[PATCH] dm crypt: add key msg
Add the facility to wipe the encryption key from memory (for example while a
laptop is suspended) and reinstate it later (when the laptop gets resumed).
Signed-off-by: Milan Broz <mbroz@redhat.com>
Signed-off-by: Alasdair G Kergon <agk@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c
index bdbd349..e1e8040 100644
--- a/drivers/md/dm-crypt.c
+++ b/drivers/md/dm-crypt.c
@@ -1,6 +1,7 @@
/*
* Copyright (C) 2003 Christophe Saout <christophe@saout.de>
* Copyright (C) 2004 Clemens Fruhwirth <clemens@endorphin.org>
+ * Copyright (C) 2006 Red Hat, Inc. All rights reserved.
*
* This file is released under the GPL.
*/
@@ -22,6 +23,7 @@
#include "dm.h"
#define DM_MSG_PREFIX "crypt"
+#define MESG_STR(x) x, sizeof(x)
/*
* per bio private data
@@ -63,6 +65,7 @@
* Crypt: maps a linear range of a block device
* and encrypts / decrypts at the same time.
*/
+enum flags { DM_CRYPT_SUSPENDED, DM_CRYPT_KEY_VALID };
struct crypt_config {
struct dm_dev *dev;
sector_t start;
@@ -86,6 +89,7 @@
char cipher[CRYPTO_MAX_ALG_NAME];
char chainmode[CRYPTO_MAX_ALG_NAME];
struct crypto_blkcipher *tfm;
+ unsigned long flags;
unsigned int key_size;
u8 key[0];
};
@@ -507,6 +511,31 @@
}
}
+static int crypt_set_key(struct crypt_config *cc, char *key)
+{
+ unsigned key_size = strlen(key) >> 1;
+
+ if (cc->key_size && cc->key_size != key_size)
+ return -EINVAL;
+
+ cc->key_size = key_size; /* initial settings */
+
+ if ((!key_size && strcmp(key, "-")) ||
+ (key_size && crypt_decode_key(cc->key, key, key_size) < 0))
+ return -EINVAL;
+
+ set_bit(DM_CRYPT_KEY_VALID, &cc->flags);
+
+ return 0;
+}
+
+static int crypt_wipe_key(struct crypt_config *cc)
+{
+ clear_bit(DM_CRYPT_KEY_VALID, &cc->flags);
+ memset(&cc->key, 0, cc->key_size * sizeof(u8));
+ return 0;
+}
+
/*
* Construct an encryption mapping:
* <cipher> <key> <iv_offset> <dev_path> <start>
@@ -539,16 +568,14 @@
key_size = strlen(argv[1]) >> 1;
- cc = kmalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
+ cc = kzalloc(sizeof(*cc) + key_size * sizeof(u8), GFP_KERNEL);
if (cc == NULL) {
ti->error =
"Cannot allocate transparent encryption context";
return -ENOMEM;
}
- cc->key_size = key_size;
- if ((!key_size && strcmp(argv[1], "-") != 0) ||
- (key_size && crypt_decode_key(cc->key, argv[1], key_size) < 0)) {
+ if (crypt_set_key(cc, argv[1])) {
ti->error = "Error decoding key";
goto bad1;
}
@@ -780,13 +807,14 @@
union map_info *map_context)
{
struct crypt_config *cc = (struct crypt_config *) ti->private;
- struct crypt_io *io = mempool_alloc(cc->io_pool, GFP_NOIO);
+ struct crypt_io *io;
struct convert_context ctx;
struct bio *clone;
unsigned int remaining = bio->bi_size;
sector_t sector = bio->bi_sector - ti->begin;
unsigned int bvec_idx = 0;
+ io = mempool_alloc(cc->io_pool, GFP_NOIO);
io->target = ti;
io->bio = bio;
io->first_clone = NULL;
@@ -883,14 +911,71 @@
return 0;
}
+static void crypt_postsuspend(struct dm_target *ti)
+{
+ struct crypt_config *cc = ti->private;
+
+ set_bit(DM_CRYPT_SUSPENDED, &cc->flags);
+}
+
+static int crypt_preresume(struct dm_target *ti)
+{
+ struct crypt_config *cc = ti->private;
+
+ if (!test_bit(DM_CRYPT_KEY_VALID, &cc->flags)) {
+ DMERR("aborting resume - crypt key is not set.");
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static void crypt_resume(struct dm_target *ti)
+{
+ struct crypt_config *cc = ti->private;
+
+ clear_bit(DM_CRYPT_SUSPENDED, &cc->flags);
+}
+
+/* Message interface
+ * key set <key>
+ * key wipe
+ */
+static int crypt_message(struct dm_target *ti, unsigned argc, char **argv)
+{
+ struct crypt_config *cc = ti->private;
+
+ if (argc < 2)
+ goto error;
+
+ if (!strnicmp(argv[0], MESG_STR("key"))) {
+ if (!test_bit(DM_CRYPT_SUSPENDED, &cc->flags)) {
+ DMWARN("not suspended during key manipulation.");
+ return -EINVAL;
+ }
+ if (argc == 3 && !strnicmp(argv[1], MESG_STR("set")))
+ return crypt_set_key(cc, argv[2]);
+ if (argc == 2 && !strnicmp(argv[1], MESG_STR("wipe")))
+ return crypt_wipe_key(cc);
+ }
+
+error:
+ DMWARN("unrecognised message received.");
+ return -EINVAL;
+}
+
static struct target_type crypt_target = {
.name = "crypt",
- .version= {1, 1, 0},
+ .version= {1, 2, 0},
.module = THIS_MODULE,
.ctr = crypt_ctr,
.dtr = crypt_dtr,
.map = crypt_map,
.status = crypt_status,
+ .postsuspend = crypt_postsuspend,
+ .preresume = crypt_preresume,
+ .resume = crypt_resume,
+ .message = crypt_message,
};
static int __init dm_crypt_init(void)