Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 0e1fc5ef authored by Roberto Sassu's avatar Roberto Sassu Committed by Tyler Hicks
Browse files

eCryptfs: verify authentication tokens before their use 



Authentication tokens content may change if another requestor calls the
update() method of the corresponding key. The new function
ecryptfs_verify_auth_tok_from_key() retrieves the authentication token from
the provided key and verifies if it is still valid before being used to
encrypt or decrypt an eCryptfs file.

Signed-off-by: default avatarRoberto Sassu <roberto.sassu@polito.it>
[tyhicks: Minor formatting changes]
Signed-off-by: default avatarTyler Hicks <tyhicks@linux.vnet.ibm.com>
parent 7762e230

fs/ecryptfs/ecryptfs_kernel.h

+0 −1
Original line number Diff line number Diff line
@@ -331,7 +331,6 @@ struct ecryptfs_global_auth_tok { 
	u32 flags;

	struct list_head mount_crypt_stat_list;

	struct key *global_auth_tok_key;

	struct ecryptfs_auth_tok *global_auth_tok;

	unsigned char sig[ECRYPTFS_SIG_SIZE_HEX + 1];

};

fs/ecryptfs/keystore.c

+133 −78
Original line number Diff line number Diff line
@@ -65,6 +65,24 @@ static int process_request_key_err(long err_code) 
	return rc;

}



static int process_find_global_auth_tok_for_sig_err(int err_code)

{

	int rc = err_code;



	switch (err_code) {

	case -ENOENT:

		ecryptfs_printk(KERN_WARNING, "Missing auth tok\n");

		break;

	case -EINVAL:

		ecryptfs_printk(KERN_WARNING, "Invalid auth tok\n");

		break;

	default:

		rc = process_request_key_err(err_code);

		break;

	}

	return rc;

}



/**

 * ecryptfs_parse_packet_length

 * @data: Pointer to memory containing length at offset
@@ -403,27 +421,117 @@ parse_tag_67_packet(struct ecryptfs_key_record *key_rec, 
	return rc;

}



/**

 * ecryptfs_verify_version

 * @version: The version number to confirm

 *

 * Returns zero on good version; non-zero otherwise

 */

static int ecryptfs_verify_version(u16 version)

{

	int rc = 0;

	unsigned char major;

	unsigned char minor;



	major = ((version >> 8) & 0xFF);

	minor = (version & 0xFF);

	if (major != ECRYPTFS_VERSION_MAJOR) {

		ecryptfs_printk(KERN_ERR, "Major version number mismatch. "

				"Expected [%d]; got [%d]\n",

				ECRYPTFS_VERSION_MAJOR, major);

		rc = -EINVAL;

		goto out;

	}

	if (minor != ECRYPTFS_VERSION_MINOR) {

		ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "

				"Expected [%d]; got [%d]\n",

				ECRYPTFS_VERSION_MINOR, minor);

		rc = -EINVAL;

		goto out;

	}

out:

	return rc;

}



/**

 * ecryptfs_verify_auth_tok_from_key

 * @auth_tok_key: key containing the authentication token

 * @auth_tok: authentication token

 *

 * Returns zero on valid auth tok; -EINVAL otherwise

 */

static int

ecryptfs_verify_auth_tok_from_key(struct key *auth_tok_key,

				  struct ecryptfs_auth_tok **auth_tok)

{

	int rc = 0;



	(*auth_tok) = ecryptfs_get_key_payload_data(auth_tok_key);

	if (ecryptfs_verify_version((*auth_tok)->version)) {

		printk(KERN_ERR "Data structure version mismatch. Userspace "

		       "tools must match eCryptfs kernel module with major "

		       "version [%d] and minor version [%d]\n",

		       ECRYPTFS_VERSION_MAJOR, ECRYPTFS_VERSION_MINOR);

		rc = -EINVAL;

		goto out;

	}

	if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD

	    && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {

		printk(KERN_ERR "Invalid auth_tok structure "

		       "returned from key query\n");

		rc = -EINVAL;

		goto out;

	}

out:

	return rc;

}



static int

ecryptfs_find_global_auth_tok_for_sig(

	struct ecryptfs_global_auth_tok **global_auth_tok,

	struct key **auth_tok_key,

	struct ecryptfs_auth_tok **auth_tok,

	struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)

{

	struct ecryptfs_global_auth_tok *walker;

	int rc = 0;



	(*global_auth_tok) = NULL;

	(*auth_tok_key) = NULL;

	(*auth_tok) = NULL;

	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);

	list_for_each_entry(walker,

			    &mount_crypt_stat->global_auth_tok_list,

			    mount_crypt_stat_list) {

		if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX) == 0) {

		if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))

			continue;



		if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {

			rc = -EINVAL;

			goto out;

		}



		rc = key_validate(walker->global_auth_tok_key);

			if (!rc)

				(*global_auth_tok) = walker;

		if (rc) {

			if (rc == -EKEYEXPIRED)

				goto out;

			goto out_invalid_auth_tok;

		}



		rc = ecryptfs_verify_auth_tok_from_key(

				walker->global_auth_tok_key, auth_tok);

		if (rc)

			goto out_invalid_auth_tok;



		(*auth_tok_key) = walker->global_auth_tok_key;

		key_get(*auth_tok_key);

		goto out;

	}

	rc = -EINVAL;

	rc = -ENOENT;

	goto out;

out_invalid_auth_tok:

	printk(KERN_WARNING "Invalidating auth tok with sig = [%s]\n", sig);

	walker->flags |= ECRYPTFS_AUTH_TOK_INVALID;

	key_put(walker->global_auth_tok_key);

	walker->global_auth_tok_key = NULL;

out:

	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);

	return rc;
@@ -451,14 +559,11 @@ ecryptfs_find_auth_tok_for_sig( 
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,

	char *sig)

{

	struct ecryptfs_global_auth_tok *global_auth_tok;

	int rc = 0;



	(*auth_tok_key) = NULL;

	(*auth_tok) = NULL;

	if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,

						  mount_crypt_stat, sig)) {



	rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,

						   mount_crypt_stat, sig);

	if (rc == -ENOENT) {

		/* if the flag ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY is set in the

		 * mount_crypt_stat structure, we prevent to use auth toks that

		 * are not inserted through the ecryptfs_add_global_auth_tok
@@ -470,8 +575,7 @@ ecryptfs_find_auth_tok_for_sig( 


		rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,

						       sig);

	} else

		(*auth_tok) = global_auth_tok->global_auth_tok;

	}

	return rc;

}
@@ -1520,38 +1624,6 @@ parse_tag_11_packet(unsigned char *data, unsigned char *contents, 
	return rc;

}



/**

 * ecryptfs_verify_version

 * @version: The version number to confirm

 *

 * Returns zero on good version; non-zero otherwise

 */

static int ecryptfs_verify_version(u16 version)

{

	int rc = 0;

	unsigned char major;

	unsigned char minor;



	major = ((version >> 8) & 0xFF);

	minor = (version & 0xFF);

	if (major != ECRYPTFS_VERSION_MAJOR) {

		ecryptfs_printk(KERN_ERR, "Major version number mismatch. "

				"Expected [%d]; got [%d]\n",

				ECRYPTFS_VERSION_MAJOR, major);

		rc = -EINVAL;

		goto out;

	}

	if (minor != ECRYPTFS_VERSION_MINOR) {

		ecryptfs_printk(KERN_ERR, "Minor version number mismatch. "

				"Expected [%d]; got [%d]\n",

				ECRYPTFS_VERSION_MINOR, minor);

		rc = -EINVAL;

		goto out;

	}

out:

	return rc;

}



int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key,

				      struct ecryptfs_auth_tok **auth_tok,

				      char *sig)
@@ -1566,29 +1638,12 @@ int ecryptfs_keyring_auth_tok_for_sig(struct key **auth_tok_key, 
		(*auth_tok_key) = NULL;

		goto out;

	}

	(*auth_tok) = ecryptfs_get_key_payload_data(*auth_tok_key);

	if (ecryptfs_verify_version((*auth_tok)->version)) {

		printk(KERN_ERR

		       "Data structure version mismatch. "

		       "Userspace tools must match eCryptfs "

		       "kernel module with major version [%d] "

		       "and minor version [%d]\n",

		       ECRYPTFS_VERSION_MAJOR,

		       ECRYPTFS_VERSION_MINOR);

		rc = -EINVAL;

		goto out_release_key;

	}

	if ((*auth_tok)->token_type != ECRYPTFS_PASSWORD

	    && (*auth_tok)->token_type != ECRYPTFS_PRIVATE_KEY) {

		printk(KERN_ERR "Invalid auth_tok structure "

		       "returned from key query\n");

		rc = -EINVAL;

		goto out_release_key;

	}

out_release_key:



	rc = ecryptfs_verify_auth_tok_from_key(*auth_tok_key, auth_tok);

	if (rc) {

		key_put(*auth_tok_key);

		(*auth_tok_key) = NULL;

		goto out;

	}

out:

	return rc;
@@ -2325,7 +2380,7 @@ ecryptfs_generate_key_packet_set(char *dest_base, 
				 size_t max)

{

	struct ecryptfs_auth_tok *auth_tok;

	struct ecryptfs_global_auth_tok *global_auth_tok;

	struct key *auth_tok_key = NULL;

	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =

		&ecryptfs_superblock_to_private(

			ecryptfs_dentry->d_sb)->mount_crypt_stat;
@@ -2344,21 +2399,16 @@ ecryptfs_generate_key_packet_set(char *dest_base, 
	list_for_each_entry(key_sig, &crypt_stat->keysig_list,

			    crypt_stat_list) {

		memset(key_rec, 0, sizeof(*key_rec));

		rc = ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,

		rc = ecryptfs_find_global_auth_tok_for_sig(&auth_tok_key,

							   &auth_tok,

							   mount_crypt_stat,

							   key_sig->keysig);

		if (rc) {

			printk(KERN_ERR "Error attempting to get the global "

			       "auth_tok; rc = [%d]\n", rc);

			printk(KERN_WARNING "Unable to retrieve auth tok with "

			       "sig = [%s]\n", key_sig->keysig);

			rc = process_find_global_auth_tok_for_sig_err(rc);

			goto out_free;

		}

		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID) {

			printk(KERN_WARNING

			       "Skipping invalid auth tok with sig = [%s]\n",

			       global_auth_tok->sig);

			continue;

		}

		auth_tok = global_auth_tok->global_auth_tok;

		if (auth_tok->token_type == ECRYPTFS_PASSWORD) {

			rc = write_tag_3_packet((dest_base + (*len)),

						&max, auth_tok,
@@ -2396,6 +2446,8 @@ ecryptfs_generate_key_packet_set(char *dest_base, 
			rc = -EINVAL;

			goto out_free;

		}

		key_put(auth_tok_key);

		auth_tok_key = NULL;

	}

	if (likely(max > 0)) {

		dest_base[(*len)] = 0x00;
@@ -2408,6 +2460,9 @@ ecryptfs_generate_key_packet_set(char *dest_base, 
out:

	if (rc)

		(*len) = 0;

	if (auth_tok_key)

		key_put(auth_tok_key);



	mutex_unlock(&crypt_stat->keysig_list_mutex);

	return rc;

}

fs/ecryptfs/main.c

+2 −2
Original line number Diff line number Diff line
@@ -239,14 +239,14 @@ static int ecryptfs_init_global_auth_toks( 
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat)

{

	struct ecryptfs_global_auth_tok *global_auth_tok;

	struct ecryptfs_auth_tok *auth_tok;

	int rc = 0;



	list_for_each_entry(global_auth_tok,

			    &mount_crypt_stat->global_auth_tok_list,

			    mount_crypt_stat_list) {

		rc = ecryptfs_keyring_auth_tok_for_sig(

			&global_auth_tok->global_auth_tok_key,

			&global_auth_tok->global_auth_tok,

			&global_auth_tok->global_auth_tok_key, &auth_tok,

			global_auth_tok->sig);

		if (rc) {

			printk(KERN_ERR "Could not find valid key in user "