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16fcad47a4
The code for hostapd-mbedtls did not work when used for OWE association.
When handling association requests, the buffer offsets and length
assumptions were incorrect, leading to never calculating the y point,
thus denying association.
Also when crafting the association response, the buffer contained the
trailing key-type.
Fix up both issues to adhere to the specification and make
hostapd-mbedtls work with the OWE security type.
Signed-off-by: David Bauer <mail@david-bauer.net>
(cherry picked from commit 39341f422f)
92 lines
3.2 KiB
Diff
92 lines
3.2 KiB
Diff
The code for hostapd-mbedtls did not work when used for OWE association.
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When handling association requests, the buffer offsets and length assumptions were incorrect, leading to never calculating the y point, thus denying association.
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Also when crafting the association response, the buffer contained the trailing key-type.
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Fix up both issues to adhere to the specification and make hostapd-mbedtls work with the OWE security type.
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--- a/src/crypto/crypto_mbedtls.c
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+++ b/src/crypto/crypto_mbedtls.c
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@@ -2299,25 +2299,30 @@ struct crypto_ecdh * crypto_ecdh_init2(i
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struct wpabuf * crypto_ecdh_get_pubkey(struct crypto_ecdh *ecdh, int inc_y)
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{
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mbedtls_ecp_group *grp = &ecdh->grp;
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- size_t len = CRYPTO_EC_plen(grp);
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+ size_t prime_len = CRYPTO_EC_plen(grp);
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+ size_t output_len = prime_len;
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+ u8 output_offset = 0;
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+ u8 buf[256];
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+
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#ifdef MBEDTLS_ECP_MONTGOMERY_ENABLED
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/* len */
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#endif
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#ifdef MBEDTLS_ECP_SHORT_WEIERSTRASS_ENABLED
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- if (mbedtls_ecp_get_type(grp) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS)
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- len = inc_y ? len*2+1 : len+1;
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+ if (mbedtls_ecp_get_type(grp) == MBEDTLS_ECP_TYPE_SHORT_WEIERSTRASS) {
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+ output_len = inc_y ? prime_len * 2 + 1 : prime_len + 1;
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+ output_offset = 1;
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+ }
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#endif
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- struct wpabuf *buf = wpabuf_alloc(len);
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- if (buf == NULL)
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+
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+ if (output_len > sizeof(buf))
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return NULL;
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+
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inc_y = inc_y ? MBEDTLS_ECP_PF_UNCOMPRESSED : MBEDTLS_ECP_PF_COMPRESSED;
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- if (mbedtls_ecp_point_write_binary(grp, &ecdh->Q, inc_y, &len,
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- wpabuf_mhead_u8(buf), len) == 0) {
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- wpabuf_put(buf, len);
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- return buf;
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+ if (mbedtls_ecp_point_write_binary(grp, &ecdh->Q, inc_y, &output_len,
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+ buf, output_len) == 0) {
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+ return wpabuf_alloc_copy(buf + output_offset, output_len - output_offset);
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}
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- wpabuf_free(buf);
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return NULL;
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}
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@@ -2379,10 +2384,7 @@ struct wpabuf * crypto_ecdh_set_peerkey(
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os_memcpy(buf+2, key, len);
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}
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len >>= 1; /*(repurpose len to prime_len)*/
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- }
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- else if (key[0] == 0x02 || key[0] == 0x03) { /* (inc_y == 0) */
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- --len; /*(repurpose len to prime_len)*/
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-
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+ } else { /* (inc_y == 0) */
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/* mbedtls_ecp_point_read_binary() does not currently support
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* MBEDTLS_ECP_PF_COMPRESSED format (buf[1] = 0x02 or 0x03)
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* (returns MBEDTLS_ERR_ECP_FEATURE_UNAVAILABLE) */
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@@ -2390,22 +2392,21 @@ struct wpabuf * crypto_ecdh_set_peerkey(
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/* derive y, amend buf[] with y for UNCOMPRESSED format */
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if (sizeof(buf)-2 < len*2 || len == 0)
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return NULL;
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+
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buf[0] = (u8)(1+len*2);
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buf[1] = 0x04;
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+ os_memcpy(buf+2, key, len);
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+
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mbedtls_mpi bn;
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mbedtls_mpi_init(&bn);
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- int ret = mbedtls_mpi_read_binary(&bn, key+1, len)
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- || crypto_mbedtls_short_weierstrass_derive_y(grp, &bn,
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- key[0] & 1)
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+ int ret = mbedtls_mpi_read_binary(&bn, key, len)
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+ || crypto_mbedtls_short_weierstrass_derive_y(grp, &bn, 0)
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|| mbedtls_mpi_write_binary(&bn, buf+2+len, len);
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mbedtls_mpi_free(&bn);
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if (ret != 0)
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return NULL;
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}
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- if (key[0] == 0) /*(repurpose len to prime_len)*/
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- len = CRYPTO_EC_plen(grp);
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-
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if (mbedtls_ecdh_read_public(&ecdh->ctx, buf, buf[0]+1))
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return NULL;
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}
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