File-copy from v4.4.100
This is the result of 'cp' from a linux-stable tree with the 'v4.4.100'
tag checked out (commit 26d6298789e695c9f627ce49a7bbd2286405798a) on
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
Please refer to that tree for all history prior to this point.
Change-Id: I8a9ee2aea93cd29c52c847d0ce33091a73ae6afe
diff --git a/fs/ext4/crypto_key.c b/fs/ext4/crypto_key.c
new file mode 100644
index 0000000..9a1bc63
--- /dev/null
+++ b/fs/ext4/crypto_key.c
@@ -0,0 +1,268 @@
+/*
+ * linux/fs/ext4/crypto_key.c
+ *
+ * Copyright (C) 2015, Google, Inc.
+ *
+ * This contains encryption key functions for ext4
+ *
+ * Written by Michael Halcrow, Ildar Muslukhov, and Uday Savagaonkar, 2015.
+ */
+
+#include <keys/encrypted-type.h>
+#include <keys/user-type.h>
+#include <linux/random.h>
+#include <linux/scatterlist.h>
+#include <uapi/linux/keyctl.h>
+
+#include "ext4.h"
+#include "xattr.h"
+
+static void derive_crypt_complete(struct crypto_async_request *req, int rc)
+{
+ struct ext4_completion_result *ecr = req->data;
+
+ if (rc == -EINPROGRESS)
+ return;
+
+ ecr->res = rc;
+ complete(&ecr->completion);
+}
+
+/**
+ * ext4_derive_key_aes() - Derive a key using AES-128-ECB
+ * @deriving_key: Encryption key used for derivation.
+ * @source_key: Source key to which to apply derivation.
+ * @derived_key: Derived key.
+ *
+ * Return: Zero on success; non-zero otherwise.
+ */
+static int ext4_derive_key_aes(char deriving_key[EXT4_AES_128_ECB_KEY_SIZE],
+ char source_key[EXT4_AES_256_XTS_KEY_SIZE],
+ char derived_key[EXT4_AES_256_XTS_KEY_SIZE])
+{
+ int res = 0;
+ struct ablkcipher_request *req = NULL;
+ DECLARE_EXT4_COMPLETION_RESULT(ecr);
+ struct scatterlist src_sg, dst_sg;
+ struct crypto_ablkcipher *tfm = crypto_alloc_ablkcipher("ecb(aes)", 0,
+ 0);
+
+ if (IS_ERR(tfm)) {
+ res = PTR_ERR(tfm);
+ tfm = NULL;
+ goto out;
+ }
+ crypto_ablkcipher_set_flags(tfm, CRYPTO_TFM_REQ_WEAK_KEY);
+ req = ablkcipher_request_alloc(tfm, GFP_NOFS);
+ if (!req) {
+ res = -ENOMEM;
+ goto out;
+ }
+ ablkcipher_request_set_callback(req,
+ CRYPTO_TFM_REQ_MAY_BACKLOG | CRYPTO_TFM_REQ_MAY_SLEEP,
+ derive_crypt_complete, &ecr);
+ res = crypto_ablkcipher_setkey(tfm, deriving_key,
+ EXT4_AES_128_ECB_KEY_SIZE);
+ if (res < 0)
+ goto out;
+ sg_init_one(&src_sg, source_key, EXT4_AES_256_XTS_KEY_SIZE);
+ sg_init_one(&dst_sg, derived_key, EXT4_AES_256_XTS_KEY_SIZE);
+ ablkcipher_request_set_crypt(req, &src_sg, &dst_sg,
+ EXT4_AES_256_XTS_KEY_SIZE, NULL);
+ res = crypto_ablkcipher_encrypt(req);
+ if (res == -EINPROGRESS || res == -EBUSY) {
+ wait_for_completion(&ecr.completion);
+ res = ecr.res;
+ }
+
+out:
+ if (req)
+ ablkcipher_request_free(req);
+ if (tfm)
+ crypto_free_ablkcipher(tfm);
+ return res;
+}
+
+void ext4_free_crypt_info(struct ext4_crypt_info *ci)
+{
+ if (!ci)
+ return;
+
+ crypto_free_ablkcipher(ci->ci_ctfm);
+ kmem_cache_free(ext4_crypt_info_cachep, ci);
+}
+
+void ext4_free_encryption_info(struct inode *inode,
+ struct ext4_crypt_info *ci)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_crypt_info *prev;
+
+ if (ci == NULL)
+ ci = ACCESS_ONCE(ei->i_crypt_info);
+ if (ci == NULL)
+ return;
+ prev = cmpxchg(&ei->i_crypt_info, ci, NULL);
+ if (prev != ci)
+ return;
+
+ ext4_free_crypt_info(ci);
+}
+
+int ext4_get_encryption_info(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+ struct ext4_crypt_info *crypt_info;
+ char full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
+ (EXT4_KEY_DESCRIPTOR_SIZE * 2) + 1];
+ struct key *keyring_key = NULL;
+ struct ext4_encryption_key *master_key;
+ struct ext4_encryption_context ctx;
+ const struct user_key_payload *ukp;
+ struct ext4_sb_info *sbi = EXT4_SB(inode->i_sb);
+ struct crypto_ablkcipher *ctfm;
+ const char *cipher_str;
+ char raw_key[EXT4_MAX_KEY_SIZE];
+ char mode;
+ int res;
+
+ if (ei->i_crypt_info)
+ return 0;
+
+ if (!ext4_read_workqueue) {
+ res = ext4_init_crypto();
+ if (res)
+ return res;
+ }
+
+ res = ext4_xattr_get(inode, EXT4_XATTR_INDEX_ENCRYPTION,
+ EXT4_XATTR_NAME_ENCRYPTION_CONTEXT,
+ &ctx, sizeof(ctx));
+ if (res < 0) {
+ if (!DUMMY_ENCRYPTION_ENABLED(sbi))
+ return res;
+ ctx.contents_encryption_mode = EXT4_ENCRYPTION_MODE_AES_256_XTS;
+ ctx.filenames_encryption_mode =
+ EXT4_ENCRYPTION_MODE_AES_256_CTS;
+ ctx.flags = 0;
+ } else if (res != sizeof(ctx))
+ return -EINVAL;
+ res = 0;
+
+ crypt_info = kmem_cache_alloc(ext4_crypt_info_cachep, GFP_KERNEL);
+ 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;
+ 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 EXT4_ENCRYPTION_MODE_AES_256_XTS:
+ cipher_str = "xts(aes)";
+ break;
+ case EXT4_ENCRYPTION_MODE_AES_256_CTS:
+ cipher_str = "cts(cbc(aes))";
+ break;
+ default:
+ printk_once(KERN_WARNING
+ "ext4: unsupported key mode %d (ino %u)\n",
+ mode, (unsigned) inode->i_ino);
+ res = -ENOKEY;
+ goto out;
+ }
+ if (DUMMY_ENCRYPTION_ENABLED(sbi)) {
+ memset(raw_key, 0x42, EXT4_AES_256_XTS_KEY_SIZE);
+ goto got_key;
+ }
+ memcpy(full_key_descriptor, EXT4_KEY_DESC_PREFIX,
+ EXT4_KEY_DESC_PREFIX_SIZE);
+ sprintf(full_key_descriptor + EXT4_KEY_DESC_PREFIX_SIZE,
+ "%*phN", EXT4_KEY_DESCRIPTOR_SIZE,
+ ctx.master_key_descriptor);
+ full_key_descriptor[EXT4_KEY_DESC_PREFIX_SIZE +
+ (2 * EXT4_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;
+ }
+ if (keyring_key->type != &key_type_logon) {
+ printk_once(KERN_WARNING
+ "ext4: key type must be logon\n");
+ res = -ENOKEY;
+ goto out;
+ }
+ down_read(&keyring_key->sem);
+ ukp = user_key_payload(keyring_key);
+ if (!ukp) {
+ /* key was revoked before we acquired its semaphore */
+ res = -EKEYREVOKED;
+ up_read(&keyring_key->sem);
+ goto out;
+ }
+ if (ukp->datalen != sizeof(struct ext4_encryption_key)) {
+ res = -EINVAL;
+ up_read(&keyring_key->sem);
+ goto out;
+ }
+ master_key = (struct ext4_encryption_key *)ukp->data;
+ BUILD_BUG_ON(EXT4_AES_128_ECB_KEY_SIZE !=
+ EXT4_KEY_DERIVATION_NONCE_SIZE);
+ if (master_key->size != EXT4_AES_256_XTS_KEY_SIZE) {
+ printk_once(KERN_WARNING
+ "ext4: key size incorrect: %d\n",
+ master_key->size);
+ res = -ENOKEY;
+ up_read(&keyring_key->sem);
+ goto out;
+ }
+ res = ext4_derive_key_aes(ctx.nonce, master_key->raw,
+ raw_key);
+ up_read(&keyring_key->sem);
+ if (res)
+ goto out;
+got_key:
+ 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,
+ ext4_encryption_key_size(mode));
+ if (res)
+ goto out;
+
+ if (cmpxchg(&ei->i_crypt_info, NULL, crypt_info) == NULL)
+ crypt_info = NULL;
+out:
+ if (res == -ENOKEY)
+ res = 0;
+ key_put(keyring_key);
+ ext4_free_crypt_info(crypt_info);
+ memzero_explicit(raw_key, sizeof(raw_key));
+ return res;
+}
+
+int ext4_has_encryption_key(struct inode *inode)
+{
+ struct ext4_inode_info *ei = EXT4_I(inode);
+
+ return (ei->i_crypt_info != NULL);
+}