[PATCH 1/2] [maverick CVE 1/2] Add mount option to check uid of device being mounted = expect uid

John Johansen john.johansen at canonical.com
Thu Aug 11 16:52:59 UTC 2011


On 08/11/2011 06:33 AM, Andy Whitcroft wrote:
> On Thu, Aug 11, 2011 at 12:48:00AM -0700, John Johansen wrote:
>> Close a TOCTOU race for mounts done via ecryptfs-mount-private.  The mount
>> source (device) can be raced when the ownership test is done in userspace.
>> Provide Ecryptfs a means to force the uid check at mount time.
>>
>> (cherry picked from commit 764355487ea220fdc2faf128d577d7f679b91f97 git://git.kernel.org/pub/scm/linux/kernel/git/ecryptfs/ecryptfs-2.6.git for-linus)
>> CVE-2011-1833
>> BugLink: http://bugs.launchpad.net/bugs/732628
>>
>> Signed-off-by: John Johansen<john.johansen at canonical.com>
>> ---
>>   fs/ecryptfs/main.c |   25 ++++++++++++++++++++++---
>>   1 files changed, 22 insertions(+), 3 deletions(-)
>>
>> diff --git a/fs/ecryptfs/main.c b/fs/ecryptfs/main.c
>> index cbd4e18..2be138a 100644
>> --- a/fs/ecryptfs/main.c
>> +++ b/fs/ecryptfs/main.c
>> @@ -208,7 +208,8 @@ enum { ecryptfs_opt_sig, ecryptfs_opt_ecryptfs_sig,
>>          ecryptfs_opt_passthrough, ecryptfs_opt_xattr_metadata,
>>          ecryptfs_opt_encrypted_view, ecryptfs_opt_fnek_sig,
>>          ecryptfs_opt_fn_cipher, ecryptfs_opt_fn_cipher_key_bytes,
>> -       ecryptfs_opt_unlink_sigs, ecryptfs_opt_err };
>> +       ecryptfs_opt_unlink_sigs, ecryptfs_opt_check_dev_ruid,
>> +       ecryptfs_opt_err };
>>
>>   static const match_table_t tokens = {
>>   	{ecryptfs_opt_sig, "sig=%s"},
>> @@ -223,6 +224,7 @@ static const match_table_t tokens = {
>>   	{ecryptfs_opt_fn_cipher, "ecryptfs_fn_cipher=%s"},
>>   	{ecryptfs_opt_fn_cipher_key_bytes, "ecryptfs_fn_key_bytes=%u"},
>>   	{ecryptfs_opt_unlink_sigs, "ecryptfs_unlink_sigs"},
>> +	{ecryptfs_opt_check_dev_ruid, "ecryptfs_check_dev_ruid"},
>>   	{ecryptfs_opt_err, NULL}
>>   };
>>
>> @@ -266,6 +268,7 @@ static void ecryptfs_init_mount_crypt_stat(
>>    * ecryptfs_parse_options
>>    * @sb: The ecryptfs super block
>>    * @options: The options pased to the kernel
>> + * @check_ruid: set to 1 if device uid should be checked against the ruid
>>    *
>>    * Parse mount options:
>>    * debug=N 	   - ecryptfs_verbosity level for debug output
>> @@ -281,7 +284,8 @@ static void ecryptfs_init_mount_crypt_stat(
>>    *
>>    * Returns zero on success; non-zero on error
>>    */
>> -static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options)
>> +static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options,
>> +				  uid_t *check_ruid)
>>   {
>>   	char *p;
>>   	int rc = 0;
>> @@ -306,6 +310,8 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options)
>>   	char *cipher_key_bytes_src;
>>   	char *fn_cipher_key_bytes_src;
>>
>> +	*check_ruid = 0;
>> +
>>   	if (!options) {
>>   		rc = -EINVAL;
>>   		goto out;
>> @@ -406,6 +412,9 @@ static int ecryptfs_parse_options(struct ecryptfs_sb_info *sbi, char *options)
>>   		case ecryptfs_opt_unlink_sigs:
>>   			mount_crypt_stat->flags |= ECRYPTFS_UNLINK_SIGS;
>>   			break;
>> +		case ecryptfs_opt_check_dev_ruid:
>> +			*check_ruid = 1;
>> +			break;
>>   		case ecryptfs_opt_err:
>>   		default:
>>   			printk(KERN_WARNING
>> @@ -497,6 +506,7 @@ static struct file_system_type ecryptfs_fs_type;
>>   static int ecryptfs_read_super(struct super_block *sb, const char *dev_name)
>>   {
>>   	struct path path;
>> +	uid_t check_ruid;
>
> Where do we initialise this to anything?  As far as I can tell we look
> this up in ecryptfs_get_sb() and then call ecryptfs_read_super() and yet
> do not pass it in, we then just use it in the next hunk.  I suspect this
> actually should be a parameter to the function.
>
oops, it looks like I grabbed the wrong patch (its the natty one) and it applied :/.  resubmitting with
the correct patch.




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