50 lines
1.5 KiB
Diff
50 lines
1.5 KiB
Diff
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iFrom ed282e9a463c068146c945984fdea7828e663861 Mon Sep 17 00:00:00 2001
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From: Tobias Brunner <tobias@strongswan.org>
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Date: Mon, 29 May 2017 11:59:34 +0200
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Subject: [PATCH] gmp: Fix RSA signature verification for m >= n
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By definition, m must be <= n-1, we didn't enforce that and because
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mpz_export() returns NULL if the passed value is zero a crash could have
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been triggered with m == n.
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Fixes CVE-2017-11185.
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---
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src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c | 12 +++++++++---
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1 file changed, 9 insertions(+), 3 deletions(-)
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diff --git a/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c b/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
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index 32a72ac9600b..a741f85d4f62 100644
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--- a/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
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+++ b/src/libstrongswan/plugins/gmp/gmp_rsa_public_key.c
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@@ -78,11 +78,17 @@ static chunk_t rsaep(private_gmp_rsa_public_key_t *this, chunk_t data)
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mpz_t m, c;
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chunk_t encrypted;
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- mpz_init(c);
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mpz_init(m);
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-
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mpz_import(m, data.len, 1, 1, 1, 0, data.ptr);
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+ if (mpz_cmp_ui(m, 0) <= 0 || mpz_cmp(m, this->n) >= 0)
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+ { /* m must be <= n-1, but 0 is a valid value, doesn't really make sense
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+ * here, though */
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+ mpz_clear(m);
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+ return chunk_empty;
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+ }
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+
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+ mpz_init(c);
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mpz_powm(c, m, this->e, this->n);
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encrypted.len = this->k;
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@@ -150,7 +156,7 @@ static bool verify_emsa_pkcs1_signature(private_gmp_rsa_public_key_t *this,
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*/
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/* check magic bytes */
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- if (*(em.ptr) != 0x00 || *(em.ptr+1) != 0x01)
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+ if (em.len < 2 || *(em.ptr) != 0x00 || *(em.ptr+1) != 0x01)
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{
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goto end;
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}
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--
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2.7.4
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