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
---
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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