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Message-Id: <20180907123646.12688-25-s.hauer@pengutronix.de>
Date: Fri, 7 Sep 2018 14:36:45 +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 24/25] 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 853c77579b4e..529856fbccd0 100644
--- a/fs/ubifs/Kconfig
+++ b/fs/ubifs/Kconfig
@@ -86,3 +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.
diff --git a/fs/ubifs/super.c b/fs/ubifs/super.c
index 12683cb87315..e3fb4dface8c 100644
--- a/fs/ubifs/super.c
+++ b/fs/ubifs/super.c
@@ -579,7 +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].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;
@@ -935,6 +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 {
@@ -946,6 +950,8 @@ enum {
Opt_no_chk_data_crc,
Opt_override_compr,
Opt_assert,
+ Opt_auth_key,
+ Opt_auth_hash_name,
Opt_ignore,
Opt_err,
};
@@ -958,6 +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"},
@@ -1081,6 +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:
@@ -1260,6 +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;
@@ -1577,7 +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);
--
2.18.0
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