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Tighten extension handling

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This adds additional checks to the processing of extensions in a ClientHello
to ensure that either no extensions are present, or if they are then they
take up the exact amount of space expected.

With thanks to the Open Crypto Audit Project for reporting this issue.

Reviewed-by: Stephen Henson <steve@openssl.org>

Conflicts:
	ssl/t1_lib.c
This commit is contained in:
Matt Caswell 2015-04-30 15:20:25 +01:00
parent f92b196723
commit 72df35acf2
1 changed files with 64 additions and 94 deletions
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158
ssl/t1_lib.c
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@ -1016,19 +1016,23 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
s->srtp_profile = NULL; s->srtp_profile = NULL;
if (data >= (d + n - 2)) if (data >= (d + n - 2)) {
goto ri_check; if (data != d + n)
goto err;
else
goto ri_check;
}
n2s(data, len); n2s(data, len);
if (data > (d + n - len)) if (data > (d + n - len))
goto ri_check; goto err;
while (data <= (d + n - 4)) { while (data <= (d + n - 4)) {
n2s(data, type); n2s(data, type);
n2s(data, size); n2s(data, size);
if (data + size > (d + n)) if (data + size > (d + n))
goto ri_check; goto err;
# if 0 # if 0
fprintf(stderr, "Received extension type %d size %d\n", type, size); fprintf(stderr, "Received extension type %d size %d\n", type, size);
# endif # endif
@ -1064,16 +1068,12 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
int servname_type; int servname_type;
int dsize; int dsize;
if (size < 2) { if (size < 2)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
n2s(data, dsize); n2s(data, dsize);
size -= 2; size -= 2;
if (dsize > size) { if (dsize > size)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
sdata = data; sdata = data;
while (dsize > 3) { while (dsize > 3) {
@ -1081,18 +1081,16 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
n2s(sdata, len); n2s(sdata, len);
dsize -= 3; dsize -= 3;
if (len > dsize) { if (len > dsize)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
if (s->servername_done == 0) if (s->servername_done == 0)
switch (servname_type) { switch (servname_type) {
case TLSEXT_NAMETYPE_host_name: case TLSEXT_NAMETYPE_host_name:
if (!s->hit) { if (!s->hit) {
if (s->session->tlsext_hostname) { if (s->session->tlsext_hostname)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
if (len > TLSEXT_MAXLEN_host_name) { if (len > TLSEXT_MAXLEN_host_name) {
*al = TLS1_AD_UNRECOGNIZED_NAME; *al = TLS1_AD_UNRECOGNIZED_NAME;
return 0; return 0;
@ -1126,31 +1124,23 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
dsize -= len; dsize -= len;
} }
if (dsize != 0) { if (dsize != 0)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
} }
# ifndef OPENSSL_NO_SRP # ifndef OPENSSL_NO_SRP
else if (type == TLSEXT_TYPE_srp) { else if (type == TLSEXT_TYPE_srp) {
if (size == 0 || ((len = data[0])) != (size - 1)) { if (size == 0 || ((len = data[0])) != (size - 1))
*al = SSL_AD_DECODE_ERROR; goto err;
return 0; if (s->srp_ctx.login != NULL)
} goto err;
if (s->srp_ctx.login != NULL) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
if ((s->srp_ctx.login = OPENSSL_malloc(len + 1)) == NULL) if ((s->srp_ctx.login = OPENSSL_malloc(len + 1)) == NULL)
return -1; return -1;
memcpy(s->srp_ctx.login, &data[1], len); memcpy(s->srp_ctx.login, &data[1], len);
s->srp_ctx.login[len] = '\0'; s->srp_ctx.login[len] = '\0';
if (strlen(s->srp_ctx.login) != len) { if (strlen(s->srp_ctx.login) != len)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
} }
# endif # endif
@ -1159,10 +1149,8 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
unsigned char *sdata = data; unsigned char *sdata = data;
int ecpointformatlist_length = *(sdata++); int ecpointformatlist_length = *(sdata++);
if (ecpointformatlist_length != size - 1) { if (ecpointformatlist_length != size - 1)
*al = TLS1_AD_DECODE_ERROR; goto err;
return 0;
}
if (!s->hit) { if (!s->hit) {
if (s->session->tlsext_ecpointformatlist) { if (s->session->tlsext_ecpointformatlist) {
OPENSSL_free(s->session->tlsext_ecpointformatlist); OPENSSL_free(s->session->tlsext_ecpointformatlist);
@ -1196,15 +1184,13 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
if (ellipticcurvelist_length != size - 2 || if (ellipticcurvelist_length != size - 2 ||
ellipticcurvelist_length < 1 || ellipticcurvelist_length < 1 ||
/* Each NamedCurve is 2 bytes. */ /* Each NamedCurve is 2 bytes. */
ellipticcurvelist_length & 1) { ellipticcurvelist_length & 1)
*al = TLS1_AD_DECODE_ERROR; goto err;
return 0;
}
if (!s->hit) { if (!s->hit) {
if (s->session->tlsext_ellipticcurvelist) { if (s->session->tlsext_ellipticcurvelist)
*al = TLS1_AD_DECODE_ERROR; goto err;
return 0;
}
s->session->tlsext_ellipticcurvelist_length = 0; s->session->tlsext_ellipticcurvelist_length = 0;
if ((s->session->tlsext_ellipticcurvelist = if ((s->session->tlsext_ellipticcurvelist =
OPENSSL_malloc(ellipticcurvelist_length)) == NULL) { OPENSSL_malloc(ellipticcurvelist_length)) == NULL) {
@ -1273,28 +1259,20 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
renegotiate_seen = 1; renegotiate_seen = 1;
} else if (type == TLSEXT_TYPE_signature_algorithms) { } else if (type == TLSEXT_TYPE_signature_algorithms) {
int dsize; int dsize;
if (sigalg_seen || size < 2) { if (sigalg_seen || size < 2)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
sigalg_seen = 1; sigalg_seen = 1;
n2s(data, dsize); n2s(data, dsize);
size -= 2; size -= 2;
if (dsize != size || dsize & 1) { if (dsize != size || dsize & 1)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0; if (!tls1_process_sigalgs(s, data, dsize))
} goto err;
if (!tls1_process_sigalgs(s, data, dsize)) {
*al = SSL_AD_DECODE_ERROR;
return 0;
}
} else if (type == TLSEXT_TYPE_status_request && } else if (type == TLSEXT_TYPE_status_request &&
s->version != DTLS1_VERSION) { s->version != DTLS1_VERSION) {
if (size < 5) { if (size < 5)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
s->tlsext_status_type = *data++; s->tlsext_status_type = *data++;
size--; size--;
@ -1304,35 +1282,26 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
/* Read in responder_id_list */ /* Read in responder_id_list */
n2s(data, dsize); n2s(data, dsize);
size -= 2; size -= 2;
if (dsize > size) { if (dsize > size)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
while (dsize > 0) { while (dsize > 0) {
OCSP_RESPID *id; OCSP_RESPID *id;
int idsize; int idsize;
if (dsize < 4) { if (dsize < 4)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
n2s(data, idsize); n2s(data, idsize);
dsize -= 2 + idsize; dsize -= 2 + idsize;
size -= 2 + idsize; size -= 2 + idsize;
if (dsize < 0) { if (dsize < 0)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
sdata = data; sdata = data;
data += idsize; data += idsize;
id = d2i_OCSP_RESPID(NULL, &sdata, idsize); id = d2i_OCSP_RESPID(NULL, &sdata, idsize);
if (!id) { if (!id)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
if (data != sdata) { if (data != sdata) {
OCSP_RESPID_free(id); OCSP_RESPID_free(id);
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
} }
if (!s->tlsext_ocsp_ids if (!s->tlsext_ocsp_ids
&& !(s->tlsext_ocsp_ids = && !(s->tlsext_ocsp_ids =
@ -1349,16 +1318,12 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
} }
/* Read in request_extensions */ /* Read in request_extensions */
if (size < 2) { if (size < 2)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
n2s(data, dsize); n2s(data, dsize);
size -= 2; size -= 2;
if (dsize != size) { if (dsize != size)
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
sdata = data; sdata = data;
if (dsize > 0) { if (dsize > 0) {
if (s->tlsext_ocsp_exts) { if (s->tlsext_ocsp_exts) {
@ -1368,10 +1333,8 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
s->tlsext_ocsp_exts = s->tlsext_ocsp_exts =
d2i_X509_EXTENSIONS(NULL, &sdata, dsize); d2i_X509_EXTENSIONS(NULL, &sdata, dsize);
if (!s->tlsext_ocsp_exts || (data + dsize != sdata)) { if (!s->tlsext_ocsp_exts || (data + dsize != sdata))
*al = SSL_AD_DECODE_ERROR; goto err;
return 0;
}
} }
} }
/* /*
@ -1432,6 +1395,10 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
data += size; data += size;
} }
/* Spurious data on the end */
if (data != d + n)
goto err;
*p = data; *p = data;
ri_check: ri_check:
@ -1447,6 +1414,9 @@ int ssl_parse_clienthello_tlsext(SSL *s, unsigned char **p, unsigned char *d,
} }
return 1; return 1;
err:
*al = SSL_AD_DECODE_ERROR;
return 0;
} }
# ifndef OPENSSL_NO_NEXTPROTONEG # ifndef OPENSSL_NO_NEXTPROTONEG