164 lines
5.3 KiB
Diff
164 lines
5.3 KiB
Diff
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 0ad0b5df315665250dfdaa4a1e087f4799edaefe Mon Sep 17 00:00:00 2001
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From: Niels Möller <nisse@lysator.liu.se>
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Date: Mon, 17 May 2021 22:02:47 +0200
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Subject: [PATCH 2/2] Add input check to rsa_decrypt family of functions.
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---
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ChangeLog | 8 ++++++++
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rsa-decrypt-tr.c | 4 ++++
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rsa-decrypt.c | 10 ++++++++++
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rsa-sec-decrypt.c | 4 ++++
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rsa.h | 5 +++--
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testsuite/rsa-encrypt-test.c | 38 ++++++++++++++++++++++++++++++------
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6 files changed, 61 insertions(+), 8 deletions(-)
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diff --git a/rsa-decrypt-tr.c b/rsa-decrypt-tr.c
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index 927a8915..4a9e9d74 100644
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--- a/rsa-decrypt-tr.c
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+++ b/rsa-decrypt-tr.c
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@@ -52,6 +52,10 @@ rsa_decrypt_tr(const struct rsa_public_key *pub,
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mp_size_t key_limb_size;
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int res;
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+ /* First check that input is in range. */
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+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, pub->n) >= 0)
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+ return 0;
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+
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key_limb_size = mpz_size(pub->n);
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TMP_GMP_ALLOC (m, key_limb_size);
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diff --git a/rsa-decrypt.c b/rsa-decrypt.c
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index 7681439d..540d8baa 100644
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--- a/rsa-decrypt.c
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+++ b/rsa-decrypt.c
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@@ -48,6 +48,16 @@ rsa_decrypt(const struct rsa_private_key *key,
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int res;
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mpz_init(m);
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+
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+ /* First check that input is in range. Since we don't have the
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+ public key available here, we need to reconstruct n. */
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+ mpz_mul (m, key->p, key->q);
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+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, m) >= 0)
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+ {
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+ mpz_clear (m);
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+ return 0;
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+ }
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+
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rsa_compute_root(key, m, gibberish);
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res = pkcs1_decrypt (key->size, m, length, message);
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diff --git a/rsa-sec-decrypt.c b/rsa-sec-decrypt.c
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index fc4757a0..4c98958d 100644
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--- a/rsa-sec-decrypt.c
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+++ b/rsa-sec-decrypt.c
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@@ -55,6 +55,10 @@ rsa_sec_decrypt(const struct rsa_public_key *pub,
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TMP_GMP_DECL (em, uint8_t);
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int res;
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+ /* First check that input is in range. */
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+ if (mpz_sgn (gibberish) < 0 || mpz_cmp (gibberish, pub->n) >= 0)
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+ return 0;
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+
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TMP_GMP_ALLOC (m, mpz_size(pub->n));
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TMP_GMP_ALLOC (em, key->size);
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diff --git a/rsa.h b/rsa.h
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index 3b10155f..2dd35a2d 100644
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--- a/rsa.h
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+++ b/rsa.h
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@@ -428,13 +428,14 @@ rsa_sec_decrypt(const struct rsa_public_key *pub,
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size_t length, uint8_t *message,
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const mpz_t gibberish);
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-/* Compute x, the e:th root of m. Calling it with x == m is allowed. */
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+/* Compute x, the e:th root of m. Calling it with x == m is allowed.
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+ It is required that 0 <= m < n. */
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void
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rsa_compute_root(const struct rsa_private_key *key,
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mpz_t x, const mpz_t m);
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/* Safer variant, using RSA blinding, and checking the result after
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- CRT. */
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+ CRT. It is required that 0 <= m < n. */
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int
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rsa_compute_root_tr(const struct rsa_public_key *pub,
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const struct rsa_private_key *key,
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diff --git a/testsuite/rsa-encrypt-test.c b/testsuite/rsa-encrypt-test.c
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index d3bc374b..d1a440f6 100644
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--- a/testsuite/rsa-encrypt-test.c
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+++ b/testsuite/rsa-encrypt-test.c
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@@ -19,11 +19,12 @@ test_main(void)
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uint8_t after;
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mpz_t gibberish;
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- mpz_t zero;
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+ mpz_t bad_input;
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rsa_private_key_init(&key);
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rsa_public_key_init(&pub);
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mpz_init(gibberish);
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+ mpz_init(bad_input);
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knuth_lfib_init(&lfib, 17);
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@@ -103,15 +104,40 @@ test_main(void)
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ASSERT(decrypted[0] == 'A');
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/* Test zero input. */
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- mpz_init_set_ui (zero, 0);
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+ mpz_set_ui (bad_input, 0);
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decrypted_length = msg_length;
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- ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, zero));
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+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
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ASSERT(!rsa_decrypt_tr(&pub, &key,
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&lfib, (nettle_random_func *) knuth_lfib_random,
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- &decrypted_length, decrypted, zero));
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+ &decrypted_length, decrypted, bad_input));
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ASSERT(!rsa_sec_decrypt(&pub, &key,
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&lfib, (nettle_random_func *) knuth_lfib_random,
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- decrypted_length, decrypted, zero));
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+ decrypted_length, decrypted, bad_input));
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+ ASSERT(decrypted_length == msg_length);
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+
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+ /* Test input that is slightly larger than n */
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+ mpz_add(bad_input, gibberish, pub.n);
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+ decrypted_length = msg_length;
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+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
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+ ASSERT(!rsa_decrypt_tr(&pub, &key,
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+ &lfib, (nettle_random_func *) knuth_lfib_random,
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+ &decrypted_length, decrypted, bad_input));
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+ ASSERT(!rsa_sec_decrypt(&pub, &key,
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+ &lfib, (nettle_random_func *) knuth_lfib_random,
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+ decrypted_length, decrypted, bad_input));
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+ ASSERT(decrypted_length == msg_length);
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+
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+ /* Test input that is considerably larger than n */
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+ mpz_mul_2exp (bad_input, pub.n, 100);
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+ mpz_add (bad_input, bad_input, gibberish);
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+ decrypted_length = msg_length;
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+ ASSERT(!rsa_decrypt(&key, &decrypted_length, decrypted, bad_input));
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+ ASSERT(!rsa_decrypt_tr(&pub, &key,
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+ &lfib, (nettle_random_func *) knuth_lfib_random,
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+ &decrypted_length, decrypted, bad_input));
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+ ASSERT(!rsa_sec_decrypt(&pub, &key,
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+ &lfib, (nettle_random_func *) knuth_lfib_random,
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+ decrypted_length, decrypted, bad_input));
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ASSERT(decrypted_length == msg_length);
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/* Test invalid key. */
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@@ -124,6 +150,6 @@ test_main(void)
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rsa_private_key_clear(&key);
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rsa_public_key_clear(&pub);
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mpz_clear(gibberish);
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- mpz_clear(zero);
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+ mpz_clear(bad_input);
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free(decrypted);
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}
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--
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2.31.1
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