keyrings fixes

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Merge tag 'keys-fixes-20230321' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs

Pull keyrings fixes from David Howells:

 - Fix request_key() so that it doesn't cache a looked up key on the
   current thread if that thread is a kernel thread.

   The cache is cleared during notify_resume - but that doesn't happen
   in kernel threads. This is causing cifs DNS keys to be
   un-invalidateable.

 - Fix a wrapper check in verify_pefile() to not round up the length.

 - Change asymmetric_keys code to log errors to make it easier for users
   to work out why failures occurred.

* tag 'keys-fixes-20230321' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs:
  asymmetric_keys: log on fatal failures in PE/pkcs7
  verify_pefile: relax wrapper length check
  keys: Do not cache key in task struct if key is requested from kernel thread

crypto/asymmetric_keys/pkcs7_verify.c

@@ -79,16 +79,16 @@ static int pkcs7_digest(struct pkcs7_message *pkcs7,
 		}
 
 		if (sinfo->msgdigest_len != sig->digest_size) {
-			pr_debug("Sig %u: Invalid digest size (%u)\n",
-				 sinfo->index, sinfo->msgdigest_len);
+			pr_warn("Sig %u: Invalid digest size (%u)\n",
+				sinfo->index, sinfo->msgdigest_len);
 			ret = -EBADMSG;
 			goto error;
 		}
 
 		if (memcmp(sig->digest, sinfo->msgdigest,
 			   sinfo->msgdigest_len) != 0) {
-			pr_debug("Sig %u: Message digest doesn't match\n",
-				 sinfo->index);
+			pr_warn("Sig %u: Message digest doesn't match\n",
+				sinfo->index);
 			ret = -EKEYREJECTED;
 			goto error;
 		}
@@ -478,7 +478,7 @@ int pkcs7_supply_detached_data(struct pkcs7_message *pkcs7,
 			       const void *data, size_t datalen)
 {
 	if (pkcs7->data) {
-		pr_debug("Data already supplied\n");
+		pr_warn("Data already supplied\n");
 		return -EINVAL;
 	}
 	pkcs7->data = data;

crypto/asymmetric_keys/verify_pefile.c

@@ -74,7 +74,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
 		break;
 
 	default:
-		pr_debug("Unknown PEOPT magic = %04hx\n", pe32->magic);
+		pr_warn("Unknown PEOPT magic = %04hx\n", pe32->magic);
 		return -ELIBBAD;
 	}
 
@@ -95,7 +95,7 @@ static int pefile_parse_binary(const void *pebuf, unsigned int pelen,
 	ctx->certs_size = ddir->certs.size;
 
 	if (!ddir->certs.virtual_address || !ddir->certs.size) {
-		pr_debug("Unsigned PE binary\n");
+		pr_warn("Unsigned PE binary\n");
 		return -ENODATA;
 	}
 
@@ -127,7 +127,7 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
 	unsigned len;
 
 	if (ctx->sig_len < sizeof(wrapper)) {
-		pr_debug("Signature wrapper too short\n");
+		pr_warn("Signature wrapper too short\n");
 		return -ELIBBAD;
 	}
 
@@ -135,19 +135,23 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
 	pr_debug("sig wrapper = { %x, %x, %x }\n",
 		 wrapper.length, wrapper.revision, wrapper.cert_type);
 
-	/* Both pesign and sbsign round up the length of certificate table
-	 * (in optional header data directories) to 8 byte alignment.
+	/* sbsign rounds up the length of certificate table (in optional
+	 * header data directories) to 8 byte alignment.  However, the PE
+	 * specification states that while entries are 8-byte aligned, this is
+	 * not included in their length, and as a result, pesign has not
+	 * rounded up since 0.110.
 	 */
-	if (round_up(wrapper.length, 8) != ctx->sig_len) {
-		pr_debug("Signature wrapper len wrong\n");
+	if (wrapper.length > ctx->sig_len) {
+		pr_warn("Signature wrapper bigger than sig len (%x > %x)\n",
+			ctx->sig_len, wrapper.length);
 		return -ELIBBAD;
 	}
 	if (wrapper.revision != WIN_CERT_REVISION_2_0) {
-		pr_debug("Signature is not revision 2.0\n");
+		pr_warn("Signature is not revision 2.0\n");
 		return -ENOTSUPP;
 	}
 	if (wrapper.cert_type != WIN_CERT_TYPE_PKCS_SIGNED_DATA) {
-		pr_debug("Signature certificate type is not PKCS\n");
+		pr_warn("Signature certificate type is not PKCS\n");
 		return -ENOTSUPP;
 	}
 
@@ -160,7 +164,7 @@ static int pefile_strip_sig_wrapper(const void *pebuf,
 	ctx->sig_offset += sizeof(wrapper);
 	ctx->sig_len -= sizeof(wrapper);
 	if (ctx->sig_len < 4) {
-		pr_debug("Signature data missing\n");
+		pr_warn("Signature data missing\n");
 		return -EKEYREJECTED;
 	}
 
@@ -194,7 +198,7 @@ check_len:
 		return 0;
 	}
 not_pkcs7:
-	pr_debug("Signature data not PKCS#7\n");
+	pr_warn("Signature data not PKCS#7\n");
 	return -ELIBBAD;
 }
 
@@ -337,8 +341,8 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
 	digest_size = crypto_shash_digestsize(tfm);
 
 	if (digest_size != ctx->digest_len) {
-		pr_debug("Digest size mismatch (%zx != %x)\n",
-			 digest_size, ctx->digest_len);
+		pr_warn("Digest size mismatch (%zx != %x)\n",
+			digest_size, ctx->digest_len);
 		ret = -EBADMSG;
 		goto error_no_desc;
 	}
@@ -369,7 +373,7 @@ static int pefile_digest_pe(const void *pebuf, unsigned int pelen,
 	 * PKCS#7 certificate.
 	 */
 	if (memcmp(digest, ctx->digest, ctx->digest_len) != 0) {
-		pr_debug("Digest mismatch\n");
+		pr_warn("Digest mismatch\n");
 		ret = -EKEYREJECTED;
 	} else {
 		pr_debug("The digests match!\n");

security/keys/request_key.c

@@ -38,9 +38,12 @@ static void cache_requested_key(struct key *key)
 #ifdef CONFIG_KEYS_REQUEST_CACHE
 	struct task_struct *t = current;
 
-	key_put(t->cached_requested_key);
-	t->cached_requested_key = key_get(key);
-	set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+	/* Do not cache key if it is a kernel thread */
+	if (!(t->flags & PF_KTHREAD)) {
+		key_put(t->cached_requested_key);
+		t->cached_requested_key = key_get(key);
+		set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
+	}
 #endif
 }