Check SRP parameters early.
Check SRP parameters when they are received so we can send back an
appropriate alert.
Reviewed-by: Kurt Roeckx <kurt@openssl.org>
diff --git a/ssl/tls_srp.c b/ssl/tls_srp.c
index c363fc3..1aa90c5 100644
--- a/ssl/tls_srp.c
+++ b/ssl/tls_srp.c
@@ -410,17 +410,46 @@
return ret;
}
+int srp_verify_server_param(SSL *s, int *al)
+ {
+ SRP_CTX *srp = &s->srp_ctx;
+ /* Sanity check parameters: we can quickly check B % N == 0
+ * by checking B != 0 since B < N
+ */
+ if (BN_ucmp(srp->g, srp->N) >=0 || BN_ucmp(srp->B, srp->N) >= 0
+ || BN_is_zero(srp->B))
+ {
+ *al = SSL3_AD_ILLEGAL_PARAMETER;
+ return 0;
+ }
+
+ if (BN_num_bits(srp->N) < srp->strength)
+ {
+ *al = TLS1_AD_INSUFFICIENT_SECURITY;
+ return 0;
+ }
+
+ if (srp->SRP_verify_param_callback)
+ {
+ if (srp->SRP_verify_param_callback(s, srp->SRP_cb_arg) <= 0)
+ {
+ *al = TLS1_AD_INSUFFICIENT_SECURITY;
+ return 0;
+ }
+ }
+ else if(!SRP_check_known_gN_param(srp->g, srp->N))
+ {
+ *al = TLS1_AD_INSUFFICIENT_SECURITY;
+ return 0;
+ }
+
+ return 1;
+ }
+
int SRP_Calc_A_param(SSL *s)
{
unsigned char rnd[SSL_MAX_MASTER_KEY_LENGTH];
- if (BN_num_bits(s->srp_ctx.N) < s->srp_ctx.strength)
- return 0;
-
- if (s->srp_ctx.SRP_verify_param_callback ==NULL &&
- !SRP_check_known_gN_param(s->srp_ctx.g,s->srp_ctx.N))
- return 0;
-
if (RAND_bytes(rnd, sizeof(rnd)) <= 0)
return 0;
s->srp_ctx.a = BN_bin2bn(rnd,sizeof(rnd), s->srp_ctx.a);
@@ -429,10 +458,6 @@
if (!(s->srp_ctx.A = SRP_Calc_A(s->srp_ctx.a,s->srp_ctx.N,s->srp_ctx.g)))
return 0;
- /* We can have a callback to verify SRP param!! */
- if (s->srp_ctx.SRP_verify_param_callback !=NULL)
- return s->srp_ctx.SRP_verify_param_callback(s,s->srp_ctx.SRP_cb_arg);
-
return 1;
}
