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/keysetup.c | 25 +++++++++++++++++++++++-- 1 file changed, 23 insertions(+), 2 deletions(-) (limited to 'fs/crypto/keysetup.c') 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; -- cgit