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-rw-r--r--fs/crypto/keysetup.c182
1 files changed, 136 insertions, 46 deletions
diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c
index fea6226afc2b..d3c3e5d9b41f 100644
--- a/fs/crypto/keysetup.c
+++ b/fs/crypto/keysetup.c
@@ -10,6 +10,7 @@
#include <crypto/skcipher.h>
#include <linux/key.h>
+#include <linux/random.h>
#include "fscrypt_private.h"
@@ -222,6 +223,16 @@ int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
return 0;
}
+void fscrypt_hash_inode_number(struct fscrypt_info *ci,
+ const struct fscrypt_master_key *mk)
+{
+ WARN_ON(ci->ci_inode->i_ino == 0);
+ WARN_ON(!mk->mk_ino_hash_key_initialized);
+
+ ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino,
+ &mk->mk_ino_hash_key);
+}
+
static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci,
struct fscrypt_master_key *mk)
{
@@ -254,13 +265,20 @@ unlock:
return err;
}
- ci->ci_hashed_ino = (u32)siphash_1u64(ci->ci_inode->i_ino,
- &mk->mk_ino_hash_key);
+ /*
+ * New inodes may not have an inode number assigned yet.
+ * Hashing their inode number is delayed until later.
+ */
+ if (ci->ci_inode->i_ino == 0)
+ WARN_ON(!(ci->ci_inode->i_state & I_CREATING));
+ else
+ fscrypt_hash_inode_number(ci, mk);
return 0;
}
static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
- struct fscrypt_master_key *mk)
+ struct fscrypt_master_key *mk,
+ bool need_dirhash_key)
{
int err;
@@ -306,7 +324,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
return err;
/* Derive a secret dirhash key for directories that need it. */
- if (S_ISDIR(ci->ci_inode->i_mode) && IS_CASEFOLDED(ci->ci_inode)) {
+ if (need_dirhash_key) {
err = fscrypt_derive_dirhash_key(ci, mk);
if (err)
return err;
@@ -326,6 +344,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
* key being removed with a new inode starting to use it.
*/
static int setup_file_encryption_key(struct fscrypt_info *ci,
+ bool need_dirhash_key,
struct key **master_key_ret)
{
struct key *key;
@@ -400,7 +419,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
err = fscrypt_setup_v1_file_key(ci, mk->mk_secret.raw);
break;
case FSCRYPT_POLICY_V2:
- err = fscrypt_setup_v2_file_key(ci, mk);
+ err = fscrypt_setup_v2_file_key(ci, mk, need_dirhash_key);
break;
default:
WARN_ON(1);
@@ -454,57 +473,28 @@ static void put_crypt_info(struct fscrypt_info *ci)
kmem_cache_free(fscrypt_info_cachep, ci);
}
-int fscrypt_get_encryption_info(struct inode *inode)
+static int
+fscrypt_setup_encryption_info(struct inode *inode,
+ const union fscrypt_policy *policy,
+ const u8 nonce[FSCRYPT_FILE_NONCE_SIZE],
+ bool need_dirhash_key)
{
struct fscrypt_info *crypt_info;
- union fscrypt_context ctx;
struct fscrypt_mode *mode;
struct key *master_key = NULL;
int res;
- if (fscrypt_has_encryption_key(inode))
- return 0;
-
res = fscrypt_initialize(inode->i_sb->s_cop->flags);
if (res)
return res;
- res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
- if (res < 0) {
- const union fscrypt_context *dummy_ctx =
- fscrypt_get_dummy_context(inode->i_sb);
-
- if (IS_ENCRYPTED(inode) || !dummy_ctx) {
- fscrypt_warn(inode,
- "Error %d getting encryption context",
- res);
- return res;
- }
- /* Fake up a context for an unencrypted directory */
- res = fscrypt_context_size(dummy_ctx);
- memcpy(&ctx, dummy_ctx, res);
- }
-
- crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_NOFS);
+ crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL);
if (!crypt_info)
return -ENOMEM;
crypt_info->ci_inode = inode;
-
- res = fscrypt_policy_from_context(&crypt_info->ci_policy, &ctx, res);
- if (res) {
- fscrypt_warn(inode,
- "Unrecognized or corrupt encryption context");
- goto out;
- }
-
- memcpy(crypt_info->ci_nonce, fscrypt_context_nonce(&ctx),
- FSCRYPT_FILE_NONCE_SIZE);
-
- if (!fscrypt_supported_policy(&crypt_info->ci_policy, inode)) {
- res = -EINVAL;
- goto out;
- }
+ crypt_info->ci_policy = *policy;
+ memcpy(crypt_info->ci_nonce, nonce, FSCRYPT_FILE_NONCE_SIZE);
mode = select_encryption_mode(&crypt_info->ci_policy, inode);
if (IS_ERR(mode)) {
@@ -514,13 +504,14 @@ int fscrypt_get_encryption_info(struct inode *inode)
WARN_ON(mode->ivsize > FSCRYPT_MAX_IV_SIZE);
crypt_info->ci_mode = mode;
- res = setup_file_encryption_key(crypt_info, &master_key);
+ res = setup_file_encryption_key(crypt_info, need_dirhash_key,
+ &master_key);
if (res)
goto out;
/*
- * Multiple tasks may race to set ->i_crypt_info, so use
- * cmpxchg_release(). This pairs with the smp_load_acquire() in
+ * For existing inodes, multiple tasks may race to set ->i_crypt_info.
+ * So use cmpxchg_release(). This pairs with the smp_load_acquire() in
* fscrypt_get_info(). I.e., here we publish ->i_crypt_info with a
* RELEASE barrier so that other tasks can ACQUIRE it.
*/
@@ -550,14 +541,113 @@ out:
up_read(&mk->mk_secret_sem);
key_put(master_key);
}
+ put_crypt_info(crypt_info);
+ return res;
+}
+
+/**
+ * fscrypt_get_encryption_info() - set up an inode's encryption key
+ * @inode: the inode to set up the key for. Must be encrypted.
+ *
+ * Set up ->i_crypt_info, if it hasn't already been done.
+ *
+ * Note: unless ->i_crypt_info is already set, this isn't %GFP_NOFS-safe. So
+ * generally this shouldn't be called from within a filesystem transaction.
+ *
+ * Return: 0 if ->i_crypt_info was set or was already set, *or* if the
+ * encryption key is unavailable. (Use fscrypt_has_encryption_key() to
+ * distinguish these cases.) Also can return another -errno code.
+ */
+int fscrypt_get_encryption_info(struct inode *inode)
+{
+ int res;
+ union fscrypt_context ctx;
+ union fscrypt_policy policy;
+
+ if (fscrypt_has_encryption_key(inode))
+ return 0;
+
+ res = inode->i_sb->s_cop->get_context(inode, &ctx, sizeof(ctx));
+ if (res < 0) {
+ fscrypt_warn(inode, "Error %d getting encryption context", res);
+ return res;
+ }
+
+ res = fscrypt_policy_from_context(&policy, &ctx, res);
+ if (res) {
+ fscrypt_warn(inode,
+ "Unrecognized or corrupt encryption context");
+ return res;
+ }
+
+ if (!fscrypt_supported_policy(&policy, inode))
+ return -EINVAL;
+
+ res = fscrypt_setup_encryption_info(inode, &policy,
+ fscrypt_context_nonce(&ctx),
+ IS_CASEFOLDED(inode) &&
+ S_ISDIR(inode->i_mode));
if (res == -ENOKEY)
res = 0;
- put_crypt_info(crypt_info);
return res;
}
EXPORT_SYMBOL(fscrypt_get_encryption_info);
/**
+ * fscrypt_prepare_new_inode() - prepare to create a new inode in a directory
+ * @dir: a possibly-encrypted directory
+ * @inode: the new inode. ->i_mode must be set already.
+ * ->i_ino doesn't need to be set yet.
+ * @encrypt_ret: (output) set to %true if the new inode will be encrypted
+ *
+ * If the directory is encrypted, set up its ->i_crypt_info in preparation for
+ * encrypting the name of the new file. Also, if the new inode will be
+ * encrypted, set up its ->i_crypt_info and set *encrypt_ret=true.
+ *
+ * This isn't %GFP_NOFS-safe, and therefore it should be called before starting
+ * any filesystem transaction to create the inode. For this reason, ->i_ino
+ * isn't required to be set yet, as the filesystem may not have set it yet.
+ *
+ * This doesn't persist the new inode's encryption context. That still needs to
+ * be done later by calling fscrypt_set_context().
+ *
+ * Return: 0 on success, -ENOKEY if the encryption key is missing, or another
+ * -errno code
+ */
+int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
+ bool *encrypt_ret)
+{
+ const union fscrypt_policy *policy;
+ u8 nonce[FSCRYPT_FILE_NONCE_SIZE];
+
+ policy = fscrypt_policy_to_inherit(dir);
+ if (policy == NULL)
+ return 0;
+ if (IS_ERR(policy))
+ return PTR_ERR(policy);
+
+ if (WARN_ON_ONCE(inode->i_mode == 0))
+ return -EINVAL;
+
+ /*
+ * Only regular files, directories, and symlinks are encrypted.
+ * Special files like device nodes and named pipes aren't.
+ */
+ if (!S_ISREG(inode->i_mode) &&
+ !S_ISDIR(inode->i_mode) &&
+ !S_ISLNK(inode->i_mode))
+ return 0;
+
+ *encrypt_ret = true;
+
+ get_random_bytes(nonce, FSCRYPT_FILE_NONCE_SIZE);
+ return fscrypt_setup_encryption_info(inode, policy, nonce,
+ IS_CASEFOLDED(dir) &&
+ S_ISDIR(inode->i_mode));
+}
+EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode);
+
+/**
* fscrypt_put_encryption_info() - free most of an inode's fscrypt data
* @inode: an inode being evicted
*