Attachment 3538 Details for Bug 3279 – Better RSA verification debugging

[patch] Better RSA verification debugging

rsa-debug.diff (text/plain), 1.55 KB, created by Damien Miller on 2021-07-16 10:32:14 AEST

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Creator: Damien Miller

Created: 2021-07-16 10:32:14 AEST

Size: 1.55 KB

patch

obsolete

>diff --git a/ssh-rsa.c b/ssh-rsa.c
>index 9b14f9a9a..a3c94867c 100644
>--- a/ssh-rsa.c
>+++ b/ssh-rsa.c
>@@ -34,6 +34,7 @@
> #include "sshkey.h"
> #include "digest.h"
> #include "log.h"
>+#include "misc.h"
> 
> #include "openbsd-compat/openssl-compat.h"
> 
>@@ -320,6 +321,19 @@ ssh_rsa_verify(const struct sshkey *key,
> 
> 	ret = openssh_RSA_verify(hash_alg, digest, dlen, sigblob, len,
> 	    key->rsa);
>+	if (ret != 0) {
>+		debug_f("alg=%s", alg == NULL ? "default" : alg);
>+		sshbuf_free(b);
>+		if ((b = sshbuf_from(sigblob, len)) == NULL)
>+			fatal_f("sshbuf_from");
>+		debug_f("sigblob=%s", sshbuf_dtob64_string(b, 0));
>+		sshbuf_free(b);
>+		if ((b = sshbuf_new()) == NULL)
>+			fatal_f("sshbuf_new");
>+		if (sshkey_format_text(key, b) != 0)
>+			fatal_f("sshkey_format_text");
>+		debug_f("key=%s", sshbuf_dup_string(b));
>+	}
>  out:
> 	freezero(sigblob, len);
> 	free(sigtype);
>@@ -399,6 +413,14 @@ rsa_hash_alg_oid(int hash_alg, const u_char **oidp, size_t *oidlenp)
> 	return 0;
> }
> 
>+static int
>+dump_libcrypto_error(const char *str, size_t len, void *u)
>+{
>+	debug("%s: libcrypto: %.*s", (char*)u, (int)len, str);
>+	return 0;
>+}
>+
>+
> static int
> openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
>     u_char *sigbuf, size_t siglen, RSA *rsa)
>@@ -428,6 +450,8 @@ openssh_RSA_verify(int hash_alg, u_char *hash, size_t hashlen,
> 	}
> 	if ((len = RSA_public_decrypt(siglen, sigbuf, decrypted, rsa,
> 	    RSA_PKCS1_PADDING)) < 0) {
>+		debug_f("failed RSA_public_decrypt");
>+		ERR_print_errors_cb(dump_libcrypto_error, (void*)__func__);
> 		ret = SSH_ERR_LIBCRYPTO_ERROR;
> 		goto done;
> 	}

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