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Hallyn" , Shuah Khan , Song Liu , "Theodore Y. Ts'o" , Yanteng Si , Yonghong Song Subject: [PATCH v10 1/3] KEYS: Introduce keyring_is_empty() Date: Fri, 13 Nov 2026 18:18:34 +0200 Message-ID: <20261113161836.3587552-2-jarkko@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261113161836.3587552-1-jarkko@kernel.org> References: <20261113161836.3587552-1-jarkko@kernel.org> X-Mailing-List: fsverity@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Introduce keyring_is_empty() in order to decouple for BPF, dm-verity and fs-verity how keyring internally manages the keys. Reviewed-by: Eric Biggers Reviewed-by: Ignat Korchagin Signed-off-by: Jarkko Sakkinen --- drivers/md/dm-verity-verify-sig.c | 2 +- fs/verity/signature.c | 2 +- include/linux/key.h | 1 + kernel/bpf/keys.c | 2 +- security/keys/keyring.c | 10 ++++++++++ .../selftests/dm-verity/test-dm-verity-keyring.sh | 2 +- 6 files changed, 15 insertions(+), 4 deletions(-) diff --git a/drivers/md/dm-verity-verify-sig.c b/drivers/md/dm-verity-verify-sig.c index 0c65c7a31da8..bd5143aae4fa 100644 --- a/drivers/md/dm-verity-verify-sig.c +++ b/drivers/md/dm-verity-verify-sig.c @@ -153,7 +153,7 @@ int verity_verify_root_hash(const void *root_hash, size_t root_hash_len, if (ret != -ENOKEY && ret != -EKEYREJECTED) return ret; - if (dm_verity_keyring->keys.nr_leaves_on_tree && + if (!keyring_is_empty(dm_verity_keyring) && dm_verity_keyring->restrict_link) ret = verify_pkcs7_signature(root_hash, root_hash_len, sig_data, sig_len, diff --git a/fs/verity/signature.c b/fs/verity/signature.c index 2f49c5d9d987..b45b39b829b2 100644 --- a/fs/verity/signature.c +++ b/fs/verity/signature.c @@ -70,7 +70,7 @@ int fsverity_verify_signature(const struct fsverity_info *vi, return 0; } - if (fsverity_keyring->keys.nr_leaves_on_tree == 0) { + if (keyring_is_empty(fsverity_keyring)) { /* * The ".fs-verity" keyring is empty, due to builtin signatures * being supported by the kernel but not actually being used. diff --git a/include/linux/key.h b/include/linux/key.h index 420412aab926..9ff10b780865 100644 --- a/include/linux/key.h +++ b/include/linux/key.h @@ -439,6 +439,7 @@ extern int restrict_link_reject(struct key *keyring, struct key *restriction_key); extern int keyring_clear(struct key *keyring); +bool keyring_is_empty(const struct key *keyring); extern key_ref_t keyring_search(key_ref_t keyring, struct key_type *type, diff --git a/kernel/bpf/keys.c b/kernel/bpf/keys.c index bffc356839ac..24e0416abc99 100644 --- a/kernel/bpf/keys.c +++ b/kernel/bpf/keys.c @@ -29,7 +29,7 @@ struct bpf_key *bpf_lookup_keyring(void) if (!bpf_keyring) return NULL; - if (!READ_ONCE(bpf_keyring->keys.nr_leaves_on_tree) || + if (keyring_is_empty(bpf_keyring) || !READ_ONCE(bpf_keyring->restrict_link)) return NULL; diff --git a/security/keys/keyring.c b/security/keys/keyring.c index 357f56360810..3d12dc4b5974 100644 --- a/security/keys/keyring.c +++ b/security/keys/keyring.c @@ -443,6 +443,16 @@ static void keyring_destroy(struct key *keyring) assoc_array_destroy(&keyring->keys, &keyring_assoc_array_ops); } +/** + * keyring_is_empty - Check whether a keyring is empty + * @keyring: The keyring to check. + */ +bool keyring_is_empty(const struct key *keyring) +{ + return READ_ONCE(keyring->keys.nr_leaves_on_tree) == 0; +} +EXPORT_SYMBOL(keyring_is_empty); + /* * Describe a keyring for /proc. */ diff --git a/tools/testing/selftests/dm-verity/test-dm-verity-keyring.sh b/tools/testing/selftests/dm-verity/test-dm-verity-keyring.sh index 1f9601ef22f8..792449d356cf 100755 --- a/tools/testing/selftests/dm-verity/test-dm-verity-keyring.sh +++ b/tools/testing/selftests/dm-verity/test-dm-verity-keyring.sh @@ -746,7 +746,7 @@ test_keyring_inactive_when_empty() { log_info "TEST: Verify dm-verity keyring is inactive when sealed empty" # When keyring_unsealed=0, the keyring is sealed immediately while empty - # This means it should NOT be used for verification (nr_leaves_on_tree=0) + # An empty keyring should NOT be used for verification. log_info "Keyring state (should be empty and sealed):" list_keyring_keys -- 2.47.3