select CRYPTO if UBIFS_FS_ADVANCED_COMPR
select CRYPTO if UBIFS_FS_LZO
select CRYPTO if UBIFS_FS_ZLIB
+ select CRYPTO if UBIFS_FS_ZSTD
select CRYPTO_LZO if UBIFS_FS_LZO
select CRYPTO_DEFLATE if UBIFS_FS_ZLIB
+ select CRYPTO_ZSTD if UBIFS_FS_ZSTD
select CRYPTO_HASH_INFO
select UBIFS_FS_XATTR if FS_ENCRYPTION
depends on MTD_UBI
help
Zlib compresses better than LZO but it is slower. Say 'Y' if unsure.
+config UBIFS_FS_ZSTD
+ bool "ZSTD compression support" if UBIFS_FS_ADVANCED_COMPR
+ depends on UBIFS_FS
+ default y
+ help
+ ZSTD compresses is a big win in speed over Zlib and
+ in compression ratio over LZO. Say 'Y' if unsure.
+
config UBIFS_ATIME_SUPPORT
bool "Access time support"
default n
config UBIFS_FS_AUTHENTICATION
bool "UBIFS authentication support"
- depends on KEYS
+ select KEYS
select CRYPTO_HMAC
+ select SYSTEM_DATA_VERIFICATION
help
Enable authentication support for UBIFS. This feature offers protection
against offline changes for both data and metadata of the filesystem.
*/
#include <linux/crypto.h>
+#include <linux/verification.h>
#include <crypto/hash.h>
#include <crypto/sha.h>
#include <crypto/algapi.h>
#include <keys/user-type.h>
+#include <keys/asymmetric-type.h>
#include "ubifs.h"
}
/**
+ * ubifs_sb_verify_signature - verify the signature of a superblock
+ * @c: UBIFS file-system description object
+ * @sup: The superblock node
+ *
+ * To support offline signed images the superblock can be signed with a
+ * PKCS#7 signature. The signature is placed directly behind the superblock
+ * node in an ubifs_sig_node.
+ *
+ * Returns 0 when the signature can be successfully verified or a negative
+ * error code if not.
+ */
+int ubifs_sb_verify_signature(struct ubifs_info *c,
+ const struct ubifs_sb_node *sup)
+{
+ int err;
+ struct ubifs_scan_leb *sleb;
+ struct ubifs_scan_node *snod;
+ const struct ubifs_sig_node *signode;
+
+ sleb = ubifs_scan(c, UBIFS_SB_LNUM, UBIFS_SB_NODE_SZ, c->sbuf, 0);
+ if (IS_ERR(sleb)) {
+ err = PTR_ERR(sleb);
+ return err;
+ }
+
+ if (sleb->nodes_cnt == 0) {
+ ubifs_err(c, "Unable to find signature node");
+ err = -EINVAL;
+ goto out_destroy;
+ }
+
+ snod = list_first_entry(&sleb->nodes, struct ubifs_scan_node, list);
+
+ if (snod->type != UBIFS_SIG_NODE) {
+ ubifs_err(c, "Signature node is of wrong type");
+ err = -EINVAL;
+ goto out_destroy;
+ }
+
+ signode = snod->node;
+
+ if (le32_to_cpu(signode->len) > snod->len + sizeof(struct ubifs_sig_node)) {
+ ubifs_err(c, "invalid signature len %d", le32_to_cpu(signode->len));
+ err = -EINVAL;
+ goto out_destroy;
+ }
+
+ if (le32_to_cpu(signode->type) != UBIFS_SIGNATURE_TYPE_PKCS7) {
+ ubifs_err(c, "Signature type %d is not supported\n",
+ le32_to_cpu(signode->type));
+ err = -EINVAL;
+ goto out_destroy;
+ }
+
+ err = verify_pkcs7_signature(sup, sizeof(struct ubifs_sb_node),
+ signode->sig, le32_to_cpu(signode->len),
+ NULL, VERIFYING_UNSPECIFIED_SIGNATURE,
+ NULL, NULL);
+
+ if (err)
+ ubifs_err(c, "Failed to verify signature");
+ else
+ ubifs_msg(c, "Successfully verified super block signature");
+
+out_destroy:
+ ubifs_scan_destroy(sleb);
+
+ return err;
+}
+
+/**
* ubifs_init_authentication - initialize UBIFS authentication support
* @c: UBIFS file-system description object
*
return err;
return 0;
}
+
+/*
+ * ubifs_hmac_zero - test if a HMAC is zero
+ * @c: UBIFS file-system description object
+ * @hmac: the HMAC to test
+ *
+ * This function tests if a HMAC is zero and returns true if it is
+ * and false otherwise.
+ */
+bool ubifs_hmac_zero(struct ubifs_info *c, const u8 *hmac)
+{
+ return !memchr_inv(hmac, 0, c->hmac_desc_len);
+}
};
#endif
+#ifdef CONFIG_UBIFS_FS_ZSTD
+static DEFINE_MUTEX(zstd_enc_mutex);
+static DEFINE_MUTEX(zstd_dec_mutex);
+
+static struct ubifs_compressor zstd_compr = {
+ .compr_type = UBIFS_COMPR_ZSTD,
+ .comp_mutex = &zstd_enc_mutex,
+ .decomp_mutex = &zstd_dec_mutex,
+ .name = "zstd",
+ .capi_name = "zstd",
+};
+#else
+static struct ubifs_compressor zstd_compr = {
+ .compr_type = UBIFS_COMPR_ZSTD,
+ .name = "zstd",
+};
+#endif
+
/* All UBIFS compressors */
struct ubifs_compressor *ubifs_compressors[UBIFS_COMPR_TYPES_CNT];
if (err)
return err;
- err = compr_init(&zlib_compr);
+ err = compr_init(&zstd_compr);
if (err)
goto out_lzo;
+ err = compr_init(&zlib_compr);
+ if (err)
+ goto out_zstd;
+
ubifs_compressors[UBIFS_COMPR_NONE] = &none_compr;
return 0;
+out_zstd:
+ compr_exit(&zstd_compr);
out_lzo:
compr_exit(&lzo_compr);
return err;
{
compr_exit(&lzo_compr);
compr_exit(&zlib_compr);
+ compr_exit(&zstd_compr);
}
*ltail_lnum = c->lhead_lnum;
c->lhead_offs += len;
- if (c->lhead_offs == c->leb_size) {
- c->lhead_lnum = ubifs_next_log_lnum(c, c->lhead_lnum);
- c->lhead_offs = 0;
- }
+ ubifs_assert(c, c->lhead_offs < c->leb_size);
remove_buds(c);
return 0;
}
+/* mst_node_check_hash - Check hash of a master node
+ * @c: UBIFS file-system description object
+ * @mst: The master node
+ * @expected: The expected hash of the master node
+ *
+ * This checks the hash of a master node against a given expected hash.
+ * Note that we have two master nodes on a UBIFS image which have different
+ * sequence numbers and consequently different CRCs. To be able to match
+ * both master nodes we exclude the common node header containing the sequence
+ * number and CRC from the hash.
+ *
+ * Returns 0 if the hashes are equal, a negative error code otherwise.
+ */
+static int mst_node_check_hash(const struct ubifs_info *c,
+ const struct ubifs_mst_node *mst,
+ const u8 *expected)
+{
+ u8 calc[UBIFS_MAX_HASH_LEN];
+ const void *node = mst;
+
+ SHASH_DESC_ON_STACK(shash, c->hash_tfm);
+
+ shash->tfm = c->hash_tfm;
+
+ crypto_shash_digest(shash, node + sizeof(struct ubifs_ch),
+ UBIFS_MST_NODE_SZ - sizeof(struct ubifs_ch), calc);
+
+ if (ubifs_check_hash(c, expected, calc))
+ return -EPERM;
+
+ return 0;
+}
+
/**
* scan_for_master - search the valid master node.
* @c: UBIFS file-system description object
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;
+ if (ubifs_hmac_zero(c, c->mst_node->hmac)) {
+ err = mst_node_check_hash(c, c->mst_node,
+ c->sup_node->hash_mst);
+ if (err)
+ ubifs_err(c, "Failed to verify master node hash");
+ } else {
+ 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");
}
+ if (err)
+ return -EPERM;
+
return 0;
out:
kfree(o);
}
-static void orphan_delete(struct ubifs_info *c, ino_t inum)
+static void orphan_delete(struct ubifs_info *c, struct ubifs_orphan *orph)
{
- struct ubifs_orphan *orph, *child_orph, *tmp_o;
-
- spin_lock(&c->orphan_lock);
-
- orph = lookup_orphan(c, inum);
- if (!orph) {
- spin_unlock(&c->orphan_lock);
- ubifs_err(c, "missing orphan ino %lu", (unsigned long)inum);
- dump_stack();
-
- return;
- }
-
if (orph->del) {
spin_unlock(&c->orphan_lock);
- dbg_gen("deleted twice ino %lu",
- (unsigned long)inum);
+ dbg_gen("deleted twice ino %lu", orph->inum);
return;
}
orph->dnext = c->orph_dnext;
c->orph_dnext = orph;
spin_unlock(&c->orphan_lock);
- dbg_gen("delete later ino %lu",
- (unsigned long)inum);
+ dbg_gen("delete later ino %lu", orph->inum);
return;
}
- list_for_each_entry_safe(child_orph, tmp_o, &orph->child_list, child_list) {
- list_del(&child_orph->child_list);
- __orphan_drop(c, child_orph);
- }
-
__orphan_drop(c, orph);
-
- spin_unlock(&c->orphan_lock);
}
/**
*/
void ubifs_delete_orphan(struct ubifs_info *c, ino_t inum)
{
- orphan_delete(c, inum);
+ struct ubifs_orphan *orph, *child_orph, *tmp_o;
+
+ spin_lock(&c->orphan_lock);
+
+ orph = lookup_orphan(c, inum);
+ if (!orph) {
+ spin_unlock(&c->orphan_lock);
+ ubifs_err(c, "missing orphan ino %lu", (unsigned long)inum);
+ dump_stack();
+
+ return;
+ }
+
+ list_for_each_entry_safe(child_orph, tmp_o, &orph->child_list, child_list) {
+ list_del(&child_orph->child_list);
+ orphan_delete(c, child_orph);
+ }
+
+ orphan_delete(c, orph);
+
+ spin_unlock(&c->orphan_lock);
}
/**
{
struct ubifs_scan_node *snod;
struct ubifs_orph_node *orph;
+ struct ubifs_ino_node *ino = NULL;
unsigned long long cmt_no;
ino_t inum;
int i, n, err, first = 1;
if (first)
first = 0;
+ ino = kmalloc(UBIFS_MAX_INO_NODE_SZ, GFP_NOFS);
+ if (!ino)
+ return -ENOMEM;
+
n = (le32_to_cpu(orph->ch.len) - UBIFS_ORPH_NODE_SZ) >> 3;
for (i = 0; i < n; i++) {
union ubifs_key key1, key2;
inum = le64_to_cpu(orph->inos[i]);
- dbg_rcvry("deleting orphaned inode %lu",
- (unsigned long)inum);
-
- lowest_ino_key(c, &key1, inum);
- highest_ino_key(c, &key2, inum);
- err = ubifs_tnc_remove_range(c, &key1, &key2);
+ ino_key_init(c, &key1, inum);
+ err = ubifs_tnc_lookup(c, &key1, ino);
if (err)
- return err;
+ goto out_free;
+
+ /*
+ * Check whether an inode can really get deleted.
+ * linkat() with O_TMPFILE allows rebirth of an inode.
+ */
+ if (ino->nlink == 0) {
+ dbg_rcvry("deleting orphaned inode %lu",
+ (unsigned long)inum);
+
+ lowest_ino_key(c, &key1, inum);
+ highest_ino_key(c, &key2, inum);
+
+ err = ubifs_tnc_remove_range(c, &key1, &key2);
+ if (err)
+ goto out_ro;
+ }
+
err = insert_dead_orphan(c, inum);
if (err)
- return err;
+ goto out_free;
}
*last_cmt_no = cmt_no;
*last_flagged = 0;
}
- return 0;
+ err = 0;
+out_free:
+ kfree(ino);
+ return err;
+
+out_ro:
+ ubifs_ro_mode(c, err);
+ kfree(ino);
+ return err;
}
/**
goto out_err;
}
if (cs_node->ch.node_type != UBIFS_CS_NODE) {
- ubifs_err(c, "Node a CS node, type is %d", cs_node->ch.node_type);
+ ubifs_err(c, "Not a CS node, type is %d", cs_node->ch.node_type);
goto out_err;
}
if (le64_to_cpu(cs_node->cmt_no) != c->cmt_no) {
return -EINVAL;
}
- err = ubifs_hmac_wkm(c, hmac_wkm);
- if (err)
- return err;
-
- if (ubifs_check_hmac(c, hmac_wkm, sup->hmac_wkm)) {
- ubifs_err(c, "provided key does not fit");
- return -ENOKEY;
+ /*
+ * The super block node can either be authenticated by a HMAC or
+ * by a signature in a ubifs_sig_node directly following the
+ * super block node to support offline image creation.
+ */
+ if (ubifs_hmac_zero(c, sup->hmac)) {
+ err = ubifs_sb_verify_signature(c, sup);
+ } else {
+ err = ubifs_hmac_wkm(c, hmac_wkm);
+ if (err)
+ return err;
+ if (ubifs_check_hmac(c, hmac_wkm, sup->hmac_wkm)) {
+ ubifs_err(c, "provided key does not fit");
+ return -ENOKEY;
+ }
+ err = ubifs_node_verify_hmac(c, sup, sizeof(*sup),
+ offsetof(struct ubifs_sb_node,
+ hmac));
}
- err = ubifs_node_verify_hmac(c, sup, sizeof(*sup),
- offsetof(struct ubifs_sb_node, hmac));
if (err)
ubifs_err(c, "Failed to authenticate superblock: %d", err);
}
/* Automatically increase file system size to the maximum size */
- c->old_leb_cnt = c->leb_cnt;
if (c->leb_cnt < c->vi.size && c->leb_cnt < c->max_leb_cnt) {
+ int old_leb_cnt = c->leb_cnt;
+
c->leb_cnt = min_t(int, c->max_leb_cnt, c->vi.size);
- if (c->ro_mount)
- dbg_mnt("Auto resizing (ro) from %d LEBs to %d LEBs",
- c->old_leb_cnt, c->leb_cnt);
- else {
- dbg_mnt("Auto resizing (sb) from %d LEBs to %d LEBs",
- c->old_leb_cnt, c->leb_cnt);
- sup->leb_cnt = cpu_to_le32(c->leb_cnt);
- err = ubifs_write_sb_node(c, sup);
- if (err)
- goto out;
- c->old_leb_cnt = c->leb_cnt;
- }
+ sup->leb_cnt = cpu_to_le32(c->leb_cnt);
+
+ c->superblock_need_write = 1;
+
+ dbg_mnt("Auto resizing from %d LEBs to %d LEBs",
+ old_leb_cnt, c->leb_cnt);
}
c->log_bytes = (long long)c->log_lebs * c->leb_size;
c->space_fixup = 0;
sup->flags &= cpu_to_le32(~UBIFS_FLG_SPACE_FIXUP);
- err = ubifs_write_sb_node(c, sup);
- if (err)
- return err;
+ c->superblock_need_write = 1;
ubifs_msg(c, "free space fixup complete");
return err;
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_SIG_NODE].min_len = UBIFS_SIG_NODE_SZ;
+ c->ranges[UBIFS_SIG_NODE].max_len = c->leb_size - UBIFS_SB_NODE_SZ;
c->ranges[UBIFS_INO_NODE].min_len = UBIFS_INO_NODE_SZ;
c->ranges[UBIFS_INO_NODE].max_len = UBIFS_MAX_INO_NODE_SZ;
c->mount_opts.compr_type = UBIFS_COMPR_LZO;
else if (!strcmp(name, "zlib"))
c->mount_opts.compr_type = UBIFS_COMPR_ZLIB;
+ else if (!strcmp(name, "zstd"))
+ c->mount_opts.compr_type = UBIFS_COMPR_ZSTD;
else {
ubifs_err(c, "unknown compressor \"%s\"", name); //FIXME: is c ready?
kfree(name);
if (err)
goto out_free;
- sz = ALIGN(c->max_idx_node_sz, c->min_io_size);
- sz = ALIGN(sz + c->max_idx_node_sz, c->min_io_size);
+ sz = ALIGN(c->max_idx_node_sz, c->min_io_size) * 2;
c->cbuf = kmalloc(sz, GFP_NOFS);
if (!c->cbuf) {
err = -ENOMEM;
goto out_lpt;
}
+ /*
+ * Handle offline signed images: Now that the master node is
+ * written and its validation no longer depends on the hash
+ * in the superblock, we can update the offline signed
+ * superblock with a HMAC version,
+ */
+ if (ubifs_authenticated(c) && ubifs_hmac_zero(c, c->sup_node->hmac)) {
+ err = ubifs_hmac_wkm(c, c->sup_node->hmac_wkm);
+ if (err)
+ goto out_lpt;
+ c->superblock_need_write = 1;
+ }
+
+ if (!c->ro_mount && c->superblock_need_write) {
+ err = ubifs_write_sb_node(c, c->sup_node);
+ if (err)
+ goto out_lpt;
+ c->superblock_need_write = 0;
+ }
+
err = dbg_check_idx_size(c, c->bi.old_idx_sz);
if (err)
goto out_lpt;
if (err)
goto out;
- if (c->old_leb_cnt != c->leb_cnt) {
- struct ubifs_sb_node *sup = c->sup_node;
-
- sup->leb_cnt = cpu_to_le32(c->leb_cnt);
- err = ubifs_write_sb_node(c, sup);
- if (err)
- goto out;
- }
-
if (c->need_recovery) {
ubifs_msg(c, "completing deferred recovery");
err = ubifs_write_rcvrd_mst_node(c);
goto out;
}
+ if (c->superblock_need_write) {
+ struct ubifs_sb_node *sup = c->sup_node;
+
+ err = ubifs_write_sb_node(c, sup);
+ if (err)
+ goto out;
+
+ c->superblock_need_write = 0;
+ }
+
c->ileb_buf = vmalloc(c->leb_size);
if (!c->ileb_buf) {
err = -ENOMEM;
* o exact match, i.e. the found zero-level znode contains key @key, then %1
* is returned and slot number of the matched branch is stored in @n;
* o not exact match, which means that zero-level znode does not contain
- * @key, then %0 is returned and slot number of the closest branch is stored
- * in @n;
+ * @key, then %0 is returned and slot number of the closest branch or %-1
+ * is stored in @n; In this case calling tnc_next() is mandatory.
* o @key is so small that it is even less than the lowest key of the
* leftmost zero-level node, then %0 is returned and %0 is stored in @n.
*
static int search_dh_cookie(struct ubifs_info *c, const union ubifs_key *key,
struct ubifs_dent_node *dent, uint32_t cookie,
- struct ubifs_znode **zn, int *n)
+ struct ubifs_znode **zn, int *n, int exact)
{
int err;
struct ubifs_znode *znode = *zn;
struct ubifs_zbranch *zbr;
union ubifs_key *dkey;
+ if (!exact) {
+ err = tnc_next(c, &znode, n);
+ if (err)
+ return err;
+ }
+
for (;;) {
zbr = &znode->zbranch[*n];
dkey = &zbr->key;
if (unlikely(err < 0))
goto out_unlock;
- err = search_dh_cookie(c, key, dent, cookie, &znode, &n);
+ err = search_dh_cookie(c, key, dent, cookie, &znode, &n, err);
out_unlock:
mutex_unlock(&c->tnc_mutex);
if (unlikely(err < 0))
goto out_free;
- err = search_dh_cookie(c, key, dent, cookie, &znode, &n);
+ err = search_dh_cookie(c, key, dent, cookie, &znode, &n, err);
if (err)
goto out_free;
}
#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)
+#define UBIFS_SIG_NODE_SZ sizeof(struct ubifs_sig_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 */
*/
#define UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT "c"
+/* Type field in ubifs_sig_node */
+#define UBIFS_SIGNATURE_TYPE_PKCS7 1
/*
* On-flash inode flags.
* UBIFS_COMPR_NONE: no compression
* UBIFS_COMPR_LZO: LZO compression
* UBIFS_COMPR_ZLIB: ZLIB compression
+ * UBIFS_COMPR_ZSTD: ZSTD compression
* UBIFS_COMPR_TYPES_CNT: count of supported compression types
*/
enum {
UBIFS_COMPR_NONE,
UBIFS_COMPR_LZO,
UBIFS_COMPR_ZLIB,
+ UBIFS_COMPR_ZSTD,
UBIFS_COMPR_TYPES_CNT,
};
* UBIFS_CS_NODE: commit start node
* UBIFS_ORPH_NODE: orphan node
* UBIFS_AUTH_NODE: authentication node
+ * UBIFS_SIG_NODE: signature node
* UBIFS_NODE_TYPES_CNT: count of supported node types
*
* Note, we index arrays by these numbers, so keep them low and contiguous.
UBIFS_CS_NODE,
UBIFS_ORPH_NODE,
UBIFS_AUTH_NODE,
+ UBIFS_SIG_NODE,
UBIFS_NODE_TYPES_CNT,
};
* @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)
+ * @hash_mst: hash of the master node, only valid for signed images in which the
+ * master node does not contain a hmac
*/
struct ubifs_sb_node {
struct ubifs_ch ch;
__u8 hmac[UBIFS_MAX_HMAC_LEN];
__u8 hmac_wkm[UBIFS_MAX_HMAC_LEN];
__le16 hash_algo;
- __u8 padding2[3838];
+ __u8 hash_mst[UBIFS_MAX_HASH_LEN];
+ __u8 padding2[3774];
} __packed;
/**
} __packed;
/**
+ * struct ubifs_sig_node - node for signing other nodes
+ * @ch: common header
+ * @type: type of the signature, currently only UBIFS_SIGNATURE_TYPE_PKCS7
+ * supported
+ * @len: The length of the signature data
+ * @padding: reserved for future, zeroes
+ * @sig: The signature data
+ */
+struct ubifs_sig_node {
+ struct ubifs_ch ch;
+ __le32 type;
+ __le32 len;
+ __u8 padding[32];
+ __u8 sig[];
+} __packed;
+
+/**
* struct ubifs_branch - key/reference/length branch
* @lnum: LEB number of the target node
* @offs: offset within @lnum
* used to store indexing nodes (@leb_size - @max_idx_node_sz)
* @leb_cnt: count of logical eraseblocks
* @max_leb_cnt: maximum count of logical eraseblocks
- * @old_leb_cnt: count of logical eraseblocks before re-size
* @ro_media: the underlying UBI volume is read-only
* @ro_mount: the file-system was mounted as read-only
* @ro_error: UBIFS switched to R/O mode because an error happened
unsigned int rw_incompat:1;
unsigned int assert_action:2;
unsigned int authenticated:1;
+ unsigned int superblock_need_write:1;
struct mutex tnc_mutex;
struct ubifs_zbranch zroot;
int idx_leb_size;
int leb_cnt;
int max_leb_cnt;
- int old_leb_cnt;
unsigned int ro_media:1;
unsigned int ro_mount:1;
unsigned int ro_error:1;
else
return 0;
}
+int ubifs_sb_verify_signature(struct ubifs_info *c,
+ const struct ubifs_sb_node *sup);
+bool ubifs_hmac_zero(struct ubifs_info *c, const u8 *hmac);
int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac);