[PATCH 11/13: eCryptfs] Keystore

Phillip Hellewell
2006-05-13T03:47:55Z

This is the 11th patch in a series of 13 constituting the kernel
components of the eCryptfs cryptographic filesystem.

eCryptfs keystore. Packet generation and parsing code. Authentication
token management code.

Signed-off-by: Phillip Hellewell <phillip@hellewell.homeip.net>
Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>

---

keystore.c | 1043 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 1043 insertions(+)

Index: linux-2.6.17-rc3-mm1-ecryptfs/fs/ecryptfs/keystore.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6.17-rc3-mm1-ecryptfs/fs/ecryptfs/keystore.c 2006-05-12 20:00:28.000000000 -0600
@@ -0,0 +1,1043 @@
+/**
+ * eCryptfs: Linux filesystem encryption layer
+ * In-kernel key management code. Includes functions to parse and
+ * write authentication token-related packets with the underlying
+ * file.
+ *
+ * Copyright (C) 2004-2006 International Business Machines Corp.
+ * Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
+ * Michael C. Thompson <mcthomps@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
+ * 02111-1307, USA.
+ */
+
+#include <linux/string.h>
+#include <linux/sched.h>
+#include <linux/syscalls.h>
+#include <linux/pagemap.h>
+#include <linux/key.h>
+#include <linux/random.h>
+#include <linux/crypto.h>
+#include <asm/scatterlist.h>
+#include "ecryptfs_kernel.h"
+
+/**
+ * request_key returned an error instead of a valid key address;
+ * determine the type of error, make appropriate log entries, and
+ * return an error code.
+ */
+int process_request_key_err(long err_code)
+{
+ int rc = 0;
+
+ switch (err_code) {
+ case ENOKEY:
+ ecryptfs_printk(KERN_WARNING, "No key\n");
+ rc = -ENOENT;
+ break;
+ case EKEYEXPIRED:
+ ecryptfs_printk(KERN_WARNING, "Key expired\n");
+ rc = -ETIME;
+ break;
+ case EKEYREVOKED:
+ ecryptfs_printk(KERN_WARNING, "Key revoked\n");
+ rc = -EINVAL;
+ break;
+ default:
+ ecryptfs_printk(KERN_WARNING, "Unknown error code: "
+ "[0x%.16x]\n", err_code);
+ rc = -EINVAL;
+ }
+ return rc;
+}
+
+static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
+{
+ struct list_head *walker;
+ struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+
+ walker = auth_tok_list_head->next;
+ while (walker != auth_tok_list_head) {
+ auth_tok_list_item =
+ list_entry(walker, struct ecryptfs_auth_tok_list_item,
+ list);
+ walker = auth_tok_list_item->list.next;
+ memset(auth_tok_list_item, 0,
+ sizeof(struct ecryptfs_auth_tok_list_item));
+ kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
+ auth_tok_list_item);
+ }
+}
+
+struct kmem_cache *ecryptfs_auth_tok_list_item_cache;
+
+/**
+ * parse_packet_length
+ * @data: Pointer to memory containing length at offset
+ * @size: This function writes the decoded size to this memory
+ * address; zero on error
+ * @length_size: The number of bytes occupied by the encoded length
+ *
+ * Returns Zero on success
+ */
+static int parse_packet_length(unsigned char *data, int *size, int *length_size)
+{
+ int rc = 0;
+
+ (*length_size) = 0;
+ (*size) = 0;
+ if (data[0] < 192) {
+ /* One-byte length */
+ (*size) = data[0];
+ (*length_size) = 1;
+ } else if (data[0] < 224) {
+ /* Two-byte length */
+ (*size) = ((data[0] - 192) * 256);
+ (*size) += (data[1] + 192);
+ (*length_size) = 2;
+ } else if (data[0] == 255) {
+ /* Five-byte length; we're not supposed to see this */
+ ecryptfs_printk(KERN_ERR, "Five-byte packet length not "
+ "supported\n");
+ rc = -EINVAL;
+ goto out;
+ } else {
+ ecryptfs_printk(KERN_ERR, "Error parsing packet length\n");
+ rc = -EINVAL;
+ goto out;
+ }
+out:
+ return rc;
+}
+
+/**
+ * write_packet_length
+ * @dest: The byte array target into which to write the
+ * length. Must have at least 5 bytes allocated.
+ * @size: The length to write.
+ * @packet_size_length: The number of bytes used to encode the
+ * packet length is written to this address.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int write_packet_length(char *dest, int size, int *packet_size_length)
+{
+ int rc = 0;
+
+ if (size < 192) {
+ dest[0] = size;
+ (*packet_size_length) = 1;
+ } else if (size < 65536) {
+ dest[0] = (((size - 192) / 256) + 192);
+ dest[1] = ((size - 192) % 256);
+ (*packet_size_length) = 2;
+ } else {
+ rc = -EINVAL;
+ ecryptfs_printk(KERN_WARNING,
+ "Unsupported packet size: [%d]\n", size);
+ }
+ return rc;
+}
+
+/**
+ * parse_tag_3_packet
+ * @crypt_stat: The cryptographic context to modify based on packet
+ * contents.
+ * @data: The raw bytes of the packet.
+ * @auth_tok_list: eCryptfs parses packets into authentication tokens;
+ * a new authentication token will be placed at the end
+ * of this list for this packet.
+ * @new_auth_tok: Pointer to a pointer to memory that this function
+ * allocates; sets the memory address of the pointer to
+ * NULL on error. This object is added to the
+ * auth_tok_list.
+ * @packet_size: This function writes the size of the parsed packet
+ * into this memory location; zero on error.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+parse_tag_3_packet(struct ecryptfs_crypt_stat *crypt_stat,
+ unsigned char *data, struct list_head *auth_tok_list,
+ struct ecryptfs_auth_tok **new_auth_tok,
+ int *packet_size, int max_packet_size)
+{
+ int rc = 0;
+ int body_size;
+ struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+ int length_size;
+
+ (*packet_size) = 0;
+ (*new_auth_tok) = NULL;
+ if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
+ ecryptfs_printk(KERN_ERR, "Enter w/ first byte != 0x%.2x\n",
+ ECRYPTFS_TAG_3_PACKET_TYPE);
+ rc = -EINVAL;
+ goto out;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ /* Released: wipe_auth_tok_list called in ecryptfs_parse_packet_set or
+ * at end of function upon failure */
+ auth_tok_list_item =
+ kmem_cache_alloc(ecryptfs_auth_tok_list_item_cache, SLAB_KERNEL);
+ if (!auth_tok_list_item) {
+ ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
+ rc = -ENOMEM;
+ goto out;
+ }
+ memset(auth_tok_list_item, 0,
+ sizeof(struct ecryptfs_auth_tok_list_item));
+ (*new_auth_tok) = &auth_tok_list_item->auth_tok;
+ rc = parse_packet_length(&data[(*packet_size)], &body_size,
+ &length_size);
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
+ "rc = [%d]\n", rc);
+ goto out_free;
+ }
+ if (body_size < (0x05 + ECRYPTFS_SALT_SIZE)) {
+ ecryptfs_printk(KERN_WARNING, "Invalid body size ([%d])\n",
+ body_size);
+ rc = -EINVAL;
+ goto out_free;
+ }
+ (*packet_size) += length_size;
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ /* There are 5 characters of additional information in the
+ * packet */
+ (*new_auth_tok)->session_key.encrypted_key_size =
+ body_size - (0x05 + ECRYPTFS_SALT_SIZE);
+ ecryptfs_printk(KERN_DEBUG, "Encrypted key size = [%d]\n",
+ (*new_auth_tok)->session_key.encrypted_key_size);
+ /* Version 4 (from RFC2440) */
+ if (data[(*packet_size)++] != 0x04) {
+ ecryptfs_printk(KERN_DEBUG, "Unknown version number "
+ "[%d]\n", data[(*packet_size) - 1]);
+ rc = -EINVAL;
+ goto out_free;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ ecryptfs_cipher_code_to_string(crypt_stat->cipher,
+ (u16)data[(*packet_size)]);
+ /* A little extra work to differentiate among the AES key
+ * sizes; see RFC2440 */
+ switch(data[(*packet_size)++]) {
+ case 0x07:
+ crypt_stat->key_size_bits = 128;
+ break;
+ case 0x08:
+ crypt_stat->key_size_bits = 192;
+ break;
+ case 0x09:
+ crypt_stat->key_size_bits = 256;
+ break;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ ecryptfs_init_crypt_ctx(crypt_stat);
+ /* S2K identifier 3 (from RFC2440) */
+ if (data[(*packet_size)++] != 0x03) {
+ ecryptfs_printk(KERN_ERR, "Only S2K ID 3 is currently "
+ "supported\n");
+ rc = -ENOSYS;
+ goto out_free;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ /* TODO: finish the hash mapping */
+ switch (data[(*packet_size)++]) {
+ case 0x01: /* See RFC2440 for these numbers and their mappings */
+ /* Choose MD5 */
+ memcpy((*new_auth_tok)->token.password.salt,
+ &data[(*packet_size)], ECRYPTFS_SALT_SIZE);
+ (*packet_size) += ECRYPTFS_SALT_SIZE;
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR,
+ "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ /* This conversion was taken straight from RFC2440 */
+ (*new_auth_tok)->token.password.hash_iterations =
+ ((u32) 16 + (data[(*packet_size)] & 15))
+ << ((data[(*packet_size)] >> 4) + 6);
+ (*packet_size)++;
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR,
+ "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ memcpy((*new_auth_tok)->session_key.encrypted_key,
+ &data[(*packet_size)],
+ (*new_auth_tok)->session_key.encrypted_key_size);
+ (*packet_size) +=
+ (*new_auth_tok)->session_key.encrypted_key_size;
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR,
+ "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out_free;
+ }
+ (*new_auth_tok)->session_key.flags &=
+ ~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
+ (*new_auth_tok)->session_key.flags |=
+ ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
+ (*new_auth_tok)->token.password.hash_algo = 0x01;
+ break;
+ default:
+ ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
+ "[%d]\n", data[(*packet_size) - 1]);
+ rc = -ENOSYS;
+ goto out_free;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ /* TODO: Use the keyring */
+ (*new_auth_tok)->uid = current->uid;
+ ECRYPTFS_SET_FLAG((*new_auth_tok)->flags, ECRYPTFS_PASSWORD);
+ /* TODO: Parametarize; we might actually want userspace to
+ * decrypt the session key. */
+ ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
+ ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
+ ECRYPTFS_CLEAR_FLAG((*new_auth_tok)->session_key.flags,
+ ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
+ list_add(&auth_tok_list_item->list, auth_tok_list);
+ goto out;
+out_free:
+ (*new_auth_tok) = NULL;
+ memset(auth_tok_list_item, 0,
+ sizeof(struct ecryptfs_auth_tok_list_item));
+ kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
+ auth_tok_list_item);
+out:
+ if (rc)
+ (*packet_size) = 0;
+ return rc;
+}
+
+/**
+ * parse_tag_11_packet
+ * @data: The raw bytes of the packet
+ * @contents: This function writes the data contents of the literal
+ * packet into this memory location
+ * @max_contents_bytes: The maximum number of bytes that this function
+ * is allowed to write into contents
+ * @tag_11_contents_size: This function writes the size of the parsed
+ * contents into this memory location; zero on
+ * error
+ * @packet_size: This function writes the size of the parsed packet
+ * into this memory location; zero on error
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+parse_tag_11_packet(unsigned char *data, unsigned char *contents,
+ int max_contents_bytes, int *tag_11_contents_size,
+ int *packet_size, int max_packet_size)
+{
+ int rc = 0;
+ int body_size;
+ int length_size;
+
+ (*packet_size) = 0;
+ (*tag_11_contents_size) = 0;
+ if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
+ ecryptfs_printk(KERN_WARNING,
+ "Invalid tag 11 packet format\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ rc = parse_packet_length(&data[(*packet_size)], &body_size,
+ &length_size);
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING,
+ "Invalid tag 11 packet format\n");
+ goto out;
+ }
+ (*packet_size) += length_size;
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ /* We have 13 bytes of surrounding packet values */
+ (*tag_11_contents_size) = (body_size - 13);
+ if ((*tag_11_contents_size) > max_contents_bytes) {
+ rc = -ENOMEM;
+ ecryptfs_printk(KERN_WARNING, "Not enough space allocated "
+ "in contents to copy entire contents of tag 11 "
+ "packet\n");
+ goto out;
+ }
+ if (data[(*packet_size)++] != 0x62) {
+ ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ if (data[(*packet_size)++] != 0x08) {
+ ecryptfs_printk(KERN_WARNING, "Unrecognizable packet\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ (*packet_size) += 12; /* We don't care about the filename or
+ * the timestamp */
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ memcpy(contents, &data[(*packet_size)], (*tag_11_contents_size));
+ (*packet_size) += (*tag_11_contents_size);
+ if (unlikely((*packet_size) > max_packet_size)) {
+ ecryptfs_printk(KERN_ERR, "Packet size exceeds max\n");
+ rc = -EINVAL;
+ goto out;
+ }
+out:
+ if (rc) {
+ (*packet_size) = 0;
+ (*tag_11_contents_size) = 0;
+ }
+ return rc;
+}
+
+/**
+ * decrypt_session_key - Decrypt the session key with the given auth_tok.
+ *
+ * Returns Zero on success; non-zero error otherwise.
+ */
+static int decrypt_session_key(struct ecryptfs_auth_tok *auth_tok,
+ struct ecryptfs_crypt_stat *crypt_stat)
+{
+ int rc = 0;
+ struct ecryptfs_password *password_s_ptr;
+ struct crypto_tfm *tfm = NULL;
+ struct scatterlist src_sg[2], dst_sg[2];
+ /* TODO: Use virt_to_scatterlist for these */
+ char *encrypted_session_key;
+ char *session_key;
+
+ password_s_ptr = &auth_tok->token.password;
+ if (ECRYPTFS_CHECK_FLAG(password_s_ptr->flags,
+ ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET))
+ ecryptfs_printk(KERN_DEBUG, "Session key encryption key "
+ "set; skipping key generation\n");
+ ecryptfs_printk(KERN_DEBUG, "Session key encryption key (size [%d])"
+ ":\n",
+ password_s_ptr->session_key_encryption_key_bytes);
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex(password_s_ptr->session_key_encryption_key,
+ password_s_ptr->
+ session_key_encryption_key_bytes);
+ tfm = crypto_alloc_tfm(crypt_stat->cipher, 0);
+ if (!tfm) {
+ ecryptfs_printk(KERN_ERR, "Error allocating crypto "
+ "context\n");
+ rc = -ENOMEM;
+ goto out;
+ }
+ crypto_cipher_setkey(tfm, password_s_ptr->session_key_encryption_key,
+ password_s_ptr->session_key_encryption_key_bytes);
+ /* TODO: virt_to_scatterlist */
+ encrypted_session_key = (char *)__get_free_page(GFP_KERNEL);
+ if (!encrypted_session_key) {
+ ecryptfs_printk(KERN_ERR, "Out of memory\n");
+ rc = -ENOMEM;
+ goto out_free_tfm;
+ }
+ session_key = (char *)__get_free_page(GFP_KERNEL);
+ if (!session_key) {
+ kfree(encrypted_session_key);
+ ecryptfs_printk(KERN_ERR, "Out of memory\n");
+ rc = -ENOMEM;
+ goto out_free_tfm;
+ }
+ memcpy(encrypted_session_key, auth_tok->session_key.encrypted_key,
+ auth_tok->session_key.encrypted_key_size);
+ src_sg[0].page = virt_to_page(encrypted_session_key);
+ src_sg[0].offset = 0;
+ ASSERT(auth_tok->session_key.encrypted_key_size < PAGE_CACHE_SIZE);
+ src_sg[0].length = auth_tok->session_key.encrypted_key_size;
+ dst_sg[0].page = virt_to_page(session_key);
+ dst_sg[0].offset = 0;
+ auth_tok->session_key.decrypted_key_size =
+ auth_tok->session_key.encrypted_key_size;
+ dst_sg[0].length = auth_tok->session_key.encrypted_key_size;
+ /* TODO: Handle error condition */
+ crypto_cipher_decrypt(tfm, dst_sg, src_sg,
+ auth_tok->session_key.encrypted_key_size);
+ auth_tok->session_key.decrypted_key_size =
+ auth_tok->session_key.encrypted_key_size;
+ memcpy(auth_tok->session_key.decrypted_key, session_key,
+ auth_tok->session_key.decrypted_key_size);
+ auth_tok->session_key.flags |= ECRYPTFS_CONTAINS_DECRYPTED_KEY;
+ memcpy(crypt_stat->key, auth_tok->session_key.decrypted_key,
+ auth_tok->session_key.decrypted_key_size);
+ ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_KEY_VALID);
+ crypt_stat->key_size_bits =
+ auth_tok->session_key.decrypted_key_size * 8;
+ ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex(crypt_stat->key,
+ crypt_stat->key_size_bits / 8);
+ memset(encrypted_session_key, 0, PAGE_CACHE_SIZE);
+ free_page((unsigned long)encrypted_session_key);
+ memset(session_key, 0, PAGE_CACHE_SIZE);
+ free_page((unsigned long)session_key);
+out_free_tfm:
+ crypto_free_tfm(tfm);
+out:
+ return rc;
+}
+
+/**
+ * ecryptfs_parse_packet_set
+ * @dest: The header page in memory
+ * @version: Version of file format, to guide parsing behavior
+ *
+ * Get crypt_stat to have the file's session key if the requisite key
+ * is available to decrypt the session key.
+ *
+ * Returns Zero if a valid authentication token was retrieved and
+ * processed; negative value for file not encrypted or for error
+ * conditions.
+ */
+int ecryptfs_parse_packet_set(struct ecryptfs_crypt_stat *crypt_stat,
+ unsigned char *src,
+ struct dentry *ecryptfs_dentry)
+{
+ int i = 0;
+ int rc = 0;
+ int found_auth_tok = 0;
+ int next_packet_is_auth_tok_packet;
+ char sig[ECRYPTFS_SIG_SIZE_HEX];
+ struct list_head auth_tok_list;
+ struct list_head *walker;
+ struct ecryptfs_auth_tok *chosen_auth_tok = NULL;
+ struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+ &ecryptfs_superblock_to_private(
+ ecryptfs_dentry->d_sb)->mount_crypt_stat;
+ struct ecryptfs_auth_tok *candidate_auth_tok = NULL;
+ int packet_size;
+ struct ecryptfs_auth_tok *new_auth_tok;
+ unsigned char sig_tmp_space[ECRYPTFS_SIG_SIZE];
+ int tag_11_contents_size;
+ int tag_11_packet_size;
+
+ INIT_LIST_HEAD(&auth_tok_list);
+ /* Parse the header to find as many packets as we can, these will be
+ * added the our &auth_tok_list */
+ next_packet_is_auth_tok_packet = 1;
+ while (next_packet_is_auth_tok_packet) {
+ int max_packet_size;
+
+ max_packet_size = ((PAGE_CACHE_SIZE - 8) - i);
+ switch (src[i]) {
+ case ECRYPTFS_TAG_3_PACKET_TYPE:
+ rc = parse_tag_3_packet(crypt_stat,
+ (unsigned char *)&src[i],
+ &auth_tok_list, &new_auth_tok,
+ &packet_size, max_packet_size);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error parsing "
+ "tag 3 packet\n");
+ rc = -EIO;
+ goto out_wipe_list;
+ }
+ i += packet_size;
+ rc = parse_tag_11_packet((unsigned char *)&src[i],
+ sig_tmp_space,
+ ECRYPTFS_SIG_SIZE,
+ &tag_11_contents_size,
+ &tag_11_packet_size,
+ max_packet_size);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "No valid "
+ "(ecryptfs-specific) literal "
+ "packet containing "
+ "authentication token "
+ "signature found after "
+ "tag 3 packet\n");
+ rc = -EIO;
+ goto out_wipe_list;
+ }
+ i += tag_11_packet_size;
+ if (ECRYPTFS_SIG_SIZE != tag_11_contents_size) {
+ ecryptfs_printk(KERN_ERR, "Expected "
+ "signature of size [%d]; "
+ "read size [%d]\n",
+ ECRYPTFS_SIG_SIZE,
+ tag_11_contents_size);
+ rc = -EIO;
+ goto out_wipe_list;
+ }
+ ecryptfs_to_hex(new_auth_tok->token.password.signature,
+ sig_tmp_space, tag_11_contents_size);
+ new_auth_tok->token.password.signature[
+ ECRYPTFS_PASSWORD_SIG_SIZE] = '\0';
+ ECRYPTFS_SET_FLAG(crypt_stat->flags,
+ ECRYPTFS_ENCRYPTED);
+ break;
+ case ECRYPTFS_TAG_11_PACKET_TYPE:
+ ecryptfs_printk(KERN_WARNING, "Invalid packet set "
+ "(Tag 11 not allowed by itself)\n");
+ rc = -EIO;
+ goto out_wipe_list;
+ break;
+ default:
+ ecryptfs_printk(KERN_DEBUG, "No packet at offset "
+ "[%d] of the file header; hex value of "
+ "character is [0x%.2x]\n", i, src[i]);
+ next_packet_is_auth_tok_packet = 0;
+ }
+ }
+ if (list_empty(&auth_tok_list)) {
+ rc = -EINVAL; /* Do not support non-encrypted files in
+ * the 0.1 release */
+ goto out;
+ }
+ /* If we have a global auth tok, then we should try to use
+ * it */
+ if (mount_crypt_stat->global_auth_tok) {
+ memcpy(sig, mount_crypt_stat->global_auth_tok_sig,
+ ECRYPTFS_SIG_SIZE_HEX);
+ chosen_auth_tok = mount_crypt_stat->global_auth_tok;
+ } else
+ BUG(); /* We should always have a global auth tok in
+ * the 0.1 release */
+ /* Scan list to see if our chosen_auth_tok works */
+ list_for_each(walker, &auth_tok_list) {
+ struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
+ auth_tok_list_item =
+ list_entry(walker, struct ecryptfs_auth_tok_list_item,
+ list);
+ candidate_auth_tok = &auth_tok_list_item->auth_tok;
+ if (unlikely(ecryptfs_verbosity > 0)) {
+ ecryptfs_printk(KERN_DEBUG,
+ "Considering cadidate auth tok:\n");
+ ecryptfs_dump_auth_tok(candidate_auth_tok);
+ }
+ /* TODO: Replace ECRYPTFS_SIG_SIZE_HEX w/ dynamic value */
+ if ((ECRYPTFS_CHECK_FLAG(candidate_auth_tok->flags,
+ ECRYPTFS_PASSWORD))
+ && !strncmp(candidate_auth_tok->token.password.signature,
+ sig, ECRYPTFS_SIG_SIZE_HEX)) {
+ found_auth_tok = 1;
+ goto leave_list;
+ /* TODO: Transfer the common salt into the
+ * crypt_stat salt */
+ }
+ }
+leave_list:
+ if (!found_auth_tok) {
+ ecryptfs_printk(KERN_ERR, "Could not find authentication "
+ "token on temporary list for sig [%.*s]\n",
+ ECRYPTFS_SIG_SIZE_HEX, sig);
+ rc = -EIO;
+ goto out_wipe_list;
+ } else {
+ memcpy(&(candidate_auth_tok->token.password),
+ &(chosen_auth_tok->token.password),
+ sizeof(struct ecryptfs_password));
+ rc = decrypt_session_key(candidate_auth_tok, crypt_stat);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error decrypting the "
+ "session key\n");
+ goto out_wipe_list;
+ }
+ rc = ecryptfs_compute_root_iv(crypt_stat);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error computing "
+ "the root IV\n");
+ goto out_wipe_list;
+ }
+ }
+ rc = ecryptfs_init_crypt_ctx(crypt_stat);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error initializing crypto "
+ "context for cipher [%s]; rc = [%d]\n",
+ crypt_stat->cipher, rc);
+ }
+out_wipe_list:
+ wipe_auth_tok_list(&auth_tok_list);
+out:
+ return rc;
+}
+
+/**
+ * write_tag_11_packet
+ * @dest: Target into which Tag 11 packet is to be written
+ * @max: Maximum packet length
+ * @contents: Byte array of contents to copy in
+ * @contents_length: Number of bytes in contents
+ * @packet_length: Length of the Tag 11 packet written; zero on error
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int
+write_tag_11_packet(char *dest, int max, char *contents, int contents_length,
+ int *packet_length)
+{
+ int rc = 0;
+ int packet_size_length;
+
+ (*packet_length) = 0;
+ if ((13 + contents_length) > max) {
+ rc = -EINVAL;
+ ecryptfs_printk(KERN_ERR, "Packet length larger than "
+ "maximum allowable\n");
+ goto out;
+ }
+ /* General packet header */
+ /* Packet tag */
+ dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
+ /* Packet length */
+ rc = write_packet_length(&dest[(*packet_length)],
+ (13 + contents_length), &packet_size_length);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error generating tag 11 packet "
+ "header; cannot generate packet length\n");
+ goto out;
+ }
+ (*packet_length) += packet_size_length;
+ /* Tag 11 specific */
+ /* One-octet field that describes how the data is formatted */
+ dest[(*packet_length)++] = 0x62; /* binary data */
+ /* One-octet filename length followed by filename */
+ dest[(*packet_length)++] = 8;
+ memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
+ (*packet_length) += 8;
+ /* Four-octet number indicating modification date */
+ memset(&dest[(*packet_length)], 0x00, 4);
+ (*packet_length) += 4;
+ /* Remainder is literal data */
+ memcpy(&dest[(*packet_length)], contents, contents_length);
+ (*packet_length) += contents_length;
+ out:
+ if (rc)
+ (*packet_length) = 0;
+ return rc;
+}
+
+/**
+ * write_tag_3_packet
+ * @dest: Buffer into which to write the packet
+ * @max: Maximum number of bytes that can be writtn
+ * @packet_size: This function will write the number of bytes that end
+ * up constituting the packet; set to zero on error
+ *
+ * Returns zero on success; non-zero on error.
+ */
+static int
+write_tag_3_packet(char *dest, int max, struct ecryptfs_auth_tok *auth_tok,
+ struct ecryptfs_crypt_stat *crypt_stat,
+ struct ecryptfs_key_record *key_rec, int *packet_size)
+{
+ int rc = 0;
+
+ int i;
+ int signature_is_valid = 0;
+ int encrypted_session_key_valid = 0;
+ char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
+ struct scatterlist dest_sg[2];
+ struct scatterlist src_sg[2];
+ struct crypto_tfm *tfm = NULL;
+ int key_rec_size;
+ int packet_size_length;
+ int cipher_code;
+
+ (*packet_size) = 0;
+ /* Check for a valid signature on the auth_tok */
+ for (i = 0; i < ECRYPTFS_SIG_SIZE_HEX; i++)
+ signature_is_valid |= auth_tok->token.password.signature[i];
+ if (!signature_is_valid)
+ BUG();
+ ecryptfs_from_hex((*key_rec).sig, auth_tok->token.password.signature,
+ ECRYPTFS_SIG_SIZE);
+ (*key_rec).enc_key_size_bits = crypt_stat->key_size_bits;
+ encrypted_session_key_valid = 0;
+ if (auth_tok->session_key.encrypted_key_size == 0)
+ auth_tok->session_key.encrypted_key_size =
+ ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES;
+ for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
+ encrypted_session_key_valid |=
+ auth_tok->session_key.encrypted_key[i];
+ if (auth_tok->session_key.encrypted_key_size == 0) {
+ ecryptfs_printk(KERN_WARNING, "auth_tok->session_key."
+ "encrypted_key_size == 0");
+ auth_tok->session_key.encrypted_key_size =
+ ECRYPTFS_DEFAULT_KEY_BYTES;
+ }
+ if (encrypted_session_key_valid) {
+ memcpy((*key_rec).enc_key,
+ auth_tok->session_key.encrypted_key,
+ auth_tok->session_key.encrypted_key_size);
+ goto encrypted_session_key_set;
+ }
+ if (ECRYPTFS_CHECK_FLAG(auth_tok->token.password.flags,
+ ECRYPTFS_SESSION_KEY_ENCRYPTION_KEY_SET)) {
+ ecryptfs_printk(KERN_DEBUG, "Using previously generated "
+ "session key encryption key of size [%d]\n",
+ auth_tok->token.password.
+ session_key_encryption_key_bytes);
+ memcpy(session_key_encryption_key,
+ auth_tok->token.password.session_key_encryption_key,
+ auth_tok->token.password.
+ session_key_encryption_key_bytes);
+ ecryptfs_printk(KERN_DEBUG,
+ "Cached session key " "encryption key: \n");
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex(session_key_encryption_key, 16);
+ }
+ if (unlikely(ecryptfs_verbosity > 0)) {
+ ecryptfs_printk(KERN_DEBUG, "Session key encryption key:"
+ "\n");
+ ecryptfs_dump_hex(session_key_encryption_key, 16);
+ }
+ /* Encrypt the key with the key encryption key */
+ /* Set up the scatterlists */
+ rc = virt_to_scatterlist(crypt_stat->key,
+ crypt_stat->key_size_bits / 8, src_sg, 2);
+ if (!rc) {
+ ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
+ "for crypt_stat session key\n");
+ rc = -ENOMEM;
+ goto out;
+ }
+ rc = virt_to_scatterlist((*key_rec).enc_key,
+ (*key_rec).enc_key_size_bits / 8, dest_sg, 2);
+ if (!rc) {
+ ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
+ "for crypt_stat encrypted session key\n");
+ rc = -ENOMEM;
+ goto out;
+ }
+ if ((tfm = crypto_alloc_tfm(crypt_stat->cipher, 0)) == NULL) {
+ ecryptfs_printk(KERN_ERR, "Could not initialize crypto "
+ "context for cipher [%s]\n",
+ crypt_stat->cipher);
+ rc = -EINVAL;
+ goto out;
+ }
+ rc = crypto_cipher_setkey(tfm, session_key_encryption_key,
+ ECRYPTFS_DEFAULT_KEY_BYTES);
+ if (rc < 0) {
+ ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
+ "context\n");
+ goto out;
+ }
+ rc = 0;
+ ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
+ crypt_stat->key_size_bits / 8);
+ crypto_cipher_encrypt(tfm, dest_sg, src_sg,
+ crypt_stat->key_size_bits / 8);
+ ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
+ if (ecryptfs_verbosity > 0)
+ ecryptfs_dump_hex((*key_rec).enc_key,
+ (*key_rec).enc_key_size_bits / 8);
+encrypted_session_key_set:
+ /* Now we have a valid key_rec. Append it to the
+ * key_rec set. */
+ key_rec_size = (sizeof(struct ecryptfs_key_record)
+ - ECRYPTFS_MAX_KEY_BYTES
+ + ((*key_rec).enc_key_size_bits / 8) );
+ /* TODO: Include a packet size limit as a parameter to this
+ * function once we have multi-packet headers (for versions
+ * later than 0.1 */
+ if (key_rec_size >= ECRYPTFS_MAX_KEYSET_SIZE) {
+ ecryptfs_printk(KERN_ERR, "Keyset too large\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ /* TODO: Packet size limit */
+ /* We have 5 bytes of surrounding packet data */
+ if ((0x05 + ECRYPTFS_SALT_SIZE
+ + ((*key_rec).enc_key_size_bits / 8)) >= PAGE_CACHE_SIZE) {
+ ecryptfs_printk(KERN_ERR, "Authentication token is too "
+ "large\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ /* This format is inspired by OpenPGP; see RFC 2440
+ * packet tag 3 */
+ dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
+ /* ver+cipher+s2k+hash+salt+iter+enc_key */
+ rc = write_packet_length(&dest[(*packet_size)],
+ (0x05 + ECRYPTFS_SALT_SIZE
+ + ((*key_rec).enc_key_size_bits / 8)),
+ &packet_size_length);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error generating tag 3 packet "
+ "header; cannot generate packet length\n");
+ goto out;
+ }
+ (*packet_size) += packet_size_length;
+ dest[(*packet_size)++] = 0x04; /* version 4 */
+ cipher_code = ecryptfs_code_for_cipher_string(crypt_stat->cipher);
+ if (cipher_code == 0) {
+ ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
+ "cipher [%s]\n", crypt_stat->cipher);
+ rc = -EINVAL;
+ goto out;
+ }
+ /* If it is AES, we need to get more specific. */
+ if (cipher_code == 0x07) {
+ switch (crypt_stat->key_size_bits) {
+ case 128:
+ break;
+ case 192:
+ cipher_code = 0x08; /* AES-192 */
+ break;
+ case 256:
+ cipher_code = 0x09; /* AES-256 */
+ break;
+ default:
+ rc = -EINVAL;
+ ecryptfs_printk(KERN_WARNING, "Unsupported AES key "
+ "size: [%d]\n",
+ crypt_stat->key_size_bits);
+ goto out;
+ }
+ }
+ dest[(*packet_size)++] = cipher_code;
+ dest[(*packet_size)++] = 0x03; /* S2K */
+ dest[(*packet_size)++] = 0x01; /* MD5 (TODO: parameterize) */
+ memcpy(&dest[(*packet_size)], auth_tok->token.password.salt,
+ ECRYPTFS_SALT_SIZE);
+ (*packet_size) += ECRYPTFS_SALT_SIZE; /* salt */
+ dest[(*packet_size)++] = 0x60; /* hash iterations (65536) */
+ memcpy(&dest[(*packet_size)], (*key_rec).enc_key,
+ (*key_rec).enc_key_size_bits / 8);
+ (*packet_size) += ((*key_rec).enc_key_size_bits / 8);
+out:
+ if (tfm)
+ crypto_free_tfm(tfm);
+ if (rc)
+ (*packet_size) = 0;
+ return rc;
+}
+
+/**
+ * ecryptfs_generate_key_packet_set
+ * @dest: Virtual address from which to write the key record set
+ * @crypt_stat: The cryptographic context from which the
+ * authentication tokens will be retrieved
+ * @ecryptfs_dentry: The dentry, used to retrieve the mount crypt stat
+ * for the global parameters
+ * @len: The amount written
+ *
+ * Generates a key packet set and writes it to the virtual address
+ * passed in.
+ *
+ * Returns zero on success; non-zero on error.
+ */
+int
+ecryptfs_generate_key_packet_set(char *dest_base,
+ struct ecryptfs_crypt_stat *crypt_stat,
+ struct dentry *ecryptfs_dentry, int *len)
+{
+ int rc = 0;
+ struct ecryptfs_auth_tok *auth_tok;
+ struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
+ &ecryptfs_superblock_to_private(
+ ecryptfs_dentry->d_sb)->mount_crypt_stat;
+ int written;
+ struct ecryptfs_key_record key_rec;
+
+ (*len) = 0;
+ if (mount_crypt_stat->global_auth_tok) {
+ auth_tok = mount_crypt_stat->global_auth_tok;
+ if (ECRYPTFS_CHECK_FLAG(auth_tok->flags, ECRYPTFS_PASSWORD)) {
+ rc = write_tag_3_packet((dest_base + (*len)),
+ PAGE_CACHE_SIZE, auth_tok,
+ crypt_stat, &key_rec,
+ &written);
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING, "Error "
+ "writing tag 3 packet\n");
+ goto out;
+ }
+ (*len) += written;
+ /* Write auth tok signature packet */
+ rc = write_tag_11_packet(
+ (dest_base + (*len)),
+ (PAGE_CACHE_SIZE - (*len)),
+ key_rec.sig, ECRYPTFS_SIG_SIZE, &written);
+ if (rc) {
+ ecryptfs_printk(KERN_ERR, "Error writing "
+ "auth tok signature packet\n");
+ goto out;
+ }
+ (*len) += written;
+ } else {
+ ecryptfs_printk(KERN_WARNING, "Unsupported "
+ "authentication token type\n");
+ rc = -EINVAL;
+ goto out;
+ }
+ if (rc) {
+ ecryptfs_printk(KERN_WARNING, "Error writing "
+ "authentication token packet with sig "
+ "= [%s]\n",
+ mount_crypt_stat->global_auth_tok_sig);
+ rc = -EIO;
+ goto out;
+ }
+ } else
+ BUG();
+ dest_base[(*len)] = 0x00;
+out:
+ if (rc)
+ (*len) = 0;
+ return rc;
+}