keystore.c

linux 内核源代码

		ecryptfs_dump_hex(key_rec->enc_key, key_rec->enc_key_size);
	}
encrypted_session_key_set:
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 1 */
	max_packet_size = (1                         /* Tag 1 identifier */
			   + 3                       /* Max Tag 1 packet size */
			   + 1                       /* Version */
			   + ECRYPTFS_SIG_SIZE       /* Key identifier */
			   + 1                       /* Cipher identifier */
			   + key_rec->enc_key_size); /* Encrypted key size */
	if (max_packet_size > (*remaining_bytes)) {
		printk(KERN_ERR "Packet length larger than maximum allowable; "
		       "need up to [%td] bytes, but there are only [%td] "
		       "available\n", max_packet_size, (*remaining_bytes));
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_size)++] = ECRYPTFS_TAG_1_PACKET_TYPE;
	rc = write_packet_length(&dest[(*packet_size)], (max_packet_size - 4),
				 &packet_size_length);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error generating tag 1 packet "
				"header; cannot generate packet length\n");
		goto out;
	}
	(*packet_size) += packet_size_length;
	dest[(*packet_size)++] = 0x03; /* version 3 */
	memcpy(&dest[(*packet_size)], key_rec->sig, ECRYPTFS_SIG_SIZE);
	(*packet_size) += ECRYPTFS_SIG_SIZE;
	dest[(*packet_size)++] = RFC2440_CIPHER_RSA;
	memcpy(&dest[(*packet_size)], key_rec->enc_key,
	       key_rec->enc_key_size);
	(*packet_size) += key_rec->enc_key_size;
out:
	if (rc)
		(*packet_size) = 0;
	else
		(*remaining_bytes) -= (*packet_size);
	return rc;
}

/**
 * write_tag_11_packet
 * @dest: Target into which Tag 11 packet is to be written
 * @remaining_bytes: 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.
 */
static int
write_tag_11_packet(char *dest, size_t *remaining_bytes, char *contents,
		    size_t contents_length, size_t *packet_length)
{
	size_t packet_size_length;
	size_t max_packet_size;
	int rc = 0;

	(*packet_length) = 0;
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 11 */
	max_packet_size = (1                   /* Tag 11 identifier */
			   + 3                 /* Max Tag 11 packet size */
			   + 1                 /* Binary format specifier */
			   + 1                 /* Filename length */
			   + 8                 /* Filename ("_CONSOLE") */
			   + 4                 /* Modification date */
			   + contents_length); /* Literal data */
	if (max_packet_size > (*remaining_bytes)) {
		printk(KERN_ERR "Packet length larger than maximum allowable; "
		       "need up to [%td] bytes, but there are only [%td] "
		       "available\n", max_packet_size, (*remaining_bytes));
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_length)++] = ECRYPTFS_TAG_11_PACKET_TYPE;
	rc = write_packet_length(&dest[(*packet_length)],
				 (max_packet_size - 4), &packet_size_length);
	if (rc) {
		printk(KERN_ERR "Error generating tag 11 packet header; cannot "
		       "generate packet length. rc = [%d]\n", rc);
		goto out;
	}
	(*packet_length) += packet_size_length;
	dest[(*packet_length)++] = 0x62; /* binary data format specifier */
	dest[(*packet_length)++] = 8;
	memcpy(&dest[(*packet_length)], "_CONSOLE", 8);
	(*packet_length) += 8;
	memset(&dest[(*packet_length)], 0x00, 4);
	(*packet_length) += 4;
	memcpy(&dest[(*packet_length)], contents, contents_length);
	(*packet_length) += contents_length;
 out:
	if (rc)
		(*packet_length) = 0;
	else
		(*remaining_bytes) -= (*packet_length);
	return rc;
}

/**
 * write_tag_3_packet
 * @dest: Buffer into which to write the packet
 * @remaining_bytes: Maximum number of bytes that can be written
 * @auth_tok: Authentication token
 * @crypt_stat: The cryptographic context
 * @key_rec: encrypted key
 * @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, size_t *remaining_bytes,
		   struct ecryptfs_auth_tok *auth_tok,
		   struct ecryptfs_crypt_stat *crypt_stat,
		   struct ecryptfs_key_record *key_rec, size_t *packet_size)
{
	size_t i;
	size_t encrypted_session_key_valid = 0;
	char session_key_encryption_key[ECRYPTFS_MAX_KEY_BYTES];
	struct scatterlist dst_sg;
	struct scatterlist src_sg;
	struct mutex *tfm_mutex = NULL;
	size_t cipher_code;
	size_t packet_size_length;
	size_t max_packet_size;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		crypt_stat->mount_crypt_stat;
	struct blkcipher_desc desc = {
		.tfm = NULL,
		.flags = CRYPTO_TFM_REQ_MAY_SLEEP
	};
	int rc = 0;

	(*packet_size) = 0;
	ecryptfs_from_hex(key_rec->sig, auth_tok->token.password.signature,
			  ECRYPTFS_SIG_SIZE);
	rc = ecryptfs_get_tfm_and_mutex_for_cipher_name(&desc.tfm, &tfm_mutex,
							crypt_stat->cipher);
	if (unlikely(rc)) {
		printk(KERN_ERR "Internal error whilst attempting to get "
		       "tfm and mutex for cipher name [%s]; rc = [%d]\n",
		       crypt_stat->cipher, rc);
		goto out;
	}
	if (mount_crypt_stat->global_default_cipher_key_size == 0) {
		struct blkcipher_alg *alg = crypto_blkcipher_alg(desc.tfm);

		printk(KERN_WARNING "No key size specified at mount; "
		       "defaulting to [%d]\n", alg->max_keysize);
		mount_crypt_stat->global_default_cipher_key_size =
			alg->max_keysize;
	}
	if (crypt_stat->key_size == 0)
		crypt_stat->key_size =
			mount_crypt_stat->global_default_cipher_key_size;
	if (auth_tok->session_key.encrypted_key_size == 0)
		auth_tok->session_key.encrypted_key_size =
			crypt_stat->key_size;
	if (crypt_stat->key_size == 24
	    && strcmp("aes", crypt_stat->cipher) == 0) {
		memset((crypt_stat->key + 24), 0, 8);
		auth_tok->session_key.encrypted_key_size = 32;
	} else
		auth_tok->session_key.encrypted_key_size = crypt_stat->key_size;
	key_rec->enc_key_size =
		auth_tok->session_key.encrypted_key_size;
	encrypted_session_key_valid = 0;
	for (i = 0; i < auth_tok->session_key.encrypted_key_size; i++)
		encrypted_session_key_valid |=
			auth_tok->session_key.encrypted_key[i];
	if (encrypted_session_key_valid) {
		ecryptfs_printk(KERN_DEBUG, "encrypted_session_key_valid != 0; "
				"using auth_tok->session_key.encrypted_key, "
				"where key_rec->enc_key_size = [%d]\n",
				key_rec->enc_key_size);
		memcpy(key_rec->enc_key,
		       auth_tok->session_key.encrypted_key,
		       key_rec->enc_key_size);
		goto encrypted_session_key_set;
	}
	if (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,
		       crypt_stat->key_size);
		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);
	}
	rc = virt_to_scatterlist(crypt_stat->key, key_rec->enc_key_size,
				 &src_sg, 1);
	if (rc != 1) {
		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
				"for crypt_stat session key; expected rc = 1; "
				"got rc = [%d]. key_rec->enc_key_size = [%d]\n",
				rc, key_rec->enc_key_size);
		rc = -ENOMEM;
		goto out;
	}
	rc = virt_to_scatterlist(key_rec->enc_key, key_rec->enc_key_size,
				 &dst_sg, 1);
	if (rc != 1) {
		ecryptfs_printk(KERN_ERR, "Error generating scatterlist "
				"for crypt_stat encrypted session key; "
				"expected rc = 1; got rc = [%d]. "
				"key_rec->enc_key_size = [%d]\n", rc,
				key_rec->enc_key_size);
		rc = -ENOMEM;
		goto out;
	}
	mutex_lock(tfm_mutex);
	rc = crypto_blkcipher_setkey(desc.tfm, session_key_encryption_key,
				     crypt_stat->key_size);
	if (rc < 0) {
		mutex_unlock(tfm_mutex);
		ecryptfs_printk(KERN_ERR, "Error setting key for crypto "
				"context; rc = [%d]\n", rc);
		goto out;
	}
	rc = 0;
	ecryptfs_printk(KERN_DEBUG, "Encrypting [%d] bytes of the key\n",
			crypt_stat->key_size);
	rc = crypto_blkcipher_encrypt(&desc, &dst_sg, &src_sg,
				      (*key_rec).enc_key_size);
	mutex_unlock(tfm_mutex);
	if (rc) {
		printk(KERN_ERR "Error encrypting; rc = [%d]\n", rc);
		goto out;
	}
	ecryptfs_printk(KERN_DEBUG, "This should be the encrypted key:\n");
	if (ecryptfs_verbosity > 0) {
		ecryptfs_printk(KERN_DEBUG, "EFEK of size [%d]:\n",
				key_rec->enc_key_size);
		ecryptfs_dump_hex(key_rec->enc_key,
				  key_rec->enc_key_size);
	}
encrypted_session_key_set:
	/* This format is inspired by OpenPGP; see RFC 2440
	 * packet tag 3 */
	max_packet_size = (1                         /* Tag 3 identifier */
			   + 3                       /* Max Tag 3 packet size */
			   + 1                       /* Version */
			   + 1                       /* Cipher code */
			   + 1                       /* S2K specifier */
			   + 1                       /* Hash identifier */
			   + ECRYPTFS_SALT_SIZE      /* Salt */
			   + 1                       /* Hash iterations */
			   + key_rec->enc_key_size); /* Encrypted key size */
	if (max_packet_size > (*remaining_bytes)) {
		printk(KERN_ERR "Packet too large; need up to [%td] bytes, but "
		       "there are only [%td] available\n", max_packet_size,
		       (*remaining_bytes));
		rc = -EINVAL;
		goto out;
	}
	dest[(*packet_size)++] = ECRYPTFS_TAG_3_PACKET_TYPE;
	/* Chop off the Tag 3 identifier(1) and Tag 3 packet size(3)
	 * to get the number of octets in the actual Tag 3 packet */
	rc = write_packet_length(&dest[(*packet_size)], (max_packet_size - 4),
				 &packet_size_length);
	if (rc) {
		printk(KERN_ERR "Error generating tag 3 packet header; cannot "
		       "generate packet length. rc = [%d]\n", rc);
		goto out;
	}
	(*packet_size) += packet_size_length;
	dest[(*packet_size)++] = 0x04; /* version 4 */
	/* TODO: Break from RFC2440 so that arbitrary ciphers can be
	 * specified with strings */
	cipher_code = ecryptfs_code_for_cipher_string(crypt_stat);
	if (cipher_code == 0) {
		ecryptfs_printk(KERN_WARNING, "Unable to generate code for "
				"cipher [%s]\n", crypt_stat->cipher);
		rc = -EINVAL;
		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);
	(*packet_size) += key_rec->enc_key_size;
out:
	if (rc)
		(*packet_size) = 0;
	else
		(*remaining_bytes) -= (*packet_size);
	return rc;
}

struct kmem_cache *ecryptfs_key_record_cache;

/**
 * ecryptfs_generate_key_packet_set
 * @dest_base: 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
 * @max: The maximum amount of data allowed to be 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, size_t *len,
				 size_t max)
{
	struct ecryptfs_auth_tok *auth_tok;
	struct ecryptfs_global_auth_tok *global_auth_tok;
	struct ecryptfs_mount_crypt_stat *mount_crypt_stat =
		&ecryptfs_superblock_to_private(
			ecryptfs_dentry->d_sb)->mount_crypt_stat;
	size_t written;
	struct ecryptfs_key_record *key_rec;
	struct ecryptfs_key_sig *key_sig;
	int rc = 0;

	(*len) = 0;
	mutex_lock(&crypt_stat->keysig_list_mutex);
	key_rec = kmem_cache_alloc(ecryptfs_key_record_cache, GFP_KERNEL);
	if (!key_rec) {
		rc = -ENOMEM;
		goto out;
	}
	list_for_each_entry(key_sig, &crypt_stat->keysig_list,
			    crypt_stat_list) {
		memset(key_rec, 0, sizeof(*key_rec));
		rc = ecryptfs_find_global_auth_tok_for_sig(&global_auth_tok,
							   mount_crypt_stat,
							   key_sig->keysig);
		if (rc) {
			printk(KERN_ERR "Error attempting to get the global "
			       "auth_tok; rc = [%d]\n", rc);
			goto out_free;
		}
		if (global_auth_tok->flags & ECRYPTFS_AUTH_TOK_INVALID) {
			printk(KERN_WARNING
			       "Skipping invalid auth tok with sig = [%s]\n",
			       global_auth_tok->sig);
			continue;
		}
		auth_tok = global_auth_tok->global_auth_tok;
		if (auth_tok->token_type == ECRYPTFS_PASSWORD) {
			rc = write_tag_3_packet((dest_base + (*len)),
						&max, auth_tok,
						crypt_stat, key_rec,
						&written);
			if (rc) {
				ecryptfs_printk(KERN_WARNING, "Error "
						"writing tag 3 packet\n");
				goto out_free;
			}
			(*len) += written;
			/* Write auth tok signature packet */
			rc = write_tag_11_packet((dest_base + (*len)), &max,
						 key_rec->sig,
						 ECRYPTFS_SIG_SIZE, &written);
			if (rc) {
				ecryptfs_printk(KERN_ERR, "Error writing "
						"auth tok signature packet\n");
				goto out_free;
			}
			(*len) += written;
		} else if (auth_tok->token_type == ECRYPTFS_PRIVATE_KEY) {
			rc = write_tag_1_packet(dest_base + (*len),
						&max, auth_tok,
						crypt_stat, key_rec, &written);
			if (rc) {
				ecryptfs_printk(KERN_WARNING, "Error "
						"writing tag 1 packet\n");
				goto out_free;
			}
			(*len) += written;
		} else {
			ecryptfs_printk(KERN_WARNING, "Unsupported "
					"authentication token type\n");
			rc = -EINVAL;
			goto out_free;
		}
	}
	if (likely(max > 0)) {
		dest_base[(*len)] = 0x00;
	} else {
		ecryptfs_printk(KERN_ERR, "Error writing boundary byte\n");
		rc = -EIO;
	}
out_free:
	kmem_cache_free(ecryptfs_key_record_cache, key_rec);
out:
	if (rc)
		(*len) = 0;
	mutex_unlock(&crypt_stat->keysig_list_mutex);
	return rc;
}

struct kmem_cache *ecryptfs_key_sig_cache;

int ecryptfs_add_keysig(struct ecryptfs_crypt_stat *crypt_stat, char *sig)
{
	struct ecryptfs_key_sig *new_key_sig;
	int rc = 0;

	new_key_sig = kmem_cache_alloc(ecryptfs_key_sig_cache, GFP_KERNEL);
	if (!new_key_sig) {
		rc = -ENOMEM;
		printk(KERN_ERR
		       "Error allocating from ecryptfs_key_sig_cache\n");
		goto out;
	}
	memcpy(new_key_sig->keysig, sig, ECRYPTFS_SIG_SIZE_HEX);
	mutex_lock(&crypt_stat->keysig_list_mutex);
	list_add(&new_key_sig->crypt_stat_list, &crypt_stat->keysig_list);
	mutex_unlock(&crypt_stat->keysig_list_mutex);
out:
	return rc;
}

struct kmem_cache *ecryptfs_global_auth_tok_cache;

int
ecryptfs_add_global_auth_tok(struct ecryptfs_mount_crypt_stat *mount_crypt_stat,
			     char *sig)
{
	struct ecryptfs_global_auth_tok *new_auth_tok;
	int rc = 0;

	new_auth_tok = kmem_cache_zalloc(ecryptfs_global_auth_tok_cache,
					GFP_KERNEL);
	if (!new_auth_tok) {
		rc = -ENOMEM;
		printk(KERN_ERR "Error allocating from "
		       "ecryptfs_global_auth_tok_cache\n");
		goto out;
	}
	memcpy(new_auth_tok->sig, sig, ECRYPTFS_SIG_SIZE_HEX);
	new_auth_tok->sig[ECRYPTFS_SIG_SIZE_HEX] = '\0';
	mutex_lock(&mount_crypt_stat->global_auth_tok_list_mutex);
	list_add(&new_auth_tok->mount_crypt_stat_list,
		 &mount_crypt_stat->global_auth_tok_list);
	mount_crypt_stat->num_global_auth_toks++;
	mutex_unlock(&mount_crypt_stat->global_auth_tok_list_mutex);
out:
	return rc;
}