From 60e463f0be9874692a56a7d419a6e39029b6290d Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 7 Feb 2023 22:21:03 -0800 Subject: fscrypt: add the test dummy encryption key on-demand When the key for an inode is not found but the inode is using the test_dummy_encryption policy, automatically add the test_dummy_encryption key to the filesystem keyring. This eliminates the need for all the individual filesystems to do this at mount time, which is a bit tricky to clean up from on failure. Note: this covers the call to fscrypt_find_master_key() from inode key setup, but not from the fscrypt ioctls. So, this isn't *exactly* the same as the key being present from the very beginning. I think we can tolerate that, though, since the inode key setup caller is the only one that actually matters in the context of test_dummy_encryption. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230208062107.199831-2-ebiggers@kernel.org --- fs/crypto/fscrypt_private.h | 1 + fs/crypto/keysetup.c | 25 +++++++++++++++++++++++-- fs/crypto/policy.c | 3 +-- 3 files changed, 25 insertions(+), 4 deletions(-) diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 316a778cec0f..17dd33d9a522 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -651,6 +651,7 @@ 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, diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 94757ccd3056..20323c0ba4c5 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -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 +451,28 @@ 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)) { + struct fscrypt_dummy_policy tmp = { dummy_policy }; + + err = fscrypt_add_test_dummy_key(sb, &tmp); + 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; diff --git a/fs/crypto/policy.c b/fs/crypto/policy.c index 893661b52376..69dca4ff5f48 100644 --- a/fs/crypto/policy.c +++ b/fs/crypto/policy.c @@ -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; -- cgit v1.2.3 From 7959eb19e4a369639ff9e55eb1147360d5ac8ddb Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 7 Feb 2023 22:21:04 -0800 Subject: ext4: stop calling fscrypt_add_test_dummy_key() Now that fs/crypto/ adds the test dummy encryption key on-demand when it's needed, there's no need for individual filesystems to call fscrypt_add_test_dummy_key(). Remove the call to it from ext4. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230208062107.199831-3-ebiggers@kernel.org --- fs/ext4/super.c | 13 +------------ 1 file changed, 1 insertion(+), 12 deletions(-) diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 260c1b3e3ef2..260bbab25db3 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -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, -- cgit v1.2.3 From 1ad2a626762dca9f3fe6954ce148f9e4fc4c1ba7 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 7 Feb 2023 22:21:05 -0800 Subject: f2fs: stop calling fscrypt_add_test_dummy_key() Now that fs/crypto/ adds the test dummy encryption key on-demand when it's needed, there's no need for individual filesystems to call fscrypt_add_test_dummy_key(). Remove the call to it from f2fs. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230208062107.199831-4-ebiggers@kernel.org --- fs/f2fs/super.c | 6 ------ 1 file changed, 6 deletions(-) diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c index 1f812b9ce985..64d3556d61a5 100644 --- a/fs/f2fs/super.c +++ b/fs/f2fs/super.c @@ -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; } -- cgit v1.2.3 From ec64036e68634231f5891faa2b7a81cdc5dcd001 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 7 Feb 2023 22:21:06 -0800 Subject: fs/super.c: stop calling fscrypt_destroy_keyring() from __put_super() Now that the key associated with the "test_dummy_operation" mount option is added on-demand when it's needed, rather than immediately when the filesystem is mounted, fscrypt_destroy_keyring() no longer needs to be called from __put_super() to avoid a memory leak on mount failure. Remove this call, which was causing confusion because it appeared to be a sleep-in-atomic bug (though it wasn't, for a somewhat-subtle reason). Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230208062107.199831-5-ebiggers@kernel.org --- fs/super.c | 1 - 1 file changed, 1 deletion(-) diff --git a/fs/super.c b/fs/super.c index 12c08cb20405..ce45b7fd27f9 100644 --- a/fs/super.c +++ b/fs/super.c @@ -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); -- cgit v1.2.3 From 097d7c1fcb8d4b52c62a36f94b8f18bc21a24934 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 7 Feb 2023 22:21:07 -0800 Subject: fscrypt: clean up fscrypt_add_test_dummy_key() Now that fscrypt_add_test_dummy_key() is only called by setup_file_encryption_key() and not by the individual filesystems, un-export it. Also change its prototype to take the fscrypt_key_specifier directly, as the caller already has it. Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20230208062107.199831-6-ebiggers@kernel.org --- fs/crypto/fscrypt_private.h | 3 +++ fs/crypto/keyring.c | 26 +++++++------------------- fs/crypto/keysetup.c | 4 +--- include/linux/fscrypt.h | 9 --------- 4 files changed, 11 insertions(+), 31 deletions(-) diff --git a/fs/crypto/fscrypt_private.h b/fs/crypto/fscrypt_private.h index 17dd33d9a522..0fec2dfc36eb 100644 --- a/fs/crypto/fscrypt_private.h +++ b/fs/crypto/fscrypt_private.h @@ -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]); diff --git a/fs/crypto/keyring.c b/fs/crypto/keyring.c index 78dd2ff306bd..78086f8dbda5 100644 --- a/fs/crypto/keyring.c +++ b/fs/crypto/keyring.c @@ -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 diff --git a/fs/crypto/keysetup.c b/fs/crypto/keysetup.c index 20323c0ba4c5..aa94fba9d17e 100644 --- a/fs/crypto/keysetup.c +++ b/fs/crypto/keysetup.c @@ -464,9 +464,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci, */ if (dummy_policy && fscrypt_policies_equal(dummy_policy, &ci->ci_policy)) { - struct fscrypt_dummy_policy tmp = { dummy_policy }; - - err = fscrypt_add_test_dummy_key(sb, &tmp); + err = fscrypt_add_test_dummy_key(sb, &mk_spec); if (err) return err; mk = fscrypt_find_master_key(sb, &mk_spec); diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h index 4f5f8a651213..44848d870046 100644 --- a/include/linux/fscrypt.h +++ b/include/linux/fscrypt.h @@ -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; -- cgit v1.2.3