Nick Kralevich | 1d1011a | 2012-09-06 10:14:03 -0700 | [diff] [blame] | 1 | /* libcap-ng.c -- |
| 2 | * Copyright 2009-10 Red Hat Inc., Durham, North Carolina. |
| 3 | * All Rights Reserved. |
| 4 | * |
| 5 | * This library is free software; you can redistribute it and/or |
| 6 | * modify it under the terms of the GNU Lesser General Public |
| 7 | * License as published by the Free Software Foundation; either |
| 8 | * version 2.1 of the License, or (at your option) any later version. |
| 9 | * |
| 10 | * This library is distributed in the hope that it will be useful, |
| 11 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 12 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| 13 | * Lesser General Public License for more details. |
| 14 | * |
| 15 | * You should have received a copy of the GNU Lesser General Public |
| 16 | * License along with this library; if not, write to the Free Software |
| 17 | * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
| 18 | * |
| 19 | * Authors: |
| 20 | * Steve Grubb <sgrubb@redhat.com> |
| 21 | */ |
| 22 | |
| 23 | #include "config.h" |
| 24 | #include "cap-ng.h" |
| 25 | #include <string.h> |
| 26 | #include <stdarg.h> |
| 27 | #include <stdio.h> |
| 28 | #if !defined(ANDROID) |
| 29 | #include <stdio_ext.h> |
| 30 | #endif |
| 31 | #include <stdlib.h> |
| 32 | #include <sys/prctl.h> |
| 33 | #include <grp.h> |
| 34 | #include <sys/stat.h> |
| 35 | #include <stdarg.h> |
| 36 | #include <errno.h> |
| 37 | #include <byteswap.h> |
| 38 | #ifdef HAVE_SYSCALL_H |
| 39 | #include <sys/syscall.h> |
| 40 | #endif |
| 41 | #ifdef HAVE_LINUX_SECUREBITS_H |
| 42 | #include <linux/securebits.h> |
| 43 | #endif |
| 44 | |
| 45 | /* |
| 46 | * Some milestones of when things became available: |
| 47 | * 2.6.24 kernel XATTR_NAME_CAPS |
| 48 | * 2.6.25 kernel PR_CAPBSET_DROP, CAPABILITY_VERSION_2 |
| 49 | * 2.6.26 kernel PR_SET_SECUREBITS, SECURE_*_LOCKED, VERSION_3 |
| 50 | */ |
| 51 | |
| 52 | /* External syscall prototypes */ |
| 53 | extern int capset(cap_user_header_t header, cap_user_data_t data); |
| 54 | extern int capget(cap_user_header_t header, const cap_user_data_t data); |
| 55 | |
| 56 | // Local defines |
| 57 | #define MASK(x) (1U << (x)) |
| 58 | #ifdef PR_CAPBSET_DROP |
| 59 | #define UPPER_MASK ~(unsigned)((~0U)<<(CAP_LAST_CAP-31)) |
| 60 | #else |
| 61 | // For v1 systems UPPER_MASK will never be used |
| 62 | #define UPPER_MASK (unsigned)(~0U) |
| 63 | #endif |
| 64 | |
| 65 | // Re-define cap_valid so its uniform between V1 and V3 |
| 66 | #undef cap_valid |
| 67 | #define cap_valid(x) ((x) <= CAP_LAST_CAP) |
| 68 | |
| 69 | // If we don't have the xattr library, then we can't |
| 70 | // compile-in file system capabilities |
| 71 | #ifndef HAVE_ATTR_XATTR_H |
| 72 | #undef VFS_CAP_U32 |
| 73 | #endif |
| 74 | |
| 75 | #ifdef VFS_CAP_U32 |
| 76 | #include <attr/xattr.h> |
| 77 | #if __BYTE_ORDER == __BIG_ENDIAN |
| 78 | #define FIXUP(x) bswap_32(x) |
| 79 | #else |
| 80 | #define FIXUP(x) (x) |
| 81 | #endif |
| 82 | #endif |
| 83 | |
| 84 | #ifndef _LINUX_CAPABILITY_VERSION_1 |
| 85 | #define _LINUX_CAPABILITY_VERSION_1 0x19980330 |
| 86 | #endif |
| 87 | #ifndef _LINUX_CAPABILITY_VERSION_2 |
| 88 | #define _LINUX_CAPABILITY_VERSION_2 0x20071026 |
| 89 | #endif |
| 90 | #ifndef _LINUX_CAPABILITY_VERSION_3 |
| 91 | #define _LINUX_CAPABILITY_VERSION_3 0x20080522 |
| 92 | #endif |
| 93 | |
| 94 | // This public API went private in the 2.6.36 kernel - hope it never changes |
| 95 | #ifndef XATTR_CAPS_SUFFIX |
| 96 | #define XATTR_CAPS_SUFFIX "capability" |
| 97 | #endif |
| 98 | #ifndef XATTR_SECURITY_PREFIX |
| 99 | #define XATTR_SECURITY_PREFIX "security." |
| 100 | #endif |
| 101 | #ifndef XATTR_NAME_CAPS |
| 102 | #define XATTR_NAME_CAPS XATTR_SECURITY_PREFIX XATTR_CAPS_SUFFIX |
| 103 | #endif |
| 104 | |
| 105 | |
| 106 | /* Child processes can't get caps back */ |
| 107 | #ifndef SECURE_NOROOT |
| 108 | #define SECURE_NOROOT 0 |
| 109 | #endif |
| 110 | #ifndef SECURE_NOROOT_LOCKED |
| 111 | #define SECURE_NOROOT_LOCKED 1 /* make bit-0 immutable */ |
| 112 | #endif |
| 113 | /* Setuid apps run by uid 0 don't get caps back */ |
| 114 | #ifndef SECURE_NO_SETUID_FIXUP |
| 115 | #define SECURE_NO_SETUID_FIXUP 2 |
| 116 | #endif |
| 117 | #ifndef SECURE_NO_SETUID_FIXUP_LOCKED |
| 118 | #define SECURE_NO_SETUID_FIXUP_LOCKED 3 /* make bit-2 immutable */ |
| 119 | #endif |
| 120 | |
| 121 | // States: new, allocated, initted, updated, applied |
| 122 | typedef enum { CAPNG_NEW, CAPNG_ERROR, CAPNG_ALLOCATED, CAPNG_INIT, |
| 123 | CAPNG_UPDATED, CAPNG_APPLIED } capng_states_t; |
| 124 | |
| 125 | // Create an easy data struct out of the kernel definitions |
| 126 | typedef union { |
| 127 | struct __user_cap_data_struct v1; |
| 128 | struct __user_cap_data_struct v3[2]; |
| 129 | } cap_data_t; |
| 130 | |
| 131 | // This struct keeps all state info |
| 132 | struct cap_ng |
| 133 | { |
| 134 | int cap_ver; |
| 135 | struct __user_cap_header_struct hdr; |
| 136 | cap_data_t data; |
| 137 | capng_states_t state; |
| 138 | __u32 bounds[2]; |
| 139 | }; |
| 140 | |
| 141 | // Global variables with per thread uniqueness |
| 142 | static __thread struct cap_ng m = { 1, |
| 143 | {0, 0}, |
| 144 | { {0, 0, 0} }, |
| 145 | CAPNG_NEW, |
| 146 | {0, 0} }; |
| 147 | |
| 148 | |
| 149 | static void init(void) |
| 150 | { |
| 151 | if (m.state != CAPNG_NEW) |
| 152 | return; |
| 153 | |
| 154 | memset(&m.hdr, 0, sizeof(m.hdr)); |
| 155 | (void)capget(&m.hdr, NULL); // Returns -EINVAL |
| 156 | if (m.hdr.version == _LINUX_CAPABILITY_VERSION_3 || |
| 157 | m.hdr.version == _LINUX_CAPABILITY_VERSION_2) { |
| 158 | m.cap_ver = 3; |
| 159 | } else if (m.hdr.version == _LINUX_CAPABILITY_VERSION_1) { |
| 160 | m.cap_ver = 1; |
| 161 | } else { |
| 162 | m.state = CAPNG_ERROR; |
| 163 | return; |
| 164 | } |
| 165 | |
| 166 | memset(&m.data, 0, sizeof(cap_data_t)); |
| 167 | #ifdef HAVE_SYSCALL_H |
| 168 | m.hdr.pid = (unsigned)syscall(__NR_gettid); |
| 169 | #else |
| 170 | m.hdr.pid = (unsigned)getpid(); |
| 171 | #endif |
| 172 | m.state = CAPNG_ALLOCATED; |
| 173 | } |
| 174 | |
| 175 | void capng_clear(capng_select_t set) |
| 176 | { |
| 177 | if (m.state == CAPNG_NEW) |
| 178 | init(); |
| 179 | if (m.state == CAPNG_ERROR) |
| 180 | return; |
| 181 | |
| 182 | if (set & CAPNG_SELECT_CAPS) |
| 183 | memset(&m.data, 0, sizeof(cap_data_t)); |
| 184 | #ifdef PR_CAPBSET_DROP |
| 185 | if (set & CAPNG_SELECT_BOUNDS) |
| 186 | memset(m.bounds, 0, sizeof(m.bounds)); |
| 187 | #endif |
| 188 | m.state = CAPNG_INIT; |
| 189 | } |
| 190 | |
| 191 | void capng_fill(capng_select_t set) |
| 192 | { |
| 193 | if (m.state == CAPNG_NEW) |
| 194 | init(); |
| 195 | if (m.state == CAPNG_ERROR) |
| 196 | return; |
| 197 | |
| 198 | if (set & CAPNG_SELECT_CAPS) { |
| 199 | if (m.cap_ver == 1) { |
| 200 | m.data.v1.effective = 0x7FFFFFFFU; |
| 201 | m.data.v1.permitted = 0x7FFFFFFFU; |
| 202 | m.data.v1.inheritable = 0; |
| 203 | } else { |
| 204 | m.data.v3[0].effective = 0xFFFFFFFFU; |
| 205 | m.data.v3[0].permitted = 0xFFFFFFFFU; |
| 206 | m.data.v3[0].inheritable = 0; |
| 207 | m.data.v3[1].effective = 0xFFFFFFFFU; |
| 208 | m.data.v3[1].permitted = 0xFFFFFFFFU; |
| 209 | m.data.v3[1].inheritable = 0; |
| 210 | } |
| 211 | } |
| 212 | #ifdef PR_CAPBSET_DROP |
| 213 | if (set & CAPNG_SELECT_BOUNDS) { |
| 214 | unsigned i; |
| 215 | for (i=0; i<sizeof(m.bounds)/sizeof(__u32); i++) |
| 216 | m.bounds[i] = 0xFFFFFFFFU; |
| 217 | } |
| 218 | #endif |
| 219 | m.state = CAPNG_INIT; |
| 220 | } |
| 221 | |
| 222 | void capng_setpid(int pid) |
| 223 | { |
| 224 | if (m.state == CAPNG_NEW) |
| 225 | init(); |
| 226 | if (m.state == CAPNG_ERROR) |
| 227 | return; |
| 228 | |
| 229 | m.hdr.pid = pid; |
| 230 | } |
| 231 | |
| 232 | #ifdef PR_CAPBSET_DROP |
| 233 | static int get_bounding_set(void) |
| 234 | { |
| 235 | char buf[64]; |
| 236 | FILE *f; |
| 237 | |
| 238 | snprintf(buf, sizeof(buf), "/proc/%u/status", m.hdr.pid ? m.hdr.pid : |
| 239 | #ifdef HAVE_SYSCALL_H |
| 240 | (unsigned)syscall(__NR_gettid)); |
| 241 | #else |
| 242 | (unsigned)getpid(); |
| 243 | #endif |
| 244 | f = fopen(buf, "re"); |
| 245 | if (f == NULL) |
| 246 | return -1; |
| 247 | #if !defined(ANDROID) |
| 248 | __fsetlocking(f, FSETLOCKING_BYCALLER); |
| 249 | #endif |
| 250 | while (fgets(buf, sizeof(buf), f)) { |
| 251 | if (strncmp(buf, "CapB", 4)) |
| 252 | continue; |
| 253 | sscanf(buf, "CapBnd: %08x%08x", &m.bounds[1], &m.bounds[0]); |
| 254 | fclose(f); |
| 255 | return 0; |
| 256 | } |
| 257 | fclose(f); |
| 258 | return -1; |
| 259 | } |
| 260 | #endif |
| 261 | |
| 262 | int capng_get_caps_process(void) |
| 263 | { |
| 264 | int rc; |
| 265 | |
| 266 | if (m.state == CAPNG_NEW) |
| 267 | init(); |
| 268 | if (m.state == CAPNG_ERROR) |
| 269 | return -1; |
| 270 | |
| 271 | rc = capget((cap_user_header_t)&m.hdr, (cap_user_data_t)&m.data); |
| 272 | if (rc == 0) { |
| 273 | m.state = CAPNG_INIT; |
| 274 | #ifdef PR_CAPBSET_DROP |
| 275 | rc = get_bounding_set(); |
| 276 | if (rc < 0) |
| 277 | m.state = CAPNG_ERROR; |
| 278 | #endif |
| 279 | } |
| 280 | |
| 281 | return rc; |
| 282 | } |
| 283 | |
| 284 | #ifdef VFS_CAP_U32 |
| 285 | static int load_data(const struct vfs_cap_data *filedata, int size) |
| 286 | { |
| 287 | unsigned int magic; |
| 288 | |
| 289 | if (m.cap_ver == 1) |
| 290 | return -1; // Should never get here but just in case |
| 291 | |
| 292 | magic = FIXUP(filedata->magic_etc); |
| 293 | switch (magic & VFS_CAP_REVISION_MASK) |
| 294 | { |
| 295 | case VFS_CAP_REVISION_1: |
| 296 | m.cap_ver = 1; |
| 297 | if (size != XATTR_CAPS_SZ_1) |
| 298 | return -1; |
| 299 | break; |
| 300 | case VFS_CAP_REVISION_2: |
| 301 | m.cap_ver = 2; |
| 302 | if (size != XATTR_CAPS_SZ_2) |
| 303 | return -1; |
| 304 | break; |
| 305 | default: |
| 306 | return -1; |
| 307 | } |
| 308 | |
| 309 | // Now stuff the data structures |
| 310 | m.data.v3[0].permitted = FIXUP(filedata->data[0].permitted); |
| 311 | m.data.v3[1].permitted = FIXUP(filedata->data[1].permitted); |
| 312 | m.data.v3[0].inheritable = FIXUP(filedata->data[0].inheritable); |
| 313 | m.data.v3[1].inheritable = FIXUP(filedata->data[1].inheritable); |
| 314 | if (magic & VFS_CAP_FLAGS_EFFECTIVE) { |
| 315 | m.data.v3[0].effective = |
| 316 | m.data.v3[0].permitted | m.data.v3[0].inheritable; |
| 317 | m.data.v3[1].effective = |
| 318 | m.data.v3[1].permitted | m.data.v3[1].inheritable; |
| 319 | } else { |
| 320 | m.data.v3[0].effective = 0; |
| 321 | m.data.v3[1].effective = 0; |
| 322 | } |
| 323 | return 0; |
| 324 | } |
| 325 | #endif |
| 326 | |
| 327 | int capng_get_caps_fd(int fd) |
| 328 | { |
| 329 | #ifndef VFS_CAP_U32 |
| 330 | return -1; |
| 331 | #else |
| 332 | int rc; |
| 333 | struct vfs_cap_data filedata; |
| 334 | |
| 335 | if (m.state == CAPNG_NEW) |
| 336 | init(); |
| 337 | if (m.state == CAPNG_ERROR) |
| 338 | return -1; |
| 339 | |
| 340 | rc = fgetxattr(fd, XATTR_NAME_CAPS, &filedata, sizeof(filedata)); |
| 341 | if (rc <= 0) |
| 342 | return -1; |
| 343 | |
| 344 | rc = load_data(&filedata, rc); |
| 345 | if (rc == 0) |
| 346 | m.state = CAPNG_INIT; |
| 347 | |
| 348 | return rc; |
| 349 | #endif |
| 350 | } |
| 351 | |
| 352 | static void v1_update(capng_act_t action, unsigned int capability, __u32 *data) |
| 353 | { |
| 354 | if (action == CAPNG_ADD) |
| 355 | *data |= MASK(capability); |
| 356 | else |
| 357 | *data &= ~(MASK(capability)); |
| 358 | } |
| 359 | |
| 360 | static void update_effective(capng_act_t action, unsigned int capability, |
| 361 | unsigned int idx) |
| 362 | { |
| 363 | if (action == CAPNG_ADD) |
| 364 | m.data.v3[idx].effective |= MASK(capability); |
| 365 | else |
| 366 | m.data.v3[idx].effective &= ~(MASK(capability)); |
| 367 | } |
| 368 | |
| 369 | static void update_permitted(capng_act_t action, unsigned int capability, |
| 370 | unsigned int idx) |
| 371 | { |
| 372 | if (action == CAPNG_ADD) |
| 373 | m.data.v3[idx].permitted |= MASK(capability); |
| 374 | else |
| 375 | m.data.v3[idx].permitted &= ~(MASK(capability)); |
| 376 | } |
| 377 | |
| 378 | static void update_inheritable(capng_act_t action, unsigned int capability, |
| 379 | unsigned int idx) |
| 380 | { |
| 381 | if (action == CAPNG_ADD) |
| 382 | m.data.v3[idx].inheritable |= MASK(capability); |
| 383 | else |
| 384 | m.data.v3[idx].inheritable &= ~(MASK(capability)); |
| 385 | } |
| 386 | |
| 387 | static void update_bounding_set(capng_act_t action, unsigned int capability, |
| 388 | unsigned int idx) |
| 389 | { |
| 390 | #ifdef PR_CAPBSET_DROP |
| 391 | if (action == CAPNG_ADD) |
| 392 | m.bounds[idx] |= MASK(capability); |
| 393 | else |
| 394 | m.bounds[idx] &= ~(MASK(capability)); |
| 395 | #endif |
| 396 | } |
| 397 | |
| 398 | int capng_update(capng_act_t action, capng_type_t type, unsigned int capability) |
| 399 | { |
| 400 | // Before updating, we expect that the data is initialized to something |
| 401 | if (m.state < CAPNG_INIT) |
| 402 | return -1; |
| 403 | if (!cap_valid(capability)) { |
| 404 | errno = EINVAL; |
| 405 | return -1; |
| 406 | } |
| 407 | |
| 408 | if (m.cap_ver == 1) { |
| 409 | if (CAPNG_EFFECTIVE & type) |
| 410 | v1_update(action, capability, &m.data.v1.effective); |
| 411 | if (CAPNG_PERMITTED & type) |
| 412 | v1_update(action, capability, &m.data.v1.permitted); |
| 413 | if (CAPNG_INHERITABLE & type) |
| 414 | v1_update(action, capability, &m.data.v1.inheritable); |
| 415 | } else { |
| 416 | int idx; |
| 417 | |
| 418 | if (capability > 31) { |
| 419 | idx = capability>>5; |
| 420 | capability %= 32; |
| 421 | } else |
| 422 | idx = 0; |
| 423 | |
| 424 | if (CAPNG_EFFECTIVE & type) |
| 425 | update_effective(action, capability, idx); |
| 426 | if (CAPNG_PERMITTED & type) |
| 427 | update_permitted(action, capability, idx); |
| 428 | if (CAPNG_INHERITABLE & type) |
| 429 | update_inheritable(action, capability, idx); |
| 430 | if (CAPNG_BOUNDING_SET & type) |
| 431 | update_bounding_set(action, capability, idx); |
| 432 | } |
| 433 | |
| 434 | m.state = CAPNG_UPDATED; |
| 435 | return 0; |
| 436 | } |
| 437 | |
| 438 | int capng_updatev(capng_act_t action, capng_type_t type, |
| 439 | unsigned int capability, ...) |
| 440 | { |
| 441 | int rc; |
| 442 | unsigned int cap; |
| 443 | va_list ap; |
| 444 | |
| 445 | rc = capng_update(action, type, capability); |
| 446 | if (rc) |
| 447 | return rc; |
| 448 | va_start(ap, capability); |
| 449 | cap = va_arg(ap, unsigned int); |
| 450 | while (cap_valid(cap)) { |
| 451 | rc = capng_update(action, type, cap); |
| 452 | if (rc) |
| 453 | break; |
| 454 | cap = va_arg(ap, unsigned int); |
| 455 | } |
| 456 | va_end(ap); |
| 457 | |
| 458 | // See if planned exit or invalid |
| 459 | if (cap == (unsigned)-1) |
| 460 | rc = 0; |
| 461 | else { |
| 462 | rc = -1; |
| 463 | errno = EINVAL; |
| 464 | } |
| 465 | |
| 466 | return rc; |
| 467 | } |
| 468 | |
| 469 | int capng_apply(capng_select_t set) |
| 470 | { |
| 471 | int rc = -1; |
| 472 | |
| 473 | // Before updating, we expect that the data is initialized to something |
| 474 | if (m.state < CAPNG_INIT) |
| 475 | return -1; |
| 476 | |
| 477 | if (set & CAPNG_SELECT_BOUNDS) { |
| 478 | #ifdef PR_CAPBSET_DROP |
| 479 | void *s = capng_save_state(); |
| 480 | capng_get_caps_process(); |
| 481 | if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP)) { |
| 482 | int i; |
| 483 | capng_restore_state(&s); |
| 484 | rc = 0; |
| 485 | for (i=0; i <= CAP_LAST_CAP && rc == 0; i++) |
| 486 | if (capng_have_capability(CAPNG_BOUNDING_SET, |
| 487 | i) == 0) |
| 488 | rc = prctl(PR_CAPBSET_DROP, i, 0, 0, 0); |
| 489 | if (rc == 0) |
| 490 | m.state = CAPNG_APPLIED; |
| 491 | } else |
| 492 | capng_restore_state(&s); |
| 493 | #else |
| 494 | rc = 0; |
| 495 | #endif |
| 496 | } |
| 497 | if (set & CAPNG_SELECT_CAPS) { |
| 498 | rc = capset((cap_user_header_t)&m.hdr, |
| 499 | (cap_user_data_t)&m.data); |
| 500 | if (rc == 0) |
| 501 | m.state = CAPNG_APPLIED; |
| 502 | } |
| 503 | return rc; |
| 504 | } |
| 505 | |
| 506 | #ifdef VFS_CAP_U32 |
| 507 | static int save_data(struct vfs_cap_data *filedata, int *size) |
| 508 | { |
| 509 | // Now stuff the data structures |
| 510 | if (m.cap_ver == 1) { |
| 511 | filedata->data[0].permitted = FIXUP(m.data.v1.permitted); |
| 512 | filedata->data[0].inheritable = FIXUP(m.data.v1.inheritable); |
| 513 | filedata->magic_etc = FIXUP(VFS_CAP_REVISION_1); |
| 514 | *size = XATTR_CAPS_SZ_1; |
| 515 | } else { |
| 516 | int eff; |
| 517 | |
| 518 | if (m.data.v3[0].effective || m.data.v3[1].effective) |
| 519 | eff = VFS_CAP_FLAGS_EFFECTIVE; |
| 520 | else |
| 521 | eff = 0; |
| 522 | filedata->data[0].permitted = FIXUP(m.data.v3[0].permitted); |
| 523 | filedata->data[0].inheritable = FIXUP(m.data.v3[0].inheritable); |
| 524 | filedata->data[1].permitted = FIXUP(m.data.v3[1].permitted); |
| 525 | filedata->data[1].inheritable = FIXUP(m.data.v3[1].inheritable); |
| 526 | filedata->magic_etc = FIXUP(VFS_CAP_REVISION_2 | eff); |
| 527 | *size = XATTR_CAPS_SZ_2; |
| 528 | } |
| 529 | |
| 530 | return 0; |
| 531 | } |
| 532 | #endif |
| 533 | |
| 534 | int capng_apply_caps_fd(int fd) |
| 535 | { |
| 536 | #ifndef VFS_CAP_U32 |
| 537 | return -1; |
| 538 | #else |
| 539 | int rc, size; |
| 540 | struct vfs_cap_data filedata; |
| 541 | struct stat buf; |
| 542 | |
| 543 | // Before updating, we expect that the data is initialized to something |
| 544 | if (m.state < CAPNG_INIT) |
| 545 | return -1; |
| 546 | |
| 547 | if (fstat(fd, &buf) != 0) |
| 548 | return -1; |
| 549 | if (S_ISLNK(buf.st_mode) || !S_ISREG(buf.st_mode)) { |
| 550 | errno = EINVAL; |
| 551 | return -1; |
| 552 | } |
| 553 | if (capng_have_capabilities(CAPNG_SELECT_CAPS) == CAPNG_NONE) |
| 554 | rc = fremovexattr(fd, XATTR_NAME_CAPS); |
| 555 | else { |
| 556 | save_data(&filedata, &size); |
| 557 | rc = fsetxattr(fd, XATTR_NAME_CAPS, &filedata, size, 0); |
| 558 | } |
| 559 | |
| 560 | if (rc == 0) |
| 561 | m.state = CAPNG_APPLIED; |
| 562 | |
| 563 | return rc; |
| 564 | #endif |
| 565 | } |
| 566 | |
| 567 | // Change uids keeping/removing only certain capabilities |
| 568 | // flag to drop supp groups |
| 569 | int capng_change_id(int uid, int gid, capng_flags_t flag) |
| 570 | { |
| 571 | int rc, need_setgid, need_setuid; |
| 572 | |
| 573 | // Before updating, we expect that the data is initialized to something |
| 574 | if (m.state < CAPNG_INIT) |
| 575 | return -1; |
| 576 | |
| 577 | // Check the current capabilities |
| 578 | #ifdef PR_CAPBSET_DROP |
| 579 | // If newer kernel, we need setpcap to change the bounding set |
| 580 | if (capng_have_capability(CAPNG_EFFECTIVE, CAP_SETPCAP) == 0 && |
| 581 | flag & CAPNG_CLEAR_BOUNDING) |
| 582 | capng_update(CAPNG_ADD, |
| 583 | CAPNG_EFFECTIVE|CAPNG_PERMITTED, CAP_SETPCAP); |
| 584 | #endif |
| 585 | if (gid == -1 || capng_have_capability(CAPNG_EFFECTIVE, CAP_SETGID)) |
| 586 | need_setgid = 0; |
| 587 | else { |
| 588 | need_setgid = 1; |
| 589 | capng_update(CAPNG_ADD, CAPNG_EFFECTIVE|CAPNG_PERMITTED, |
| 590 | CAP_SETGID); |
| 591 | } |
| 592 | if (uid == -1 || capng_have_capability(CAPNG_EFFECTIVE, CAP_SETUID)) |
| 593 | need_setuid = 0; |
| 594 | else { |
| 595 | need_setuid = 1; |
| 596 | capng_update(CAPNG_ADD, CAPNG_EFFECTIVE|CAPNG_PERMITTED, |
| 597 | CAP_SETUID); |
| 598 | } |
| 599 | |
| 600 | // Tell system we want to keep caps across uid change |
| 601 | if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0)) |
| 602 | return -2; |
| 603 | |
| 604 | // Change to the temp capabilities |
| 605 | rc = capng_apply(CAPNG_SELECT_CAPS); |
| 606 | if (rc < 0) |
| 607 | return -3; |
| 608 | |
| 609 | // Clear bounding set if needed while we have CAP_SETPCAP |
| 610 | if (flag & CAPNG_CLEAR_BOUNDING) { |
| 611 | capng_clear(CAPNG_BOUNDING_SET); |
| 612 | rc = capng_apply(CAPNG_SELECT_BOUNDS); |
| 613 | if (rc) |
| 614 | return -8; |
| 615 | } |
| 616 | |
| 617 | // Change gid |
| 618 | if (gid != -1) { |
| 619 | rc = setresgid(gid, gid, gid); |
| 620 | if (rc) |
| 621 | return -4; |
| 622 | } |
| 623 | |
| 624 | // See if we need to unload supplemental groups |
| 625 | if ((flag & CAPNG_DROP_SUPP_GRP) && gid != -1) { |
| 626 | if (setgroups(0, NULL)) |
| 627 | return -5; |
| 628 | } |
| 629 | |
| 630 | // Change uid |
| 631 | if (uid != -1) { |
| 632 | rc = setresuid(uid, uid, uid); |
| 633 | if (rc) |
| 634 | return -6; |
| 635 | } |
| 636 | |
| 637 | // Tell it we are done keeping capabilities |
| 638 | rc = prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0); |
| 639 | if (rc) |
| 640 | return -7; |
| 641 | |
| 642 | // Now throw away CAP_SETPCAP so no more changes |
| 643 | if (need_setgid) |
| 644 | capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED, |
| 645 | CAP_SETGID); |
| 646 | if (need_setuid) |
| 647 | capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED, |
| 648 | CAP_SETUID); |
| 649 | |
| 650 | // Now drop setpcap & apply |
| 651 | capng_update(CAPNG_DROP, CAPNG_EFFECTIVE|CAPNG_PERMITTED, |
| 652 | CAP_SETPCAP); |
| 653 | rc = capng_apply(CAPNG_SELECT_CAPS); |
| 654 | if (rc < 0) |
| 655 | return -9; |
| 656 | |
| 657 | // Done |
| 658 | m.state = CAPNG_UPDATED; |
| 659 | return 0; |
| 660 | } |
| 661 | |
| 662 | int capng_lock(void) |
| 663 | { |
| 664 | #ifdef PR_SET_SECUREBITS |
| 665 | int rc = prctl(PR_SET_SECUREBITS, |
| 666 | 1 << SECURE_NOROOT | |
| 667 | 1 << SECURE_NOROOT_LOCKED | |
| 668 | 1 << SECURE_NO_SETUID_FIXUP | |
| 669 | 1 << SECURE_NO_SETUID_FIXUP_LOCKED, 0, 0, 0); |
| 670 | if (rc) |
| 671 | return -1; |
| 672 | #endif |
| 673 | |
| 674 | return 0; |
| 675 | } |
| 676 | |
| 677 | // -1 - error, 0 - no caps, 1 partial caps, 2 full caps |
| 678 | capng_results_t capng_have_capabilities(capng_select_t set) |
| 679 | { |
| 680 | int empty = 0, full = 0; |
| 681 | |
| 682 | // First, try to init with current set |
| 683 | if (m.state < CAPNG_INIT) |
| 684 | capng_get_caps_process(); |
| 685 | |
| 686 | // If we still don't have anything, error out |
| 687 | if (m.state < CAPNG_INIT) |
| 688 | return CAPNG_FAIL; |
| 689 | |
| 690 | if (set & CAPNG_SELECT_CAPS) { |
| 691 | if (m.cap_ver == 1) { |
| 692 | if (m.data.v1.effective == 0) |
| 693 | empty = 1; |
| 694 | // after fill, 30 bits starts from upper to lower |
| 695 | else if (m.data.v1.effective == 0x7FFFFFFFU) |
| 696 | full = 1; |
| 697 | // actual capabilities read from system |
| 698 | else if (m.data.v1.effective == 0xFFFFFEFFU) |
| 699 | full = 1; |
| 700 | else |
| 701 | return CAPNG_PARTIAL; |
| 702 | } else { |
| 703 | if (m.data.v3[0].effective == 0) |
| 704 | empty = 1; |
| 705 | else if (m.data.v3[0].effective == 0xFFFFFFFFU) |
| 706 | full = 1; |
| 707 | else |
| 708 | return CAPNG_PARTIAL; |
| 709 | if ((m.data.v3[1].effective & UPPER_MASK) == 0) |
| 710 | empty = 1; |
| 711 | else if ((m.data.v3[1].effective & UPPER_MASK) == |
| 712 | UPPER_MASK) |
| 713 | full = 1; |
| 714 | else |
| 715 | return CAPNG_PARTIAL; |
| 716 | } |
| 717 | } |
| 718 | #ifdef PR_CAPBSET_DROP |
| 719 | if (set & CAPNG_SELECT_BOUNDS) { |
| 720 | if (m.bounds[0] == 0) |
| 721 | empty = 1; |
| 722 | else if (m.bounds[0] == 0xFFFFFFFFU) |
| 723 | full = 1; |
| 724 | else |
| 725 | return CAPNG_PARTIAL; |
| 726 | if ((m.bounds[1] & UPPER_MASK) == 0) |
| 727 | empty = 1; |
| 728 | else if ((m.bounds[1] & UPPER_MASK) == UPPER_MASK) |
| 729 | full = 1; |
| 730 | else |
| 731 | return CAPNG_PARTIAL; |
| 732 | } |
| 733 | #endif |
| 734 | |
| 735 | if (empty == 1 && full == 0) |
| 736 | return CAPNG_NONE; |
| 737 | else if (empty == 0 && full == 1) |
| 738 | return CAPNG_FULL; |
| 739 | |
| 740 | return CAPNG_PARTIAL; |
| 741 | } |
| 742 | |
| 743 | static int check_effective(unsigned int capability, unsigned int idx) |
| 744 | { |
| 745 | return MASK(capability) & m.data.v3[idx].effective ? 1 : 0; |
| 746 | } |
| 747 | |
| 748 | static int check_permitted(unsigned int capability, unsigned int idx) |
| 749 | { |
| 750 | return MASK(capability) & m.data.v3[idx].permitted ? 1 : 0; |
| 751 | } |
| 752 | |
| 753 | static int check_inheritable(unsigned int capability, unsigned int idx) |
| 754 | { |
| 755 | return MASK(capability) & m.data.v3[idx].inheritable ? 1 : 0; |
| 756 | } |
| 757 | |
| 758 | static int bounds_bit_check(unsigned int capability, unsigned int idx) |
| 759 | { |
| 760 | #ifdef PR_CAPBSET_DROP |
| 761 | return MASK(capability) & m.bounds[idx] ? 1 : 0; |
| 762 | #else |
| 763 | return 0; |
| 764 | #endif |
| 765 | } |
| 766 | |
| 767 | static int v1_check(unsigned int capability, __u32 data) |
| 768 | { |
| 769 | return MASK(capability) & data ? 1 : 0; |
| 770 | } |
| 771 | |
| 772 | int capng_have_capability(capng_type_t which, unsigned int capability) |
| 773 | { |
| 774 | // First, try to init with current set |
| 775 | if (m.state < CAPNG_INIT) |
| 776 | capng_get_caps_process(); |
| 777 | |
| 778 | // If we still don't have anything, error out |
| 779 | if (m.state < CAPNG_INIT) |
| 780 | return CAPNG_FAIL; |
| 781 | if (m.cap_ver == 1 && capability > 31) |
| 782 | return 0; |
| 783 | if (!cap_valid(capability)) |
| 784 | return 0; |
| 785 | |
| 786 | if (m.cap_ver == 1) { |
| 787 | if (which == CAPNG_EFFECTIVE) |
| 788 | return v1_check(capability, m.data.v1.effective); |
| 789 | else if (which == CAPNG_PERMITTED) |
| 790 | return v1_check(capability, m.data.v1.permitted); |
| 791 | else if (which == CAPNG_INHERITABLE) |
| 792 | return v1_check(capability, m.data.v1.inheritable); |
| 793 | } else { |
| 794 | unsigned int idx; |
| 795 | |
| 796 | if (capability > 31) { |
| 797 | idx = capability>>5; |
| 798 | capability %= 32; |
| 799 | } else |
| 800 | idx = 0; |
| 801 | |
| 802 | if (which == CAPNG_EFFECTIVE) |
| 803 | return check_effective(capability, idx); |
| 804 | else if (which == CAPNG_PERMITTED) |
| 805 | return check_permitted(capability, idx); |
| 806 | else if (which == CAPNG_INHERITABLE) |
| 807 | return check_inheritable(capability, idx); |
| 808 | else if (which == CAPNG_BOUNDING_SET) |
| 809 | return bounds_bit_check(capability, idx); |
| 810 | } |
| 811 | return 0; |
| 812 | } |
| 813 | |
| 814 | char *capng_print_caps_numeric(capng_print_t where, capng_select_t set) |
| 815 | { |
| 816 | char *ptr = NULL; |
| 817 | |
| 818 | if (m.state < CAPNG_INIT) |
| 819 | return ptr; |
| 820 | |
| 821 | if (where == CAPNG_PRINT_STDOUT) { |
| 822 | if (set & CAPNG_SELECT_CAPS) { |
| 823 | if (m.cap_ver == 1) { |
| 824 | printf( "Effective: %08X\n" |
| 825 | "Permitted: %08X\n" |
| 826 | "Inheritable: %08X\n", |
| 827 | m.data.v1.effective, |
| 828 | m.data.v1.permitted, |
| 829 | m.data.v1.inheritable); |
| 830 | } else { |
| 831 | printf( "Effective: %08X, %08X\n" |
| 832 | "Permitted: %08X, %08X\n" |
| 833 | "Inheritable: %08X, %08X\n", |
| 834 | m.data.v3[1].effective & UPPER_MASK, |
| 835 | m.data.v3[0].effective, |
| 836 | m.data.v3[1].permitted & UPPER_MASK, |
| 837 | m.data.v3[0].permitted, |
| 838 | m.data.v3[1].inheritable & UPPER_MASK, |
| 839 | m.data.v3[0].inheritable); |
| 840 | |
| 841 | } |
| 842 | } |
| 843 | #ifdef PR_CAPBSET_DROP |
| 844 | if (set & CAPNG_SELECT_BOUNDS) |
| 845 | printf("Bounding Set: %08X, %08X\n", |
| 846 | m.bounds[1] & UPPER_MASK, m.bounds[0]); |
| 847 | #endif |
| 848 | } else if (where == CAPNG_PRINT_BUFFER) { |
| 849 | if (set & CAPNG_SELECT_CAPS) { |
| 850 | // Make it big enough for bounding set, too |
| 851 | ptr = malloc(160); |
| 852 | if (m.cap_ver == 1) { |
| 853 | snprintf(ptr, 160, |
| 854 | "Effective: %08X\n" |
| 855 | "Permitted: %08X\n" |
| 856 | "Inheritable: %08X\n", |
| 857 | m.data.v1.effective, |
| 858 | m.data.v1.permitted, |
| 859 | m.data.v1.inheritable); |
| 860 | } else { |
| 861 | snprintf(ptr, 160, |
| 862 | "Effective: %08X, %08X\n" |
| 863 | "Permitted: %08X, %08X\n" |
| 864 | "Inheritable: %08X, %08X\n", |
| 865 | m.data.v3[1].effective & UPPER_MASK, |
| 866 | m.data.v3[0].effective, |
| 867 | m.data.v3[1].permitted & UPPER_MASK, |
| 868 | m.data.v3[0].permitted, |
| 869 | m.data.v3[1].inheritable & UPPER_MASK, |
| 870 | m.data.v3[0].inheritable); |
| 871 | } |
| 872 | } |
| 873 | if (set & CAPNG_SELECT_BOUNDS) { |
| 874 | #ifdef PR_CAPBSET_DROP |
| 875 | char *s; |
| 876 | if (ptr == NULL ){ |
| 877 | ptr = malloc(40); |
| 878 | if (ptr == NULL) |
| 879 | return ptr; |
| 880 | *ptr = 0; |
| 881 | s = ptr; |
| 882 | } else |
| 883 | s = ptr + strlen(ptr); |
| 884 | snprintf(s, 40, "Bounding Set: %08X, %08X\n", |
| 885 | m.bounds[1] & UPPER_MASK, m.bounds[0]); |
| 886 | #endif |
| 887 | } |
| 888 | } |
| 889 | |
| 890 | return ptr; |
| 891 | } |
| 892 | |
| 893 | char *capng_print_caps_text(capng_print_t where, capng_type_t which) |
| 894 | { |
| 895 | unsigned int i; |
| 896 | int once = 0, cnt = 0; |
| 897 | char *ptr = NULL; |
| 898 | |
| 899 | if (m.state < CAPNG_INIT) |
| 900 | return ptr; |
| 901 | |
| 902 | for (i=0; i<=CAP_LAST_CAP; i++) { |
| 903 | if (capng_have_capability(which, i)) { |
| 904 | const char *n = capng_capability_to_name(i); |
| 905 | if (n == NULL) |
| 906 | n = "unknown"; |
| 907 | if (where == CAPNG_PRINT_STDOUT) { |
| 908 | if (once == 0) { |
| 909 | printf("%s", n); |
| 910 | once++; |
| 911 | } else |
| 912 | printf(", %s", n); |
| 913 | } else if (where == CAPNG_PRINT_BUFFER) { |
| 914 | int len; |
| 915 | if (once == 0) { |
| 916 | ptr = malloc(CAP_LAST_CAP*18); |
| 917 | if (ptr == NULL) |
| 918 | return ptr; |
| 919 | len = sprintf(ptr+cnt, "%s", n); |
| 920 | once++; |
| 921 | } else |
| 922 | len = sprintf(ptr+cnt, ", %s", n); |
| 923 | if (len > 0) |
| 924 | cnt+=len; |
| 925 | } |
| 926 | } |
| 927 | } |
| 928 | if (once == 0) { |
| 929 | if (where == CAPNG_PRINT_STDOUT) |
| 930 | printf("none"); |
| 931 | else |
| 932 | ptr = strdup("none"); |
| 933 | } |
| 934 | return ptr; |
| 935 | } |
| 936 | |
| 937 | void *capng_save_state(void) |
| 938 | { |
| 939 | void *ptr = malloc(sizeof(m)); |
| 940 | if (ptr) |
| 941 | memcpy(ptr, &m, sizeof(m)); |
| 942 | return ptr; |
| 943 | } |
| 944 | |
| 945 | void capng_restore_state(void **state) |
| 946 | { |
| 947 | if (state) { |
| 948 | void *ptr = *state; |
| 949 | if (ptr) |
| 950 | memcpy(&m, ptr, sizeof(m)); |
| 951 | free(ptr); |
| 952 | *state = NULL; |
| 953 | } |
| 954 | } |
| 955 | |