79 lines
2.7 KiB
Diff
79 lines
2.7 KiB
Diff
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Copied from upstream nettle git repository.
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Removed changes to ChangeLog, to allow this patch to apply to nettle-3.5.
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From 7616541e6eff73353bf682c62e3a68e4fe696707 Mon Sep 17 00:00:00 2001
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From: Niels Möller <nisse@lysator.liu.se>
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Date: Thu, 6 May 2021 21:29:56 +0200
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Subject: [PATCH] Add check that message length to _pkcs1_sec_decrypt is valid.
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* pkcs1-sec-decrypt.c (_pkcs1_sec_decrypt): Check that message
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length is valid, for given key size.
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* testsuite/rsa-sec-decrypt-test.c (test_main): Add test cases for
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calls to rsa_sec_decrypt specifying a too large message length.
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---
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ChangeLog | 7 +++++++
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pkcs1-sec-decrypt.c | 4 +++-
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testsuite/rsa-sec-decrypt-test.c | 17 ++++++++++++++++-
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3 files changed, 26 insertions(+), 2 deletions(-)
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diff --git a/pkcs1-sec-decrypt.c b/pkcs1-sec-decrypt.c
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index 4f13080e..16833691 100644
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--- a/pkcs1-sec-decrypt.c
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+++ b/pkcs1-sec-decrypt.c
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@@ -63,7 +63,9 @@ _pkcs1_sec_decrypt (size_t length, uint8_t *message,
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volatile int ok;
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size_t i, t;
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- assert (padded_message_length >= length);
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+ /* Message independent branch */
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+ if (length + 11 > padded_message_length)
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+ return 0;
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t = padded_message_length - length - 1;
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diff --git a/testsuite/rsa-sec-decrypt-test.c b/testsuite/rsa-sec-decrypt-test.c
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index fb0ed3a1..3419322e 100644
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--- a/testsuite/rsa-sec-decrypt-test.c
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+++ b/testsuite/rsa-sec-decrypt-test.c
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@@ -55,6 +55,7 @@ rsa_decrypt_for_test(const struct rsa_public_key *pub,
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#endif
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#define PAYLOAD_SIZE 50
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+#define DECRYPTED_SIZE 256
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void
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test_main(void)
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{
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@@ -63,7 +64,7 @@ test_main(void)
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struct knuth_lfib_ctx random_ctx;
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uint8_t plaintext[PAYLOAD_SIZE];
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- uint8_t decrypted[PAYLOAD_SIZE];
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+ uint8_t decrypted[DECRYPTED_SIZE];
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uint8_t verifybad[PAYLOAD_SIZE];
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unsigned n_size = 1024;
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mpz_t gibberish;
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@@ -99,6 +100,20 @@ test_main(void)
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PAYLOAD_SIZE, decrypted, gibberish) == 1);
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ASSERT (MEMEQ (PAYLOAD_SIZE, plaintext, decrypted));
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+ ASSERT (pub.size > 10);
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+ ASSERT (pub.size <= DECRYPTED_SIZE);
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+
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+ /* Check that too large message length is rejected, largest
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+ valid size is pub.size - 11. */
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+ ASSERT (!rsa_decrypt_for_test (&pub, &key, &random_ctx,
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+ (nettle_random_func *) knuth_lfib_random,
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+ pub.size - 10, decrypted, gibberish));
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+
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+ /* This case used to result in arithmetic underflow and a crash. */
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+ ASSERT (!rsa_decrypt_for_test (&pub, &key, &random_ctx,
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+ (nettle_random_func *) knuth_lfib_random,
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+ pub.size, decrypted, gibberish));
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+
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/* bad one */
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memcpy(decrypted, verifybad, PAYLOAD_SIZE);
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nettle_mpz_random_size(garbage, &random_ctx,
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--
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2.31.1
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