| Message ID | 20210705143652.116125-3-jarkko@kernel.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | selftests/sgx: Trigger the page reclaimer and #PF handler | expand |
On 7/5/21 7:36 AM, Jarkko Sakkinen wrote: > From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> > > Q1 and Q2 are numbers with *maximum* length of 384 bytes. If the calculated > length of Q1 and Q2 is less than 384 bytes, things will go wrong. > > E.g. if Q2 is 383 bytes, then > > 1. The bytes of q2 are copied to sigstruct->q2 in calc_q1q2(). > 2. The entire sigstruct->q2 is reversed, which results it being > 256 * Q2, given that the last byte of sigstruct->q2 is added > to before the bytes given by calc_q1q2(). > > Either change in key or measurement can trigger the bug. E.g. an unmeasured > heap could cause a devastating change in Q1 or Q2. > > Reverse exactly the bytes of Q1 and Q2 in calc_q1q2() before returning to > the caller. > > Fixes: 2adcba79e69d ("selftests/x86: Add a selftest for SGX") > Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/ > Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> This looks fine, but can I suggest a Subject: tweak? selftests/sgx: Fix calculations for sub-maximum field sizes In any case: Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com>
On Tue, Jul 06, 2021 at 01:53:20PM -0700, Dave Hansen wrote: > On 7/5/21 7:36 AM, Jarkko Sakkinen wrote: > > From: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> > > > > Q1 and Q2 are numbers with *maximum* length of 384 bytes. If the calculated > > length of Q1 and Q2 is less than 384 bytes, things will go wrong. > > > > E.g. if Q2 is 383 bytes, then > > > > 1. The bytes of q2 are copied to sigstruct->q2 in calc_q1q2(). > > 2. The entire sigstruct->q2 is reversed, which results it being > > 256 * Q2, given that the last byte of sigstruct->q2 is added > > to before the bytes given by calc_q1q2(). > > > > Either change in key or measurement can trigger the bug. E.g. an unmeasured > > heap could cause a devastating change in Q1 or Q2. > > > > Reverse exactly the bytes of Q1 and Q2 in calc_q1q2() before returning to > > the caller. > > > > Fixes: 2adcba79e69d ("selftests/x86: Add a selftest for SGX") > > Link: https://lore.kernel.org/linux-sgx/20210301051836.30738-1-tianjia.zhang@linux.alibaba.com/ > > Signed-off-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> > > Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> > > This looks fine, but can I suggest a Subject: tweak? > > selftests/sgx: Fix calculations for sub-maximum field sizes WFM > > In any case: > > Reviewed-by: Dave Hansen <dave.hansen@linux.intel.com> Thank you. /Jarkko
diff --git a/tools/testing/selftests/sgx/sigstruct.c b/tools/testing/selftests/sgx/sigstruct.c index dee7a3d6c5a5..92bbc5a15c39 100644 --- a/tools/testing/selftests/sgx/sigstruct.c +++ b/tools/testing/selftests/sgx/sigstruct.c @@ -55,10 +55,27 @@ static bool alloc_q1q2_ctx(const uint8_t *s, const uint8_t *m, return true; } +static void reverse_bytes(void *data, int length) +{ + int i = 0; + int j = length - 1; + uint8_t temp; + uint8_t *ptr = data; + + while (i < j) { + temp = ptr[i]; + ptr[i] = ptr[j]; + ptr[j] = temp; + i++; + j--; + } +} + static bool calc_q1q2(const uint8_t *s, const uint8_t *m, uint8_t *q1, uint8_t *q2) { struct q1q2_ctx ctx; + int len; if (!alloc_q1q2_ctx(s, m, &ctx)) { fprintf(stderr, "Not enough memory for Q1Q2 calculation\n"); @@ -89,8 +106,10 @@ static bool calc_q1q2(const uint8_t *s, const uint8_t *m, uint8_t *q1, goto out; } - BN_bn2bin(ctx.q1, q1); - BN_bn2bin(ctx.q2, q2); + len = BN_bn2bin(ctx.q1, q1); + reverse_bytes(q1, len); + len = BN_bn2bin(ctx.q2, q2); + reverse_bytes(q2, len); free_q1q2_ctx(&ctx); return true; @@ -152,22 +171,6 @@ static RSA *gen_sign_key(void) return key; } -static void reverse_bytes(void *data, int length) -{ - int i = 0; - int j = length - 1; - uint8_t temp; - uint8_t *ptr = data; - - while (i < j) { - temp = ptr[i]; - ptr[i] = ptr[j]; - ptr[j] = temp; - i++; - j--; - } -} - enum mrtags { MRECREATE = 0x0045544145524345, MREADD = 0x0000000044444145, @@ -367,8 +370,6 @@ bool encl_measure(struct encl *encl) /* BE -> LE */ reverse_bytes(sigstruct->signature, SGX_MODULUS_SIZE); reverse_bytes(sigstruct->modulus, SGX_MODULUS_SIZE); - reverse_bytes(sigstruct->q1, SGX_MODULUS_SIZE); - reverse_bytes(sigstruct->q2, SGX_MODULUS_SIZE); EVP_MD_CTX_destroy(ctx); RSA_free(key);