On 4/25/23 10:35 AM, Roberto Sassu wrote:
From: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
Introduce the bpf_verify_umd_signature() kfunc, to verify UMD-parsed
signatures. The parameters and usage are the same as for
bpf_verify_pkcs7_signature().
Signed-off-by: Roberto Sassu <roberto.sassu@xxxxxxxxxx>
---
kernel/trace/bpf_trace.c | 69 ++++++++++++++++++++++++++++++++--------
1 file changed, 55 insertions(+), 14 deletions(-)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index e8da032bb6f..c9cae337596 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -1271,7 +1271,7 @@ __bpf_kfunc struct bpf_key *bpf_lookup_user_key(u32 serial, u64 flags)
* The key pointer is marked as invalid, to prevent bpf_key_put() from
* attempting to decrement the key reference count on that pointer. The key
* pointer set in such way is currently understood only by
- * verify_pkcs7_signature().
+ * verify_pkcs7_signature() and verify_umd_signature().
*
* Set *id* to one of the values defined in include/linux/verification.h:
* 0 for the primary keyring (immutable keyring of system keys);
@@ -1317,6 +1317,27 @@ __bpf_kfunc void bpf_key_put(struct bpf_key *bkey)
}
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
+static int validate_key(struct bpf_key *trusted_keyring)
+{
+ int ret = 0;
+
+ if (trusted_keyring->has_ref) {
+ /*
+ * Do the permission check deferred in bpf_lookup_user_key().
+ * See bpf_lookup_user_key() for more details.
+ *
+ * A call to key_task_permission() here would be redundant, as
+ * it is already done by keyring_search() called by
+ * find_asymmetric_key().
+ */
+ ret = key_validate(trusted_keyring->key);
+ if (ret < 0)
+ return ret;
The above
if (ret < 0)
return ret;
can be removed.
+ }
+
+ return ret;
+}
+
/**
* bpf_verify_pkcs7_signature - verify a PKCS#7 signature
* @data_ptr: data to verify
@@ -1334,19 +1355,9 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
{
int ret;
- if (trusted_keyring->has_ref) {
- /*
- * Do the permission check deferred in bpf_lookup_user_key().
- * See bpf_lookup_user_key() for more details.
- *
- * A call to key_task_permission() here would be redundant, as
- * it is already done by keyring_search() called by
- * find_asymmetric_key().
- */
- ret = key_validate(trusted_keyring->key);
- if (ret < 0)
- return ret;
- }
+ ret = validate_key(trusted_keyring);
+ if (ret < 0)
+ return ret;
return verify_pkcs7_signature(data_ptr->data,
bpf_dynptr_get_size(data_ptr),
@@ -1356,6 +1367,35 @@ __bpf_kfunc int bpf_verify_pkcs7_signature(struct bpf_dynptr_kern *data_ptr,
VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
NULL);
}
+
+/**
+ * bpf_verify_umd_signature - Verify a UMD-parsed signature
+ * @data_ptr: Data to verify
+ * @sig_ptr: Signature of the data
+ * @trusted_keyring: Keyring with keys trusted for signature verification
+ *
+ * Verify the UMD-parsed signature *sig_ptr* against the supplied *data_ptr*
+ * with keys in a keyring referenced by *trusted_keyring*.
+ *
+ * Return: 0 on success, a negative value on error.
+ */
+__bpf_kfunc int bpf_verify_umd_signature(struct bpf_dynptr_kern *data_ptr,
+ struct bpf_dynptr_kern *sig_ptr,
+ struct bpf_key *trusted_keyring)
+{
+ int ret;
+
+ ret = validate_key(trusted_keyring);
+ if (ret < 0)
+ return ret;
+
+ return verify_umd_signature(data_ptr->data,
+ bpf_dynptr_get_size(data_ptr),
+ sig_ptr->data, bpf_dynptr_get_size(sig_ptr),
+ trusted_keyring->key,
+ VERIFYING_UNSPECIFIED_SIGNATURE, NULL,
+ NULL);
+}
#endif /* CONFIG_SYSTEM_DATA_VERIFICATION */
__diag_pop();
@@ -1366,6 +1406,7 @@ BTF_ID_FLAGS(func, bpf_lookup_system_key, KF_ACQUIRE | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_key_put, KF_RELEASE)
#ifdef CONFIG_SYSTEM_DATA_VERIFICATION
BTF_ID_FLAGS(func, bpf_verify_pkcs7_signature, KF_SLEEPABLE)
+BTF_ID_FLAGS(func, bpf_verify_umd_signature, KF_SLEEPABLE)
#endif
BTF_SET8_END(key_sig_kfunc_set)
