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-rw-r--r--fs/ubifs/Kconfig3
-rw-r--r--fs/ubifs/auth.c86
-rw-r--r--fs/ubifs/master.c53
-rw-r--r--fs/ubifs/sb.c52
-rw-r--r--fs/ubifs/super.c41
-rw-r--r--fs/ubifs/ubifs-media.h28
-rw-r--r--fs/ubifs/ubifs.h6
7 files changed, 225 insertions, 44 deletions
diff --git a/fs/ubifs/Kconfig b/fs/ubifs/Kconfig
index 06c35c64162b..3902a677743e 100644
--- a/fs/ubifs/Kconfig
+++ b/fs/ubifs/Kconfig
@@ -77,8 +77,9 @@ config UBIFS_FS_SECURITY
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.
diff --git a/fs/ubifs/auth.c b/fs/ubifs/auth.c
index 60f43b93d06e..d9af2de9084a 100644
--- a/fs/ubifs/auth.c
+++ b/fs/ubifs/auth.c
@@ -10,10 +10,12 @@
*/
#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"
@@ -199,6 +201,77 @@ int __ubifs_node_check_hash(const struct ubifs_info *c, const void *node,
}
/**
+ * 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
*
@@ -478,3 +551,16 @@ int ubifs_hmac_wkm(struct ubifs_info *c, u8 *hmac)
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);
+}
diff --git a/fs/ubifs/master.c b/fs/ubifs/master.c
index b42a768709c0..52a85c01397e 100644
--- a/fs/ubifs/master.c
+++ b/fs/ubifs/master.c
@@ -48,6 +48,39 @@ int ubifs_compare_master_node(struct ubifs_info *c, void *m1, void *m2)
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
@@ -102,14 +135,22 @@ static int scan_for_master(struct ubifs_info *c)
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:
diff --git a/fs/ubifs/sb.c b/fs/ubifs/sb.c
index 12c2afdb5804..a551eb3e9b89 100644
--- a/fs/ubifs/sb.c
+++ b/fs/ubifs/sb.c
@@ -578,17 +578,26 @@ static int authenticate_sb_node(struct ubifs_info *c,
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);
@@ -744,21 +753,16 @@ int ubifs_read_superblock(struct ubifs_info *c)
}
/* 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;
@@ -916,9 +920,7 @@ int ubifs_fixup_free_space(struct ubifs_info *c)
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;
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index af683734bbdd..13b8f68f6c24 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -566,6 +566,8 @@ static int init_constants_early(struct ubifs_info *c)
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;
@@ -1359,6 +1361,26 @@ static int mount_ubifs(struct ubifs_info *c)
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;
@@ -1643,15 +1665,6 @@ static int ubifs_remount_rw(struct ubifs_info *c)
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);
@@ -1683,6 +1696,16 @@ static int ubifs_remount_rw(struct ubifs_info *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;
diff --git a/fs/ubifs/ubifs-media.h b/fs/ubifs/ubifs-media.h
index 86f0f2be116c..355d3081d882 100644
--- a/fs/ubifs/ubifs-media.h
+++ b/fs/ubifs/ubifs-media.h
@@ -275,6 +275,8 @@ enum {
#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 */
@@ -301,6 +303,8 @@ enum {
*/
#define UBIFS_XATTR_NAME_ENCRYPTION_CONTEXT "c"
+/* Type field in ubifs_sig_node */
+#define UBIFS_SIGNATURE_TYPE_PKCS7 1
/*
* On-flash inode flags.
@@ -361,6 +365,7 @@ enum {
* 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.
@@ -381,6 +386,7 @@ enum {
UBIFS_CS_NODE,
UBIFS_ORPH_NODE,
UBIFS_AUTH_NODE,
+ UBIFS_SIG_NODE,
UBIFS_NODE_TYPES_CNT,
};
@@ -638,6 +644,8 @@ struct ubifs_pad_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)
+ * @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;
@@ -668,7 +676,8 @@ struct ubifs_sb_node {
__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;
/**
@@ -771,6 +780,23 @@ struct ubifs_auth_node {
} __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
diff --git a/fs/ubifs/ubifs.h b/fs/ubifs/ubifs.h
index 745b23e5b406..c55f212dcb75 100644
--- a/fs/ubifs/ubifs.h
+++ b/fs/ubifs/ubifs.h
@@ -1104,7 +1104,6 @@ struct ubifs_debug_info;
* 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
@@ -1295,6 +1294,7 @@ struct ubifs_info {
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;
@@ -1352,7 +1352,6 @@ struct ubifs_info {
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;
@@ -1680,6 +1679,9 @@ static inline int ubifs_auth_node_sz(const struct ubifs_info *c)
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);
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-03 03:29:36 +0000