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Message-Id: <20180704124137.13396-9-s.hauer@pengutronix.de>
Date: Wed, 4 Jul 2018 14:41:20 +0200
From: Sascha Hauer <s.hauer@...gutronix.de>
To: linux-mtd@...ts.infradead.org
Cc: David Gstir <david@...ma-star.at>,
Richard Weinberger <richard@....at>, kernel@...gutronix.de,
linux-kernel@...r.kernel.org, Sascha Hauer <s.hauer@...gutronix.de>
Subject: [PATCH 08/25] ubifs: Format changes for authentication support
This patch adds the changes to the on disk format needed for
authentication support. We'll add:
* a HMAC covering super block node
* a HMAC covering the master node
* a hash over the root index node to the master node
* a hash over the LPT to the master node
* a flag to the filesystem flag indicating the filesystem is
authenticated
* an authentication node necessary to authenticate the nodes written
to the journal heads while they are written.
* a HMAC of a well known message to the super block node to be able
to check if the correct key is provided
And finally, not visible in this patch, nevertheless explained here:
* hashes over the referenced child nodes in each branch of a index node
Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
fs/ubifs/debug.c | 6 ++++++
fs/ubifs/super.c | 1 +
fs/ubifs/ubifs-media.h | 46 +++++++++++++++++++++++++++++++++++++++---
3 files changed, 50 insertions(+), 3 deletions(-)
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 7cd8a7b95299..249c9e71252c 100644
--- a/fs/ubifs/debug.c
+++ b/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);
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 9e44baec30a3..6b2d80391111 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -577,6 +577,7 @@ 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].len = UBIFS_AUTH_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;
diff --git a/fs/ubifs/ubifs-media.h b/fs/ubifs/ubifs-media.h
index e8c23c9d4f4a..8b7c1844014f 100644
--- a/fs/ubifs/ubifs-media.h
+++ b/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;
--
2.18.0
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