk_data_crc"},
 	{Opt_no_chk_data_crc, "no_chk_data_crc"},
 	{Opt_override_compr, "compr=%s"},
+	{Opt_auth_key, "auth_key=%s"},
+	{Opt_auth_hash_name, "auth_hash_name=%s"},
 	{Opt_ignore, "ubi=%s"},
 	{Opt_ignore, "vol=%s"},
 	{Opt_assert, "assert=%s"},
@@ -1070,6 +1089,16 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
 			kfree(act);
 			break;
 		}
+		case Opt_auth_key:
+			c->auth_key_name = kstrdup(args[0].from, GFP_KERNEL);
+			if (!c->auth_key_name)
+				return -ENOMEM;
+			break;
+		case Opt_auth_hash_name:
+			c->auth_hash_name = kstrdup(args[0].from, GFP_KERNEL);
+			if (!c->auth_hash_name)
+				return -ENOMEM;
+			break;
 		case Opt_ignore:
 			break;
 		default:
@@ -1249,6 +1278,19 @@ static int mount_ubifs(struct ubifs_info *c)
 
 	c->mounting = 1;
 
+	if (c->auth_key_name) {
+		if (IS_ENABLED(CONFIG_UBIFS_FS_AUTHENTICATION)) {
+			err = ubifs_init_authentication(c);
+			if (err)
+				goto out_free;
+		} else {
+			ubifs_err(c, "auth_key_name, but UBIFS is built without"
+				  " authentication support");
+			err = -EINVAL;
+			goto out_free;
+		}
+	}
+
 	err = ubifs_read_superblock(c);
 	if (err)
 		goto out_free;
@@ -1367,12 +1409,21 @@ static int mount_ubifs(struct ubifs_info *c)
 		}
 
 		if (c->need_recovery) {
-			err = ubifs_recover_size(c);
-			if (err)
-				goto out_orphans;
+			if (!ubifs_authenticated(c)) {
+				err = ubifs_recover_size(c, true);
+				if (err)
+					goto out_orphans;
+			}
+
 			err = ubifs_rcvry_gc_commit(c);
 			if (err)
 				goto out_orphans;
+
+			if (ubifs_authenticated(c)) {
+				err = ubifs_recover_size(c, false);
+				if (err)
+					goto out_orphans;
+			}
 		} else {
 			err = take_gc_lnum(c);
 			if (err)
@@ -1391,7 +1442,7 @@ static int mount_ubifs(struct ubifs_info *c)
 		if (err)
 			goto out_orphans;
 	} else if (c->need_recovery) {
-		err = ubifs_recover_size(c);
+		err = ubifs_recover_size(c, false);
 		if (err)
 			goto out_orphans;
 	} else {
@@ -1557,7 +1608,10 @@ static void ubifs_umount(struct ubifs_info *c)
 	free_wbufs(c);
 	free_orphans(c);
 	ubifs_lpt_free(c, 0);
+	ubifs_exit_authentication(c);
 
+	kfree(c->auth_key_name);
+	kfree(c->auth_hash_name);
 	kfree(c->cbuf);
 	kfree(c->rcvrd_mst_node);
 	kfree(c->mst_node);
@@ -1605,16 +1659,10 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 		goto out;
 
 	if (c->old_leb_cnt != c->leb_cnt) {
-		struct ubifs_sb_node *sup;
+		struct ubifs_sb_node *sup = c->sup_node;
 
-		sup = ubifs_read_sb_node(c);
-		if (IS_ERR(sup)) {
-			err = PTR_ERR(sup);
-			goto out;
-		}
 		sup->leb_cnt = cpu_to_le32(c->leb_cnt);
 		err = ubifs_write_sb_node(c, sup);
-		kfree(sup);
 		if (err)
 			goto out;
 	}
@@ -1624,9 +1672,11 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 		err = ubifs_write_rcvrd_mst_node(c);
 		if (err)
 			goto out;
-		err = ubifs_recover_size(c);
-		if (err)
-			goto out;
+		if (!ubifs_authenticated(c)) {
+			err = ubifs_recover_size(c, true);
+			if (err)
+				goto out;
+		}
 		err = ubifs_clean_lebs(c, c->sbuf);
 		if (err)
 			goto out;
@@ -1692,10 +1742,19 @@ static int ubifs_remount_rw(struct ubifs_info *c)
 			goto out;
 	}
 
-	if (c->need_recovery)
+	if (c->need_recovery) {
 		err = ubifs_rcvry_gc_commit(c);
-	else
+		if (err)
+			goto out;
+
+		if (ubifs_authenticated(c)) {
+			err = ubifs_recover_size(c, false);
+			if (err)
+				goto out;
+		}
+	} else {
 		err = ubifs_leb_unmap(c, c->gc_lnum);
+	}
 	if (err)
 		goto out;
 

fs/ubifs/tnc.c

@@ -35,7 +35,7 @@
 #include "ubifs.h"
 
 static int try_read_node(const struct ubifs_info *c, void *buf, int type,
-			 int len, int lnum, int offs);
+			 struct ubifs_zbranch *zbr);
 static int fallible_read_node(struct ubifs_info *c, const union ubifs_key *key,
 			      struct ubifs_zbranch *zbr, void *node);
 
@@ -433,9 +433,7 @@ static int tnc_read_hashed_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
  * @c: UBIFS file-system description object
  * @buf: buffer to read to
  * @type: node type
- * @len: node length (not aligned)
- * @lnum: LEB number of node to read
- * @offs: offset of node to read
+ * @zbr: the zbranch describing the node to read
  *
  * This function tries to read a node of known type and length, checks it and
  * stores it in @buf. This function returns %1 if a node is present and %0 if
@@ -453,8 +451,11 @@ static int tnc_read_hashed_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
  * journal nodes may potentially be corrupted, so checking is required.
  */
 static int try_read_node(const struct ubifs_info *c, void *buf, int type,
-			 int len, int lnum, int offs)
+			 struct ubifs_zbranch *zbr)
 {
+	int len = zbr->len;
+	int lnum = zbr->lnum;
+	int offs = zbr->offs;
 	int err, node_len;
 	struct ubifs_ch *ch = buf;
 	uint32_t crc, node_crc;
@@ -487,6 +488,12 @@ static int try_read_node(const struct ubifs_info *c, void *buf, int type,
 	if (crc != node_crc)
 		return 0;
 
+	err = ubifs_node_check_hash(c, buf, zbr->hash);
+	if (err) {
+		ubifs_bad_hash(c, buf, zbr->hash, lnum, offs);
+		return 0;
+	}
+
 	return 1;
 }
 
@@ -507,8 +514,7 @@ static int fallible_read_node(struct ubifs_info *c, const union ubifs_key *key,
 
 	dbg_tnck(key, "LEB %d:%d, key ", zbr->lnum, zbr->offs);
 
-	ret = try_read_node(c, node, key_type(c, key), zbr->len, zbr->lnum,
-			    zbr->offs);
+	ret = try_read_node(c, node, key_type(c, key), zbr);
 	if (ret == 1) {
 		union ubifs_key node_key;
 		struct ubifs_dent_node *dent = node;
@@ -1713,6 +1719,12 @@ static int validate_data_node(struct ubifs_info *c, void *buf,
 		goto out;
 	}
 
+	err = ubifs_node_check_hash(c, buf, zbr->hash);
+	if (err) {
+		ubifs_bad_hash(c, buf, zbr->hash, zbr->lnum, zbr->offs);
+		return err;
+	}
+
 	len = le32_to_cpu(ch->len);
 	if (len != zbr->len) {
 		ubifs_err(c, "bad node length %d, expected %d", len, zbr->len);
@@ -2260,13 +2272,14 @@ static int tnc_insert(struct ubifs_info *c, struct ubifs_znode *znode,
  * @lnum: LEB number of node
  * @offs: node offset
  * @len: node length
+ * @hash: The hash over the node
  *
  * This function adds a node with key @key to TNC. The node may be new or it may
  * obsolete some existing one. Returns %0 on success or negative error code on
  * failure.
  */
 int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
-		  int offs, int len)
+		  int offs, int len, const u8 *hash)
 {
 	int found, n, err = 0;
 	struct ubifs_znode *znode;
@@ -2281,6 +2294,7 @@ int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
 		zbr.lnum = lnum;
 		zbr.offs = offs;
 		zbr.len = len;
+		ubifs_copy_hash(c, hash, zbr.hash);
 		key_copy(c, key, &zbr.key);
 		err = tnc_insert(c, znode, &zbr, n + 1);
 	} else if (found == 1) {
@@ -2291,6 +2305,7 @@ int ubifs_tnc_add(struct ubifs_info *c, const union ubifs_key *key, int lnum,
 		zbr->lnum = lnum;
 		zbr->offs = offs;
 		zbr->len = len;
+		ubifs_copy_hash(c, hash, zbr->hash);
 	} else
 		err = found;
 	if (!err)
@@ -2392,13 +2407,14 @@ int ubifs_tnc_replace(struct ubifs_info *c, const union ubifs_key *key,
  * @lnum: LEB number of node
  * @offs: node offset
  * @len: node length
+ * @hash: The hash over the node
  * @nm: node name
  *
  * This is the same as 'ubifs_tnc_add()' but it should be used with keys which
  * may have collisions, like directory entry keys.
  */
 int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
-		     int lnum, int offs, int len,
+		     int lnum, int offs, int len, const u8 *hash,
 		     const struct fscrypt_name *nm)
 {
 	int found, n, err = 0;
@@ -2441,6 +2457,7 @@ int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
 			zbr->lnum = lnum;
 			zbr->offs = offs;
 			zbr->len = len;
+			ubifs_copy_hash(c, hash, zbr->hash);
 			goto out_unlock;
 		}
 	}
@@ -2452,6 +2469,7 @@ int ubifs_tnc_add_nm(struct ubifs_info *c, const union ubifs_key *key,
 		zbr.lnum = lnum;
 		zbr.offs = offs;
 		zbr.len = len;
+		ubifs_copy_hash(c, hash, zbr.hash);
 		key_copy(c, key, &zbr.key);
 		err = tnc_insert(c, znode, &zbr, n + 1);
 		if (err)

fs/ubifs/tnc_commit.c

@@ -38,6 +38,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
 			 struct ubifs_znode *znode, int lnum, int offs, int len)
 {
 	struct ubifs_znode *zp;
+	u8 hash[UBIFS_HASH_ARR_SZ];
 	int i, err;
 
 	/* Make index node */
@@ -52,6 +53,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
 		br->lnum = cpu_to_le32(zbr->lnum);
 		br->offs = cpu_to_le32(zbr->offs);
 		br->len = cpu_to_le32(zbr->len);
+		ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
 		if (!zbr->lnum || !zbr->len) {
 			ubifs_err(c, "bad ref in znode");
 			ubifs_dump_znode(c, znode);
@@ -62,6 +64,7 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
 		}
 	}
 	ubifs_prepare_node(c, idx, len, 0);
+	ubifs_node_calc_hash(c, idx, hash);
 
 	znode->lnum = lnum;
 	znode->offs = offs;
@@ -78,10 +81,12 @@ static int make_idx_node(struct ubifs_info *c, struct ubifs_idx_node *idx,
 		zbr->lnum = lnum;
 		zbr->offs = offs;
 		zbr->len = len;
+		ubifs_copy_hash(c, hash, zbr->hash);
 	} else {
 		c->zroot.lnum = lnum;
 		c->zroot.offs = offs;
 		c->zroot.len = len;
+		ubifs_copy_hash(c, hash, c->zroot.hash);
 	}
 	c->calc_idx_sz += ALIGN(len, 8);
 
@@ -647,6 +652,8 @@ static int get_znodes_to_commit(struct ubifs_info *c)
 			znode->cnext = c->cnext;
 			break;
 		}
+		znode->cparent = znode->parent;
+		znode->ciip = znode->iip;
 		znode->cnext = cnext;
 		znode = cnext;
 		cnt += 1;
@@ -840,6 +847,8 @@ static int write_index(struct ubifs_info *c)
 	}
 
 	while (1) {
+		u8 hash[UBIFS_HASH_ARR_SZ];
+
 		cond_resched();
 
 		znode = cnext;
@@ -857,6 +866,7 @@ static int write_index(struct ubifs_info *c)
 			br->lnum = cpu_to_le32(zbr->lnum);
 			br->offs = cpu_to_le32(zbr->offs);
 			br->len = cpu_to_le32(zbr->len);
+			ubifs_copy_hash(c, zbr->hash, ubifs_branch_hash(c, br));
 			if (!zbr->lnum || !zbr->len) {
 				ubifs_err(c, "bad ref in znode");
 				ubifs_dump_znode(c, znode);
@@ -868,6 +878,23 @@ static int write_index(struct ubifs_info *c)
 		}
 		len = ubifs_idx_node_sz(c, znode->child_cnt);
 		ubifs_prepare_node(c, idx, len, 0);
+		ubifs_node_calc_hash(c, idx, hash);
+
+		mutex_lock(&c->tnc_mutex);
+
+		if (znode->cparent)
+			ubifs_copy_hash(c, hash,
+					znode->cparent->zbranch[znode->ciip].hash);
+
+		if (znode->parent) {
+			if (!ubifs_zn_obsolete(znode))
+				ubifs_copy_hash(c, hash,
+					znode->parent->zbranch[znode->iip].hash);
+		} else {
+			ubifs_copy_hash(c, hash, c->zroot.hash);
+		}
+
+		mutex_unlock(&c->tnc_mutex);
 
 		/* Determine the index node position */
 		if (lnum == -1) {

fs/ubifs/tnc_misc.c

@@ -265,9 +265,7 @@ long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
 /**
  * read_znode - read an indexing node from flash and fill znode.
  * @c: UBIFS file-system description object
- * @lnum: LEB of the indexing node to read
- * @offs: node offset
- * @len: node length
+ * @zzbr: the zbranch describing the node to read
  * @znode: znode to read to
  *
  * This function reads an indexing node from the flash media and fills znode
@@ -276,9 +274,12 @@ long ubifs_destroy_tnc_subtree(const struct ubifs_info *c,
  * is wrong with it, this function prints complaint messages and returns
  * %-EINVAL.
  */
-static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
+static int read_znode(struct ubifs_info *c, struct ubifs_zbranch *zzbr,
 		      struct ubifs_znode *znode)
 {
+	int lnum = zzbr->lnum;
+	int offs = zzbr->offs;
+	int len = zzbr->len;
 	int i, err, type, cmp;
 	struct ubifs_idx_node *idx;
 
@@ -292,6 +293,12 @@ static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
 		return err;
 	}
 
+	err = ubifs_node_check_hash(c, idx, zzbr->hash);
+	if (err) {
+		ubifs_bad_hash(c, idx, zzbr->hash, lnum, offs);
+		return err;
+	}
+
 	znode->child_cnt = le16_to_cpu(idx->child_cnt);
 	znode->level = le16_to_cpu(idx->level);
 
@@ -308,13 +315,14 @@ static int read_znode(struct ubifs_info *c, int lnum, int offs, int len,
 	}
 
 	for (i = 0; i < znode->child_cnt; i++) {
-		const struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
+		struct ubifs_branch *br = ubifs_idx_branch(c, idx, i);
 		struct ubifs_zbranch *zbr = &znode->zbranch[i];
 
 		key_read(c, &br->key, &zbr->key);
 		zbr->lnum = le32_to_cpu(br->lnum);
 		zbr->offs = le32_to_cpu(br->offs);
 		zbr->len  = le32_to_cpu(br->len);
+		ubifs_copy_hash(c, ubifs_branch_hash(c, br), zbr->hash);
 		zbr->znode = NULL;
 
 		/* Validate branch */
@@ -425,7 +433,7 @@ struct ubifs_znode *ubifs_load_znode(struct ubifs_info *c,
 	if (!znode)
 		return ERR_PTR(-ENOMEM);
 
-	err = read_znode(c, zbr->lnum, zbr->offs, zbr->len, znode);
+	err = read_znode(c, zbr, znode);
 	if (err)
 		goto out;
 
@@ -496,5 +504,11 @@ int ubifs_tnc_read_node(struct ubifs_info *c, struct ubifs_zbranch *zbr,
 		return -EINVAL;
 	}
 
+	err = ubifs_node_check_hash(c, node, zbr->hash);
+	if (err) {
+		ubifs_bad_hash(c, node, zbr->hash, zbr->lnum, zbr->offs);
+		return err;
+	}
+
 	return 0;
 }

fs/ubifs/ubifs-media.h

@@ -286,6 +286,7 @@ enum {
 #define UBIFS_IDX_NODE_SZ  sizeof(struct ubifs_idx_node)
 #define UBIFS_CS_NODE_SZ   sizeof(struct ubifs_cs_node)
 #define UBIFS_ORPH_NODE_SZ sizeof(struct ubifs_orph_node)
+#define UBIFS_AUTH_NODE_SZ sizeof(struct ubifs_auth_node)
 /* Extended attribute entry nodes are identical to directory entry nodes */
 #define UBIFS_XENT_NODE_SZ UBIFS_DENT_NODE_SZ
 /* Only this does not have to be multiple of 8 bytes */
@@ -300,6 +301,12 @@ enum {
 /* The largest UBIFS node */
 #define UBIFS_MAX_NODE_SZ UBIFS_MAX_INO_NODE_SZ
 
+/* The maxmimum size of a hash, enough for sha512 */
+#define UBIFS_MAX_HASH_LEN 64
+
+/* The maxmimum size of a hmac, enough for hmac(sha512) */
+#define UBIFS_MAX_HMAC_LEN 64
+
 /*
  * xattr name of UBIFS encryption context, we don't use a prefix
  * nor a long name to not waste space on the flash.
@@ -365,6 +372,7 @@ enum {
  * UBIFS_IDX_NODE: index node
  * UBIFS_CS_NODE: commit start node
  * UBIFS_ORPH_NODE: orphan node
+ * UBIFS_AUTH_NODE: authentication node
  * UBIFS_NODE_TYPES_CNT: count of supported node types
  *
  * Note, we index arrays by these numbers, so keep them low and contiguous.
@@ -384,6 +392,7 @@ enum {
 	UBIFS_IDX_NODE,
 	UBIFS_CS_NODE,
 	UBIFS_ORPH_NODE,
+	UBIFS_AUTH_NODE,
 	UBIFS_NODE_TYPES_CNT,
 };
 
@@ -421,15 +430,19 @@ enum {
  * UBIFS_FLG_DOUBLE_HASH: store a 32bit cookie in directory entry nodes to
  *			  support 64bit cookies for lookups by hash
  * UBIFS_FLG_ENCRYPTION: this filesystem contains encrypted files
+ * UBIFS_FLG_AUTHENTICATION: this filesystem contains hashes for authentication
  */
 enum {
 	UBIFS_FLG_BIGLPT = 0x02,
 	UBIFS_FLG_SPACE_FIXUP = 0x04,
 	UBIFS_FLG_DOUBLE_HASH = 0x08,
 	UBIFS_FLG_ENCRYPTION = 0x10,
+	UBIFS_FLG_AUTHENTICATION = 0x20,
 };
 
-#define UBIFS_FLG_MASK (UBIFS_FLG_BIGLPT|UBIFS_FLG_SPACE_FIXUP|UBIFS_FLG_DOUBLE_HASH|UBIFS_FLG_ENCRYPTION)
+#define UBIFS_FLG_MASK (UBIFS_FLG_BIGLPT | UBIFS_FLG_SPACE_FIXUP | \
+		UBIFS_FLG_DOUBLE_HASH | UBIFS_FLG_ENCRYPTION | \
+		UBIFS_FLG_AUTHENTICATION)
 
 /**
  * struct ubifs_ch - common header node.
@@ -633,6 +646,10 @@ struct ubifs_pad_node {
  * @time_gran: time granularity in nanoseconds
  * @uuid: UUID generated when the file system image was created
  * @ro_compat_version: UBIFS R/O compatibility version
+ * @hmac: HMAC to authenticate the superblock node
+ * @hmac_wkm: HMAC of a well known message (the string "UBIFS") as a convenience
+ *            to the user to check if the correct key is passed.
+ * @hash_algo: The hash algo used for this filesystem (one of enum hash_algo)
  */
 struct ubifs_sb_node {
 	struct ubifs_ch ch;
@@ -660,7 +677,10 @@ struct ubifs_sb_node {
 	__le32 time_gran;
 	__u8 uuid[16];
 	__le32 ro_compat_version;
-	__u8 padding2[3968];
+	__u8 hmac[UBIFS_MAX_HMAC_LEN];
+	__u8 hmac_wkm[UBIFS_MAX_HMAC_LEN];
+	__le16 hash_algo;
+	__u8 padding2[3838];
 } __packed;
 
 /**
@@ -695,6 +715,9 @@ struct ubifs_sb_node {
  * @empty_lebs: number of empty logical eraseblocks
  * @idx_lebs: number of indexing logical eraseblocks
  * @leb_cnt: count of LEBs used by file-system
+ * @hash_root_idx: the hash of the root index node
+ * @hash_lpt: the hash of the LPT
+ * @hmac: HMAC to authenticate the master node
  * @padding: reserved for future, zeroes
  */
 struct ubifs_mst_node {
@@ -727,7 +750,10 @@ struct ubifs_mst_node {
 	__le32 empty_lebs;
 	__le32 idx_lebs;
 	__le32 leb_cnt;
-	__u8 padding[344];
+	__u8 hash_root_idx[UBIFS_MAX_HASH_LEN];
+	__u8 hash_lpt[UBIFS_MAX_HASH_LEN];
+	__u8 hmac[UBIFS_MAX_HMAC_LEN];
+	__u8 padding[152];
 } __packed;
 
 /**
@@ -746,12 +772,26 @@ struct ubifs_ref_node {
 	__u8 padding[28];
 } __packed;
 
+/**
+ * struct ubifs_auth_node - node for authenticating other nodes
+ * @ch: common header
+ * @hmac: The HMAC
+ */
+struct ubifs_auth_node {
+	struct ubifs_ch ch;
+	__u8 hmac[];
+} __packed;
+
 /**
  * struct ubifs_branch - key/reference/length branch
  * @lnum: LEB number of the target node
  * @offs: offset within @lnum
  * @len: target node length
  * @key: key
+ *
+ * In an authenticated UBIFS we have the hash of the referenced node after @key.
+ * This can't be added to the struct type definition because @key is a
+ * dynamically sized element already.
  */
 struct ubifs_branch {
 	__le32 lnum;