[PATCH 1/5] eCryptfs: Filename Encryption: Tag 70 packets

[Michael Halcrow]

A tag 70 packet contains a filename encrypted with a Filename Encryption
Key (FNEK). This patch implements functions for writing and parsing tag
70 packets. This patch also adds definitions and extends structures to
support filename encryption.

Signed-off-by: Michael Halcrow <mhalcrow@xxxxxxxxxx>
---
 fs/ecryptfs/crypto.c          |   11 +-
 fs/ecryptfs/ecryptfs_kernel.h |   38 +++-
 fs/ecryptfs/keystore.c        |  634 ++++++++++++++++++++++++++++++++++++----
 3 files changed, 613 insertions(+), 70 deletions(-)

diff --git a/fs/ecryptfs/crypto.c b/fs/ecryptfs/crypto.c
index 6046239..4857327 100644
--- a/fs/ecryptfs/crypto.c
+++ b/fs/ecryptfs/crypto.c
@@ -1149,19 +1149,20 @@ ecryptfs_cipher_code_str_map[] = {
 
 /**
  * ecryptfs_code_for_cipher_string
- * @crypt_stat: The cryptographic context
+ * @cipher_name: The string alias for the cipher
+ * @key_bytes: Length of key in bytes; used for AES code selection
  *
  * Returns zero on no match, or the cipher code on match
  */
-u8 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
+u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes)
 {
 	int i;
 	u8 code = 0;
 	struct ecryptfs_cipher_code_str_map_elem *map =
 		ecryptfs_cipher_code_str_map;
 
-	if (strcmp(crypt_stat->cipher, "aes") == 0) {
-		switch (crypt_stat->key_size) {
+	if (strcmp(cipher_name, "aes") == 0) {
+		switch (key_bytes) {
 		case 16:
 			code = RFC2440_CIPHER_AES_128;
 			break;
@@ -1173,7 +1174,7 @@ u8 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat)
 		}
 	} else {
 		for (i = 0; i < ARRAY_SIZE(ecryptfs_cipher_code_str_map); i++)
-			if (strcmp(crypt_stat->cipher, map[i].cipher_str) == 0){
+			if (strcmp(cipher_name, map[i].cipher_str) == 0) {
 				code = map[i].cipher_code;
 				break;
 			}
diff --git a/fs/ecryptfs/ecryptfs_kernel.h b/fs/ecryptfs/ecryptfs_kernel.h
index a75026d..76a95bd 100644
--- a/fs/ecryptfs/ecryptfs_kernel.h
+++ b/fs/ecryptfs/ecryptfs_kernel.h
@@ -199,6 +199,7 @@ ecryptfs_get_key_payload_data(struct key *key)
 #define ECRYPTFS_DEFAULT_CIPHER "aes"
 #define ECRYPTFS_DEFAULT_KEY_BYTES 16
 #define ECRYPTFS_DEFAULT_HASH "md5"
+#define ECRYPTFS_TAG_70_DIGEST ECRYPTFS_DEFAULT_HASH
 #define ECRYPTFS_TAG_1_PACKET_TYPE 0x01
 #define ECRYPTFS_TAG_3_PACKET_TYPE 0x8C
 #define ECRYPTFS_TAG_11_PACKET_TYPE 0xED
@@ -206,7 +207,25 @@ ecryptfs_get_key_payload_data(struct key *key)
 #define ECRYPTFS_TAG_65_PACKET_TYPE 0x41
 #define ECRYPTFS_TAG_66_PACKET_TYPE 0x42
 #define ECRYPTFS_TAG_67_PACKET_TYPE 0x43
+#define ECRYPTFS_TAG_70_PACKET_TYPE 0x46 /* FNEK-encrypted filename
+					  * as dentry name */
+#define ECRYPTFS_TAG_71_PACKET_TYPE 0x47 /* FNEK-encrypted filename in
+					  * metadata */
+#define ECRYPTFS_TAG_72_PACKET_TYPE 0x48 /* FEK-encrypted filename as
+					  * dentry name */
+#define ECRYPTFS_TAG_73_PACKET_TYPE 0x49 /* FEK-encrypted filename as
+					  * metadata */
+/* Constraint: ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES >=
+ * ECRYPTFS_MAX_IV_BYTES */
+#define ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES 16
+#define ECRYPTFS_NON_NULL 0x42 /* A reasonable substitute for NULL */
 #define MD5_DIGEST_SIZE 16
+#define ECRYPTFS_TAG_70_DIGEST_SIZE MD5_DIGEST_SIZE
+#define ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX "ECRYPTFS_FEK_ENCRYPTED."
+#define ECRYPTFS_FEK_ENCRYPTED_FILENAME_PREFIX_SIZE 23
+#define ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX "ECRYPTFS_FNEK_ENCRYPTED."
+#define ECRYPTFS_FNEK_ENCRYPTED_FILENAME_PREFIX_SIZE 24
+#define ECRYPTFS_ENCRYPTED_DENTRY_NAME_LEN (18 + 1 + 4 + 1 + 32)
 
 struct ecryptfs_key_sig {
 	struct list_head crypt_stat_list;
@@ -332,13 +351,20 @@ struct ecryptfs_mount_crypt_stat {
 #define ECRYPTFS_XATTR_METADATA_ENABLED        0x00000002
 #define ECRYPTFS_ENCRYPTED_VIEW_ENABLED        0x00000004
 #define ECRYPTFS_MOUNT_CRYPT_STAT_INITIALIZED  0x00000008
+#define ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES      0x00000010
+#define ECRYPTFS_GLOBAL_ENCFN_USE_MOUNT_FNEK   0x00000020
+#define ECRYPTFS_GLOBAL_ENCFN_USE_FEK          0x00000040
 	u32 flags;
 	struct list_head global_auth_tok_list;
 	struct mutex global_auth_tok_list_mutex;
 	size_t num_global_auth_toks;
 	size_t global_default_cipher_key_size;
+	size_t global_default_fn_cipher_key_bytes;
 	unsigned char global_default_cipher_name[ECRYPTFS_MAX_CIPHER_NAME_SIZE
 						 + 1];
+	unsigned char global_default_fn_cipher_name[
+		ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
+	char global_default_fnek_sig[ECRYPTFS_SIG_SIZE_HEX + 1];
 };
 
 /* superblock private data. */
@@ -599,7 +625,7 @@ int ecryptfs_read_and_validate_header_region(char *data,
 					     struct inode *ecryptfs_inode);
 int ecryptfs_read_and_validate_xattr_region(char *page_virt,
 					    struct dentry *ecryptfs_dentry);
-u8 ecryptfs_code_for_cipher_string(struct ecryptfs_crypt_stat *crypt_stat);
+u8 ecryptfs_code_for_cipher_string(char *cipher_name, size_t key_bytes);
 int ecryptfs_cipher_code_to_string(char *str, u8 cipher_code);
 void ecryptfs_set_default_sizes(struct ecryptfs_crypt_stat *crypt_stat);
 int ecryptfs_generate_key_packet_set(char *dest_base,
@@ -694,5 +720,15 @@ int ecryptfs_privileged_open(struct file **lower_file,
 			     struct vfsmount *lower_mnt,
 			     const struct cred *cred);
 int ecryptfs_init_persistent_file(struct dentry *ecryptfs_dentry);
+int
+ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
+			     size_t *packet_size,
+			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+			     char *filename, size_t filename_size);
+int
+ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
+			     size_t *packet_size,
+			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+			     char *data, size_t max_packet_size);
 
 #endif /* #ifndef ECRYPTFS_KERNEL_H */
diff --git a/fs/ecryptfs/keystore.c b/fs/ecryptfs/keystore.c
index e22bc39..1e16893 100644
--- a/fs/ecryptfs/keystore.c
+++ b/fs/ecryptfs/keystore.c
@@ -403,6 +403,569 @@ out:
 }
 
 static int
+ecryptfs_find_global_auth_tok_for_sig(
+	struct ecryptfs_global_auth_tok **global_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;
+	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) {
+			(*global_auth_tok) = walker;
+			goto out;
+		}
+	}
+	rc = -EINVAL;
+out:
+	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
+	return rc;
+}
+
+/**
+ * ecryptfs_find_auth_tok_for_sig
+ * @auth_tok: Set to the matching auth_tok; NULL if not found
+ * @crypt_stat: inode crypt_stat crypto context
+ * @sig: Sig of auth_tok to find
+ *
+ * For now, this function simply looks at the registered auth_tok's
+ * linked off the mount_crypt_stat, so all the auth_toks that can be
+ * used must be registered at mount time. This function could
+ * potentially try a lot harder to find auth_tok's (e.g., by calling
+ * out to ecryptfsd to dynamically retrieve an auth_tok object) so
+ * that static registration of auth_tok's will no longer be necessary.
+ *
+ * Returns zero on no error; non-zero on error
+ */
+static int
+ecryptfs_find_auth_tok_for_sig(
+	struct ecryptfs_auth_tok **auth_tok,
+	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+	char *sig)
+{
+	struct ecryptfs_global_auth_tok *global_auth_tok;
+	int rc = 0;
+
+	(*auth_tok) = NULL;
+	if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
+						  mount_crypt_stat, sig)) {
+		struct key *auth_tok_key;
+
+		rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
+						       sig);
+	} else
+		(*auth_tok) = global_auth_tok->global_auth_tok;
+	return rc;
+}
+
+/**
+ * write_tag_70_packet can gobble a lot of stack space. We stuff most
+ * of the function's parameters in a kmalloc'd struct to help reduce
+ * eCryptfs' overall stack usage.
+ */
+struct ecryptfs_write_tag_70_packet_silly_stack {
+	u8 cipher_code;
+	size_t max_packet_size;
+	size_t packet_size_len;
+	size_t block_aligned_filename_size;
+	size_t block_size;
+	size_t i;
+	size_t j;
+	size_t num_rand_bytes;
+	struct mutex *tfm_mutex;
+	char *block_aligned_filename;
+	struct ecryptfs_auth_tok *auth_tok;
+	struct scatterlist src_sg;
+	struct scatterlist dst_sg;
+	struct blkcipher_desc desc;
+	char iv[ECRYPTFS_MAX_IV_BYTES];
+	char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
+	char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
+	struct hash_desc hash_desc;
+	struct scatterlist hash_sg;
+};
+
+/**
+ * write_tag_70_packet - Write encrypted filename (EFN) packet against FNEK
+ * @filename: NULL-terminated filename string
+ *
+ * This is the simplest mechanism for achieving filename encryption in
+ * eCryptfs. It encrypts the given filename with the mount-wide
+ * filename encryption key (FNEK) and stores it in a packet to @dest,
+ * which the callee will encode and write directly into the dentry
+ * name.
+ */
+int
+ecryptfs_write_tag_70_packet(char *dest, size_t *remaining_bytes,
+			     size_t *packet_size,
+			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+			     char *filename, size_t filename_size)
+{
+	struct ecryptfs_write_tag_70_packet_silly_stack *s;
+	int rc = 0;
+
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s) {
+		printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
+		       "[%d] bytes of kernel memory\n", __func__, sizeof(*s));
+		goto out;
+	}
+	s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+	(*packet_size) = 0;
+	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
+		&s->desc.tfm,
+		&s->tfm_mutex, mount_crypt_stat->global_default_fn_cipher_name);
+	if (unlikely(rc)) {
+		printk(KERN_ERR "Internal error whilst attempting to get "
+		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
+		       mount_crypt_stat->global_default_fn_cipher_name, rc);
+		goto out;
+	}
+	mutex_lock(s->tfm_mutex);
+	s->block_size = crypto_blkcipher_blocksize(s->desc.tfm);
+	/* Plus one for the \0 separator between the random prefix
+	 * and the plaintext filename */
+	s->num_rand_bytes = (ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES + 1);
+	s->block_aligned_filename_size = (s->num_rand_bytes + filename_size);
+	if ((s->block_aligned_filename_size % s->block_size) != 0) {
+		s->num_rand_bytes += (s->block_size
+				      - (s->block_aligned_filename_size
+					 % s->block_size));
+		s->block_aligned_filename_size = (s->num_rand_bytes
+						  + filename_size);
+	}
+	/* Octet 0: Tag 70 identifier
+	 * Octets 1-N1: Tag 70 packet size (includes cipher identifier
+	 *              and block-aligned encrypted filename size)
+	 * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
+	 * Octet N2-N3: Cipher identifier (1 octet)
+	 * Octets N3-N4: Block-aligned encrypted filename
+	 *  - Consists of a minimum number of random characters, a \0
+	 *    separator, and then the filename */
+	s->max_packet_size = (1                   /* Tag 70 identifier */
+			      + 3                 /* Max Tag 70 packet size */
+			      + ECRYPTFS_SIG_SIZE /* FNEK sig */
+			      + 1                 /* Cipher identifier */
+			      + s->block_aligned_filename_size);
+	if (dest == NULL) {
+		(*packet_size) = s->max_packet_size;
+		goto out_unlock;
+	}
+	if (s->max_packet_size > (*remaining_bytes)) {
+		printk(KERN_WARNING "%s: Require [%d] bytes to write; only "
+		       "[%d] available\n", __func__, s->max_packet_size,
+		       (*remaining_bytes));
+		rc = -EINVAL;
+		goto out_unlock;
+	}
+	s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
+					    GFP_KERNEL);
+	if (!s->block_aligned_filename) {
+		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
+		       "kzalloc [%Zd] bytes\n", __func__,
+		       s->block_aligned_filename_size);
+		rc = -ENOMEM;
+		goto out_unlock;
+	}
+	s->i = 0;
+	dest[s->i++] = ECRYPTFS_TAG_70_PACKET_TYPE;
+	rc = ecryptfs_write_packet_length(&dest[s->i],
+					  (ECRYPTFS_SIG_SIZE
+					   + 1 /* Cipher code */
+					   + s->block_aligned_filename_size),
+					  &s->packet_size_len);
+	if (rc) {
+		printk(KERN_ERR "%s: Error generating tag 70 packet "
+		       "header; cannot generate packet length; rc = [%d]\n",
+		       __func__, rc);
+		goto out_free_unlock;
+	}
+	s->i += s->packet_size_len;
+	ecryptfs_from_hex(&dest[s->i],
+			  mount_crypt_stat->global_default_fnek_sig,
+			  ECRYPTFS_SIG_SIZE);
+	s->i += ECRYPTFS_SIG_SIZE;
+	s->cipher_code = ecryptfs_code_for_cipher_string(
+		mount_crypt_stat->global_default_fn_cipher_name,
+		mount_crypt_stat->global_default_fn_cipher_key_bytes);
+	if (s->cipher_code == 0) {
+		printk(KERN_WARNING "%s: Unable to generate code for "
+		       "cipher [%s] with key bytes [%d]\n", __func__,
+		       mount_crypt_stat->global_default_fn_cipher_name,
+		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
+		rc = -EINVAL;
+		goto out_free_unlock;
+	}
+	dest[s->i++] = s->cipher_code;
+	rc = ecryptfs_find_auth_tok_for_sig(
+		&s->auth_tok, mount_crypt_stat,
+		mount_crypt_stat->global_default_fnek_sig);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to find auth tok for "
+		       "fnek sig [%s]; rc = [%d]\n", __func__,
+		       mount_crypt_stat->global_default_fnek_sig, rc);
+		goto out_free_unlock;
+	}
+	/* TODO: Support other key modules than passphrase for
+	 * filename encryption */
+	BUG_ON(s->auth_tok->token_type != ECRYPTFS_PASSWORD);
+	sg_init_one(
+		&s->hash_sg,
+		(u8 *)s->auth_tok->token.password.session_key_encryption_key,
+		s->auth_tok->token.password.session_key_encryption_key_bytes);
+	s->hash_desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+	s->hash_desc.tfm = crypto_alloc_hash(ECRYPTFS_TAG_70_DIGEST, 0,
+					     CRYPTO_ALG_ASYNC);
+	if (IS_ERR(s->hash_desc.tfm)) {
+			rc = PTR_ERR(s->hash_desc.tfm);
+			printk(KERN_ERR "%s: Error attempting to "
+			       "allocate hash crypto context; rc = [%d]\n",
+			       __func__, rc);
+			goto out_free_unlock;
+	}
+	rc = crypto_hash_init(&s->hash_desc);
+	if (rc) {
+		printk(KERN_ERR
+		       "%s: Error initializing crypto hash; rc = [%d]\n",
+		       __func__, rc);
+		goto out_release_free_unlock;
+	}
+	rc = crypto_hash_update(
+		&s->hash_desc, &s->hash_sg,
+		s->auth_tok->token.password.session_key_encryption_key_bytes);
+	if (rc) {
+		printk(KERN_ERR
+		       "%s: Error updating crypto hash; rc = [%d]\n",
+		       __func__, rc);
+		goto out_release_free_unlock;
+	}
+	rc = crypto_hash_final(&s->hash_desc, s->hash);
+	if (rc) {
+		printk(KERN_ERR
+		       "%s: Error finalizing crypto hash; rc = [%d]\n",
+		       __func__, rc);
+		goto out_release_free_unlock;
+	}
+	for (s->j = 0; s->j < (s->num_rand_bytes - 1); s->j++) {
+		s->block_aligned_filename[s->j] =
+			s->hash[(s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)];
+		if ((s->j % ECRYPTFS_TAG_70_DIGEST_SIZE)
+		    == (ECRYPTFS_TAG_70_DIGEST_SIZE - 1)) {
+			sg_init_one(&s->hash_sg, (u8 *)s->hash,
+				    ECRYPTFS_TAG_70_DIGEST_SIZE);
+			rc = crypto_hash_init(&s->hash_desc);
+			if (rc) {
+				printk(KERN_ERR
+				       "%s: Error initializing crypto hash; "
+				       "rc = [%d]\n", __func__, rc);
+				goto out_release_free_unlock;
+			}
+			rc = crypto_hash_update(&s->hash_desc, &s->hash_sg,
+						ECRYPTFS_TAG_70_DIGEST_SIZE);
+			if (rc) {
+				printk(KERN_ERR
+				       "%s: Error updating crypto hash; "
+				       "rc = [%d]\n", __func__, rc);
+				goto out_release_free_unlock;
+			}
+			rc = crypto_hash_final(&s->hash_desc, s->tmp_hash);
+			if (rc) {
+				printk(KERN_ERR
+				       "%s: Error finalizing crypto hash; "
+				       "rc = [%d]\n", __func__, rc);
+				goto out_release_free_unlock;
+			}
+			memcpy(s->hash, s->tmp_hash,
+			       ECRYPTFS_TAG_70_DIGEST_SIZE);
+		}
+		if (s->block_aligned_filename[s->j] == '\0')
+			s->block_aligned_filename[s->j] = ECRYPTFS_NON_NULL;
+	}
+	memcpy(&s->block_aligned_filename[s->num_rand_bytes], filename,
+	       filename_size);
+	rc = virt_to_scatterlist(s->block_aligned_filename,
+				 s->block_aligned_filename_size, &s->src_sg, 1);
+	if (rc != 1) {
+		printk(KERN_ERR "%s: Internal error whilst attempting to "
+		       "convert filename memory to scatterlist; "
+		       "expected rc = 1; got rc = [%d]. "
+		       "block_aligned_filename_size = [%d]\n", __func__, rc,
+		       s->block_aligned_filename_size);
+		goto out_release_free_unlock;
+	}
+	rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
+				 &s->dst_sg, 1);
+	if (rc != 1) {
+		printk(KERN_ERR "%s: Internal error whilst attempting to "
+		       "convert encrypted filename memory to scatterlist; "
+		       "expected rc = 1; got rc = [%d]. "
+		       "block_aligned_filename_size = [%d]\n", __func__, rc,
+		       s->block_aligned_filename_size);
+		goto out_release_free_unlock;
+	}
+	/* The characters in the first block effectively do the job
+	 * of the IV here, so we just use 0's for the IV. Note the
+	 * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
+	 * >= ECRYPTFS_MAX_IV_BYTES. */
+	memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
+	s->desc.info = s->iv;
+	rc = crypto_blkcipher_setkey(
+		s->desc.tfm,
+		s->auth_tok->token.password.session_key_encryption_key,
+		mount_crypt_stat->global_default_fn_cipher_key_bytes);
+	if (rc < 0) {
+		printk(KERN_ERR "%s: Error setting key for crypto context; "
+		       "rc = [%d]. s->auth_tok->token.password.session_key_"
+		       "encryption_key = [0x%p]; mount_crypt_stat->"
+		       "global_default_fn_cipher_key_bytes = [%Zd]\n", __func__,
+		       rc,
+		       s->auth_tok->token.password.session_key_encryption_key,
+		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
+		goto out_release_free_unlock;
+	}
+	rc = crypto_blkcipher_encrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
+					 s->block_aligned_filename_size);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to encrypt filename; "
+		       "rc = [%d]\n", __func__, rc);
+		goto out_release_free_unlock;
+	}
+	s->i += s->block_aligned_filename_size;
+	(*packet_size) = s->i;
+	(*remaining_bytes) -= (*packet_size);
+out_release_free_unlock:
+	crypto_free_hash(s->hash_desc.tfm);
+out_free_unlock:
+	memset(s->block_aligned_filename, 0, s->block_aligned_filename_size);
+	kfree(s->block_aligned_filename);
+out_unlock:
+	mutex_unlock(s->tfm_mutex);
+out:
+	kfree(s);
+	return rc;
+}
+
+struct ecryptfs_parse_tag_70_packet_silly_stack {
+	u8 cipher_code;
+	size_t max_packet_size;
+	size_t packet_size_len;
+	size_t parsed_tag_70_packet_size;
+	size_t block_aligned_filename_size;
+	size_t block_size;
+	size_t i;
+	struct mutex *tfm_mutex;
+	char *decrypted_filename;
+	struct ecryptfs_auth_tok *auth_tok;
+	struct scatterlist src_sg;
+	struct scatterlist dst_sg;
+	struct blkcipher_desc desc;
+	char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
+	char iv[ECRYPTFS_MAX_IV_BYTES];
+	char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE];
+};
+
+/**
+ * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
+ * @filename: This function kmalloc's the memory for the filename
+ */
+int
+ecryptfs_parse_tag_70_packet(char **filename, size_t *filename_size,
+			     size_t *packet_size,
+			     struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
+			     char *data, size_t max_packet_size)
+{
+	struct ecryptfs_parse_tag_70_packet_silly_stack *s;
+	int rc = 0;
+
+	(*packet_size) = 0;
+	(*filename_size) = 0;
+	(*filename) = NULL;
+	s = kmalloc(sizeof(*s), GFP_KERNEL);
+	if (!s) {
+		printk(KERN_ERR "%s: Out of memory whilst trying to kmalloc "
+		       "[%d] bytes of kernel memory\n", __func__, sizeof(*s));
+		goto out;
+	}
+	s->desc.flags = CRYPTO_TFM_REQ_MAY_SLEEP;
+	if (max_packet_size < (1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1)) {
+		printk(KERN_WARNING "%s: max_packet_size is [%Zd]; it must be "
+		       "at least [%d]\n", __func__, max_packet_size,
+			(1 + 1 + ECRYPTFS_SIG_SIZE + 1 + 1));
+		rc = -EINVAL;
+		goto out;
+	}
+	/* Octet 0: Tag 70 identifier
+	 * Octets 1-N1: Tag 70 packet size (includes cipher identifier
+	 *              and block-aligned encrypted filename size)
+	 * Octets N1-N2: FNEK sig (ECRYPTFS_SIG_SIZE)
+	 * Octet N2-N3: Cipher identifier (1 octet)
+	 * Octets N3-N4: Block-aligned encrypted filename
+	 *  - Consists of a minimum number of random numbers, a \0
+	 *    separator, and then the filename */
+	if (data[(*packet_size)++] != ECRYPTFS_TAG_70_PACKET_TYPE) {
+		printk(KERN_WARNING "%s: Invalid packet tag [0x%.2x]; must be "
+		       "tag [0x%.2x]\n", __func__,
+		       data[((*packet_size) - 1)], ECRYPTFS_TAG_70_PACKET_TYPE);
+		rc = -EINVAL;
+		goto out;
+	}
+	rc = ecryptfs_parse_packet_length(&data[(*packet_size)],
+					  &s->parsed_tag_70_packet_size,
+					  &s->packet_size_len);
+	if (rc) {
+		printk(KERN_WARNING "%s: Error parsing packet length; "
+		       "rc = [%d]\n", __func__, rc);
+		goto out;
+	}
+	s->block_aligned_filename_size = (s->parsed_tag_70_packet_size
+					  - ECRYPTFS_SIG_SIZE - 1);
+	if ((1 + s->packet_size_len + s->parsed_tag_70_packet_size)
+	    > max_packet_size) {
+		printk(KERN_WARNING "%s: max_packet_size is [%d]; real packet "
+		       "size is [%d]\n", __func__, max_packet_size,
+		       (1 + s->packet_size_len + 1
+			+ s->block_aligned_filename_size));
+		rc = -EINVAL;
+		goto out;
+	}
+	(*packet_size) += s->packet_size_len;
+	ecryptfs_to_hex(s->fnek_sig_hex, &data[(*packet_size)],
+			ECRYPTFS_SIG_SIZE);
+	s->fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX] = '\0';
+	(*packet_size) += ECRYPTFS_SIG_SIZE;
+	s->cipher_code = data[(*packet_size)++];
+	rc = ecryptfs_cipher_code_to_string(s->cipher_string, s->cipher_code);
+	if (rc) {
+		printk(KERN_WARNING "%s: Cipher code [%d] is invalid\n",
+		       __func__, s->cipher_code);
+		goto out;
+	}
+	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->desc.tfm,
+							&s->tfm_mutex,
+							s->cipher_string);
+	if (unlikely(rc)) {
+		printk(KERN_ERR "Internal error whilst attempting to get "
+		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
+		       s->cipher_string, rc);
+		goto out;
+	}
+	mutex_lock(s->tfm_mutex);
+	rc = virt_to_scatterlist(&data[(*packet_size)],
+				 s->block_aligned_filename_size, &s->src_sg, 1);
+	if (rc != 1) {
+		printk(KERN_ERR "%s: Internal error whilst attempting to "
+		       "convert encrypted filename memory to scatterlist; "
+		       "expected rc = 1; got rc = [%d]. "
+		       "block_aligned_filename_size = [%d]\n", __func__, rc,
+		       s->block_aligned_filename_size);
+		goto out_unlock;
+	}
+	(*packet_size) += s->block_aligned_filename_size;
+	s->decrypted_filename = kmalloc(s->block_aligned_filename_size,
+					GFP_KERNEL);
+	if (!s->decrypted_filename) {
+		printk(KERN_ERR "%s: Out of memory whilst attempting to "
+		       "kmalloc [%d] bytes\n", __func__,
+		       s->block_aligned_filename_size);
+		rc = -ENOMEM;
+		goto out_unlock;
+	}
+	rc = virt_to_scatterlist(s->decrypted_filename,
+				 s->block_aligned_filename_size, &s->dst_sg, 1);
+	if (rc != 1) {
+		printk(KERN_ERR "%s: Internal error whilst attempting to "
+		       "convert decrypted filename memory to scatterlist; "
+		       "expected rc = 1; got rc = [%d]. "
+		       "block_aligned_filename_size = [%d]\n", __func__, rc,
+		       s->block_aligned_filename_size);
+		goto out_free_unlock;
+	}
+	/* The characters in the first block effectively do the job of
+	 * the IV here, so we just use 0's for the IV. Note the
+	 * constraint that ECRYPTFS_FILENAME_MIN_RANDOM_PREPEND_BYTES
+	 * >= ECRYPTFS_MAX_IV_BYTES. */
+	memset(s->iv, 0, ECRYPTFS_MAX_IV_BYTES);
+	s->desc.info = s->iv;
+	rc = ecryptfs_find_auth_tok_for_sig(&s->auth_tok, mount_crypt_stat,
+					    s->fnek_sig_hex);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to find auth tok for "
+		       "fnek sig [%s]; rc = [%d]\n", __func__, s->fnek_sig_hex,
+		       rc);
+		goto out_free_unlock;
+	}
+	/* TODO: Support other key modules than passphrase for
+	 * filename encryption */
+	BUG_ON(s->auth_tok->token_type != ECRYPTFS_PASSWORD);
+	rc = crypto_blkcipher_setkey(
+		s->desc.tfm,
+		s->auth_tok->token.password.session_key_encryption_key,
+		mount_crypt_stat->global_default_fn_cipher_key_bytes);
+	if (rc < 0) {
+		printk(KERN_ERR "%s: Error setting key for crypto context; "
+		       "rc = [%d]. s->auth_tok->token.password.session_key_"
+		       "encryption_key = [0x%p]; mount_crypt_stat->"
+		       "global_default_fn_cipher_key_bytes = [%Zd]\n", __func__,
+		       rc,
+		       s->auth_tok->token.password.session_key_encryption_key,
+		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
+		goto out_free_unlock;
+	}
+	rc = crypto_blkcipher_decrypt_iv(&s->desc, &s->dst_sg, &s->src_sg,
+					 s->block_aligned_filename_size);
+	if (rc) {
+		printk(KERN_ERR "%s: Error attempting to decrypt filename; "
+		       "rc = [%d]\n", __func__, rc);
+		goto out_free_unlock;
+	}
+	s->i = 0;
+	while (s->decrypted_filename[s->i] != '\0'
+	       && s->i < s->block_aligned_filename_size)
+		s->i++;
+	if (s->i == s->block_aligned_filename_size) {
+		printk(KERN_WARNING "%s: Invalid tag 70 packet; could not "
+		       "find valid separator between random characters and "
+		       "the filename\n", __func__);
+		rc = -EINVAL;
+		goto out_free_unlock;
+	}
+	s->i++;
+	(*filename_size) = (s->block_aligned_filename_size - s->i);
+	if (!((*filename_size) > 0 && (*filename_size < PATH_MAX))) {
+		printk(KERN_WARNING "%s: Filename size is [%Zd], which is "
+		       "invalid\n", __func__, (*filename_size));
+		rc = -EINVAL;
+		goto out_free_unlock;
+	}
+	(*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
+	if (!(*filename)) {
+		printk(KERN_ERR "%s: Out of memory whilst attempting to "
+		       "kmalloc [%d] bytes\n", __func__,
+		       ((*filename_size) + 1));
+		rc = -ENOMEM;
+		goto out_free_unlock;
+	}
+	memcpy((*filename), &s->decrypted_filename[s->i], (*filename_size));
+	(*filename)[(*filename_size)] = '\0';
+out_free_unlock:
+	kfree(s->decrypted_filename);
+out_unlock:
+	mutex_unlock(s->tfm_mutex);
+out:
+	if (rc) {
+		(*packet_size) = 0;
+		(*filename_size) = 0;
+		(*filename) = NULL;
+	}
+	kfree(s);
+	return rc;
+}
+
+static int
 ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
 {
 	int rc = 0;
@@ -897,30 +1460,6 @@ out:
 	return rc;
 }
 
-static int
-ecryptfs_find_global_auth_tok_for_sig(
-	struct ecryptfs_global_auth_tok **global_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;
-	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) {
-			(*global_auth_tok) = walker;
-			goto out;
-		}
-	}
-	rc = -EINVAL;
-out:
-	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
-	return rc;
-}
-
 /**
  * ecryptfs_verify_version
  * @version: The version number to confirm
@@ -990,43 +1529,6 @@ out:
 }
 
 /**
- * ecryptfs_find_auth_tok_for_sig
- * @auth_tok: Set to the matching auth_tok; NULL if not found
- * @crypt_stat: inode crypt_stat crypto context
- * @sig: Sig of auth_tok to find
- *
- * For now, this function simply looks at the registered auth_tok's
- * linked off the mount_crypt_stat, so all the auth_toks that can be
- * used must be registered at mount time. This function could
- * potentially try a lot harder to find auth_tok's (e.g., by calling
- * out to ecryptfsd to dynamically retrieve an auth_tok object) so
- * that static registration of auth_tok's will no longer be necessary.
- *
- * Returns zero on no error; non-zero on error
- */
-static int
-ecryptfs_find_auth_tok_for_sig(
-	struct ecryptfs_auth_tok **auth_tok,
-	struct ecryptfs_crypt_stat *crypt_stat, char *sig)
-{
-	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
-		crypt_stat->mount_crypt_stat;
-	struct ecryptfs_global_auth_tok *global_auth_tok;
-	int rc = 0;
-
-	(*auth_tok) = NULL;
-	if (ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
-						  mount_crypt_stat, sig)) {
-		struct key *auth_tok_key;
-
-		rc = ecryptfs_keyring_auth_tok_for_sig(&auth_tok_key, auth_tok,
-						       sig);
-	} else
-		(*auth_tok) = global_auth_tok->global_auth_tok;
-	return rc;
-}
-
-/**
  * decrypt_passphrase_encrypted_session_key - Decrypt the session key with the given auth_tok.
  * @auth_tok: The passphrase authentication token to use to encrypt the FEK
  * @crypt_stat: The cryptographic context
@@ -1259,7 +1761,8 @@ find_next_matching_auth_tok:
 			rc = -EINVAL;
 			goto out_wipe_list;
 		}
-		ecryptfs_find_auth_tok_for_sig(&matching_auth_tok, crypt_stat,
+		ecryptfs_find_auth_tok_for_sig(&matching_auth_tok,
+					       crypt_stat->mount_crypt_stat,
 					       candidate_auth_tok_sig);
 		if (matching_auth_tok) {
 			found_auth_tok = 1;
@@ -1339,7 +1842,9 @@ pki_encrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
 	int rc;
 
 	rc = write_tag_66_packet(auth_tok->token.private_key.signature,
-				 ecryptfs_code_for_cipher_string(crypt_stat),
+				 ecryptfs_code_for_cipher_string(
+					 crypt_stat->cipher,
+					 crypt_stat->key_size),
 				 crypt_stat, &payload, &payload_len);
 	if (rc) {
 		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet\n");
@@ -1699,7 +2204,8 @@ encrypted_session_key_set:
 	dest[(*packet_size)++] = 0x04; /* version 4 */
 	/* TODO: Break from RFC2440 so that arbitrary ciphers can be
 	 * specified with strings */
-	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
+	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher,
+						      crypt_stat->key_size);
 	if (cipher_code == 0) {
 		ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
 				"cipher [%s]\n", crypt_stat->cipher);
-- 
1.5.3.6

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