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Message-Id: <20180704124137.13396-24-s.hauer@pengutronix.de>
Date: Wed, 4 Jul 2018 14:41:35 +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 23/25] ubifs: Enable authentication support
With the preparations all being done this patch now enables authentication
support for UBIFS. Authentication is enabled when the newly introduced
auth_key and auth_hash_name mount options are passed. auth_key provides
the key which is used for authentication whereas auth_hash_name provides
the hashing algorithm used for this FS. Passing these options make
authentication mandatory and only UBIFS images that can be authenticated
with the given key are allowed.
Signed-off-by: Sascha Hauer <s.hauer@...gutronix.de>
---
Documentation/filesystems/ubifs.txt | 7 ++++++
fs/ubifs/Kconfig | 10 ++++++++
fs/ubifs/super.c | 36 ++++++++++++++++++++++++++++-
3 files changed, 52 insertions(+), 1 deletion(-)
diff --git a/Documentation/filesystems/ubifs.txt b/Documentation/filesystems/ubifs.txt
index a0a61d2f389f..acc80442a3bb 100644
--- a/Documentation/filesystems/ubifs.txt
+++ b/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
diff --git a/fs/ubifs/Kconfig b/fs/ubifs/Kconfig
index 2a0b5f1134a4..9da1e7c21b7f 100644
--- a/fs/ubifs/Kconfig
+++ b/fs/ubifs/Kconfig
@@ -75,3 +75,13 @@ 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.
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index de7bf613addc..b2ccd2d7ce4d 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -577,7 +577,9 @@ 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].len = UBIFS_AUTH_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;
@@ -932,6 +934,8 @@ static int check_volume_empty(struct ubifs_info *c)
* Opt_chk_data_crc: check CRCs when reading data nodes
* Opt_no_chk_data_crc: do not check CRCs when reading data nodes
* Opt_override_compr: override default compressor
+ * 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 {
@@ -942,6 +946,8 @@ enum {
Opt_chk_data_crc,
Opt_no_chk_data_crc,
Opt_override_compr,
+ Opt_auth_key,
+ Opt_auth_hash_name,
Opt_ignore,
Opt_err,
};
@@ -954,6 +960,8 @@ 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_err, NULL},
@@ -1056,6 +1064,16 @@ static int ubifs_parse_options(struct ubifs_info *c, char *options,
c->default_compr = c->mount_opts.compr_type;
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:
@@ -1235,6 +1253,19 @@ 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;
@@ -1552,7 +1583,10 @@ 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);
--
2.18.0
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