/*++ /* NAME /* tls_dh /* SUMMARY /* Diffie-Hellman parameter support /* SYNOPSIS /* #define TLS_INTERNAL /* #include /* /* void tls_set_dh_from_file(path, bits) /* const char *path; /* int bits; /* /* void tls_auto_eecdh_curves(ctx, configured) /* SSL_CTX *ctx; /* char *configured; /* /* void tls_set_eecdh_curve(server_ctx, grade) /* SSL_CTX *server_ctx; /* const char *grade; /* /* DH *tls_tmp_dh_cb(ssl, export, keylength) /* SSL *ssl; /* unused */ /* int export; /* int keylength; /* DESCRIPTION /* This module maintains parameters for Diffie-Hellman key generation. /* /* tls_tmp_dh_cb() is a call-back routine for the /* SSL_CTX_set_tmp_dh_callback() function. /* /* tls_set_dh_from_file() overrides compiled-in DH parameters /* with those specified in the named files. The file format /* is as expected by the PEM_read_DHparams() routine. The /* "bits" argument must be 512 or 1024. /* /* tls_auto_eecdh_curves() enables negotiation of the most preferred curve /* among the curves specified by the "configured" argument. /* /* tls_set_eecdh_curve() enables ephemeral Elliptic-Curve DH /* key exchange algorithms by instantiating in the server SSL /* context a suitable curve (corresponding to the specified /* EECDH security grade) from the set of named curves in RFC /* 4492 Section 5.1.1. Errors generate warnings, but do not /* disable TLS, rather we continue without EECDH. A zero /* result indicates that the grade is invalid or the corresponding /* curve could not be used. The "auto" grade enables multiple /* curves, with the actual curve chosen as the most preferred /* among those supported by both the server and the client. /* DIAGNOSTICS /* In case of error, tls_set_dh_from_file() logs a warning and /* ignores the request. /* LICENSE /* .ad /* .fi /* This software is free. You can do with it whatever you want. /* The original author kindly requests that you acknowledge /* the use of his software. /* AUTHOR(S) /* Originally written by: /* Lutz Jaenicke /* BTU Cottbus /* Allgemeine Elektrotechnik /* Universitaetsplatz 3-4 /* D-03044 Cottbus, Germany /* /* Updated by: /* Wietse Venema /* IBM T.J. Watson Research /* P.O. Box 704 /* Yorktown Heights, NY 10598, USA /*--*/ /* System library. */ #include #ifdef USE_TLS #include /* Utility library. */ #include #include #include /* * Global library */ #include /* TLS library. */ #define TLS_INTERNAL #include #include #ifndef OPENSSL_NO_ECDH #include #endif /* Application-specific. */ /* * Compiled-in DH parameters. Used when no parameters are explicitly loaded * from a site-specific file. Using an ASN.1 DER encoding avoids the need * to explicitly manipulate the internal representation of DH parameter * objects. * * 512-bit parameters are used for export ciphers, and 2048-bit parameters are * used for non-export ciphers. The non-export group is now 2048-bit, as * 1024 bits is increasingly considered to weak by clients. When greater * security is required, use EECDH. */ /*- * Generated via: * $ openssl dhparam -2 -outform DER 512 2>/dev/null | * hexdump -ve '/1 "0x%02x, "' | fmt * TODO: generate at compile-time. But that is no good for the majority of * sites that install pre-compiled binaries, and breaks reproducible builds. * Instead, generate at installation time and use main.cf configuration. */ static unsigned char dh512_der[] = { 0x30, 0x46, 0x02, 0x41, 0x00, 0xd8, 0xbf, 0x11, 0xd6, 0x41, 0x2a, 0x7a, 0x9c, 0x78, 0xb2, 0xaa, 0x41, 0x23, 0x0a, 0xdc, 0xcf, 0xb7, 0x19, 0xc5, 0x16, 0x4c, 0xcb, 0x4a, 0xd0, 0xd2, 0x1f, 0x1f, 0x70, 0x24, 0x86, 0x6f, 0x51, 0x52, 0xc6, 0x5b, 0x28, 0xbb, 0x82, 0xe1, 0x24, 0x91, 0x3d, 0x4d, 0x95, 0x56, 0xf8, 0x0b, 0x2c, 0xe0, 0x36, 0x67, 0x88, 0x64, 0x15, 0x1f, 0x45, 0xd5, 0xb8, 0x0a, 0x00, 0x03, 0x76, 0x32, 0x0b, 0x02, 0x01, 0x02, }; /*- * Generated via: * $ openssl dhparam -2 -outform DER 2048 2>/dev/null | * hexdump -ve '/1 "0x%02x, "' | fmt * TODO: generate at compile-time. But that is no good for the majority of * sites that install pre-compiled binaries, and breaks reproducible builds. * Instead, generate at installation time and use main.cf configuration. */ static unsigned char dh2048_der[] = { 0x30, 0x82, 0x01, 0x08, 0x02, 0x82, 0x01, 0x01, 0x00, 0xbf, 0x28, 0x1b, 0x68, 0x69, 0x90, 0x2f, 0x37, 0x9f, 0x5a, 0x50, 0x23, 0x73, 0x2c, 0x11, 0xf2, 0xac, 0x7c, 0x3e, 0x58, 0xb9, 0x23, 0x3e, 0x02, 0x07, 0x4d, 0xba, 0xd9, 0x2c, 0xc1, 0x9e, 0xf9, 0xc4, 0x2f, 0xbc, 0x8d, 0x86, 0x4b, 0x2a, 0x87, 0x86, 0x93, 0x32, 0x0f, 0x72, 0x40, 0xfe, 0x7e, 0xa2, 0xc1, 0x32, 0xf0, 0x65, 0x9c, 0xc3, 0x19, 0x25, 0x2d, 0xeb, 0x6a, 0x49, 0x94, 0x79, 0x2d, 0xa1, 0xbe, 0x05, 0x26, 0xac, 0x8d, 0x69, 0xdc, 0x2e, 0x7e, 0xb5, 0xfd, 0x3c, 0x2b, 0x7d, 0x43, 0x22, 0x53, 0xf6, 0x1e, 0x04, 0x45, 0xd7, 0x53, 0x84, 0xfd, 0x6b, 0x12, 0x72, 0x47, 0x04, 0xaf, 0xa4, 0xac, 0x4b, 0x55, 0xb6, 0x79, 0x42, 0x40, 0x88, 0x54, 0x48, 0xd5, 0x4d, 0x3a, 0xb2, 0xbf, 0x6c, 0x26, 0x95, 0x29, 0xdd, 0x8b, 0x9e, 0xed, 0xb8, 0x60, 0x8e, 0xb5, 0x35, 0xb6, 0x22, 0x44, 0x1f, 0xfb, 0x56, 0x74, 0xfe, 0xf0, 0x2c, 0xe6, 0x0c, 0x22, 0xc9, 0x35, 0xb3, 0x1b, 0x96, 0xbb, 0x0a, 0x5a, 0xc3, 0x09, 0xa0, 0xcc, 0xa5, 0x40, 0x90, 0x0f, 0x59, 0xa2, 0x89, 0x69, 0x2a, 0x69, 0x79, 0xe4, 0xd3, 0x24, 0xc6, 0x8c, 0xda, 0xbc, 0x98, 0x3a, 0x5b, 0x16, 0xae, 0x63, 0x6c, 0x0b, 0x43, 0x4f, 0xf3, 0x2e, 0xc8, 0xa9, 0x6b, 0x58, 0x6a, 0xa9, 0x8e, 0x64, 0x09, 0x3d, 0x88, 0x44, 0x4f, 0x97, 0x2c, 0x1d, 0x98, 0xb0, 0xa9, 0xc0, 0xb6, 0x8d, 0x19, 0x37, 0x1f, 0xb7, 0xc9, 0x86, 0xa8, 0xdc, 0x37, 0x4d, 0x64, 0x27, 0xf3, 0xf5, 0x2b, 0x7b, 0x6b, 0x76, 0x84, 0x3f, 0xc1, 0x23, 0x97, 0x2d, 0x71, 0xf7, 0xb6, 0xc2, 0x35, 0x28, 0x10, 0x96, 0xd6, 0x69, 0x0c, 0x2e, 0x1f, 0x9f, 0xdf, 0x82, 0x81, 0x57, 0x57, 0x39, 0xa5, 0xf2, 0x81, 0x29, 0x57, 0xf9, 0x2f, 0xd0, 0x03, 0xab, 0x02, 0x01, 0x02, }; /* * Cached results. */ static DH *dh_1024 = 0; static DH *dh_512 = 0; /* tls_set_dh_from_file - set Diffie-Hellman parameters from file */ void tls_set_dh_from_file(const char *path, int bits) { FILE *paramfile; DH **dhPtr; switch (bits) { case 512: dhPtr = &dh_512; break; case 1024: dhPtr = &dh_1024; break; default: msg_panic("Invalid DH parameters size %d, file %s", bits, path); } /* * This function is the first to set the DH parameters, but free any * prior value just in case the call sequence changes some day. */ if (*dhPtr) { DH_free(*dhPtr); *dhPtr = 0; } if ((paramfile = fopen(path, "r")) != 0) { if ((*dhPtr = PEM_read_DHparams(paramfile, 0, 0, 0)) == 0) { msg_warn("cannot load %d-bit DH parameters from file %s" " -- using compiled-in defaults", bits, path); tls_print_errors(); } (void) fclose(paramfile); /* 200411 */ } else { msg_warn("cannot load %d-bit DH parameters from file %s: %m" " -- using compiled-in defaults", bits, path); } } /* tls_get_dh - get compiled-in DH parameters */ static DH *tls_get_dh(const unsigned char *p, size_t plen) { const unsigned char *endp = p; DH *dh = 0; if (d2i_DHparams(&dh, &endp, plen) && plen == endp - p) return (dh); msg_warn("cannot load compiled-in DH parameters"); if (dh) DH_free(dh); return (0); } /* tls_tmp_dh_cb - call-back for Diffie-Hellman parameters */ DH *tls_tmp_dh_cb(SSL *unused_ssl, int export, int keylength) { DH *dh_tmp; if (export && keylength == 512) { /* 40-bit export cipher */ if (dh_512 == 0) dh_512 = tls_get_dh(dh512_der, sizeof(dh512_der)); dh_tmp = dh_512; } else { /* ADH, DHE-RSA or DSA */ if (dh_1024 == 0) dh_1024 = tls_get_dh(dh2048_der, sizeof(dh2048_der)); dh_tmp = dh_1024; } return (dh_tmp); } void tls_auto_eecdh_curves(SSL_CTX *ctx, const char *configured) { #ifndef OPENSSL_NO_ECDH SSL_CTX *tmpctx; int *nids; int space = 5; int n = 0; int unknown = 0; char *save; char *curves; char *curve; if ((tmpctx = SSL_CTX_new(TLS_method())) == 0) { msg_warn("cannot allocate temp SSL_CTX, using default ECDHE curves"); tls_print_errors(); return; } nids = mymalloc(space * sizeof(int)); curves = save = mystrdup(configured); #define RETURN do { \ myfree(save); \ myfree(nids); \ SSL_CTX_free(tmpctx); \ return; \ } while (0) while ((curve = mystrtok(&curves, CHARS_COMMA_SP)) != 0) { int nid = EC_curve_nist2nid(curve); if (nid == NID_undef) nid = OBJ_sn2nid(curve); if (nid == NID_undef) nid = OBJ_ln2nid(curve); if (nid == NID_undef) { msg_warn("ignoring unknown ECDHE curve \"%s\"", curve); continue; } /* * Validate the NID by trying it as the sole EC curve for a * throw-away SSL context. Silently skip unsupported code points. * This way, we can list X25519 and X448 as soon as the nids are * assigned, and before the supporting code is implemented. They'll * be silently skipped when not yet supported. */ if (SSL_CTX_set1_curves(tmpctx, &nid, 1) <= 0) { ++unknown; continue; } if (++n > space) { space *= 2; nids = myrealloc(nids, space * sizeof(int)); } nids[n - 1] = nid; } if (n == 0) { if (unknown > 0) msg_warn("none of the configured ECDHE curves are supported"); RETURN; } if (SSL_CTX_set1_curves(ctx, nids, n) <= 0) { msg_warn("failed to configure ECDHE curves"); tls_print_errors(); RETURN; } /* * This is a NOP in OpenSSL 1.1.0 and later, where curves are always * auto-negotiated. */ #if OPENSSL_VERSION_NUMBER < 0x10100000UL if (SSL_CTX_set_ecdh_auto(ctx, 1) <= 0) { msg_warn("failed to enable automatic ECDHE curve selection"); tls_print_errors(); RETURN; } #endif RETURN; #endif } #define TLS_EECDH_INVALID 0 #define TLS_EECDH_NONE 1 #define TLS_EECDH_STRONG 2 #define TLS_EECDH_ULTRA 3 #define TLS_EECDH_AUTO 4 void tls_set_eecdh_curve(SSL_CTX *server_ctx, const char *grade) { #ifndef OPENSSL_NO_ECDH int g; static NAME_CODE eecdh_table[] = { "none", TLS_EECDH_NONE, "strong", TLS_EECDH_STRONG, "ultra", TLS_EECDH_ULTRA, "auto", TLS_EECDH_AUTO, 0, TLS_EECDH_INVALID, }; switch (g = name_code(eecdh_table, NAME_CODE_FLAG_NONE, grade)) { default: msg_panic("Invalid eecdh grade code: %d", g); case TLS_EECDH_INVALID: msg_warn("Invalid TLS eecdh grade \"%s\": EECDH disabled", grade); return; case TLS_EECDH_STRONG: tls_auto_eecdh_curves(server_ctx, var_tls_eecdh_strong); return; case TLS_EECDH_ULTRA: tls_auto_eecdh_curves(server_ctx, var_tls_eecdh_ultra); return; case TLS_EECDH_NONE: /* * Pretend "none" is "auto", the former is no longer supported or * wise */ msg_warn("The \"none\" eecdh grade is no longer supported, " "using \"auto\" instead"); case TLS_EECDH_AUTO: tls_auto_eecdh_curves(server_ctx, var_tls_eecdh_auto); return; } #endif return; } #ifdef TEST int main(int unused_argc, char **unused_argv) { tls_tmp_dh_cb(0, 1, 512); tls_tmp_dh_cb(0, 1, 1024); tls_tmp_dh_cb(0, 1, 2048); tls_tmp_dh_cb(0, 0, 512); return (0); } #endif #endif