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mount-encrypted: handle lack of dm-crypt "allow_discard"

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On kernels prior to 3.1, the "allow_discard" option does not exist.
Allow for this by attempting to set up the table twice if the
allow_discard attempt fails.

BUG=chrome-os-partner:11529
TEST=link build, boots 3.2 ok, falls back when option is invalid.

Change-Id: I904d3770543ebdeb0eace9ffa8e6c654cf97976d
Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/28024
Reviewed-by: Elly Jones <ellyjones@chromium.org>
This commit is contained in:
Kees Cook
2012-07-20 10:16:31 -07:00
committed by Gerrit
parent b1aa7aea2d
commit 7b20efdc4a
3 changed files with 21 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

15
utility/mount-encrypted.c
View File

@@ -60,6 +60,7 @@ static const char * const kStaticKeyDefault = "default unsafe static key";
static const char * const kStaticKeyFactory = "factory unsafe static key";
static const int kModeProduction = 0;
static const int kModeFactory = 1;
static const int kCryptAllowDiscard = 1;
enum migration_method {
MIGRATE_TEST_ONLY,
@@ -761,10 +762,22 @@ static int setup_encrypted(int mode)
/* Mount loopback device with dm-crypt using the encryption key. */
INFO("Setting up dm-crypt %s as %s.", lodev, dmcrypt_dev);
if (!dm_setup(sectors, encryption_key, dmcrypt_name, lodev,
dmcrypt_dev)) {
dmcrypt_dev, kCryptAllowDiscard)) {
/* If dm_setup() fails, it could be due to lacking
* "allow_discard" support, so try again with discard
* disabled. There doesn't seem to be a way to query
* the kernel for this feature short of a fallible
* version test or just trying to set up the dm table
* again, so do the latter.
*/
if (!dm_setup(sectors, encryption_key, dmcrypt_name, lodev,
dmcrypt_dev, !kCryptAllowDiscard)) {
ERROR("dm_setup failed");
goto lo_cleanup;
}
INFO("%s: dm-crypt does not support discard; disabling.",
dmcrypt_dev);
}
/* Decide now if any migration will happen. If so, we will not
* grow the new filesystem in the background, since we need to

8
utility/mount-helpers.c
View File

@@ -297,16 +297,16 @@ failed:
}
int dm_setup(size_t sectors, const gchar *encryption_key, const char *name,
const gchar *device, const char *path)
const gchar *device, const char *path, int discard)
{
/* Mount loopback device with dm-crypt using the encryption key. */
gchar *table = g_strdup_printf("0 %zu crypt " \
"aes-cbc-essiv:sha256 %s " \
"0 %s 0 " \
"1 allow_discards",
"0 %s 0%s",
sectors,
encryption_key,
device);
device,
discard ? " 1 allow_discards" : "");
if (!table) {
PERROR("g_strdup_printf");
return 0;

2
utility/mount-helpers.h
View File

@@ -22,7 +22,7 @@ int loop_detach_name(const char *name);
/* Encrypted device mapper setup/teardown. */
int dm_setup(size_t sectors, const gchar *encryption_key, const char *name,
const gchar *device, const char *path);
const gchar *device, const char *path, int discard);
int dm_teardown(const gchar *device);
char *dm_get_key(const gchar *device);