diff options
Diffstat (limited to 'libextra/auth_srp.c')
| -rw-r--r-- | libextra/auth_srp.c | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/libextra/auth_srp.c b/libextra/auth_srp.c index 84d47cb49b..0ca1ebd53c 100644 --- a/libextra/auth_srp.c +++ b/libextra/auth_srp.c @@ -345,6 +345,28 @@ int _gnutls_proc_srp_client_kx(gnutls_session state, opaque * data, size_t _data return 0; } +/* Checks if b%n==0 which is a fatal srp error. + * Returns a proper error code in that case, and 0 when + * all are ok. + */ +static int check_b_mod_n( GNUTLS_MPI b, GNUTLS_MPI n) +{ +int ret; +GNUTLS_MPI r = _gnutls_mpi_alloc_like(b); + + _gnutls_mpi_mod( r, b, n); + ret = _gnutls_mpi_cmp_ui(r, 0); + + _gnutls_mpi_release( &r); + + if (ret == 0) { + gnutls_assert(); + return GNUTLS_E_SRP_PROTOCOL_FAILURE; + } + + return 0; +} + /* receive the key exchange message ( n, g, s, B) */ int _gnutls_proc_srp_server_kx(gnutls_session state, opaque * data, size_t _data_size) @@ -438,6 +460,12 @@ int _gnutls_proc_srp_server_kx(gnutls_session state, opaque * data, size_t _data gnutls_assert(); return GNUTLS_E_MPI_SCAN_FAILED; } + + if ( (ret = check_b_mod_n( B, N)) < 0) { + gnutls_assert(); + return ret; + } + /* generate x = SHA(s | SHA(U | ":" | p)) * (or the equivalent using bcrypt) |