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fscrypt updates for 6.3

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Simplify the implementation of the test_dummy_encryption mount option by
 adding the "test dummy key" on-demand.
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Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux

Pull fscrypt updates from Eric Biggers:
 "Simplify the implementation of the test_dummy_encryption mount option
  by adding the 'test dummy key' on-demand"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
  fscrypt: clean up fscrypt_add_test_dummy_key()
  fs/super.c: stop calling fscrypt_destroy_keyring() from __put_super()
  f2fs: stop calling fscrypt_add_test_dummy_key()
  ext4: stop calling fscrypt_add_test_dummy_key()
  fscrypt: add the test dummy encryption key on-demand
This commit is contained in:
Linus Torvalds 2023-02-20 12:29:27 -08:00
commit f18f9845f2
8 changed files with 34 additions and 51 deletions
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4
fs/crypto/fscrypt_private.h
View File

@ -573,6 +573,9 @@ fscrypt_find_master_key(struct super_block *sb,
int fscrypt_get_test_dummy_key_identifier(
u8 key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
int fscrypt_add_test_dummy_key(struct super_block *sb,
struct fscrypt_key_specifier *key_spec);
int fscrypt_verify_key_added(struct super_block *sb,
const u8 identifier[FSCRYPT_KEY_IDENTIFIER_SIZE]);
@ -651,6 +654,7 @@ bool fscrypt_policies_equal(const union fscrypt_policy *policy1,
const union fscrypt_policy *policy2);
int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
struct fscrypt_key_specifier *key_spec);
const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb);
bool fscrypt_supported_policy(const union fscrypt_policy *policy_u,
const struct inode *inode);
int fscrypt_policy_from_context(union fscrypt_policy *policy_u,

26
fs/crypto/keyring.c
View File

@ -211,10 +211,6 @@ static int allocate_filesystem_keyring(struct super_block *sb)
* are still available at this time; this is important because after user file
* accesses have been allowed, this function may need to evict keys from the
* keyslots of an inline crypto engine, which requires the block device(s).
*
* This is also called when the super_block is being freed. This is needed to
* avoid a memory leak if mounting fails after the "test_dummy_encryption"
* option was processed, as in that case the unmount-time call isn't made.
*/
void fscrypt_destroy_keyring(struct super_block *sb)
{
@ -778,34 +774,26 @@ out:
/**
* fscrypt_add_test_dummy_key() - add the test dummy encryption key
* @sb: the filesystem instance to add the key to
* @dummy_policy: the encryption policy for test_dummy_encryption
* @key_spec: the key specifier of the test dummy encryption key
*
* If needed, add the key for the test_dummy_encryption mount option to the
* filesystem. To prevent misuse of this mount option, a per-boot random key is
* used instead of a hardcoded one. This makes it so that any encrypted files
* created using this option won't be accessible after a reboot.
* Add the key for the test_dummy_encryption mount option to the filesystem. To
* prevent misuse of this mount option, a per-boot random key is used instead of
* a hardcoded one. This makes it so that any encrypted files created using
* this option won't be accessible after a reboot.
*
* Return: 0 on success, -errno on failure
*/
int fscrypt_add_test_dummy_key(struct super_block *sb,
const struct fscrypt_dummy_policy *dummy_policy)
struct fscrypt_key_specifier *key_spec)
{
const union fscrypt_policy *policy = dummy_policy->policy;
struct fscrypt_key_specifier key_spec;
struct fscrypt_master_key_secret secret;
int err;
if (!policy)
return 0;
err = fscrypt_policy_to_key_spec(policy, &key_spec);
if (err)
return err;
fscrypt_get_test_dummy_secret(&secret);
err = add_master_key(sb, &secret, &key_spec);
err = add_master_key(sb, &secret, key_spec);
wipe_master_key_secret(&secret);
return err;
}
EXPORT_SYMBOL_GPL(fscrypt_add_test_dummy_key);
/*
* Verify that the current user has added a master key with the given identifier

23
fs/crypto/keysetup.c
View File

@ -438,6 +438,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
bool need_dirhash_key,
struct fscrypt_master_key **mk_ret)
{
struct super_block *sb = ci->ci_inode->i_sb;
struct fscrypt_key_specifier mk_spec;
struct fscrypt_master_key *mk;
int err;
@ -450,8 +451,26 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
if (err)
return err;
mk = fscrypt_find_master_key(ci->ci_inode->i_sb, &mk_spec);
if (!mk) {
mk = fscrypt_find_master_key(sb, &mk_spec);
if (unlikely(!mk)) {
const union fscrypt_policy *dummy_policy =
fscrypt_get_dummy_policy(sb);
/*
* Add the test_dummy_encryption key on-demand. In principle,
* it should be added at mount time. Do it here instead so that
* the individual filesystems don't need to worry about adding
* this key at mount time and cleaning up on mount failure.
*/
if (dummy_policy &&
fscrypt_policies_equal(dummy_policy, &ci->ci_policy)) {
err = fscrypt_add_test_dummy_key(sb, &mk_spec);
if (err)
return err;
mk = fscrypt_find_master_key(sb, &mk_spec);
}
}
if (unlikely(!mk)) {
if (ci->ci_policy.version != FSCRYPT_POLICY_V1)
return -ENOKEY;

3
fs/crypto/policy.c
View File

@ -53,8 +53,7 @@ int fscrypt_policy_to_key_spec(const union fscrypt_policy *policy,
}
}
static const union fscrypt_policy *
fscrypt_get_dummy_policy(struct super_block *sb)
const union fscrypt_policy *fscrypt_get_dummy_policy(struct super_block *sb)
{
if (!sb->s_cop->get_dummy_policy)
return NULL;

13
fs/ext4/super.c
View File

@ -2635,7 +2635,6 @@ static int ext4_check_test_dummy_encryption(const struct fs_context *fc,
{
const struct ext4_fs_context *ctx = fc->fs_private;
const struct ext4_sb_info *sbi = EXT4_SB(sb);
int err;
if (!fscrypt_is_dummy_policy_set(&ctx->dummy_enc_policy))
return 0;
@ -2668,17 +2667,7 @@ static int ext4_check_test_dummy_encryption(const struct fs_context *fc,
"Conflicting test_dummy_encryption options");
return -EINVAL;
}
/*
* fscrypt_add_test_dummy_key() technically changes the super_block, so
* technically it should be delayed until ext4_apply_options() like the
* other changes. But since we never get here for remounts (see above),
* and this is the last chance to report errors, we do it here.
*/
err = fscrypt_add_test_dummy_key(sb, &ctx->dummy_enc_policy);
if (err)
ext4_msg(NULL, KERN_WARNING,
"Error adding test dummy encryption key [%d]", err);
return err;
return 0;
}
static void ext4_apply_test_dummy_encryption(struct ext4_fs_context *ctx,

6
fs/f2fs/super.c
View File

@ -540,12 +540,6 @@ static int f2fs_set_test_dummy_encryption(struct super_block *sb,
opt, err);
return -EINVAL;
}
err = fscrypt_add_test_dummy_key(sb, policy);
if (err) {
f2fs_warn(sbi, "Error adding test dummy encryption key [%d]",
err);
return err;
}
f2fs_warn(sbi, "Test dummy encryption mode enabled");
return 0;
}

1
fs/super.c
View File

@ -291,7 +291,6 @@ static void __put_super(struct super_block *s)
WARN_ON(s->s_inode_lru.node);
WARN_ON(!list_empty(&s->s_mounts));
security_sb_free(s);
fscrypt_destroy_keyring(s);
put_user_ns(s->s_user_ns);
kfree(s->s_subtype);
call_rcu(&s->rcu, destroy_super_rcu);

9
include/linux/fscrypt.h
View File

@ -309,8 +309,6 @@ fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
/* keyring.c */
void fscrypt_destroy_keyring(struct super_block *sb);
int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
int fscrypt_add_test_dummy_key(struct super_block *sb,
const struct fscrypt_dummy_policy *dummy_policy);
int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
@ -530,13 +528,6 @@ static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
return -EOPNOTSUPP;
}
static inline int
fscrypt_add_test_dummy_key(struct super_block *sb,
const struct fscrypt_dummy_policy *dummy_policy)
{
return 0;
}
static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;