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 /* Useful macros */
  90 /* Maximum number for 64 bit integer is a string with 21 digits: 2^64 - 1 = 21 */
  91 #define LXC_NUMSTRLEN64 21
  92 #define LXC_LINELEN 4096
  93 #define LXC_IDMAPLEN 4096
  94
  95 /* returns 1 on success, 0 if there were any failures */
  96 extern int lxc_rmdir_onedev(char *path, const char *exclude);
  97 extern int get_u16(unsigned short *val, const char *arg, int base);
  98 extern int mkdir_p(const char *dir, mode_t mode);
  99 extern char *get_rundir(void);
 100
 101 /* Define getline() if missing from the C library */
 102 #ifndef HAVE_GETLINE
 103 #ifdef HAVE_FGETLN
 104 #include <../include/getline.h>
 105 #endif
 106 #endif
 107
 108 /* Define setns() if missing from the C library */
 109 #ifndef HAVE_SETNS
 110 static inline int setns(int fd, int nstype)
 111 {
 112 #ifdef __NR_setns
 113         return syscall(__NR_setns, fd, nstype);
 114 #elif defined(__NR_set_ns)
 115         return syscall(__NR_set_ns, fd, nstype);
 116 #else
 117         errno = ENOSYS;
 118         return -1;
 119 #endif
 120 }
 121 #endif
 122
 123 /* Define unshare() if missing from the C library */
 124 #ifndef HAVE_UNSHARE
 125 static inline int unshare(int flags)
 126 {
 127 #ifdef __NR_unshare
 128         return syscall(__NR_unshare, flags);
 129 #else
 130         errno = ENOSYS;
 131         return -1;
 132 #endif
 133 }
 134 #else
 135 extern int unshare(int);
 136 #endif
 137
 138 /* Define signalfd() if missing from the C library */
 139 #ifdef HAVE_SYS_SIGNALFD_H
 140 #  include <sys/signalfd.h>
 141 #else
 142 /* assume kernel headers are too old */
 143 #include <stdint.h>
 144 struct signalfd_siginfo
 145 {
 146         uint32_t ssi_signo;
 147         int32_t ssi_errno;
 148         int32_t ssi_code;
 149         uint32_t ssi_pid;
 150         uint32_t ssi_uid;
 151         int32_t ssi_fd;
 152         uint32_t ssi_tid;
 153         uint32_t ssi_band;
 154         uint32_t ssi_overrun;
 155         uint32_t ssi_trapno;
 156         int32_t ssi_status;
 157         int32_t ssi_int;
 158         uint64_t ssi_ptr;
 159         uint64_t ssi_utime;
 160         uint64_t ssi_stime;
 161         uint64_t ssi_addr;
 162         uint8_t __pad[48];
 163 };
 164
 165 #  ifndef __NR_signalfd4
 166 /* assume kernel headers are too old */
 167 #    if __i386__
 168 #      define __NR_signalfd4 327
 169 #    elif __x86_64__
 170 #      define __NR_signalfd4 289
 171 #    elif __powerpc__
 172 #      define __NR_signalfd4 313
 173 #    elif __s390x__
 174 #      define __NR_signalfd4 322
 175 #    elif __arm__
 176 #      define __NR_signalfd4 355
 177 #    elif __mips__ && _MIPS_SIM == _ABIO32
 178 #      define __NR_signalfd4 4324
 179 #    elif __mips__ && _MIPS_SIM == _ABI64
 180 #      define __NR_signalfd4 5283
 181 #    elif __mips__ && _MIPS_SIM == _ABIN32
 182 #      define __NR_signalfd4 6287
 183 #    endif
 184 #endif
 185
 186 #  ifndef __NR_signalfd
 187 /* assume kernel headers are too old */
 188 #    if __i386__
 189 #      define __NR_signalfd 321
 190 #    elif __x86_64__
 191 #      define __NR_signalfd 282
 192 #    elif __powerpc__
 193 #      define __NR_signalfd 305
 194 #    elif __s390x__
 195 #      define __NR_signalfd 316
 196 #    elif __arm__
 197 #      define __NR_signalfd 349
 198 #    elif __mips__ && _MIPS_SIM == _ABIO32
 199 #      define __NR_signalfd 4317
 200 #    elif __mips__ && _MIPS_SIM == _ABI64
 201 #      define __NR_signalfd 5276
 202 #    elif __mips__ && _MIPS_SIM == _ABIN32
 203 #      define __NR_signalfd 6280
 204 #    endif
 205 #endif
 206
 207 static inline int signalfd(int fd, const sigset_t *mask, int flags)
 208 {
 209         int retval;
 210
 211         retval = syscall (__NR_signalfd4, fd, mask, _NSIG / 8, flags);
 212         if (errno == ENOSYS && flags == 0)
 213                 retval = syscall (__NR_signalfd, fd, mask, _NSIG / 8);
 214         return retval;
 215 }
 216 #endif
 217
 218 /* loop devices */
 219 #ifndef LO_FLAGS_AUTOCLEAR
 220 #define LO_FLAGS_AUTOCLEAR 4
 221 #endif
 222
 223 #ifndef LOOP_CTL_GET_FREE
 224 #define LOOP_CTL_GET_FREE 0x4C82
 225 #endif
 226
 227 /* memfd_create() */
 228 #ifndef MFD_CLOEXEC
 229 #define MFD_CLOEXEC 0x0001U
 230 #endif
 231
 232 #ifndef MFD_ALLOW_SEALING
 233 #define MFD_ALLOW_SEALING 0x0002U
 234 #endif
 235
 236 #ifndef HAVE_MEMFD_CREATE
 237 static inline int memfd_create(const char *name, unsigned int flags) {
 238         #ifndef __NR_memfd_create
 239                 #if defined __i386__
 240                         #define __NR_memfd_create 356
 241                 #elif defined __x86_64__
 242                         #define __NR_memfd_create 319
 243                 #elif defined __arm__
 244                         #define __NR_memfd_create 385
 245                 #elif defined __aarch64__
 246                         #define __NR_memfd_create 279
 247                 #elif defined __s390__
 248                         #define __NR_memfd_create 350
 249                 #elif defined __powerpc__
 250                         #define __NR_memfd_create 360
 251                 #elif defined __sparc__
 252                         #define __NR_memfd_create 348
 253                 #elif defined __blackfin__
 254                         #define __NR_memfd_create 390
 255                 #elif defined __ia64__
 256                         #define __NR_memfd_create 1340
 257                 #elif defined _MIPS_SIM
 258                         #if _MIPS_SIM == _MIPS_SIM_ABI32
 259                                 #define __NR_memfd_create 4354
 260                         #endif
 261                         #if _MIPS_SIM == _MIPS_SIM_NABI32
 262                                 #define __NR_memfd_create 6318
 263                         #endif
 264                         #if _MIPS_SIM == _MIPS_SIM_ABI64
 265                                 #define __NR_memfd_create 5314
 266                         #endif
 267                 #endif
 268         #endif
 269         #ifdef __NR_memfd_create
 270         return syscall(__NR_memfd_create, name, flags);
 271         #else
 272         errno = ENOSYS;
 273         return -1;
 274         #endif
 275 }
 276 #else
 277 extern int memfd_create(const char *name, unsigned int flags);
 278 #endif
 279
 280 static inline int lxc_set_cloexec(int fd)
 281 {
 282         return fcntl(fd, F_SETFD, FD_CLOEXEC);
 283 }
 284
 285 /* Struct to carry child pid from lxc_popen() to lxc_pclose().
 286  * Not an opaque struct to allow direct access to the underlying FILE *
 287  * (i.e., struct lxc_popen_FILE *file; fgets(buf, sizeof(buf), file->f))
 288  * without additional wrappers.
 289  */
 290 struct lxc_popen_FILE {
 291         int pipe;
 292         FILE *f;
 293         pid_t child_pid;
 294 };
 295
 296 /* popen(command, "re") replacement that restores default signal mask
 297  * via sigprocmask(2) (unblocks all signals) after fork(2) but prior to calling exec(3).
 298  * In short, popen(command, "re") does pipe() + fork()                 + exec()
 299  * while lxc_popen(command)       does pipe() + fork() + sigprocmask() + exec().
 300  * Returns pointer to struct lxc_popen_FILE, that should be freed with lxc_pclose().
 301  * On error returns NULL.
 302  */
 303 extern struct lxc_popen_FILE *lxc_popen(const char *command);
 304
 305 /* pclose() replacement to be used on struct lxc_popen_FILE *,
 306  * returned by lxc_popen().
 307  * Waits for associated process to terminate, returns its exit status and
 308  * frees resources, pointed to by struct lxc_popen_FILE *.
 309  */
 310 extern int lxc_pclose(struct lxc_popen_FILE *fp);
 311
 312 /**
 313  * BUILD_BUG_ON - break compile if a condition is true.
 314  * @condition: the condition which the compiler should know is false.
 315  *
 316  * If you have some code which relies on certain constants being equal, or
 317  * other compile-time-evaluated condition, you should use BUILD_BUG_ON to
 318  * detect if someone changes it.
 319  *
 320  * The implementation uses gcc's reluctance to create a negative array, but
 321  * gcc (as of 4.4) only emits that error for obvious cases (eg. not arguments
 322  * to inline functions).  So as a fallback we use the optimizer; if it can't
 323  * prove the condition is false, it will cause a link error on the undefined
 324  * "__build_bug_on_failed".  This error message can be harder to track down
 325  * though, hence the two different methods.
 326  */
 327 #ifndef __OPTIMIZE__
 328 #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
 329 #else
 330 extern int __build_bug_on_failed;
 331 #define BUILD_BUG_ON(condition)                                 \
 332         do {                                                    \
 333                 ((void)sizeof(char[1 - 2*!!(condition)]));      \
 334                 if (condition) __build_bug_on_failed = 1;       \
 335         } while(0)
 336 #endif
 337
 338 /*
 339  * wait on a child we forked
 340  */
 341 extern int wait_for_pid(pid_t pid);
 342 extern int lxc_wait_for_pid_status(pid_t pid);
 343
 344 /* send and receive buffers completely */
 345 extern ssize_t lxc_write_nointr(int fd, const void* buf, size_t count);
 346 extern ssize_t lxc_read_nointr(int fd, void* buf, size_t count);
 347 extern ssize_t lxc_read_nointr_expect(int fd, void *buf, size_t count,
 348                                       const void *expected_buf);
 349 #if HAVE_LIBGNUTLS
 350 #define SHA_DIGEST_LENGTH 20
 351 extern int sha1sum_file(char *fnam, unsigned char *md_value);
 352 #endif
 353
 354 /* read and write whole files */
 355 extern int lxc_write_to_file(const char *filename, const void *buf,
 356                              size_t count, bool add_newline);
 357 extern int lxc_read_from_file(const char *filename, void* buf, size_t count);
 358
 359 /* convert variadic argument lists to arrays (for execl type argument lists) */
 360 extern char** lxc_va_arg_list_to_argv(va_list ap, size_t skip, int do_strdup);
 361 extern const char** lxc_va_arg_list_to_argv_const(va_list ap, size_t skip);
 362
 363 /* Some simple string functions; if they return pointers, they are allocated
 364  * buffers.
 365  */
 366 extern char *lxc_string_replace(const char *needle, const char *replacement,
 367                                 const char *haystack);
 368 extern bool lxc_string_in_array(const char *needle, const char **haystack);
 369 extern char *lxc_string_join(const char *sep, const char **parts,
 370                              bool use_as_prefix);
 371 /* Normalize and split path: Leading and trailing / are removed, multiple
 372  * / are compactified, .. and . are resolved (.. on the top level is considered
 373  * identical to .).
 374  * Examples:
 375  *     /            ->   { NULL }
 376  *     foo/../bar   ->   { bar, NULL }
 377  *     ../../       ->   { NULL }
 378  *     ./bar/baz/.. ->   { bar, NULL }
 379  *     foo//bar     ->   { foo, bar, NULL }
 380  */
 381 extern char **lxc_normalize_path(const char *path);
 382 /* remove multiple slashes from the path, e.g. ///foo//bar -> /foo/bar */
 383 extern char *lxc_deslashify(const char *path);
 384 extern char *lxc_append_paths(const char *first, const char *second);
 385 /* Note: the following two functions use strtok(), so they will never
 386  *       consider an empty element, even if two delimiters are next to
 387  *       each other.
 388  */
 389 extern bool lxc_string_in_list(const char *needle, const char *haystack,
 390                                char sep);
 391 extern char **lxc_string_split(const char *string, char sep);
 392 extern char **lxc_string_split_and_trim(const char *string, char sep);
 393 extern char **lxc_string_split_quoted(char *string);
 394 /* Append string to NULL-terminated string array. */
 395 extern int lxc_append_string(char ***list, char *entry);
 396
 397 /* some simple array manipulation utilities */
 398 typedef void (*lxc_free_fn)(void *);
 399 typedef void *(*lxc_dup_fn)(void *);
 400 extern int lxc_grow_array(void ***array, size_t *capacity, size_t new_size,
 401                           size_t capacity_increment);
 402 extern void lxc_free_array(void **array, lxc_free_fn element_free_fn);
 403 extern size_t lxc_array_len(void **array);
 404
 405 extern void **lxc_append_null_to_array(void **array, size_t count);
 406
 407 /* mmap() wrapper. lxc_strmmap() will take care to \0-terminate files so that
 408  * normal string-handling functions can be used on the buffer. */
 409 extern void *lxc_strmmap(void *addr, size_t length, int prot, int flags, int fd,
 410                          off_t offset);
 411 /* munmap() wrapper. Use it to free memory mmap()ed with lxc_strmmap(). */
 412 extern int lxc_strmunmap(void *addr, size_t length);
 413
 414 /* initialize rand with urandom */
 415 extern int randseed(bool);
 416
 417 inline static bool am_unpriv(void) {
 418         return geteuid() != 0;
 419 }
 420
 421 /*
 422  * parse /proc/self/uid_map to find what @orig maps to
 423  */
 424 extern uid_t get_ns_uid(uid_t orig);
 425
 426 extern bool dir_exists(const char *path);
 427
 428 #define FNV1A_64_INIT ((uint64_t)0xcbf29ce484222325ULL)
 429 extern uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval);
 430
 431 extern int detect_shared_rootfs(void);
 432 extern bool detect_ramfs_rootfs(void);
 433 extern char *on_path(const char *cmd, const char *rootfs);
 434 extern bool file_exists(const char *f);
 435 extern bool cgns_supported(void);
 436 extern char *choose_init(const char *rootfs);
 437 extern int print_to_file(const char *file, const char *content);
 438 extern bool switch_to_ns(pid_t pid, const char *ns);
 439 extern int is_dir(const char *path);
 440 extern char *get_template_path(const char *t);
 441 extern int safe_mount(const char *src, const char *dest, const char *fstype,
 442                       unsigned long flags, const void *data,
 443                       const char *rootfs);
 444 extern int lxc_mount_proc_if_needed(const char *rootfs);
 445 extern int open_devnull(void);
 446 extern int set_stdfds(int fd);
 447 extern int null_stdfds(void);
 448 extern int lxc_count_file_lines(const char *fn);
 449 extern int lxc_preserve_ns(const int pid, const char *ns);
 450
 451 /* Check whether a signal is blocked by a process. */
 452 extern bool task_blocking_signal(pid_t pid, int signal);
 453
 454 /* Helper functions to parse numbers. */
 455 extern int lxc_safe_uint(const char *numstr, unsigned int *converted);
 456 extern int lxc_safe_int(const char *numstr, int *converted);
 457 extern int lxc_safe_long(const char *numstr, long int *converted);
 458 extern int lxc_safe_long_long(const char *numstr, long long int *converted);
 459 extern int lxc_safe_ulong(const char *numstr, unsigned long *converted);
 460 /* Handles B, kb, MB, GB. Detects overflows and reports -ERANGE. */
 461 extern int parse_byte_size_string(const char *s, int64_t *converted);
 462
 463 /* Switch to a new uid and gid. */
 464 extern int lxc_switch_uid_gid(uid_t uid, gid_t gid);
 465 extern int lxc_setgroups(int size, gid_t list[]);
 466
 467 /* Find an unused loop device and associate it with source. */
 468 extern int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags);
 469
 470 /* Clear all mounts on a given node.
 471  * >= 0 successfully cleared. The number returned is the number of umounts
 472  *      performed.
 473  * < 0  error umounting. Return -errno.
 474  */
 475 extern int lxc_unstack_mountpoint(const char *path, bool lazy);
 476
 477 /*
 478  * run_command runs a command and collect it's std{err,out} output in buf.
 479  *
 480  * @param[out] buf     The buffer where the commands std{err,out] output will be
 481  *                     read into. If no output was produced, buf will be memset
 482  *                     to 0.
 483  * @param[in] buf_size The size of buf. This function will reserve one byte for
 484  *                     \0-termination.
 485  * @param[in] child_fn The function to be run in the child process. This
 486  *                     function must exec.
 487  * @param[in] args     Arguments to be passed to child_fn.
 488  */
 489 extern int run_command(char *buf, size_t buf_size, int (*child_fn)(void *),
 490                        void *args);
 491
 492 /* Concatenate all passed-in strings into one path. Do not fail. If any piece
 493  * is not prefixed with '/', add a '/'.
 494  */
 495 extern char *must_make_path(const char *first, ...) __attribute__((sentinel));
 496
 497 /* return copy of string @entry;  do not fail. */
 498 extern char *must_copy_string(const char *entry);
 499
 500 /* Re-alllocate a pointer, do not fail */
 501 extern void *must_realloc(void *orig, size_t sz);
 502
 503 /* __typeof__ should be safe to use with all compilers. */
 504 typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
 505 extern bool has_fs_type(const char *path, fs_type_magic magic_val);
 506 extern bool is_fs_type(const struct statfs *fs, fs_type_magic magic_val);
 507 extern bool lxc_nic_exists(char *nic);
 508 extern int lxc_make_tmpfile(char *template, bool rm);
 509 extern uint64_t lxc_getpagesize(void);
 510
 511 /* If n is not a power of 2 this function will return the next power of 2
 512  * greater than that number. Note that this function always returns the *next*
 513  * power of 2 *greater* that number not the *nearest*. For example, passing 1025
 514  * as argument this function will return 2048 although the closest power of 2
 515  * would be 1024.
 516  * If the caller passes in 0 they will receive 0 in return since this is invalid
 517  * input and 0 is not a power of 2.
 518  */
 519 extern uint64_t lxc_find_next_power2(uint64_t n);
 520
 521 #endif /* __LXC_UTILS_H */