src/lxc/utils.h

   1 /*
   2  * lxc: linux Container library
   3  *
   4  * (C) Copyright IBM Corp. 2007, 2008
   5  *
   6  * Authors:
   7  * Daniel Lezcano <daniel.lezcano at free.fr>
   8  *
   9  * This library is free software; you can redistribute it and/or
  10  * modify it under the terms of the GNU Lesser General Public
  11  * License as published by the Free Software Foundation; either
  12  * version 2.1 of the License, or (at your option) any later version.
  13  *
  14  * This library is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  17  * Lesser General Public License for more details.
  18  *
  19  * You should have received a copy of the GNU Lesser General Public
  20  * License along with this library; if not, write to the Free Software
  21  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  22  */
  23 #ifndef __LXC_UTILS_H
  24 #define __LXC_UTILS_H
  25
  26 /* Properly support loop devices on 32bit systems. */
  27 #define _FILE_OFFSET_BITS 64
  28
  29 #include "config.h"
  30
  31 #include <errno.h>
  32 #include <stdarg.h>
  33 #include <stdio.h>
  34 #include <stdbool.h>
  35 #include <unistd.h>
  36 #include <linux/loop.h>
  37 #include <linux/magic.h>
  38 #include <sys/syscall.h>
  39 #include <sys/types.h>
  40 #include <sys/vfs.h>
  41
  42 #ifdef HAVE_LINUX_MEMFD_H
  43 #include <linux/memfd.h>
  44 #endif
  45
  46 #include "initutils.h"
  47
  48 /* Define __S_ISTYPE if missing from the C library. */
  49 #ifndef __S_ISTYPE
  50 #define __S_ISTYPE(mode, mask) (((mode)&S_IFMT) == (mask))
  51 #endif
  52
  53 #if HAVE_LIBCAP
  54 #ifndef CAP_SETFCAP
  55 #define CAP_SETFCAP 31
  56 #endif
  57
  58 #ifndef CAP_MAC_OVERRIDE
  59 #define CAP_MAC_OVERRIDE 32
  60 #endif
  61
  62 #ifndef CAP_MAC_ADMIN
  63 #define CAP_MAC_ADMIN 33
  64 #endif
  65 #endif
  66
  67 #ifndef PR_CAPBSET_DROP
  68 #define PR_CAPBSET_DROP 24
  69 #endif
  70
  71 #ifndef LO_FLAGS_AUTOCLEAR
  72 #define LO_FLAGS_AUTOCLEAR 4
  73 #endif
  74
  75 #ifndef CAP_SETUID
  76 #define CAP_SETUID 7
  77 #endif
  78
  79 #ifndef CAP_SETGID
  80 #define CAP_SETGID 6
  81 #endif
  82
  83 /* needed for cgroup automount checks, regardless of whether we
  84  * have included linux/capability.h or not */
  85 #ifndef CAP_SYS_ADMIN
  86 #define CAP_SYS_ADMIN 21
  87 #endif
  88
  89 #ifndef CGROUP_SUPER_MAGIC
  90 #define CGROUP_SUPER_MAGIC 0x27e0eb
  91 #endif
  92
  93 #ifndef CGROUP2_SUPER_MAGIC
  94 #define CGROUP2_SUPER_MAGIC 0x63677270
  95 #endif
  96
  97 /* Useful macros */
  98 /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
  99 #define LXC_NUMSTRLEN64 21
 100 #define LXC_LINELEN 4096
 101 #define LXC_IDMAPLEN 4096
 102
 103 /* returns 1 on success, 0 if there were any failures */
 104 extern int lxc_rmdir_onedev(const char *path, const char *exclude);
 105 extern int get_u16(unsigned short *val, const char *arg, int base);
 106 extern int mkdir_p(const char *dir, mode_t mode);
 107 extern char *get_rundir(void);
 108
 109 /* Define getline() if missing from the C library */
 110 #ifndef HAVE_GETLINE
 111 #ifdef HAVE_FGETLN
 112 #include <../include/getline.h>
 113 #endif
 114 #endif
 115
 116 /* Define setns() if missing from the C library */
 117 #ifndef HAVE_SETNS
 118 static inline int setns(int fd, int nstype)
 119 {
 120 #ifdef __NR_setns
 121         return syscall(__NR_setns, fd, nstype);
 122 #elif defined(__NR_set_ns)
 123         return syscall(__NR_set_ns, fd, nstype);
 124 #else
 125         errno = ENOSYS;
 126         return -1;
 127 #endif
 128 }
 129 #endif
 130
 131 /* Define sethostname() if missing from the C library */
 132 #ifndef HAVE_SETHOSTNAME
 133 static inline int sethostname(const char * name, size_t len)
 134 {
 135 #ifdef __NR_sethostname
 136 return syscall(__NR_sethostname, name, len);
 137 #else
 138 errno = ENOSYS;
 139 return -1;
 140 #endif
 141 }
 142 #endif
 143
 144 /* Define unshare() if missing from the C library */
 145 #ifndef HAVE_UNSHARE
 146 static inline int unshare(int flags)
 147 {
 148 #ifdef __NR_unshare
 149         return syscall(__NR_unshare, flags);
 150 #else
 151         errno = ENOSYS;
 152         return -1;
 153 #endif
 154 }
 155 #else
 156 extern int unshare(int);
 157 #endif
 158
 159 /* Define signalfd() if missing from the C library */
 160 #ifdef HAVE_SYS_SIGNALFD_H
 161 #  include <sys/signalfd.h>
 162 #else
 163 /* assume kernel headers are too old */
 164 #include <stdint.h>
 165 struct signalfd_siginfo
 166 {
 167         uint32_t ssi_signo;
 168         int32_t ssi_errno;
 169         int32_t ssi_code;
 170         uint32_t ssi_pid;
 171         uint32_t ssi_uid;
 172         int32_t ssi_fd;
 173         uint32_t ssi_tid;
 174         uint32_t ssi_band;
 175         uint32_t ssi_overrun;
 176         uint32_t ssi_trapno;
 177         int32_t ssi_status;
 178         int32_t ssi_int;
 179         uint64_t ssi_ptr;
 180         uint64_t ssi_utime;
 181         uint64_t ssi_stime;
 182         uint64_t ssi_addr;
 183         uint8_t __pad[48];
 184 };
 185
 186 #  ifndef __NR_signalfd4
 187 /* assume kernel headers are too old */
 188 #    if __i386__
 189 #      define __NR_signalfd4 327
 190 #    elif __x86_64__
 191 #      define __NR_signalfd4 289
 192 #    elif __powerpc__
 193 #      define __NR_signalfd4 313
 194 #    elif __s390x__
 195 #      define __NR_signalfd4 322
 196 #    elif __arm__
 197 #      define __NR_signalfd4 355
 198 #    elif __mips__ && _MIPS_SIM == _ABIO32
 199 #      define __NR_signalfd4 4324
 200 #    elif __mips__ && _MIPS_SIM == _ABI64
 201 #      define __NR_signalfd4 5283
 202 #    elif __mips__ && _MIPS_SIM == _ABIN32
 203 #      define __NR_signalfd4 6287
 204 #    endif
 205 #endif
 206
 207 #  ifndef __NR_signalfd
 208 /* assume kernel headers are too old */
 209 #    if __i386__
 210 #      define __NR_signalfd 321
 211 #    elif __x86_64__
 212 #      define __NR_signalfd 282
 213 #    elif __powerpc__
 214 #      define __NR_signalfd 305
 215 #    elif __s390x__
 216 #      define __NR_signalfd 316
 217 #    elif __arm__
 218 #      define __NR_signalfd 349
 219 #    elif __mips__ && _MIPS_SIM == _ABIO32
 220 #      define __NR_signalfd 4317
 221 #    elif __mips__ && _MIPS_SIM == _ABI64
 222 #      define __NR_signalfd 5276
 223 #    elif __mips__ && _MIPS_SIM == _ABIN32
 224 #      define __NR_signalfd 6280
 225 #    endif
 226 #endif
 227
 228 static inline int signalfd(int fd, const sigset_t *mask, int flags)
 229 {
 230         int retval;
 231
 232         retval = syscall (__NR_signalfd4, fd, mask, _NSIG / 8, flags);
 233         if (errno == ENOSYS && flags == 0)
 234                 retval = syscall (__NR_signalfd, fd, mask, _NSIG / 8);
 235         return retval;
 236 }
 237 #endif
 238
 239 /* loop devices */
 240 #ifndef LO_FLAGS_AUTOCLEAR
 241 #define LO_FLAGS_AUTOCLEAR 4
 242 #endif
 243
 244 #ifndef LOOP_CTL_GET_FREE
 245 #define LOOP_CTL_GET_FREE 0x4C82
 246 #endif
 247
 248 /* memfd_create() */
 249 #ifndef MFD_CLOEXEC
 250 #define MFD_CLOEXEC 0x0001U
 251 #endif
 252
 253 #ifndef MFD_ALLOW_SEALING
 254 #define MFD_ALLOW_SEALING 0x0002U
 255 #endif
 256
 257 #ifndef HAVE_MEMFD_CREATE
 258 static inline int memfd_create(const char *name, unsigned int flags) {
 259         #ifndef __NR_memfd_create
 260                 #if defined __i386__
 261                         #define __NR_memfd_create 356
 262                 #elif defined __x86_64__
 263                         #define __NR_memfd_create 319
 264                 #elif defined __arm__
 265                         #define __NR_memfd_create 385
 266                 #elif defined __aarch64__
 267                         #define __NR_memfd_create 279
 268                 #elif defined __s390__
 269                         #define __NR_memfd_create 350
 270                 #elif defined __powerpc__
 271                         #define __NR_memfd_create 360
 272                 #elif defined __sparc__
 273                         #define __NR_memfd_create 348
 274                 #elif defined __blackfin__
 275                         #define __NR_memfd_create 390
 276                 #elif defined __ia64__
 277                         #define __NR_memfd_create 1340
 278                 #elif defined _MIPS_SIM
 279                         #if _MIPS_SIM == _MIPS_SIM_ABI32
 280                                 #define __NR_memfd_create 4354
 281                         #endif
 282                         #if _MIPS_SIM == _MIPS_SIM_NABI32
 283                                 #define __NR_memfd_create 6318
 284                         #endif
 285                         #if _MIPS_SIM == _MIPS_SIM_ABI64
 286                                 #define __NR_memfd_create 5314
 287                         #endif
 288                 #endif
 289         #endif
 290         #ifdef __NR_memfd_create
 291         return syscall(__NR_memfd_create, name, flags);
 292         #else
 293         errno = ENOSYS;
 294         return -1;
 295         #endif
 296 }
 297 #else
 298 extern int memfd_create(const char *name, unsigned int flags);
 299 #endif
 300
 301 static inline int lxc_set_cloexec(int fd)
 302 {
 303         return fcntl(fd, F_SETFD, FD_CLOEXEC);
 304 }
 305
 306 /* Struct to carry child pid from lxc_popen() to lxc_pclose().
 307  * Not an opaque struct to allow direct access to the underlying FILE *
 308  * (i.e., struct lxc_popen_FILE *file; fgets(buf, sizeof(buf), file->f))
 309  * without additional wrappers.
 310  */
 311 struct lxc_popen_FILE {
 312         int pipe;
 313         FILE *f;
 314         pid_t child_pid;
 315 };
 316
 317 /* popen(command, "re") replacement that restores default signal mask
 318  * via sigprocmask(2) (unblocks all signals) after fork(2) but prior to calling exec(3).
 319  * In short, popen(command, "re") does pipe() + fork()                 + exec()
 320  * while lxc_popen(command)       does pipe() + fork() + sigprocmask() + exec().
 321  * Returns pointer to struct lxc_popen_FILE, that should be freed with lxc_pclose().
 322  * On error returns NULL.
 323  */
 324 extern struct lxc_popen_FILE *lxc_popen(const char *command);
 325
 326 /* pclose() replacement to be used on struct lxc_popen_FILE *,
 327  * returned by lxc_popen().
 328  * Waits for associated process to terminate, returns its exit status and
 329  * frees resources, pointed to by struct lxc_popen_FILE *.
 330  */
 331 extern int lxc_pclose(struct lxc_popen_FILE *fp);
 332
 333 /**
 334  * BUILD_BUG_ON - break compile if a condition is true.
 335  * @condition: the condition which the compiler should know is false.
 336  *
 337  * If you have some code which relies on certain constants being equal, or
 338  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
 339  * detect if someone changes it.
 340  *
 341  * The implementation uses gcc's reluctance to create a negative array, but
 342  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
 343  * to inline functions).  So as a fallback we use the optimizer; if it can't
 344  * prove the condition is false, it will cause a link error on the undefined
 345  * "__build_bug_on_failed".  This error message can be harder to track down
 346  * though, hence the two different methods.
 347  */
 348 #ifndef __OPTIMIZE__
 349 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 350 #else
 351 extern int __build_bug_on_failed;
 352 #define BUILD_BUG_ON(condition)                                 \
 353         do {                                                    \
 354                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
 355                 if (condition) __build_bug_on_failed = 1;       \
 356         } while(0)
 357 #endif
 358
 359 /*
 360  * wait on a child we forked
 361  */
 362 extern int wait_for_pid(pid_t pid);
 363 extern int lxc_wait_for_pid_status(pid_t pid);
 364
 365 /* send and receive buffers completely */
 366 extern ssize_t lxc_write_nointr(int fd, const void* buf, size_t count);
 367 extern ssize_t lxc_read_nointr(int fd, void* buf, size_t count);
 368 extern ssize_t lxc_read_nointr_expect(int fd, void *buf, size_t count,
 369                                       const void *expected_buf);
 370 #if HAVE_LIBGNUTLS
 371 #define SHA_DIGEST_LENGTH 20
 372 extern int sha1sum_file(char *fnam, unsigned char *md_value);
 373 #endif
 374
 375 /* read and write whole files */
 376 extern int lxc_write_to_file(const char *filename, const void *buf,
 377                              size_t count, bool add_newline);
 378 extern int lxc_read_from_file(const char *filename, void* buf, size_t count);
 379
 380 /* convert variadic argument lists to arrays (for execl type argument lists) */
 381 extern char** lxc_va_arg_list_to_argv(va_list ap, size_t skip, int do_strdup);
 382 extern const char** lxc_va_arg_list_to_argv_const(va_list ap, size_t skip);
 383
 384 /* Some simple string functions; if they return pointers, they are allocated
 385  * buffers.
 386  */
 387 extern char *lxc_string_replace(const char *needle, const char *replacement,
 388                                 const char *haystack);
 389 extern bool lxc_string_in_array(const char *needle, const char **haystack);
 390 extern char *lxc_string_join(const char *sep, const char **parts,
 391                              bool use_as_prefix);
 392 /* Normalize and split path: Leading and trailing / are removed, multiple
 393  * / are compactified, .. and . are resolved (.. on the top level is considered
 394  * identical to .).
 395  * Examples:
 396  *     /            ->   { NULL }
 397  *     foo/../bar   ->   { bar, NULL }
 398  *     ../../       ->   { NULL }
 399  *     ./bar/baz/.. ->   { bar, NULL }
 400  *     foo//bar     ->   { foo, bar, NULL }
 401  */
 402 extern char **lxc_normalize_path(const char *path);
 403 /* remove multiple slashes from the path, e.g. ///foo//bar -> /foo/bar */
 404 extern char *lxc_deslashify(const char *path);
 405 extern char *lxc_append_paths(const char *first, const char *second);
 406 /* Note: the following two functions use strtok(), so they will never
 407  *       consider an empty element, even if two delimiters are next to
 408  *       each other.
 409  */
 410 extern bool lxc_string_in_list(const char *needle, const char *haystack,
 411                                char sep);
 412 extern char **lxc_string_split(const char *string, char sep);
 413 extern char **lxc_string_split_and_trim(const char *string, char sep);
 414 extern char **lxc_string_split_quoted(char *string);
 415 /* Append string to NULL-terminated string array. */
 416 extern int lxc_append_string(char ***list, char *entry);
 417
 418 /* some simple array manipulation utilities */
 419 typedef void (*lxc_free_fn)(void *);
 420 typedef void *(*lxc_dup_fn)(void *);
 421 extern int lxc_grow_array(void ***array, size_t *capacity, size_t new_size,
 422                           size_t capacity_increment);
 423 extern void lxc_free_array(void **array, lxc_free_fn element_free_fn);
 424 extern size_t lxc_array_len(void **array);
 425
 426 extern void **lxc_append_null_to_array(void **array, size_t count);
 427
 428 /* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that
 429  * normal string-handling functions can be used on the buffer. */
 430 extern void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
 431                          off_t offset);
 432 /* munmap() wrapper. Use it to free memory mmap()ed with lxc_strmmap(). */
 433 extern int lxc_strmunmap(void *addr, size_t length);
 434
 435 /* initialize rand with urandom */
 436 extern int randseed(bool);
 437
 438 /* are we unprivileged with respect to our namespaces */
 439 inline static bool am_guest_unpriv(void) {
 440         return geteuid() != 0;
 441 }
 442
 443 /* are we unprivileged with respect to init_user_ns */
 444 inline static bool am_host_unpriv(void)
 445 {
 446         FILE *f;
 447         uid_t user, host, count;
 448         int ret;
 449
 450         if (geteuid() != 0)
 451                 return true;
 452
 453         /* Now: are we in a user namespace? Because then we're also
 454          * unprivileged.
 455          */
 456         f = fopen("/proc/self/uid_map", "r");
 457         if (!f) {
 458                 return false;
 459         }
 460
 461         ret = fscanf(f, "%u %u %u", &user, &host, &count);
 462         fclose(f);
 463         if (ret != 3) {
 464                 return false;
 465         }
 466
 467         if (user != 0 || host != 0 || count != UINT32_MAX)
 468                 return true;
 469         return false;
 470 }
 471
 472 /*
 473  * parse /proc/self/uid_map to find what @orig maps to
 474  */
 475 extern uid_t get_ns_uid(uid_t orig);
 476
 477 extern bool dir_exists(const char *path);
 478
 479 #define FNV1A_64_INIT ((uint64_t)0xcbf29ce484222325ULL)
 480 extern uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval);
 481
 482 extern int detect_shared_rootfs(void);
 483 extern bool detect_ramfs_rootfs(void);
 484 extern char *on_path(const char *cmd, const char *rootfs);
 485 extern bool file_exists(const char *f);
 486 extern bool cgns_supported(void);
 487 extern char *choose_init(const char *rootfs);
 488 extern int print_to_file(const char *file, const char *content);
 489 extern bool switch_to_ns(pid_t pid, const char *ns);
 490 extern int is_dir(const char *path);
 491 extern char *get_template_path(const char *t);
 492 extern int safe_mount(const char *src, const char *dest, const char *fstype,
 493                       unsigned long flags, const void *data,
 494                       const char *rootfs);
 495 extern int lxc_mount_proc_if_needed(const char *rootfs);
 496 extern int open_devnull(void);
 497 extern int set_stdfds(int fd);
 498 extern int null_stdfds(void);
 499 extern int lxc_count_file_lines(const char *fn);
 500 extern int lxc_preserve_ns(const int pid, const char *ns);
 501
 502 /* Check whether a signal is blocked by a process. */
 503 extern bool task_blocking_signal(pid_t pid, int signal);
 504
 505 /* Helper functions to parse numbers. */
 506 extern int lxc_safe_uint(const char *numstr, unsigned int *converted);
 507 extern int lxc_safe_int(const char *numstr, int *converted);
 508 extern int lxc_safe_long(const char *numstr, long int *converted);
 509 extern int lxc_safe_long_long(const char *numstr, long long int *converted);
 510 extern int lxc_safe_ulong(const char *numstr, unsigned long *converted);
 511 /* Handles B, kb, MB, GB. Detects overflows and reports -ERANGE. */
 512 extern int parse_byte_size_string(const char *s, int64_t *converted);
 513
 514 /* Switch to a new uid and gid. */
 515 extern int lxc_switch_uid_gid(uid_t uid, gid_t gid);
 516 extern int lxc_setgroups(int size, gid_t list[]);
 517
 518 /* Find an unused loop device and associate it with source. */
 519 extern int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags);
 520
 521 /* Clear all mounts on a given node.
 522  * >= 0 successfully cleared. The number returned is the number of umounts
 523  *      performed.
 524  * < 0  error umounting. Return -errno.
 525  */
 526 extern int lxc_unstack_mountpoint(const char *path, bool lazy);
 527
 528 /*
 529  * run_command runs a command and collect it's std{err,out} output in buf.
 530  *
 531  * @param[out] buf     The buffer where the commands std{err,out] output will be
 532  *                     read into. If no output was produced, buf will be memset
 533  *                     to 0.
 534  * @param[in] buf_size The size of buf. This function will reserve one byte for
 535  *                     \0-termination.
 536  * @param[in] child_fn The function to be run in the child process. This
 537  *                     function must exec.
 538  * @param[in] args     Arguments to be passed to child_fn.
 539  */
 540 extern int run_command(char *buf, size_t buf_size, int (*child_fn)(void *),
 541                        void *args);
 542
 543 /* Concatenate all passed-in strings into one path. Do not fail. If any piece
 544  * is not prefixed with '/', add a '/'.
 545  */
 546 __attribute__((sentinel)) extern char *must_make_path(const char *first, ...);
 547 __attribute__((sentinel)) extern char *must_append_path(char *first, ...);
 548
 549 /* return copy of string @entry;  do not fail. */
 550 extern char *must_copy_string(const char *entry);
 551
 552 /* Re-alllocate a pointer, do not fail */
 553 extern void *must_realloc(void *orig, size_t sz);
 554
 555 /* __typeof__ should be safe to use with all compilers. */
 556 typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
 557 extern bool has_fs_type(const char *path, fs_type_magic magic_val);
 558 extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
 559 extern bool lxc_nic_exists(char *nic);
 560 extern int lxc_make_tmpfile(char *template, bool rm);
 561
 562 static inline uint64_t lxc_getpagesize(void)
 563 {
 564         int64_t pgsz;
 565
 566         pgsz = sysconf(_SC_PAGESIZE);
 567         if (pgsz <= 0)
 568                 pgsz = 1 << 12;
 569
 570         return pgsz;
 571 }
 572
 573 /* If n is not a power of 2 this function will return the next power of 2
 574  * greater than that number. Note that this function always returns the *next*
 575  * power of 2 *greater* that number not the *nearest*. For example, passing 1025
 576  * as argument this function will return 2048 although the closest power of 2
 577  * would be 1024.
 578  * If the caller passes in 0 they will receive 0 in return since this is invalid
 579  * input and 0 is not a power of 2.
 580  */
 581 extern uint64_t lxc_find_next_power2(uint64_t n);
 582
 583 static inline pid_t lxc_raw_gettid(void)
 584 {
 585 #ifdef SYS_gettid
 586         return syscall(SYS_gettid);
 587 #else
 588         return lxc_raw_getpid();
 589 #endif
 590 }
 591
 592 /* Set a signal the child process will receive after the parent has died. */
 593 extern int lxc_set_death_signal(int signal);
 594
 595 #endif /* __LXC_UTILS_H */