static int validate_user_key(struct fscrypt_info *crypt_info,
struct fscrypt_context *ctx, u8 *raw_key,
u8 *prefix, int prefix_size)
{
u8 *full_key_descriptor;
struct key *keyring_key;
struct fscrypt_key *master_key;
const struct user_key_payload *ukp;
int full_key_len = prefix_size + (FS_KEY_DESCRIPTOR_SIZE * 2) + 1;
int res;
full_key_descriptor = kmalloc(full_key_len, GFP_NOFS);
if (!full_key_descriptor)
return -ENOMEM;
memcpy(full_key_descriptor, prefix, prefix_size);
sprintf(full_key_descriptor + prefix_size,
"%*phN", FS_KEY_DESCRIPTOR_SIZE,
ctx->master_key_descriptor);
full_key_descriptor[full_key_len - 1] = '\0';
keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
kfree(full_key_descriptor);
if (IS_ERR(keyring_key))
return PTR_ERR(keyring_key);
if (keyring_key->type != &key_type_logon) {
printk_once(KERN_WARNING
"%s: key type must be logon\n", __func__);
res = -ENOKEY;
goto out;
}
down_read(&keyring_key->sem);
ukp = user_key_payload(keyring_key);
if (ukp->datalen != sizeof(struct fscrypt_key)) {
res = -EINVAL;
up_read(&keyring_key->sem);
goto out;
}
master_key = (struct fscrypt_key *)ukp->data;
BUILD_BUG_ON(FS_AES_128_ECB_KEY_SIZE != FS_KEY_DERIVATION_NONCE_SIZE);
if (master_key->size != FS_AES_256_XTS_KEY_SIZE) {
printk_once(KERN_WARNING
"%s: key size incorrect: %d\n",
__func__, master_key->size);
res = -ENOKEY;
up_read(&keyring_key->sem);
goto out;
}
res = derive_key_aes(ctx->nonce, master_key->raw, raw_key);
up_read(&keyring_key->sem);
if (res)
goto out;
crypt_info->ci_keyring_key = keyring_key;
return 0;
out:
key_put(keyring_key);
return res;
}
/*
* request_user_key - request the user key
*
* Use a user provided key to encrypt/decrypt an encrypted-key.
*/
static struct key *request_user_key(const char *master_desc, const u8 **master_key,
size_t *master_keylen)
{
const struct user_key_payload *upayload;
struct key *ukey;
ukey = request_key(&key_type_user, master_desc, NULL);
if (IS_ERR(ukey))
goto error;
down_read(&ukey->sem);
upayload = user_key_payload(ukey);
*master_key = upayload->data;
*master_keylen = upayload->datalen;
error:
return ukey;
}
/*
* read the key data
* - the key's semaphore is read-locked
*/
long user_read(const struct key *key, char __user *buffer, size_t buflen)
{
const struct user_key_payload *upayload;
long ret;
upayload = user_key_payload(key);
ret = upayload->datalen;
/* we can return the data as is */
if (buffer && buflen > 0) {
if (buflen > upayload->datalen)
buflen = upayload->datalen;
if (copy_to_user(buffer, upayload->data, buflen) != 0)
ret = -EFAULT;
}
return ret;
}
int _f2fs_get_encryption_info(struct inode *inode)
{
struct f2fs_inode_info *fi = F2FS_I(inode);
struct f2fs_crypt_info *crypt_info;
char full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
(F2FS_KEY_DESCRIPTOR_SIZE * 2) + 1];
struct key *keyring_key = NULL;
struct f2fs_encryption_key *master_key;
struct f2fs_encryption_context ctx;
const struct user_key_payload *ukp;
struct crypto_ablkcipher *ctfm;
const char *cipher_str;
char raw_key[F2FS_MAX_KEY_SIZE];
char mode;
int res;
res = f2fs_crypto_initialize();
if (res)
return res;
retry:
crypt_info = ACCESS_ONCE(fi->i_crypt_info);
if (crypt_info) {
if (!crypt_info->ci_keyring_key ||
key_validate(crypt_info->ci_keyring_key) == 0)
return 0;
f2fs_free_encryption_info(inode, crypt_info);
goto retry;
}
res = f2fs_getxattr(inode, F2FS_XATTR_INDEX_ENCRYPTION,
F2FS_XATTR_NAME_ENCRYPTION_CONTEXT,
&ctx, sizeof(ctx), NULL);
if (res < 0)
return res;
else if (res != sizeof(ctx))
return -EINVAL;
res = 0;
crypt_info = kmem_cache_alloc(f2fs_crypt_info_cachep, GFP_NOFS);
if (!crypt_info)
return -ENOMEM;
crypt_info->ci_flags = ctx.flags;
crypt_info->ci_data_mode = ctx.contents_encryption_mode;
crypt_info->ci_filename_mode = ctx.filenames_encryption_mode;
crypt_info->ci_ctfm = NULL;
crypt_info->ci_keyring_key = NULL;
memcpy(crypt_info->ci_master_key, ctx.master_key_descriptor,
sizeof(crypt_info->ci_master_key));
if (S_ISREG(inode->i_mode))
mode = crypt_info->ci_data_mode;
else if (S_ISDIR(inode->i_mode) || S_ISLNK(inode->i_mode))
mode = crypt_info->ci_filename_mode;
else
BUG();
switch (mode) {
case F2FS_ENCRYPTION_MODE_AES_256_XTS:
cipher_str = "xts(aes)";
break;
case F2FS_ENCRYPTION_MODE_AES_256_CTS:
cipher_str = "cts(cbc(aes))";
break;
default:
printk_once(KERN_WARNING
"f2fs: unsupported key mode %d (ino %u)\n",
mode, (unsigned) inode->i_ino);
res = -ENOKEY;
goto out;
}
memcpy(full_key_descriptor, F2FS_KEY_DESC_PREFIX,
F2FS_KEY_DESC_PREFIX_SIZE);
sprintf(full_key_descriptor + F2FS_KEY_DESC_PREFIX_SIZE,
"%*phN", F2FS_KEY_DESCRIPTOR_SIZE,
ctx.master_key_descriptor);
full_key_descriptor[F2FS_KEY_DESC_PREFIX_SIZE +
(2 * F2FS_KEY_DESCRIPTOR_SIZE)] = '\0';
keyring_key = request_key(&key_type_logon, full_key_descriptor, NULL);
if (IS_ERR(keyring_key)) {
res = PTR_ERR(keyring_key);
keyring_key = NULL;
goto out;
}
crypt_info->ci_keyring_key = keyring_key;
BUG_ON(keyring_key->type != &key_type_logon);
ukp = user_key_payload(keyring_key);
if (ukp->datalen != sizeof(struct f2fs_encryption_key)) {
res = -EINVAL;
goto out;
}
master_key = (struct f2fs_encryption_key *)ukp->data;
BUILD_BUG_ON(F2FS_AES_128_ECB_KEY_SIZE !=
F2FS_KEY_DERIVATION_NONCE_SIZE);
BUG_ON(master_key->size != F2FS_AES_256_XTS_KEY_SIZE);
res = f2fs_derive_key_aes(ctx.nonce, master_key->raw,
raw_key);
if (res)
goto out;
ctfm = crypto_alloc_ablkcipher(cipher_str, 0, 0);
if (!ctfm || IS_ERR(ctfm)) {
res = ctfm ? PTR_ERR(ctfm) : -ENOMEM;
printk(KERN_DEBUG
"%s: error %d (inode %u) allocating crypto tfm\n",
__func__, res, (unsigned) inode->i_ino);
goto out;
}
crypt_info->ci_ctfm = ctfm;
crypto_ablkcipher_clear_flags(ctfm, ~0);
crypto_tfm_set_flags(crypto_ablkcipher_tfm(ctfm),
CRYPTO_TFM_REQ_WEAK_KEY);
res = crypto_ablkcipher_setkey(ctfm, raw_key,
f2fs_encryption_key_size(mode));
if (res)
goto out;
memzero_explicit(raw_key, sizeof(raw_key));
if (cmpxchg(&fi->i_crypt_info, NULL, crypt_info) != NULL) {
f2fs_free_crypt_info(crypt_info);
goto retry;
}
return 0;
out:
if (res == -ENOKEY && !S_ISREG(inode->i_mode))
res = 0;
f2fs_free_crypt_info(crypt_info);
memzero_explicit(raw_key, sizeof(raw_key));
return res;
}
/**
* dns_query - Query the DNS
* @type: Query type (or NULL for straight host->IP lookup)
* @name: Name to look up
* @namelen: Length of name
* @options: Request options (or NULL if no options)
* @_result: Where to place the returned data.
* @_expiry: Where to store the result expiry time (or NULL)
*
* The data will be returned in the pointer at *result, and the caller is
* responsible for freeing it.
*
* The description should be of the form "[<query_type>:]<domain_name>", and
* the options need to be appropriate for the query type requested. If no
* query_type is given, then the query is a straight hostname to IP address
* lookup.
*
* The DNS resolution lookup is performed by upcalling to userspace by way of
* requesting a key of type dns_resolver.
*
* Returns the size of the result on success, -ve error code otherwise.
*/
int dns_query(const char *type, const char *name, size_t namelen,
const char *options, char **_result, time_t *_expiry)
{
struct key *rkey;
const struct user_key_payload *upayload;
const struct cred *saved_cred;
size_t typelen, desclen;
char *desc, *cp;
int ret, len;
kenter("%s,%*.*s,%zu,%s",
type, (int)namelen, (int)namelen, name, namelen, options);
if (!name || namelen == 0 || !_result)
return -EINVAL;
/* construct the query key description as "[<type>:]<name>" */
typelen = 0;
desclen = 0;
if (type) {
typelen = strlen(type);
if (typelen < 1)
return -EINVAL;
desclen += typelen + 1;
}
if (!namelen)
namelen = strnlen(name, 256);
if (namelen < 3 || namelen > 255)
return -EINVAL;
desclen += namelen + 1;
desc = kmalloc(desclen, GFP_KERNEL);
if (!desc)
return -ENOMEM;
cp = desc;
if (type) {
memcpy(cp, type, typelen);
cp += typelen;
*cp++ = ':';
}
memcpy(cp, name, namelen);
cp += namelen;
*cp = '\0';
if (!options)
options = "";
kdebug("call request_key(,%s,%s)", desc, options);
/* make the upcall, using special credentials to prevent the use of
* add_key() to preinstall malicious redirections
*/
saved_cred = override_creds(dns_resolver_cache);
rkey = request_key(&key_type_dns_resolver, desc, options);
revert_creds(saved_cred);
kfree(desc);
if (IS_ERR(rkey)) {
ret = PTR_ERR(rkey);
goto out;
}
down_read(&rkey->sem);
set_bit(KEY_FLAG_ROOT_CAN_INVAL, &rkey->flags);
rkey->perm |= KEY_USR_VIEW;
ret = key_validate(rkey);
if (ret < 0)
goto put;
/* If the DNS server gave an error, return that to the caller */
ret = PTR_ERR(rkey->payload.data[dns_key_error]);
if (ret)
goto put;
upayload = user_key_payload(rkey);
len = upayload->datalen;
ret = -ENOMEM;
*_result = kmalloc(len + 1, GFP_KERNEL);
if (!*_result)
goto put;
memcpy(*_result, upayload->data, len);
(*_result)[len] = '\0';
if (_expiry)
*_expiry = rkey->expiry;
ret = len;
put:
up_read(&rkey->sem);
key_put(rkey);
out:
kleave(" = %d", ret);
return ret;
}
