keystore.c 79.3 KB
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/**
 * 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>
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 *              Trevor S. Highland <trevor.highland@gmail.com>
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 *
 * 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.
 */

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#include <crypto/hash.h>
#include <crypto/skcipher.h>
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#include <linux/string.h>
#include <linux/pagemap.h>
#include <linux/key.h>
#include <linux/random.h>
#include <linux/scatterlist.h>
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#include <linux/slab.h>
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#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.
 */
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static int process_request_key_err(long err_code)
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{
	int rc = 0;

	switch (err_code) {
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	case -ENOKEY:
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		ecryptfs_printk(KERN_WARNING, "No key\n");
		rc = -ENOENT;
		break;
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	case -EKEYEXPIRED:
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		ecryptfs_printk(KERN_WARNING, "Key expired\n");
		rc = -ETIME;
		break;
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	case -EKEYREVOKED:
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		ecryptfs_printk(KERN_WARNING, "Key revoked\n");
		rc = -EINVAL;
		break;
	default:
		ecryptfs_printk(KERN_WARNING, "Unknown error code: "
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				"[0x%.16lx]\n", err_code);
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		rc = -EINVAL;
	}
	return rc;
}

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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;
}

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/**
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 * ecryptfs_parse_packet_length
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 * @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
 *
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 * Returns zero on success; non-zero on error
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 */
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int ecryptfs_parse_packet_length(unsigned char *data, size_t *size,
				 size_t *length_size)
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{
	int rc = 0;

	(*length_size) = 0;
	(*size) = 0;
	if (data[0] < 192) {
		/* One-byte length */
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		(*size) = data[0];
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		(*length_size) = 1;
	} else if (data[0] < 224) {
		/* Two-byte length */
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		(*size) = (data[0] - 192) * 256;
		(*size) += data[1] + 192;
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		(*length_size) = 2;
	} else if (data[0] == 255) {
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		/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
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		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;
}

/**
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 * ecryptfs_write_packet_length
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 * @dest: The byte array target into which to write the length. Must
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 *        have at least ECRYPTFS_MAX_PKT_LEN_SIZE bytes allocated.
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 * @size: The length to write.
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 * @packet_size_length: The number of bytes used to encode the packet
 *                      length is written to this address.
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 *
 * Returns zero on success; non-zero on error.
 */
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int ecryptfs_write_packet_length(char *dest, size_t size,
				 size_t *packet_size_length)
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{
	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 {
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		/* If support is added, adjust ECRYPTFS_MAX_PKT_LEN_SIZE */
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		rc = -EINVAL;
		ecryptfs_printk(KERN_WARNING,
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				"Unsupported packet size: [%zd]\n", size);
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	}
	return rc;
}

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static int
write_tag_64_packet(char *signature, struct ecryptfs_session_key *session_key,
		    char **packet, size_t *packet_len)
{
	size_t i = 0;
	size_t data_len;
	size_t packet_size_len;
	char *message;
	int rc;

	/*
	 *              ***** TAG 64 Packet Format *****
	 *    | Content Type                       | 1 byte       |
	 *    | Key Identifier Size                | 1 or 2 bytes |
	 *    | Key Identifier                     | arbitrary    |
	 *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
	 *    | Encrypted File Encryption Key      | arbitrary    |
	 */
	data_len = (5 + ECRYPTFS_SIG_SIZE_HEX
		    + session_key->encrypted_key_size);
	*packet = kmalloc(data_len, GFP_KERNEL);
	message = *packet;
	if (!message) {
		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	message[i++] = ECRYPTFS_TAG_64_PACKET_TYPE;
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	rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
					  &packet_size_len);
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	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	i += packet_size_len;
	memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
	i += ECRYPTFS_SIG_SIZE_HEX;
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	rc = ecryptfs_write_packet_length(&message[i],
					  session_key->encrypted_key_size,
					  &packet_size_len);
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	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 64 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	i += packet_size_len;
	memcpy(&message[i], session_key->encrypted_key,
	       session_key->encrypted_key_size);
	i += session_key->encrypted_key_size;
	*packet_len = i;
out:
	return rc;
}

static int
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parse_tag_65_packet(struct ecryptfs_session_key *session_key, u8 *cipher_code,
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		    struct ecryptfs_message *msg)
{
	size_t i = 0;
	char *data;
	size_t data_len;
	size_t m_size;
	size_t message_len;
	u16 checksum = 0;
	u16 expected_checksum = 0;
	int rc;

	/*
	 *              ***** TAG 65 Packet Format *****
	 *         | Content Type             | 1 byte       |
	 *         | Status Indicator         | 1 byte       |
	 *         | File Encryption Key Size | 1 or 2 bytes |
	 *         | File Encryption Key      | arbitrary    |
	 */
	message_len = msg->data_len;
	data = msg->data;
	if (message_len < 4) {
		rc = -EIO;
		goto out;
	}
	if (data[i++] != ECRYPTFS_TAG_65_PACKET_TYPE) {
		ecryptfs_printk(KERN_ERR, "Type should be ECRYPTFS_TAG_65\n");
		rc = -EIO;
		goto out;
	}
	if (data[i++]) {
		ecryptfs_printk(KERN_ERR, "Status indicator has non-zero value "
				"[%d]\n", data[i-1]);
		rc = -EIO;
		goto out;
	}
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	rc = ecryptfs_parse_packet_length(&data[i], &m_size, &data_len);
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	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
				"rc = [%d]\n", rc);
		goto out;
	}
	i += data_len;
	if (message_len < (i + m_size)) {
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		ecryptfs_printk(KERN_ERR, "The message received from ecryptfsd "
				"is shorter than expected\n");
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		rc = -EIO;
		goto out;
	}
	if (m_size < 3) {
		ecryptfs_printk(KERN_ERR,
				"The decrypted key is not long enough to "
				"include a cipher code and checksum\n");
		rc = -EIO;
		goto out;
	}
	*cipher_code = data[i++];
	/* The decrypted key includes 1 byte cipher code and 2 byte checksum */
	session_key->decrypted_key_size = m_size - 3;
	if (session_key->decrypted_key_size > ECRYPTFS_MAX_KEY_BYTES) {
		ecryptfs_printk(KERN_ERR, "key_size [%d] larger than "
				"the maximum key size [%d]\n",
				session_key->decrypted_key_size,
				ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
		rc = -EIO;
		goto out;
	}
	memcpy(session_key->decrypted_key, &data[i],
	       session_key->decrypted_key_size);
	i += session_key->decrypted_key_size;
	expected_checksum += (unsigned char)(data[i++]) << 8;
	expected_checksum += (unsigned char)(data[i++]);
	for (i = 0; i < session_key->decrypted_key_size; i++)
		checksum += session_key->decrypted_key[i];
	if (expected_checksum != checksum) {
		ecryptfs_printk(KERN_ERR, "Invalid checksum for file "
				"encryption  key; expected [%x]; calculated "
				"[%x]\n", expected_checksum, checksum);
		rc = -EIO;
	}
out:
	return rc;
}


static int
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write_tag_66_packet(char *signature, u8 cipher_code,
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		    struct ecryptfs_crypt_stat *crypt_stat, char **packet,
		    size_t *packet_len)
{
	size_t i = 0;
	size_t j;
	size_t data_len;
	size_t checksum = 0;
	size_t packet_size_len;
	char *message;
	int rc;

	/*
	 *              ***** TAG 66 Packet Format *****
	 *         | Content Type             | 1 byte       |
	 *         | Key Identifier Size      | 1 or 2 bytes |
	 *         | Key Identifier           | arbitrary    |
	 *         | File Encryption Key Size | 1 or 2 bytes |
	 *         | File Encryption Key      | arbitrary    |
	 */
	data_len = (5 + ECRYPTFS_SIG_SIZE_HEX + crypt_stat->key_size);
	*packet = kmalloc(data_len, GFP_KERNEL);
	message = *packet;
	if (!message) {
		ecryptfs_printk(KERN_ERR, "Unable to allocate memory\n");
		rc = -ENOMEM;
		goto out;
	}
	message[i++] = ECRYPTFS_TAG_66_PACKET_TYPE;
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	rc = ecryptfs_write_packet_length(&message[i], ECRYPTFS_SIG_SIZE_HEX,
					  &packet_size_len);
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	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	i += packet_size_len;
	memcpy(&message[i], signature, ECRYPTFS_SIG_SIZE_HEX);
	i += ECRYPTFS_SIG_SIZE_HEX;
	/* The encrypted key includes 1 byte cipher code and 2 byte checksum */
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	rc = ecryptfs_write_packet_length(&message[i], crypt_stat->key_size + 3,
					  &packet_size_len);
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	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 66 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	i += packet_size_len;
	message[i++] = cipher_code;
	memcpy(&message[i], crypt_stat->key, crypt_stat->key_size);
	i += crypt_stat->key_size;
	for (j = 0; j < crypt_stat->key_size; j++)
		checksum += crypt_stat->key[j];
	message[i++] = (checksum / 256) % 256;
	message[i++] = (checksum % 256);
	*packet_len = i;
out:
	return rc;
}

static int
parse_tag_67_packet(struct ecryptfs_key_record *key_rec,
		    struct ecryptfs_message *msg)
{
	size_t i = 0;
	char *data;
	size_t data_len;
	size_t message_len;
	int rc;

	/*
	 *              ***** TAG 65 Packet Format *****
	 *    | Content Type                       | 1 byte       |
	 *    | Status Indicator                   | 1 byte       |
	 *    | Encrypted File Encryption Key Size | 1 or 2 bytes |
	 *    | Encrypted File Encryption Key      | arbitrary    |
	 */
	message_len = msg->data_len;
	data = msg->data;
	/* verify that everything through the encrypted FEK size is present */
	if (message_len < 4) {
		rc = -EIO;
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		printk(KERN_ERR "%s: message_len is [%zd]; minimum acceptable "
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		       "message length is [%d]\n", __func__, message_len, 4);
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		goto out;
	}
	if (data[i++] != ECRYPTFS_TAG_67_PACKET_TYPE) {
		rc = -EIO;
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		printk(KERN_ERR "%s: Type should be ECRYPTFS_TAG_67\n",
		       __func__);
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		goto out;
	}
	if (data[i++]) {
		rc = -EIO;
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		printk(KERN_ERR "%s: Status indicator has non zero "
		       "value [%d]\n", __func__, data[i-1]);

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		goto out;
	}
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	rc = ecryptfs_parse_packet_length(&data[i], &key_rec->enc_key_size,
					  &data_len);
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	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error parsing packet length; "
				"rc = [%d]\n", rc);
		goto out;
	}
	i += data_len;
	if (message_len < (i + key_rec->enc_key_size)) {
		rc = -EIO;
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		printk(KERN_ERR "%s: message_len [%zd]; max len is [%zd]\n",
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		       __func__, message_len, (i + key_rec->enc_key_size));
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		goto out;
	}
	if (key_rec->enc_key_size > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
		rc = -EIO;
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		printk(KERN_ERR "%s: Encrypted key_size [%zd] larger than "
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		       "the maximum key size [%d]\n", __func__,
		       key_rec->enc_key_size,
		       ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES);
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		goto out;
	}
	memcpy(key_rec->enc_key, &data[i], key_rec->enc_key_size);
out:
	return rc;
}

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/**
 * 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
 *
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 * Returns zero on valid auth tok; -EINVAL if the payload is invalid; or
 * -EKEYREVOKED if the key was revoked before we acquired its semaphore.
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 */
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);
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	if (IS_ERR(*auth_tok)) {
		rc = PTR_ERR(*auth_tok);
		*auth_tok = NULL;
		goto out;
	}

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	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;
}

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static int
ecryptfs_find_global_auth_tok_for_sig(
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	struct key **auth_tok_key,
	struct ecryptfs_auth_tok **auth_tok,
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	struct ecryptfs_mount_crypt_stat *mount_crypt_stat, char *sig)
{
	struct ecryptfs_global_auth_tok *walker;
	int rc = 0;

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	(*auth_tok_key) = NULL;
	(*auth_tok) = NULL;
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	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) {
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		if (memcmp(walker->sig, sig, ECRYPTFS_SIG_SIZE_HEX))
			continue;

		if (walker->flags & ECRYPTFS_AUTH_TOK_INVALID) {
			rc = -EINVAL;
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			goto out;
		}
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		rc = key_validate(walker->global_auth_tok_key);
		if (rc) {
			if (rc == -EKEYEXPIRED)
				goto out;
			goto out_invalid_auth_tok;
		}

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		down_write(&(walker->global_auth_tok_key->sem));
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		rc = ecryptfs_verify_auth_tok_from_key(
				walker->global_auth_tok_key, auth_tok);
		if (rc)
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			goto out_invalid_auth_tok_unlock;
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		(*auth_tok_key) = walker->global_auth_tok_key;
		key_get(*auth_tok_key);
		goto out;
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	}
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	rc = -ENOENT;
	goto out;
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out_invalid_auth_tok_unlock:
	up_write(&(walker->global_auth_tok_key->sem));
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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;
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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(
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	struct key **auth_tok_key,
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	struct ecryptfs_auth_tok **auth_tok,
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
	char *sig)
{
	int rc = 0;

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	rc = ecryptfs_find_global_auth_tok_for_sig(auth_tok_key, auth_tok,
						   mount_crypt_stat, sig);
	if (rc == -ENOENT) {
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		/* 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
		 * function.
		 */
		if (mount_crypt_stat->flags
				& ECRYPTFS_GLOBAL_MOUNT_AUTH_TOK_ONLY)
			return -EINVAL;

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		rc = ecryptfs_keyring_auth_tok_for_sig(auth_tok_key, auth_tok,
588
						       sig);
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	}
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	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;
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	struct scatterlist src_sg[2];
	struct scatterlist dst_sg[2];
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	struct crypto_skcipher *skcipher_tfm;
	struct skcipher_request *skcipher_req;
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	char iv[ECRYPTFS_MAX_IV_BYTES];
	char hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
	char tmp_hash[ECRYPTFS_TAG_70_DIGEST_SIZE];
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	struct crypto_shash *hash_tfm;
	struct shash_desc *hash_desc;
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};

/**
 * 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;
638
	struct key *auth_tok_key = NULL;
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	int rc = 0;

641
	s = kzalloc(sizeof(*s), GFP_KERNEL);
642
	if (!s)
643
		return -ENOMEM;
644

645
	(*packet_size) = 0;
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	rc = ecryptfs_find_auth_tok_for_sig(
		&auth_tok_key,
		&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;
	}
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	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(
657
		&s->skcipher_tfm,
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		&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);
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	s->block_size = crypto_skcipher_blocksize(s->skcipher_tfm);
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	/* 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 */
686
	s->max_packet_size = (ECRYPTFS_TAG_70_MAX_METADATA_SIZE
687
			      + s->block_aligned_filename_size);
688
	if (!dest) {
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		(*packet_size) = s->max_packet_size;
		goto out_unlock;
	}
	if (s->max_packet_size > (*remaining_bytes)) {
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		printk(KERN_WARNING "%s: Require [%zd] bytes to write; only "
		       "[%zd] available\n", __func__, s->max_packet_size,
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		       (*remaining_bytes));
		rc = -EINVAL;
		goto out_unlock;
	}
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	s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
	if (!s->skcipher_req) {
		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
		       "skcipher_request_alloc for %s\n", __func__,
		       crypto_skcipher_driver_name(s->skcipher_tfm));
		rc = -ENOMEM;
		goto out_unlock;
	}

	skcipher_request_set_callback(s->skcipher_req,
				      CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

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	s->block_aligned_filename = kzalloc(s->block_aligned_filename_size,
					    GFP_KERNEL);
	if (!s->block_aligned_filename) {
		rc = -ENOMEM;
		goto out_unlock;
	}
	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 "
740
		       "cipher [%s] with key bytes [%zd]\n", __func__,
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		       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;
	/* TODO: Support other key modules than passphrase for
	 * filename encryption */
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	if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
		rc = -EOPNOTSUPP;
		printk(KERN_INFO "%s: Filename encryption only supports "
		       "password tokens\n", __func__);
		goto out_free_unlock;
	}
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	s->hash_tfm = crypto_alloc_shash(ECRYPTFS_TAG_70_DIGEST, 0, 0);
	if (IS_ERR(s->hash_tfm)) {
			rc = PTR_ERR(s->hash_tfm);
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			printk(KERN_ERR "%s: Error attempting to "
			       "allocate hash crypto context; rc = [%d]\n",
			       __func__, rc);
			goto out_free_unlock;
	}
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	s->hash_desc = kmalloc(sizeof(*s->hash_desc) +
			       crypto_shash_descsize(s->hash_tfm), GFP_KERNEL);
	if (!s->hash_desc) {
		rc = -ENOMEM;
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		goto out_release_free_unlock;
	}
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	s->hash_desc->tfm = s->hash_tfm;
	s->hash_desc->flags = CRYPTO_TFM_REQ_MAY_SLEEP;

	rc = crypto_shash_digest(s->hash_desc,
				 (u8 *)s->auth_tok->token.password.session_key_encryption_key,
				 s->auth_tok->token.password.session_key_encryption_key_bytes,
				 s->hash);
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	if (rc) {
		printk(KERN_ERR
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		       "%s: Error computing crypto hash; rc = [%d]\n",
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		       __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)) {
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			rc = crypto_shash_digest(s->hash_desc, (u8 *)s->hash,
						ECRYPTFS_TAG_70_DIGEST_SIZE,
						s->tmp_hash);
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			if (rc) {
				printk(KERN_ERR
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				       "%s: Error computing crypto hash; "
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				       "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,
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				 s->block_aligned_filename_size, s->src_sg, 2);
	if (rc < 1) {
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		printk(KERN_ERR "%s: Internal error whilst attempting to "
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		       "convert filename memory to scatterlist; rc = [%d]. "
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		       "block_aligned_filename_size = [%zd]\n", __func__, rc,
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		       s->block_aligned_filename_size);
		goto out_release_free_unlock;
	}
	rc = virt_to_scatterlist(&dest[s->i], s->block_aligned_filename_size,
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				 s->dst_sg, 2);
	if (rc < 1) {
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		printk(KERN_ERR "%s: Internal error whilst attempting to "
		       "convert encrypted filename memory to scatterlist; "
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		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
		       __func__, rc, s->block_aligned_filename_size);
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		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. */
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	rc = crypto_skcipher_setkey(
		s->skcipher_tfm,
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		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->"
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		       "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
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		       rc,
		       s->auth_tok->token.password.session_key_encryption_key,
		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
		goto out_release_free_unlock;
	}
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	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
				   s->block_aligned_filename_size, s->iv);
	rc = crypto_skcipher_encrypt(s->skcipher_req);
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	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:
854
	crypto_free_shash(s->hash_tfm);
855
out_free_unlock:
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Johannes Weiner committed
856
	kzfree(s->block_aligned_filename);
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out_unlock:
	mutex_unlock(s->tfm_mutex);
out:
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	if (auth_tok_key) {
		up_write(&(auth_tok_key->sem));
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		key_put(auth_tok_key);
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	}
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	skcipher_request_free(s->skcipher_req);
	kzfree(s->hash_desc);
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	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;
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	struct scatterlist src_sg[2];
	struct scatterlist dst_sg[2];
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	struct crypto_skcipher *skcipher_tfm;
	struct skcipher_request *skcipher_req;
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	char fnek_sig_hex[ECRYPTFS_SIG_SIZE_HEX + 1];
	char iv[ECRYPTFS_MAX_IV_BYTES];
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	char cipher_string[ECRYPTFS_MAX_CIPHER_NAME_SIZE + 1];
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};

/**
 * parse_tag_70_packet - Parse and process FNEK-encrypted passphrase packet
 * @filename: This function kmalloc's the memory for the filename
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 * @filename_size: This function sets this to the amount of memory
 *                 kmalloc'd for the filename
 * @packet_size: This function sets this to the the number of octets
 *               in the packet parsed
 * @mount_crypt_stat: The mount-wide cryptographic context
 * @data: The memory location containing the start of the tag 70
 *        packet
 * @max_packet_size: The maximum legal size of the packet to be parsed
 *                   from @data
 *
 * Returns zero on success; non-zero otherwise
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 */
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;
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	struct key *auth_tok_key = NULL;
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	int rc = 0;

	(*packet_size) = 0;
	(*filename_size) = 0;
	(*filename) = NULL;
918
	s = kzalloc(sizeof(*s), GFP_KERNEL);
919
	if (!s)
920
		return -ENOMEM;
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922
	if (max_packet_size < ECRYPTFS_TAG_70_MIN_METADATA_SIZE) {
923
		printk(KERN_WARNING "%s: max_packet_size is [%zd]; it must be "
924
		       "at least [%d]\n", __func__, max_packet_size,
925
		       ECRYPTFS_TAG_70_MIN_METADATA_SIZE);
926 927 928 929 930 931 932 933 934 935 936 937 938 939 940 941 942 943 944 945 946 947 948 949 950 951 952 953 954 955
		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) {
956 957
		printk(KERN_WARNING "%s: max_packet_size is [%zd]; real packet "
		       "size is [%zd]\n", __func__, max_packet_size,
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		       (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;
	}
975 976 977 978 979 980 981 982 983
	rc = ecryptfs_find_auth_tok_for_sig(&auth_tok_key,
					    &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;
	}
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	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&s->skcipher_tfm,
985 986 987 988 989 990 991 992 993 994
							&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)],
995 996
				 s->block_aligned_filename_size, s->src_sg, 2);
	if (rc < 1) {
997 998
		printk(KERN_ERR "%s: Internal error whilst attempting to "
		       "convert encrypted filename memory to scatterlist; "
999 1000
		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
		       __func__, rc, s->block_aligned_filename_size);
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010
		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) {
		rc = -ENOMEM;
		goto out_unlock;
	}
	rc = virt_to_scatterlist(s->decrypted_filename,
1011 1012
				 s->block_aligned_filename_size, s->dst_sg, 2);
	if (rc < 1) {
1013 1014
		printk(KERN_ERR "%s: Internal error whilst attempting to "
		       "convert decrypted filename memory to scatterlist; "
1015 1016
		       "rc = [%d]. block_aligned_filename_size = [%zd]\n",
		       __func__, rc, s->block_aligned_filename_size);
1017 1018
		goto out_free_unlock;
	}
1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031

	s->skcipher_req = skcipher_request_alloc(s->skcipher_tfm, GFP_KERNEL);
	if (!s->skcipher_req) {
		printk(KERN_ERR "%s: Out of kernel memory whilst attempting to "
		       "skcipher_request_alloc for %s\n", __func__,
		       crypto_skcipher_driver_name(s->skcipher_tfm));
		rc = -ENOMEM;
		goto out_free_unlock;
	}

	skcipher_request_set_callback(s->skcipher_req,
				      CRYPTO_TFM_REQ_MAY_SLEEP, NULL, NULL);

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	/* 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. */
	/* TODO: Support other key modules than passphrase for
	 * filename encryption */
1038 1039 1040 1041 1042 1043
	if (s->auth_tok->token_type != ECRYPTFS_PASSWORD) {
		rc = -EOPNOTSUPP;
		printk(KERN_INFO "%s: Filename encryption only supports "
		       "password tokens\n", __func__);
		goto out_free_unlock;
	}
1044 1045
	rc = crypto_skcipher_setkey(
		s->skcipher_tfm,
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		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->"
1052
		       "global_default_fn_cipher_key_bytes = [%zd]\n", __func__,
1053 1054 1055 1056 1057
		       rc,
		       s->auth_tok->token.password.session_key_encryption_key,
		       mount_crypt_stat->global_default_fn_cipher_key_bytes);
		goto out_free_unlock;
	}
1058 1059 1060
	skcipher_request_set_crypt(s->skcipher_req, s->src_sg, s->dst_sg,
				   s->block_aligned_filename_size, s->iv);
	rc = crypto_skcipher_decrypt(s->skcipher_req);
1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078
	if (rc) {
		printk(KERN_ERR "%s: Error attempting to decrypt filename; "
		       "rc = [%d]\n", __func__, rc);
		goto out_free_unlock;
	}
	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))) {
1079
		printk(KERN_WARNING "%s: Filename size is [%zd], which is "
1080 1081 1082 1083 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099 1100
		       "invalid\n", __func__, (*filename_size));
		rc = -EINVAL;
		goto out_free_unlock;
	}
	(*filename) = kmalloc(((*filename_size) + 1), GFP_KERNEL);
	if (!(*filename)) {
		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;
	}
1101 1102
	if (auth_tok_key) {
		up_write(&(auth_tok_key->sem));
1103
		key_put(auth_tok_key);
1104
	}
1105
	skcipher_request_free(s->skcipher_req);
1106 1107 1108 1109
	kfree(s);
	return rc;
}

1110 1111 1112 1113 1114 1115 1116 1117 1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130
static int
ecryptfs_get_auth_tok_sig(char **sig, struct ecryptfs_auth_tok *auth_tok)
{
	int rc = 0;

	(*sig) = NULL;
	switch (auth_tok->token_type) {
	case ECRYPTFS_PASSWORD:
		(*sig) = auth_tok->token.password.signature;
		break;
	case ECRYPTFS_PRIVATE_KEY:
		(*sig) = auth_tok->token.private_key.signature;
		break;
	default:
		printk(KERN_ERR "Cannot get sig for auth_tok of type [%d]\n",
		       auth_tok->token_type);
		rc = -EINVAL;
	}
	return rc;
}

1131
/**
1132 1133 1134
 * decrypt_pki_encrypted_session_key - Decrypt the session key with the given auth_tok.
 * @auth_tok: The key authentication token used to decrypt the session key
 * @crypt_stat: The cryptographic context
1135
 *
1136
 * Returns zero on success; non-zero error otherwise.
1137
 */
1138 1139 1140
static int
decrypt_pki_encrypted_session_key(struct ecryptfs_auth_tok *auth_tok,
				  struct ecryptfs_crypt_stat *crypt_stat)
1141
{
1142
	u8 cipher_code = 0;
1143 1144
	struct ecryptfs_msg_ctx *msg_ctx;
	struct ecryptfs_message *msg = NULL;
1145
	char *auth_tok_sig;
1146
	char *payload = NULL;
1147
	size_t payload_len = 0;
1148 1149
	int rc;

1150 1151
	rc = ecryptfs_get_auth_tok_sig(&auth_tok_sig, auth_tok);
	if (rc) {
1152 1153 1154 1155 1156
		printk(KERN_ERR "Unrecognized auth tok type: [%d]\n",
		       auth_tok->token_type);
		goto out;
	}
	rc = write_tag_64_packet(auth_tok_sig, &(auth_tok->session_key),
1157
				 &payload, &payload_len);
1158
	if (rc) {
1159
		ecryptfs_printk(KERN_ERR, "Failed to write tag 64 packet\n");
1160 1161
		goto out;
	}
1162
	rc = ecryptfs_send_message(payload, payload_len, &msg_ctx);
1163
	if (rc) {
1164
		ecryptfs_printk(KERN_ERR, "Error sending message to "
1165
				"ecryptfsd: %d\n", rc);
1166 1167 1168 1169 1170 1171 1172 1173 1174 1175 1176 1177 1178 1179 1180 1181 1182 1183 1184 1185 1186 1187 1188 1189 1190 1191 1192 1193 1194 1195 1196 1197 1198
		goto out;
	}
	rc = ecryptfs_wait_for_response(msg_ctx, &msg);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Failed to receive tag 65 packet "
				"from the user space daemon\n");
		rc = -EIO;
		goto out;
	}
	rc = parse_tag_65_packet(&(auth_tok->session_key),
				 &cipher_code, msg);
	if (rc) {
		printk(KERN_ERR "Failed to parse tag 65 packet; rc = [%d]\n",
		       rc);
		goto out;
	}
	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);
	crypt_stat->key_size = auth_tok->session_key.decrypted_key_size;
	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher, cipher_code);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Cipher code [%d] is invalid\n",
				cipher_code)
		goto out;
	}
	crypt_stat->flags |= ECRYPTFS_KEY_VALID;
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "Decrypted session key:\n");
		ecryptfs_dump_hex(crypt_stat->key,
				  crypt_stat->key_size);
	}
out:
1199
	kfree(msg);
1200
	kfree(payload);
1201 1202 1203 1204 1205 1206
	return rc;
}

static void wipe_auth_tok_list(struct list_head *auth_tok_list_head)
{
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
1207
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item_tmp;
1208

1209 1210 1211
	list_for_each_entry_safe(auth_tok_list_item, auth_tok_list_item_tmp,
				 auth_tok_list_head, list) {
		list_del(&auth_tok_list_item->list);
1212 1213 1214 1215 1216 1217 1218 1219 1220
		kmem_cache_free(ecryptfs_auth_tok_list_item_cache,
				auth_tok_list_item);
	}
}

struct kmem_cache *ecryptfs_auth_tok_list_item_cache;

/**
 * parse_tag_1_packet
1221
 * @crypt_stat: The cryptographic context to modify based on packet contents
1222 1223
 * @data: The raw bytes of the packet.
 * @auth_tok_list: eCryptfs parses packets into authentication tokens;
1224 1225
 *                 a new authentication token will be placed at the
 *                 end of this list for this packet.
1226 1227 1228 1229 1230 1231
 * @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.
1232
 * @max_packet_size: The maximum allowable packet size
1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_1_packet(struct ecryptfs_crypt_stat *crypt_stat,
		   unsigned char *data, struct list_head *auth_tok_list,
		   struct ecryptfs_auth_tok **new_auth_tok,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
	int rc = 0;

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;
1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260
	/**
	 * This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 1
	 *
	 * Tag 1 identifier (1 byte)
	 * Max Tag 1 packet size (max 3 bytes)
	 * Version (1 byte)
	 * Key identifier (8 bytes; ECRYPTFS_SIG_SIZE)
	 * Cipher identifier (1 byte)
	 * Encrypted key size (arbitrary)
	 *
	 * 12 bytes minimum packet size
1261
	 */
1262 1263
	if (unlikely(max_packet_size < 12)) {
		printk(KERN_ERR "Invalid max packet size; must be >=12\n");
1264 1265 1266 1267
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_1_PACKET_TYPE) {
1268 1269
		printk(KERN_ERR "Enter w/ first byte != 0x%.2x\n",
		       ECRYPTFS_TAG_1_PACKET_TYPE);
1270 1271 1272 1273 1274 1275
		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 =
1276 1277
		kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache,
				  GFP_KERNEL);
1278
	if (!auth_tok_list_item) {
1279
		printk(KERN_ERR "Unable to allocate memory\n");
1280 1281 1282 1283
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
1284 1285
	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
					  &length_size);
1286
	if (rc) {
1287 1288
		printk(KERN_WARNING "Error parsing packet length; "
		       "rc = [%d]\n", rc);
1289 1290
		goto out_free;
	}
1291
	if (unlikely(body_size < (ECRYPTFS_SIG_SIZE + 2))) {
1292
		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1293 1294 1295 1296 1297
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
1298
		printk(KERN_WARNING "Packet size exceeds max\n");
1299 1300 1301 1302
		rc = -EINVAL;
		goto out_free;
	}
	if (unlikely(data[(*packet_size)++] != 0x03)) {
1303 1304
		printk(KERN_WARNING "Unknown version number [%d]\n",
		       data[(*packet_size) - 1]);
1305 1306 1307 1308 1309 1310 1311 1312 1313 1314
		rc = -EINVAL;
		goto out_free;
	}
	ecryptfs_to_hex((*new_auth_tok)->token.private_key.signature,
			&data[(*packet_size)], ECRYPTFS_SIG_SIZE);
	*packet_size += ECRYPTFS_SIG_SIZE;
	/* This byte is skipped because the kernel does not need to
	 * know which public key encryption algorithm was used */
	(*packet_size)++;
	(*new_auth_tok)->session_key.encrypted_key_size =
1315
		body_size - (ECRYPTFS_SIG_SIZE + 2);
1316 1317
	if ((*new_auth_tok)->session_key.encrypted_key_size
	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
1318
		printk(KERN_WARNING "Tag 1 packet contains key larger "
1319
		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
1320 1321 1322 1323
		rc = -EINVAL;
		goto out;
	}
	memcpy((*new_auth_tok)->session_key.encrypted_key,
1324
	       &data[(*packet_size)], (body_size - (ECRYPTFS_SIG_SIZE + 2)));
1325 1326 1327 1328 1329 1330
	(*packet_size) += (*new_auth_tok)->session_key.encrypted_key_size;
	(*new_auth_tok)->session_key.flags &=
		~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
	(*new_auth_tok)->session_key.flags |=
		ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
	(*new_auth_tok)->token_type = ECRYPTFS_PRIVATE_KEY;
1331
	(*new_auth_tok)->flags = 0;
1332 1333 1334 1335
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
		~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1336 1337 1338 1339 1340 1341 1342 1343 1344 1345 1346 1347 1348 1349
	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;
}

1350 1351 1352 1353 1354 1355 1356 1357 1358 1359 1360 1361 1362 1363 1364 1365 1366 1367 1368 1369 1370 1371 1372 1373 1374 1375 1376
/**
 * 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.
 * @max_packet_size: maximum number of bytes to parse
 *
 * 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,
		   size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	struct ecryptfs_auth_tok_list_item *auth_tok_list_item;
	size_t length_size;
1377
	int rc = 0;
1378 1379 1380

	(*packet_size) = 0;
	(*new_auth_tok) = NULL;
1381 1382 1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393 1394 1395
	/**
	 *This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 3
	 *
	 * Tag 3 identifier (1 byte)
	 * Max Tag 3 packet size (max 3 bytes)
	 * Version (1 byte)
	 * Cipher code (1 byte)
	 * S2K specifier (1 byte)
	 * Hash identifier (1 byte)
	 * Salt (ECRYPTFS_SALT_SIZE)
	 * Hash iterations (1 byte)
	 * Encrypted key (arbitrary)
	 *
	 * (ECRYPTFS_SALT_SIZE + 7) minimum packet size
1396
	 */
1397 1398
	if (max_packet_size < (ECRYPTFS_SALT_SIZE + 7)) {
		printk(KERN_ERR "Max packet size too large\n");
1399 1400 1401 1402
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_3_PACKET_TYPE) {
1403 1404
		printk(KERN_ERR "First byte != 0x%.2x; invalid packet\n",
		       ECRYPTFS_TAG_3_PACKET_TYPE);
1405 1406 1407 1408 1409 1410
		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 =
1411
	    kmem_cache_zalloc(ecryptfs_auth_tok_list_item_cache, GFP_KERNEL);
1412
	if (!auth_tok_list_item) {
1413
		printk(KERN_ERR "Unable to allocate memory\n");
1414 1415 1416 1417
		rc = -ENOMEM;
		goto out;
	}
	(*new_auth_tok) = &auth_tok_list_item->auth_tok;
1418 1419
	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
					  &length_size);
1420
	if (rc) {
1421 1422
		printk(KERN_WARNING "Error parsing packet length; rc = [%d]\n",
		       rc);
1423 1424
		goto out_free;
	}
1425
	if (unlikely(body_size < (ECRYPTFS_SALT_SIZE + 5))) {
1426
		printk(KERN_WARNING "Invalid body size ([%td])\n", body_size);
1427 1428 1429 1430 1431
		rc = -EINVAL;
		goto out_free;
	}
	(*packet_size) += length_size;
	if (unlikely((*packet_size) + body_size > max_packet_size)) {
1432
		printk(KERN_ERR "Packet size exceeds max\n");
1433 1434 1435 1436
		rc = -EINVAL;
		goto out_free;
	}
	(*new_auth_tok)->session_key.encrypted_key_size =
1437
		(body_size - (ECRYPTFS_SALT_SIZE + 5));
1438 1439 1440 1441 1442 1443 1444
	if ((*new_auth_tok)->session_key.encrypted_key_size
	    > ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES) {
		printk(KERN_WARNING "Tag 3 packet contains key larger "
		       "than ECRYPTFS_MAX_ENCRYPTED_KEY_BYTES\n");
		rc = -EINVAL;
		goto out_free;
	}
1445
	if (unlikely(data[(*packet_size)++] != 0x04)) {
1446 1447
		printk(KERN_WARNING "Unknown version number [%d]\n",
		       data[(*packet_size) - 1]);
1448 1449 1450
		rc = -EINVAL;
		goto out_free;
	}
1451 1452 1453 1454
	rc = ecryptfs_cipher_code_to_string(crypt_stat->cipher,
					    (u16)data[(*packet_size)]);
	if (rc)
		goto out_free;
1455 1456 1457 1458 1459 1460 1461 1462 1463 1464
	/* A little extra work to differentiate among the AES key
	 * sizes; see RFC2440 */
	switch(data[(*packet_size)++]) {
	case RFC2440_CIPHER_AES_192:
		crypt_stat->key_size = 24;
		break;
	default:
		crypt_stat->key_size =
			(*new_auth_tok)->session_key.encrypted_key_size;
	}
1465 1466 1467
	rc = ecryptfs_init_crypt_ctx(crypt_stat);
	if (rc)
		goto out_free;
1468
	if (unlikely(data[(*packet_size)++] != 0x03)) {
1469
		printk(KERN_WARNING "Only S2K ID 3 is currently supported\n");
1470 1471 1472 1473 1474 1475 1476 1477 1478 1479 1480 1481 1482 1483 1484
		rc = -ENOSYS;
		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;
		/* 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)++;
1485 1486 1487
		/* Friendly reminder:
		 * (*new_auth_tok)->session_key.encrypted_key_size =
		 *         (body_size - (ECRYPTFS_SALT_SIZE + 5)); */
1488 1489 1490 1491 1492 1493 1494 1495 1496
		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;
		(*new_auth_tok)->session_key.flags &=
			~ECRYPTFS_CONTAINS_DECRYPTED_KEY;
		(*new_auth_tok)->session_key.flags |=
			ECRYPTFS_CONTAINS_ENCRYPTED_KEY;
1497
		(*new_auth_tok)->token.password.hash_algo = 0x01; /* MD5 */
1498 1499 1500 1501 1502 1503 1504 1505 1506 1507
		break;
	default:
		ecryptfs_printk(KERN_ERR, "Unsupported hash algorithm: "
				"[%d]\n", data[(*packet_size) - 1]);
		rc = -ENOSYS;
		goto out_free;
	}
	(*new_auth_tok)->token_type = ECRYPTFS_PASSWORD;
	/* TODO: Parametarize; we might actually want userspace to
	 * decrypt the session key. */
1508 1509 1510 1511
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_DECRYPT);
	(*new_auth_tok)->session_key.flags &=
			    ~(ECRYPTFS_USERSPACE_SHOULD_TRY_TO_ENCRYPT);
1512 1513 1514 1515 1516 1517 1518 1519 1520 1521 1522 1523 1524 1525 1526 1527 1528 1529 1530 1531 1532 1533 1534 1535 1536 1537 1538 1539 1540 1541 1542 1543 1544 1545 1546 1547 1548
	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
 * @max_packet_size: maximum number of bytes to parse
 *
 * Returns zero on success; non-zero on error.
 */
static int
parse_tag_11_packet(unsigned char *data, unsigned char *contents,
		    size_t max_contents_bytes, size_t *tag_11_contents_size,
		    size_t *packet_size, size_t max_packet_size)
{
	size_t body_size;
	size_t length_size;
1549
	int rc = 0;
1550 1551 1552

	(*packet_size) = 0;
	(*tag_11_contents_size) = 0;
1553 1554 1555 1556 1557 1558 1559 1560 1561 1562 1563 1564 1565
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 11
	 *
	 * Tag 11 identifier (1 byte)
	 * Max Tag 11 packet size (max 3 bytes)
	 * Binary format specifier (1 byte)
	 * Filename length (1 byte)
	 * Filename ("_CONSOLE") (8 bytes)
	 * Modification date (4 bytes)
	 * Literal data (arbitrary)
	 *
	 * We need at least 16 bytes of data for the packet to even be
	 * valid.
1566
	 */
1567 1568
	if (max_packet_size < 16) {
		printk(KERN_ERR "Maximum packet size too small\n");
1569 1570 1571 1572
		rc = -EINVAL;
		goto out;
	}
	if (data[(*packet_size)++] != ECRYPTFS_TAG_11_PACKET_TYPE) {
1573
		printk(KERN_WARNING "Invalid tag 11 packet format\n");
1574 1575 1576
		rc = -EINVAL;
		goto out;
	}
1577 1578
	rc = ecryptfs_parse_packet_length(&data[(*packet_size)], &body_size,
					  &length_size);
1579
	if (rc) {
1580
		printk(KERN_WARNING "Invalid tag 11 packet format\n");
1581 1582
		goto out;
	}
1583
	if (body_size < 14) {
<