/mandos/trunk : revision 237.2.35

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() */

47

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

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() */

75

setgid(), pause() */

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;

128

130

129

131

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

130

132

typedef struct {

142

144

.dh_bits = 1024, .priority = "SECURE256"

143

145

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

144

146

147

sig_atomic_t quit_now = 0;

148

int signal_received = 0;

149

145

150

/*

146

151

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

147

152

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

474

479

static int init_gnutls_session(gnutls_session_t *session){

475

480

int ret;

476

481

/* GnuTLS session creation */

477

ret = gnutls_init(session, GNUTLS_SERVER);

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);

478

488

if(ret != GNUTLS_E_SUCCESS){

479

489

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

480

490

safer_gnutls_strerror(ret));

482

492

483

493

{

484

494

const char *err;

485

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

486

502

if(ret != GNUTLS_E_SUCCESS){

487

503

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

488

504

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

492

508

}

493

509

}

494

510

495

ret = gnutls_credentials_set(*session, GNUTLS_CRD_CERTIFICATE,

496

mc.cred);

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);

497

519

if(ret != GNUTLS_E_SUCCESS){

498

520

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

499

521

safer_gnutls_strerror(ret));

502

524

}

503

525

504

526

/* ignore client certificate if any. */

505

gnutls_certificate_server_set_request(*session,

506

GNUTLS_CERT_IGNORE);

527

gnutls_certificate_server_set_request(*session, GNUTLS_CERT_IGNORE);

507

528

508

529

gnutls_dh_set_prime_bits(*session, mc.dh_bits);

509

530

514

535

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

515

536

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

516

537

517

sig_atomic_t quit_now = 0;

518

int signal_received = 0;

519

520

538

/* Called when a Mandos server is found */

521

539

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

522

540

AvahiIfIndex if_index,

528

546

struct sockaddr_in6 in6;

529

547

} to;

530

548

char *buffer = NULL;

531

char *decrypted_buffer;

549

char *decrypted_buffer = NULL;

532

550

size_t buffer_length = 0;

533

551

size_t buffer_capacity = 0;

534

552

size_t written;

535

int retval = 0;

553

int retval = -1;

536

554

gnutls_session_t session;

537

555

int pf; /* Protocol family */

538

556

565

583

tcp_sd = socket(pf, SOCK_STREAM, 0);

566

584

if(tcp_sd < 0){

567

585

perror("socket");

568

retval = -1;

569

586

goto mandos_end;

570

587

}

571

588

583

600

}

584

601

if(ret < 0 ){

585

602

perror("inet_pton");

586

retval = -1;

587

603

goto mandos_end;

588

604

}

589

605

if(ret == 0){

590

606

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

591

retval = -1;

592

607

goto mandos_end;

593

608

}

594

609

if(af == AF_INET6){

602

617

if(if_index == AVAHI_IF_UNSPEC){

603

618

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

604

619

" without a network interface\n");

605

retval = -1;

606

620

goto mandos_end;

607

621

}

608

622

/* Set the network interface number as scope */

661

675

}

662

676

if(ret < 0){

663

677

perror("connect");

664

retval = -1;

665

678

goto mandos_end;

666

679

}

667

680

677

690

out_size - written));

678

691

if(ret == -1){

679

692

perror("write");

680

retval = -1;

681

693

goto mandos_end;

682

694

}

683

695

written += (size_t)ret;

723

735

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

724

736

gnutls_perror(ret);

725

737

}

726

retval = -1;

727

738

goto mandos_end;

728

739

}

729

740

744

755

buffer_capacity);

745

756

if(buffer_capacity == 0){

746

757

perror("incbuffer");

747

retval = -1;

748

758

goto mandos_end;

749

759

}

750

760

773

783

if(ret < 0){

774

784

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

775

785

gnutls_perror(ret);

776

retval = -1;

777

786

goto mandos_end;

778

787

}

779

788

break;

780

789

default:

781

790

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

782

791

" encrypted session with Mandos server\n");

783

retval = -1;

784

792

gnutls_bye(session, GNUTLS_SHUT_RDWR);

785

793

goto mandos_end;

786

794

}

797

805

goto mandos_end;

798

806

}

799

807

800

gnutls_bye(session, GNUTLS_SHUT_RDWR);

801

802

if(quit_now){

803

goto mandos_end;

804

}

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);

805

814

806

815

if(buffer_length > 0){

807

816

ssize_t decrypted_buffer_size;

824

833

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

825

834

strerror(errno));

826

835

}

827

retval = -1;

828

break;

836

goto mandos_end;

829

837

}

830

838

written += (size_t)ret;

831

839

}

832

free(decrypted_buffer);

833

} else {

834

retval = -1;

840

retval = 0;

835

841

}

836

} else {

837

retval = -1;

838

842

}

839

843

840

844

/* Shutdown procedure */

841

845

842

846

mandos_end:

847

free(decrypted_buffer);

843

848

free(buffer);

844

849

if(tcp_sd >= 0){

845

850

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

971

976

errno = old_errno;

972

977

}

973

978

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

974

1074

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

975

1075

AvahiSServiceBrowser *sb = NULL;

976

1076

int error;

978

1078

intmax_t tmpmax;

979

1079

char *tmp;

980

1080

int exitcode = EXIT_SUCCESS;

981

const char *interface = "eth0";

1081

const char *interface = "";

982

1082

struct ifreq network;

983

1083

int sd = -1;

984

1084

bool take_down_interface = false;

985

1085

uid_t uid;

986

1086

gid_t gid;

987

char *connect_to = NULL;

988

1087

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

989

1088

bool tempdir_created = false;

990

1089

AvahiIfIndex if_index = AVAHI_IF_UNSPEC;

995

1094

bool gpgme_initialized = false;

996

1095

float delay = 2.5f;

997

1096

998

struct sigaction old_sigterm_action;

1097

struct sigaction old_sigterm_action = { .sa_handler = SIG_DFL };

999

1098

struct sigaction sigterm_action = { .sa_handler = handle_sigterm };

1000

1099

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

1001

1121

{

1002

1122

struct argp_option options[] = {

1003

1123

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

1099

1219

if(not debug){

1100

1220

avahi_set_log_function(empty_log);

1101

1221

}

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

}

1102

1247

1103

1248

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

1104

1249

from the signal handler */

1175

1320

}

1176

1321

1177

1322

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

1178

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

1323

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

1179

1324

if_index = (AvahiIfIndex) if_nametoindex(interface);

1180

1325

if(if_index == 0){

1181

1326

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

1187

1332

goto end;

1188

1333

}

1189

1334

1335

/* Re-raise priviliges */

1336

errno = 0;

1337

ret = seteuid(0);

1338

if(ret == -1){

1339

perror("seteuid");

1340

}

1341

1190

1342

#ifdef __linux__

1191

1343

/* Lower kernel loglevel to KERN_NOTICE to avoid KERN_INFO

1192

1344

messages to mess up the prompt */

1210

1362

}

1211

1363

}

1212

1364

#endif /* __linux__ */

1365

/* Lower privileges */

1366

errno = 0;

1367

ret = seteuid(uid);

1368

if(ret == -1){

1369

perror("seteuid");

1370

}

1213

1371

goto end;

1214

1372

}

1215

1373

strcpy(network.ifr_name, interface);

1225

1383

}

1226

1384

#endif /* __linux__ */

1227

1385

exitcode = EXIT_FAILURE;

1386

/* Lower privileges */

1387

errno = 0;

1388

ret = seteuid(uid);

1389

if(ret == -1){

1390

perror("seteuid");

1391

}

1228

1392

goto end;

1229

1393

}

1230

1394

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

1233

1397

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

1234

1398

if(ret == -1){

1235

1399

take_down_interface = false;

1236

perror("ioctl SIOCSIFFLAGS");

1400

perror("ioctl SIOCSIFFLAGS +IFF_UP");

1237

1401

exitcode = EXIT_FAILURE;

1238

1402

#ifdef __linux__

1239

1403

if(restore_loglevel){

1243

1407

}

1244

1408

}

1245

1409

#endif /* __linux__ */

1410

/* Lower privileges */

1411

errno = 0;

1412

ret = seteuid(uid);

1413

if(ret == -1){

1414

perror("seteuid");

1415

}

1246

1416

goto end;

1247

1417

}

1248

1418

}

1276

1446

}

1277

1447

}

1278

1448

#endif /* __linux__ */

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");

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

}

1309

1463

}

1310

1464

}

1311

1465

1500

1654

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

1501

1655

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

1502

1656

if(ret == -1){

1503

perror("ioctl SIOCSIFFLAGS");

1657

perror("ioctl SIOCSIFFLAGS -IFF_UP");

1504

1658

}

1505

1659

}

1506

1660

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

1507

1661

if(ret == -1){

1508

1662

perror("close");

1509

1663

}

1510

/* Lower privileges, permanently this time */

1664

/* Lower privileges permanently */

1511

1665

errno = 0;

1512

1666

ret = setuid(uid);

1513

1667

if(ret == -1){

1563

1717

if(quit_now){

1564

1718

sigemptyset(&old_sigterm_action.sa_mask);

1565

1719

old_sigterm_action.sa_handler = SIG_DFL;

1566

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

1720

ret = (int)TEMP_FAILURE_RETRY(sigaction(signal_received,

1721

&old_sigterm_action,

1722

NULL));

1567

1723

if(ret == -1){

1568

1724

perror("sigaction");

1569

1725

}

1570

raise(signal_received);

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());

1571

1734

}

1572

1735

1573

1736

return exitcode;