/mandos/trunk : revision 366

44

#include <stdint.h> /* uint16_t, uint32_t */

45

#include <stddef.h> /* NULL, size_t, ssize_t */

46

#include <stdlib.h> /* free(), EXIT_SUCCESS, EXIT_FAILURE,

47

srand(), strtof(), abort() */

47

srand(), strtof() */

48

#include <stdbool.h> /* bool, false, true */

49

#include <string.h> /* memset(), strcmp(), strlen(),

50

strerror(), asprintf(), strcpy() */

72

*/

73

#include <unistd.h> /* close(), SEEK_SET, off_t, write(),

74

getuid(), getgid(), seteuid(),

75

setgid(), pause() */

75

setgid() */

76

#include <arpa/inet.h> /* inet_pton(), htons */

77

#include <iso646.h> /* not, or, and */

78

#include <argp.h> /* struct argp_option, error_t, struct

125

static const char mandos_protocol_version[] = "1";

126

const char *argp_program_version = "mandos-client " VERSION;

127

const char *argp_program_bug_address = "<mandos@fukt.bsnet.se>";

128

static const char sys_class_net[] = "/sys/class/net";

129

char *connect_to = NULL;

130

128

131

129

/* Used for passing in values through the Avahi callback functions */

132

130

typedef struct {

144

142

.dh_bits = 1024, .priority = "SECURE256"

145

143

":!CTYPE-X.509:+CTYPE-OPENPGP" };

146

144

147

sig_atomic_t quit_now = 0;

148

int signal_received = 0;

149

150

145

/*

151

146

* Make additional room in "buffer" for at least BUFFER_SIZE more

152

147

* bytes. "buffer_capacity" is how much is currently allocated,

479

474

static int init_gnutls_session(gnutls_session_t *session){

480

475

int ret;

481

476

/* GnuTLS session creation */

482

do {

483

ret = gnutls_init(session, GNUTLS_SERVER);

484

if(quit_now){

485

return -1;

486

}

487

} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);

477

ret = gnutls_init(session, GNUTLS_SERVER);

488

478

if(ret != GNUTLS_E_SUCCESS){

489

479

fprintf(stderr, "Error in GnuTLS session initialization: %s\n",

490

480

safer_gnutls_strerror(ret));

492

482

493

483

{

494

484

const char *err;

495

do {

496

ret = gnutls_priority_set_direct(*session, mc.priority, &err);

497

if(quit_now){

498

gnutls_deinit(*session);

499

return -1;

500

}

501

} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);

485

ret = gnutls_priority_set_direct(*session, mc.priority, &err);

502

486

if(ret != GNUTLS_E_SUCCESS){

503

487

fprintf(stderr, "Syntax error at: %s\n", err);

504

488

fprintf(stderr, "GnuTLS error: %s\n",

508

492

}

509

493

}

510

494

511

do {

512

ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,

513

mc.cred);

514

if(quit_now){

515

gnutls_deinit(*session);

516

return -1;

517

}

518

} while(ret == GNUTLS_E_INTERRUPTED or ret == GNUTLS_E_AGAIN);

495

ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,

496

mc.cred);

519

497

if(ret != GNUTLS_E_SUCCESS){

520

498

fprintf(stderr, "Error setting GnuTLS credentials: %s\n",

521

499

safer_gnutls_strerror(ret));

524

502

}

525

503

526

504

/* ignore client certificate if any. */

527

gnutls_certificate_server_set_request(*session, GNUTLS_CERT_IGNORE);

505

gnutls_certificate_server_set_request(*session,

506

GNUTLS_CERT_IGNORE);

528

507

529

508

gnutls_dh_set_prime_bits(*session, mc.dh_bits);

530

509

535

514

static void empty_log(__attribute__((unused)) AvahiLogLevel level,

536

515

__attribute__((unused)) const char *txt){}

537

516

517

sig_atomic_t quit_now = 0;

518

int signal_received = 0;

519

538

520

/* Called when a Mandos server is found */

539

521

static int start_mandos_communication(const char *ip, uint16_t port,

540

522

AvahiIfIndex if_index,

546

528

struct sockaddr_in6 in6;

547

529

} to;

548

530

char *buffer = NULL;

549

char *decrypted_buffer = NULL;

531

char *decrypted_buffer;

550

532

size_t buffer_length = 0;

551

533

size_t buffer_capacity = 0;

552

534

size_t written;

553

int retval = -1;

535

int retval = 0;

554

536

gnutls_session_t session;

555

537

int pf; /* Protocol family */

556

538

583

565

tcp_sd = socket(pf, SOCK_STREAM, 0);

584

566

if(tcp_sd < 0){

585

567

perror("socket");

568

retval = -1;

586

569

goto mandos_end;

587

570

}

588

571

600

583

}

601

584

if(ret < 0 ){

602

585

perror("inet_pton");

586

retval = -1;

603

587

goto mandos_end;

604

588

}

605

589

if(ret == 0){

606

590

fprintf(stderr, "Bad address: %s\n", ip);

591

retval = -1;

607

592

goto mandos_end;

608

593

}

609

594

if(af == AF_INET6){

617

602

if(if_index == AVAHI_IF_UNSPEC){

618

603

fprintf(stderr, "An IPv6 link-local address is incomplete"

619

604

" without a network interface\n");

605

retval = -1;

620

606

goto mandos_end;

621

607

}

622

608

/* Set the network interface number as scope */

675

661

}

676

662

if(ret < 0){

677

663

perror("connect");

664

retval = -1;

678

665

goto mandos_end;

679

666

}

680

667

690

677

out_size - written));

691

678

if(ret == -1){

692

679

perror("write");

680

retval = -1;

693

681

goto mandos_end;

694

682

}

695

683

written += (size_t)ret;

735

723

fprintf(stderr, "*** GnuTLS Handshake failed ***\n");

736

724

gnutls_perror(ret);

737

725

}

726

retval = -1;

738

727

goto mandos_end;

739

728

}

740

729

755

744

buffer_capacity);

756

745

if(buffer_capacity == 0){

757

746

perror("incbuffer");

747

retval = -1;

758

748

goto mandos_end;

759

749

}

760

750

783

773

if(ret < 0){

784

774

fprintf(stderr, "*** GnuTLS Re-handshake failed ***\n");

785

775

gnutls_perror(ret);

776

retval = -1;

786

777

goto mandos_end;

787

778

}

788

779

break;

789

780

default:

790

781

fprintf(stderr, "Unknown error while reading data from"

791

782

" encrypted session with Mandos server\n");

783

retval = -1;

792

784

gnutls_bye(session, GNUTLS_SHUT_RDWR);

793

785

goto mandos_end;

794

786

}

805

797

goto mandos_end;

806

798

}

807

799

808

do {

809

ret = gnutls_bye(session, GNUTLS_SHUT_RDWR);

810

if(quit_now){

811

goto mandos_end;

812

}

813

} while(ret == GNUTLS_E_AGAIN or ret == GNUTLS_E_INTERRUPTED);

800

gnutls_bye(session, GNUTLS_SHUT_RDWR);

801

802

if(quit_now){

803

goto mandos_end;

804

}

814

805

815

806

if(buffer_length > 0){

816

807

ssize_t decrypted_buffer_size;

833

824

fprintf(stderr, "Error writing encrypted data: %s\n",

834

825

strerror(errno));

835

826

}

836

goto mandos_end;

827

retval = -1;

828

break;

837

829

}

838

830

written += (size_t)ret;

839

831

}

840

retval = 0;

832

free(decrypted_buffer);

833

} else {

834

retval = -1;

841

835

}

836

} else {

837

retval = -1;

842

838

}

843

839

844

840

/* Shutdown procedure */

845

841

846

842

mandos_end:

847

free(decrypted_buffer);

848

843

free(buffer);

849

844

if(tcp_sd >= 0){

850

845

ret = (int)TEMP_FAILURE_RETRY(close(tcp_sd));

976

971

errno = old_errno;

977

972

}

978

973

979

/*

980

* This function determines if a directory entry in /sys/class/net

981

* corresponds to an acceptable network device.

982

* (This function is passed to scandir(3) as a filter function.)

983

*/

984

int good_interface(const struct dirent *if_entry){

985

ssize_t ssret;

986

char *flagname = NULL;

987

int ret = asprintf(&flagname, "%s/%s/flags", sys_class_net,

988

if_entry->d_name);

989

if(ret < 0){

990

perror("asprintf");

991

return 0;

992

}

993

if(if_entry->d_name[0] == '.'){

994

return 0;

995

}

996

int flags_fd = (int)TEMP_FAILURE_RETRY(open(flagname, O_RDONLY));

997

if(flags_fd == -1){

998

perror("open");

999

return 0;

1000

}

1001

typedef short ifreq_flags; /* ifreq.ifr_flags in netdevice(7) */

1002

/* read line from flags_fd */

1003

ssize_t to_read = (sizeof(ifreq_flags)*2)+3; /* "0x1003\n" */

1004

char *flagstring = malloc((size_t)to_read+1); /* +1 for final \0 */

1005

flagstring[(size_t)to_read] = '\0';

1006

if(flagstring == NULL){

1007

perror("malloc");

1008

close(flags_fd);

1009

return 0;

1010

}

1011

while(to_read > 0){

1012

ssret = (ssize_t)TEMP_FAILURE_RETRY(read(flags_fd, flagstring,

1013

(size_t)to_read));

1014

if(ssret == -1){

1015

perror("read");

1016

free(flagstring);

1017

close(flags_fd);

1018

return 0;

1019

}

1020

to_read -= ssret;

1021

if(ssret == 0){

1022

break;

1023

}

1024

}

1025

close(flags_fd);

1026

intmax_t tmpmax;

1027

char *tmp;

1028

errno = 0;

1029

tmpmax = strtoimax(flagstring, &tmp, 0);

1030

if(errno != 0 or tmp == flagstring or (*tmp != '\0'

1031

and not (isspace(*tmp)))

1032

or tmpmax != (ifreq_flags)tmpmax){

1033

if(debug){

1034

fprintf(stderr, "Invalid flags \"%s\" for interface \"%s\"\n",

1035

flagstring, if_entry->d_name);

1036

}

1037

free(flagstring);

1038

return 0;

1039

}

1040

free(flagstring);

1041

ifreq_flags flags = (ifreq_flags)tmpmax;

1042

/* Reject the loopback device */

1043

if(flags & IFF_LOOPBACK){

1044

if(debug){

1045

fprintf(stderr, "Rejecting loopback interface \"%s\"\n",

1046

if_entry->d_name);

1047

}

1048

return 0;

1049

}

1050

/* Accept point-to-point devices only if connect_to is specified */

1051

if(connect_to != NULL and (flags & IFF_POINTOPOINT)){

1052

if(debug){

1053

fprintf(stderr, "Accepting point-to-point interface \"%s\"\n",

1054

if_entry->d_name);

1055

}

1056

return 1;

1057

}

1058

/* Otherwise, reject non-broadcast-capable devices */

1059

if(not (flags & IFF_BROADCAST)){

1060

if(debug){

1061

fprintf(stderr, "Rejecting non-broadcast interface \"%s\"\n",

1062

if_entry->d_name);

1063

}

1064

return 0;

1065

}

1066

/* Accept this device */

1067

if(debug){

1068

fprintf(stderr, "Interface \"%s\" is acceptable\n",

1069

if_entry->d_name);

1070

}

1071

return 1;

1072

}

1073

1074

974

int main(int argc, char *argv[]){

1075

975

AvahiSServiceBrowser *sb = NULL;

1076

976

int error;

1078

978

intmax_t tmpmax;

1079

979

char *tmp;

1080

980

int exitcode = EXIT_SUCCESS;

1081

const char *interface = "";

981

const char *interface = "eth0";

1082

982

struct ifreq network;

1083

983

int sd = -1;

1084

984

bool take_down_interface = false;

1085

985

uid_t uid;

1086

986

gid_t gid;

987

char *connect_to = NULL;

1087

988

char tempdir[] = "/tmp/mandosXXXXXX";

1088

989

bool tempdir_created = false;

1089

990

AvahiIfIndex if_index = AVAHI_IF_UNSPEC;

1094

995

bool gpgme_initialized = false;

1095

996

float delay = 2.5f;

1096

997

1097

struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };

998

struct sigaction old_sigterm_action;

1098

999

struct sigaction sigterm_action = { .sa_handler = handle_sigterm };

1099

1000

1100

uid = getuid();

1101

gid = getgid();

1102

1103

/* Lower any group privileges we might have, just to be safe */

1104

errno = 0;

1105

ret = setgid(gid);

1106

if(ret == -1){

1107

perror("setgid");

1108

}

1109

1110

/* Lower user privileges (temporarily) */

1111

errno = 0;

1112

ret = seteuid(uid);

1113

if(ret == -1){

1114

perror("seteuid");

1115

}

1116

1117

if(quit_now){

1118

goto end;

1119

}

1120

1121

1001

{

1122

1002

struct argp_option options[] = {

1123

1003

{ .name = "debug", .key = 128,

1219

1099

if(not debug){

1220

1100

avahi_set_log_function(empty_log);

1221

1101

}

1222

1223

if(interface[0] == '\0'){

1224

struct dirent **direntries;

1225

ret = scandir(sys_class_net, &direntries, good_interface,

1226

alphasort);

1227

if(ret >= 1){

1228

/* Pick the first good interface */

1229

interface = strdup(direntries[0]->d_name);

1230

if(debug){

1231

fprintf(stderr, "Using interface \"%s\"\n", interface);

1232

}

1233

if(interface == NULL){

1234

perror("malloc");

1235

free(direntries);

1236

exitcode = EXIT_FAILURE;

1237

goto end;

1238

}

1239

free(direntries);

1240

} else {

1241

free(direntries);

1242

fprintf(stderr, "Could not find a network interface\n");

1243

exitcode = EXIT_FAILURE;

1244

goto end;

1245

}

1246

}

1247

1102

1248

1103

/* Initialize Avahi early so avahi_simple_poll_quit() can be called

1249

1104

from the signal handler */

1320

1175

}

1321

1176

1322

1177

/* If the interface is down, bring it up */

1323

if(strcmp(interface, "none") != 0){

1178

if(interface[0] != '\0'){

1324

1179

if_index = (AvahiIfIndex) if_nametoindex(interface);

1325

1180

if(if_index == 0){

1326

1181

fprintf(stderr, "No such interface: \"%s\"\n", interface);

1332

1187

goto end;

1333

1188

}

1334

1189

1335

/* Re-raise priviliges */

1336

errno = 0;

1337

ret = seteuid(0);

1338

if(ret == -1){

1339

perror("seteuid");

1340

}

1341

1342

1190

#ifdef __linux__

1343

1191

/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO

1344

1192

messages to mess up the prompt */

1362

1210

}

1363

1211

}

1364

1212

#endif /* __linux__ */

1365

/* Lower privileges */

1366

errno = 0;

1367

ret = seteuid(uid);

1368

if(ret == -1){

1369

perror("seteuid");

1370

}

1371

1213

goto end;

1372

1214

}

1373

1215

strcpy(network.ifr_name, interface);

1383

1225

}

1384

1226

#endif /* __linux__ */

1385

1227

exitcode = EXIT_FAILURE;

1386

/* Lower privileges */

1387

errno = 0;

1388

ret = seteuid(uid);

1389

if(ret == -1){

1390

perror("seteuid");

1391

}

1392

1228

goto end;

1393

1229

}

1394

1230

if((network.ifr_flags & IFF_UP) == 0){

1397

1233

ret = ioctl(sd, SIOCSIFFLAGS, &network);

1398

1234

if(ret == -1){

1399

1235

take_down_interface = false;

1400

perror("ioctl SIOCSIFFLAGS +IFF_UP");

1236

perror("ioctl SIOCSIFFLAGS");

1401

1237

exitcode = EXIT_FAILURE;

1402

1238

#ifdef __linux__

1403

1239

if(restore_loglevel){

1407

1243

}

1408

1244

}

1409

1245

#endif /* __linux__ */

1410

/* Lower privileges */

1411

errno = 0;

1412

ret = seteuid(uid);

1413

if(ret == -1){

1414

perror("seteuid");

1415

}

1416

1246

goto end;

1417

1247

}

1418

1248

}

1446

1276

}

1447

1277

}

1448

1278

#endif /* __linux__ */

1449

/* Lower privileges */

1450

errno = 0;

1451

if(take_down_interface){

1452

/* Lower privileges */

1453

ret = seteuid(uid);

1454

if(ret == -1){

1455

perror("seteuid");

1456

}

1457

} else {

1458

/* Lower privileges permanently */

1459

ret = setuid(uid);

1460

if(ret == -1){

1461

perror("setuid");

1462

}

1279

}

1280

1281

if(quit_now){

1282

goto end;

1283

}

1284

1285

uid = getuid();

1286

gid = getgid();

1287

1288

/* Drop any group privileges we might have, just to be safe */

1289

errno = 0;

1290

ret = setgid(gid);

1291

if(ret == -1){

1292

perror("setgid");

1293

}

1294

1295

/* Drop user privileges */

1296

errno = 0;

1297

/* Will we need privileges later? */

1298

if(take_down_interface){

1299

/* Drop user privileges temporarily */

1300

ret = seteuid(uid);

1301

if(ret == -1){

1302

perror("seteuid");

1303

}

1304

} else {

1305

/* Drop user privileges permanently */

1306

ret = setuid(uid);

1307

if(ret == -1){

1308

perror("setuid");

1463

1309

}

1464

1310

}

1465

1311

1654

1500

network.ifr_flags &= ~IFF_UP; /* clear flag */

1655

1501

ret = ioctl(sd, SIOCSIFFLAGS, &network);

1656

1502

if(ret == -1){

1657

perror("ioctl SIOCSIFFLAGS -IFF_UP");

1503

perror("ioctl SIOCSIFFLAGS");

1658

1504

}

1659

1505

}

1660

1506

ret = (int)TEMP_FAILURE_RETRY(close(sd));

1661

1507

if(ret == -1){

1662

1508

perror("close");

1663

1509

}

1664

/* Lower privileges permanently */

1510

/* Lower privileges, permanently this time */

1665

1511

errno = 0;

1666

1512

ret = setuid(uid);

1667

1513

if(ret == -1){

1717

1563

if(quit_now){

1718

1564

sigemptyset(&old_sigterm_action.sa_mask);

1719

1565

old_sigterm_action.sa_handler = SIG_DFL;

1720

ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,

1721

&old_sigterm_action,

1722

NULL));

1566

ret = sigaction(signal_received, &old_sigterm_action, NULL);

1723

1567

if(ret == -1){

1724

1568

perror("sigaction");

1725

1569

}

1726

do {

1727

ret = raise(signal_received);

1728

} while(ret != 0 and errno == EINTR);

1729

if(ret != 0){

1730

perror("raise");

1731

abort();

1732

}

1733

TEMP_FAILURE_RETRY(pause());

1570

raise(signal_received);

1734

1571

}

1735

1572

1736

1573

return exitcode;