/* * lxc: linux Container library * * (C) Copyright IBM Corp. 2007, 2008 * * Authors: * Daniel Lezcano * * This library is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * This library is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with this library; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ #include "config.h" #define __STDC_FORMAT_MACROS /* Required for PRIu64 to work. */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "log.h" #include "lxclock.h" #include "namespace.h" #include "parse.h" #include "utils.h" #ifndef HAVE_STRLCPY #include "include/strlcpy.h" #endif #ifndef HAVE_STRLCAT #include "include/strlcat.h" #endif #ifndef O_PATH #define O_PATH 010000000 #endif #ifndef O_NOFOLLOW #define O_NOFOLLOW 00400000 #endif lxc_log_define(utils, lxc); /* * if path is btrfs, tries to remove it and any subvolumes beneath it */ extern bool btrfs_try_remove_subvol(const char *path); static int _recursive_rmdir(const char *dirname, dev_t pdev, const char *exclude, int level, bool onedev) { struct dirent *direntp; DIR *dir; int ret, failed=0; char pathname[MAXPATHLEN]; bool hadexclude = false; dir = opendir(dirname); if (!dir) { ERROR("failed to open %s", dirname); return -1; } while ((direntp = readdir(dir))) { struct stat mystat; int rc; if (!strcmp(direntp->d_name, ".") || !strcmp(direntp->d_name, "..")) continue; rc = snprintf(pathname, MAXPATHLEN, "%s/%s", dirname, direntp->d_name); if (rc < 0 || rc >= MAXPATHLEN) { ERROR("pathname too long"); failed=1; continue; } if (!level && exclude && !strcmp(direntp->d_name, exclude)) { ret = rmdir(pathname); if (ret < 0) { switch(errno) { case ENOTEMPTY: INFO("Not deleting snapshot %s", pathname); hadexclude = true; break; case ENOTDIR: ret = unlink(pathname); if (ret) INFO("Failed to remove %s", pathname); break; default: SYSERROR("Failed to rmdir %s", pathname); failed = 1; break; } } continue; } ret = lstat(pathname, &mystat); if (ret) { ERROR("Failed to stat %s", pathname); failed = 1; continue; } if (onedev && mystat.st_dev != pdev) { /* TODO should we be checking /proc/self/mountinfo for * pathname and not doing this if found? */ if (btrfs_try_remove_subvol(pathname)) INFO("Removed btrfs subvolume at %s\n", pathname); continue; } if (S_ISDIR(mystat.st_mode)) { if (_recursive_rmdir(pathname, pdev, exclude, level+1, onedev) < 0) failed=1; } else { if (unlink(pathname) < 0) { SYSERROR("Failed to delete %s", pathname); failed=1; } } } if (rmdir(dirname) < 0 && !btrfs_try_remove_subvol(dirname) && !hadexclude) { ERROR("Failed to delete %s", dirname); failed=1; } ret = closedir(dir); if (ret) { ERROR("Failed to close directory %s", dirname); failed=1; } return failed ? -1 : 0; } /* In overlayfs, st_dev is unreliable. So on overlayfs we don't do the * lxc_rmdir_onedev() */ static bool is_native_overlayfs(const char *path) { if (has_fs_type(path, OVERLAY_SUPER_MAGIC) || has_fs_type(path, OVERLAYFS_SUPER_MAGIC)) return true; return false; } /* returns 0 on success, -1 if there were any failures */ extern int lxc_rmdir_onedev(const char *path, const char *exclude) { struct stat mystat; bool onedev = true; if (is_native_overlayfs(path)) onedev = false; if (lstat(path, &mystat) < 0) { if (errno == ENOENT) return 0; ERROR("Failed to stat %s", path); return -1; } return _recursive_rmdir(path, mystat.st_dev, exclude, 0, onedev); } /* borrowed from iproute2 */ extern int get_u16(unsigned short *val, const char *arg, int base) { unsigned long res; char *ptr; if (!arg || !*arg) return -1; errno = 0; res = strtoul(arg, &ptr, base); if (!ptr || ptr == arg || *ptr || res > 0xFFFF || errno != 0) return -1; *val = res; return 0; } extern int mkdir_p(const char *dir, mode_t mode) { const char *tmp = dir; const char *orig = dir; char *makeme; do { dir = tmp + strspn(tmp, "/"); tmp = dir + strcspn(dir, "/"); makeme = strndup(orig, dir - orig); if (*makeme) { if (mkdir(makeme, mode) && errno != EEXIST) { SYSERROR("failed to create directory '%s'", makeme); free(makeme); return -1; } } free(makeme); } while(tmp != dir); return 0; } char *get_rundir() { char *rundir; const char *homedir; struct stat sb; if (stat(RUNTIME_PATH, &sb) < 0) return NULL; if (geteuid() == sb.st_uid || getegid() == sb.st_gid) { rundir = strdup(RUNTIME_PATH); return rundir; } rundir = getenv("XDG_RUNTIME_DIR"); if (rundir) { rundir = strdup(rundir); return rundir; } INFO("XDG_RUNTIME_DIR isn't set in the environment."); homedir = getenv("HOME"); if (!homedir) { ERROR("HOME isn't set in the environment."); return NULL; } rundir = malloc(sizeof(char) * (17 + strlen(homedir))); if (!rundir) return NULL; sprintf(rundir, "%s/.cache/lxc/run/", homedir); return rundir; } int wait_for_pid(pid_t pid) { int status, ret; again: ret = waitpid(pid, &status, 0); if (ret == -1) { if (errno == EINTR) goto again; return -1; } if (ret != pid) goto again; if (!WIFEXITED(status) || WEXITSTATUS(status) != 0) return -1; return 0; } int lxc_wait_for_pid_status(pid_t pid) { int status, ret; again: ret = waitpid(pid, &status, 0); if (ret == -1) { if (errno == EINTR) goto again; return -1; } if (ret != pid) goto again; return status; } #if HAVE_LIBGNUTLS #include #include __attribute__((constructor)) static void gnutls_lxc_init(void) { gnutls_global_init(); } int sha1sum_file(char *fnam, unsigned char *digest) { char *buf; int ret; FILE *f; long flen; if (!fnam) return -1; f = fopen_cloexec(fnam, "r"); if (!f) { SYSERROR("Error opening template"); return -1; } if (fseek(f, 0, SEEK_END) < 0) { SYSERROR("Error seeking to end of template"); fclose(f); return -1; } if ((flen = ftell(f)) < 0) { SYSERROR("Error telling size of template"); fclose(f); return -1; } if (fseek(f, 0, SEEK_SET) < 0) { SYSERROR("Error seeking to start of template"); fclose(f); return -1; } if ((buf = malloc(flen+1)) == NULL) { SYSERROR("Out of memory"); fclose(f); return -1; } if (fread(buf, 1, flen, f) != flen) { SYSERROR("Failure reading template"); free(buf); fclose(f); return -1; } if (fclose(f) < 0) { SYSERROR("Failre closing template"); free(buf); return -1; } buf[flen] = '\0'; ret = gnutls_hash_fast(GNUTLS_DIG_SHA1, buf, flen, (void *)digest); free(buf); return ret; } #endif struct lxc_popen_FILE *lxc_popen(const char *command) { int ret; int pipe_fds[2]; pid_t child_pid; struct lxc_popen_FILE *fp = NULL; ret = pipe2(pipe_fds, O_CLOEXEC); if (ret < 0) return NULL; child_pid = fork(); if (child_pid < 0) goto on_error; if (!child_pid) { sigset_t mask; close(pipe_fds[0]); /* duplicate stdout */ if (pipe_fds[1] != STDOUT_FILENO) ret = dup2(pipe_fds[1], STDOUT_FILENO); else ret = fcntl(pipe_fds[1], F_SETFD, 0); if (ret < 0) { close(pipe_fds[1]); _exit(EXIT_FAILURE); } /* duplicate stderr */ if (pipe_fds[1] != STDERR_FILENO) ret = dup2(pipe_fds[1], STDERR_FILENO); else ret = fcntl(pipe_fds[1], F_SETFD, 0); close(pipe_fds[1]); if (ret < 0) _exit(EXIT_FAILURE); /* unblock all signals */ ret = sigfillset(&mask); if (ret < 0) _exit(EXIT_FAILURE); ret = pthread_sigmask(SIG_UNBLOCK, &mask, NULL); if (ret < 0) _exit(EXIT_FAILURE); execl("/bin/sh", "sh", "-c", command, (char *)NULL); _exit(127); } close(pipe_fds[1]); pipe_fds[1] = -1; fp = malloc(sizeof(*fp)); if (!fp) goto on_error; memset(fp, 0, sizeof(*fp)); fp->child_pid = child_pid; fp->pipe = pipe_fds[0]; /* From now on, closing fp->f will also close fp->pipe. So only ever * call fclose(fp->f). */ fp->f = fdopen(pipe_fds[0], "r"); if (!fp->f) goto on_error; return fp; on_error: /* We can only close pipe_fds[0] if fdopen() didn't succeed or wasn't * called yet. Otherwise the fd belongs to the file opened by fdopen() * since it isn't dup()ed. */ if (fp && !fp->f && pipe_fds[0] >= 0) close(pipe_fds[0]); if (pipe_fds[1] >= 0) close(pipe_fds[1]); if (fp && fp->f) fclose(fp->f); if (fp) free(fp); return NULL; } int lxc_pclose(struct lxc_popen_FILE *fp) { pid_t wait_pid; int wstatus = 0; if (!fp) return -1; do { wait_pid = waitpid(fp->child_pid, &wstatus, 0); } while (wait_pid < 0 && errno == EINTR); fclose(fp->f); free(fp); if (wait_pid < 0) return -1; return wstatus; } int randseed(bool srand_it) { /* srand pre-seed function based on /dev/urandom */ unsigned int seed = time(NULL) + getpid(); FILE *f; f = fopen("/dev/urandom", "r"); if (f) { int ret = fread(&seed, sizeof(seed), 1, f); if (ret != 1) SYSDEBUG("unable to fread /dev/urandom, fallback to time+pid rand seed"); fclose(f); } if (srand_it) srand(seed); return seed; } uid_t get_ns_uid(uid_t orig) { char *line = NULL; size_t sz = 0; uid_t nsid, hostid, range; FILE *f = fopen("/proc/self/uid_map", "r"); if (!f) return 0; while (getline(&line, &sz, f) != -1) { if (sscanf(line, "%u %u %u", &nsid, &hostid, &range) != 3) continue; if (hostid <= orig && hostid + range > orig) { nsid += orig - hostid; goto found; } } nsid = 0; found: fclose(f); free(line); return nsid; } bool dir_exists(const char *path) { struct stat sb; int ret; ret = stat(path, &sb); if (ret < 0) /* Could be something other than eexist, just say "no". */ return false; return S_ISDIR(sb.st_mode); } /* Note we don't use SHA-1 here as we don't want to depend on HAVE_GNUTLS. * FNV has good anti collision properties and we're not worried * about pre-image resistance or one-way-ness, we're just trying to make * the name unique in the 108 bytes of space we have. */ uint64_t fnv_64a_buf(void *buf, size_t len, uint64_t hval) { unsigned char *bp; for(bp = buf; bp < (unsigned char *)buf + len; bp++) { /* xor the bottom with the current octet */ hval ^= (uint64_t)*bp; /* gcc optimised: * multiply by the 64 bit FNV magic prime mod 2^64 */ hval += (hval << 1) + (hval << 4) + (hval << 5) + (hval << 7) + (hval << 8) + (hval << 40); } return hval; } bool is_shared_mountpoint(const char *path) { char buf[LXC_LINELEN]; FILE *f; int i; char *p, *p2; f = fopen("/proc/self/mountinfo", "r"); if (!f) return 0; while (fgets(buf, LXC_LINELEN, f)) { for (p = buf, i = 0; p && i < 4; i++) p = strchr(p + 1, ' '); if (!p) continue; p2 = strchr(p + 1, ' '); if (!p2) continue; *p2 = '\0'; if (strcmp(p + 1, path) == 0) { /* This is the path. Is it shared? */ p = strchr(p2 + 1, ' '); if (p && strstr(p, "shared:")) { fclose(f); return true; } } } fclose(f); return false; } /* * Detect whether / is mounted MS_SHARED. The only way I know of to * check that is through /proc/self/mountinfo. * I'm only checking for /. If the container rootfs or mount location * is MS_SHARED, but not '/', then you're out of luck - figuring that * out would be too much work to be worth it. */ int detect_shared_rootfs(void) { if (is_shared_mountpoint("/")) return 1; return 0; } bool switch_to_ns(pid_t pid, const char *ns) { int fd, ret; char nspath[MAXPATHLEN]; /* Switch to new ns */ ret = snprintf(nspath, MAXPATHLEN, "/proc/%d/ns/%s", pid, ns); if (ret < 0 || ret >= MAXPATHLEN) return false; fd = open(nspath, O_RDONLY); if (fd < 0) { SYSERROR("Failed to open %s", nspath); return false; } ret = setns(fd, 0); if (ret) { SYSERROR("Failed to set process %d to %s of %d.", pid, ns, fd); close(fd); return false; } close(fd); return true; } /* * looking at fs/proc_namespace.c, it appears we can * actually expect the rootfs entry to very specifically contain * " - rootfs rootfs " * IIUC, so long as we've chrooted so that rootfs is not our root, * the rootfs entry should always be skipped in mountinfo contents. */ bool detect_ramfs_rootfs(void) { FILE *f; char *p, *p2; char *line = NULL; size_t len = 0; int i; f = fopen("/proc/self/mountinfo", "r"); if (!f) return false; while (getline(&line, &len, f) != -1) { for (p = line, i = 0; p && i < 4; i++) p = strchr(p + 1, ' '); if (!p) continue; p2 = strchr(p + 1, ' '); if (!p2) continue; *p2 = '\0'; if (strcmp(p + 1, "/") == 0) { /* This is '/'. Is it the ramfs? */ p = strchr(p2 + 1, '-'); if (p && strncmp(p, "- rootfs rootfs ", 16) == 0) { free(line); fclose(f); INFO("Rootfs is located on ramfs"); return true; } } } free(line); fclose(f); return false; } char *on_path(const char *cmd, const char *rootfs) { char *entry = NULL, *path = NULL; char cmdpath[MAXPATHLEN]; int ret; path = getenv("PATH"); if (!path) return NULL; path = strdup(path); if (!path) return NULL; lxc_iterate_parts (entry, path, ":") { if (rootfs) ret = snprintf(cmdpath, MAXPATHLEN, "%s/%s/%s", rootfs, entry, cmd); else ret = snprintf(cmdpath, MAXPATHLEN, "%s/%s", entry, cmd); if (ret < 0 || ret >= MAXPATHLEN) continue; if (access(cmdpath, X_OK) == 0) { free(path); return strdup(cmdpath); } } free(path); return NULL; } bool cgns_supported(void) { return file_exists("/proc/self/ns/cgroup"); } /* historically lxc-init has been under /usr/lib/lxc and under * /usr/lib/$ARCH/lxc. It now lives as $prefix/sbin/init.lxc. */ char *choose_init(const char *rootfs) { char *retv = NULL; const char *empty = "", *tmp; int ret, env_set = 0; if (!getenv("PATH")) { if (setenv("PATH", "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", 0)) SYSERROR("Failed to setenv"); env_set = 1; } retv = on_path("init.lxc", rootfs); if (env_set) { if (unsetenv("PATH")) SYSERROR("Failed to unsetenv"); } if (retv) return retv; retv = malloc(PATH_MAX); if (!retv) return NULL; if (rootfs) tmp = rootfs; else tmp = empty; ret = snprintf(retv, PATH_MAX, "%s/%s/%s", tmp, SBINDIR, "/init.lxc"); if (ret < 0 || ret >= PATH_MAX) { ERROR("pathname too long"); goto out1; } if (access(retv, X_OK) == 0) return retv; ret = snprintf(retv, PATH_MAX, "%s/%s/%s", tmp, LXCINITDIR, "/lxc/lxc-init"); if (ret < 0 || ret >= PATH_MAX) { ERROR("pathname too long"); goto out1; } if (access(retv, X_OK) == 0) return retv; ret = snprintf(retv, PATH_MAX, "%s/usr/lib/lxc/lxc-init", tmp); if (ret < 0 || ret >= PATH_MAX) { ERROR("pathname too long"); goto out1; } if (access(retv, X_OK) == 0) return retv; ret = snprintf(retv, PATH_MAX, "%s/sbin/lxc-init", tmp); if (ret < 0 || ret >= PATH_MAX) { ERROR("pathname too long"); goto out1; } if (access(retv, X_OK) == 0) return retv; /* * Last resort, look for the statically compiled init.lxc which we * hopefully bind-mounted in. * If we are called during container setup, and we get to this point, * then the init.lxc.static from the host will need to be bind-mounted * in. So we return NULL here to indicate that. */ if (rootfs) goto out1; ret = snprintf(retv, PATH_MAX, "/init.lxc.static"); if (ret < 0 || ret >= PATH_MAX) { WARN("Nonsense - name /lxc.init.static too long"); goto out1; } if (access(retv, X_OK) == 0) return retv; out1: free(retv); return NULL; } /* * Given the '-t' template option to lxc-create, figure out what to * do. If the template is a full executable path, use that. If it * is something like 'sshd', then return $templatepath/lxc-sshd. * On success return the template, on error return NULL. */ char *get_template_path(const char *t) { int ret, len; char *tpath; if (t[0] == '/' && access(t, X_OK) == 0) { tpath = strdup(t); return tpath; } len = strlen(LXCTEMPLATEDIR) + strlen(t) + strlen("/lxc-") + 1; tpath = malloc(len); if (!tpath) return NULL; ret = snprintf(tpath, len, "%s/lxc-%s", LXCTEMPLATEDIR, t); if (ret < 0 || ret >= len) { free(tpath); return NULL; } if (access(tpath, X_OK) < 0) { SYSERROR("bad template: %s", t); free(tpath); return NULL; } return tpath; } /* * @path: a pathname where / replaced with '\0'. * @offsetp: pointer to int showing which path segment was last seen. * Updated on return to reflect the next segment. * @fulllen: full original path length. * Returns a pointer to the next path segment, or NULL if done. */ static char *get_nextpath(char *path, int *offsetp, int fulllen) { int offset = *offsetp; if (offset >= fulllen) return NULL; while (path[offset] != '\0' && offset < fulllen) offset++; while (path[offset] == '\0' && offset < fulllen) offset++; *offsetp = offset; return (offset < fulllen) ? &path[offset] : NULL; } /* * Check that @subdir is a subdir of @dir. @len is the length of * @dir (to avoid having to recalculate it). */ static bool is_subdir(const char *subdir, const char *dir, size_t len) { size_t subdirlen = strlen(subdir); if (subdirlen < len) return false; if (strncmp(subdir, dir, len) != 0) return false; if (dir[len-1] == '/') return true; if (subdir[len] == '/' || subdirlen == len) return true; return false; } /* * Check if the open fd is a symlink. Return -ELOOP if it is. Return * -ENOENT if we couldn't fstat. Return 0 if the fd is ok. */ static int check_symlink(int fd) { struct stat sb; int ret; ret = fstat(fd, &sb); if (ret < 0) return -ENOENT; if (S_ISLNK(sb.st_mode)) return -ELOOP; return 0; } /* * Open a file or directory, provided that it contains no symlinks. * * CAVEAT: This function must not be used for other purposes than container * setup before executing the container's init */ static int open_if_safe(int dirfd, const char *nextpath) { int newfd = openat(dirfd, nextpath, O_RDONLY | O_NOFOLLOW); if (newfd >= 0) /* Was not a symlink, all good. */ return newfd; if (errno == ELOOP) return newfd; if (errno == EPERM || errno == EACCES) { /* We're not root (cause we got EPERM) so try opening with * O_PATH. */ newfd = openat(dirfd, nextpath, O_PATH | O_NOFOLLOW); if (newfd >= 0) { /* O_PATH will return an fd for symlinks. We know * nextpath wasn't a symlink at last openat, so if fd is * now a link, then something * fishy is going on. */ int ret = check_symlink(newfd); if (ret < 0) { close(newfd); newfd = ret; } } } return newfd; } /* * Open a path intending for mounting, ensuring that the final path * is inside the container's rootfs. * * CAVEAT: This function must not be used for other purposes than container * setup before executing the container's init * * @target: path to be opened * @prefix_skip: a part of @target in which to ignore symbolic links. This * would be the container's rootfs. * * Return an open fd for the path, or <0 on error. */ static int open_without_symlink(const char *target, const char *prefix_skip) { int curlen = 0, dirfd, fulllen, i; char *dup = NULL; fulllen = strlen(target); /* make sure prefix-skip makes sense */ if (prefix_skip && strlen(prefix_skip) > 0) { curlen = strlen(prefix_skip); if (!is_subdir(target, prefix_skip, curlen)) { ERROR("WHOA there - target '%s' didn't start with prefix '%s'", target, prefix_skip); return -EINVAL; } /* * get_nextpath() expects the curlen argument to be * on a (turned into \0) / or before it, so decrement * curlen to make sure that happens */ if (curlen) curlen--; } else { prefix_skip = "/"; curlen = 0; } /* Make a copy of target which we can hack up, and tokenize it */ if ((dup = strdup(target)) == NULL) { SYSERROR("Out of memory checking for symbolic link"); return -ENOMEM; } for (i = 0; i < fulllen; i++) { if (dup[i] == '/') dup[i] = '\0'; } dirfd = open(prefix_skip, O_RDONLY); if (dirfd < 0) goto out; while (1) { int newfd, saved_errno; char *nextpath; if ((nextpath = get_nextpath(dup, &curlen, fulllen)) == NULL) goto out; newfd = open_if_safe(dirfd, nextpath); saved_errno = errno; close(dirfd); dirfd = newfd; if (newfd < 0) { errno = saved_errno; if (errno == ELOOP) SYSERROR("%s in %s was a symbolic link!", nextpath, target); goto out; } } out: free(dup); return dirfd; } /* * Safely mount a path into a container, ensuring that the mount target * is under the container's @rootfs. (If @rootfs is NULL, then the container * uses the host's /) * * CAVEAT: This function must not be used for other purposes than container * setup before executing the container's init */ int safe_mount(const char *src, const char *dest, const char *fstype, unsigned long flags, const void *data, const char *rootfs) { int destfd, ret, saved_errno; /* Only needs enough for /proc/self/fd/. */ char srcbuf[50], destbuf[50]; int srcfd = -1; const char *mntsrc = src; if (!rootfs) rootfs = ""; /* todo - allow symlinks for relative paths if 'allowsymlinks' option is passed */ if (flags & MS_BIND && src && src[0] != '/') { INFO("this is a relative bind mount"); srcfd = open_without_symlink(src, NULL); if (srcfd < 0) return srcfd; ret = snprintf(srcbuf, 50, "/proc/self/fd/%d", srcfd); if (ret < 0 || ret > 50) { close(srcfd); ERROR("Out of memory"); return -EINVAL; } mntsrc = srcbuf; } destfd = open_without_symlink(dest, rootfs); if (destfd < 0) { if (srcfd != -1) { saved_errno = errno; close(srcfd); errno = saved_errno; } return destfd; } ret = snprintf(destbuf, 50, "/proc/self/fd/%d", destfd); if (ret < 0 || ret > 50) { if (srcfd != -1) close(srcfd); close(destfd); ERROR("Out of memory"); return -EINVAL; } ret = mount(mntsrc, destbuf, fstype, flags, data); saved_errno = errno; if (srcfd != -1) close(srcfd); close(destfd); if (ret < 0) { errno = saved_errno; SYSERROR("Failed to mount %s onto %s", src ? src : "(null)", dest); return ret; } return 0; } /* * Mount a proc under @rootfs if proc self points to a pid other than * my own. This is needed to have a known-good proc mount for setting * up LSMs both at container startup and attach. * * @rootfs : the rootfs where proc should be mounted * * Returns < 0 on failure, 0 if the correct proc was already mounted * and 1 if a new proc was mounted. * * NOTE: not to be called from inside the container namespace! */ int lxc_mount_proc_if_needed(const char *rootfs) { char path[MAXPATHLEN]; int link_to_pid, linklen, mypid, ret; char link[INTTYPE_TO_STRLEN(pid_t)] = {0}; ret = snprintf(path, MAXPATHLEN, "%s/proc/self", rootfs); if (ret < 0 || ret >= MAXPATHLEN) { SYSERROR("proc path name too long"); return -1; } linklen = readlink(path, link, INTTYPE_TO_STRLEN(pid_t)); ret = snprintf(path, MAXPATHLEN, "%s/proc", rootfs); if (ret < 0 || ret >= MAXPATHLEN) { SYSERROR("proc path name too long"); return -1; } /* /proc not mounted */ if (linklen < 0) { if (mkdir(path, 0755) && errno != EEXIST) return -1; goto domount; } else if (linklen >= INTTYPE_TO_STRLEN(pid_t)) { link[linklen - 1] = '\0'; ERROR("readlink returned truncated content: \"%s\"", link); return -1; } mypid = lxc_raw_getpid(); INFO("I am %d, /proc/self points to \"%s\"", mypid, link); if (lxc_safe_int(link, &link_to_pid) < 0) return -1; /* correct procfs is already mounted */ if (link_to_pid == mypid) return 0; ret = umount2(path, MNT_DETACH); if (ret < 0) WARN("failed to umount \"%s\" with MNT_DETACH", path); domount: /* rootfs is NULL */ if (!strcmp(rootfs, "")) ret = mount("proc", path, "proc", 0, NULL); else ret = safe_mount("proc", path, "proc", 0, NULL, rootfs); if (ret < 0) return -1; INFO("mounted /proc in container for security transition"); return 1; } int open_devnull(void) { int fd = open("/dev/null", O_RDWR); if (fd < 0) SYSERROR("Can't open /dev/null"); return fd; } int set_stdfds(int fd) { int ret; if (fd < 0) return -1; ret = dup2(fd, STDIN_FILENO); if (ret < 0) return -1; ret = dup2(fd, STDOUT_FILENO); if (ret < 0) return -1; ret = dup2(fd, STDERR_FILENO); if (ret < 0) return -1; return 0; } int null_stdfds(void) { int ret = -1; int fd; fd = open_devnull(); if (fd >= 0) { ret = set_stdfds(fd); close(fd); } return ret; } /* Check whether a signal is blocked by a process. */ /* /proc/pid-to-str/status\0 = (5 + 21 + 7 + 1) */ #define __PROC_STATUS_LEN (6 + INTTYPE_TO_STRLEN(pid_t) + 7 + 1) bool task_blocks_signal(pid_t pid, int signal) { int ret; char status[__PROC_STATUS_LEN]; FILE *f; uint64_t sigblk = 0, one = 1; size_t n = 0; bool bret = false; char *line = NULL; ret = snprintf(status, __PROC_STATUS_LEN, "/proc/%d/status", pid); if (ret < 0 || ret >= __PROC_STATUS_LEN) return bret; f = fopen(status, "r"); if (!f) return bret; while (getline(&line, &n, f) != -1) { char *numstr; if (strncmp(line, "SigBlk:", 7)) continue; numstr = lxc_trim_whitespace_in_place(line + 7); ret = lxc_safe_uint64(numstr, &sigblk, 16); if (ret < 0) goto out; break; } if (sigblk & (one << (signal - 1))) bret = true; out: free(line); fclose(f); return bret; } int lxc_preserve_ns(const int pid, const char *ns) { int ret; /* 5 /proc + 21 /int_as_str + 3 /ns + 20 /NS_NAME + 1 \0 */ #define __NS_PATH_LEN 50 char path[__NS_PATH_LEN]; /* This way we can use this function to also check whether namespaces * are supported by the kernel by passing in the NULL or the empty * string. */ ret = snprintf(path, __NS_PATH_LEN, "/proc/%d/ns%s%s", pid, !ns || strcmp(ns, "") == 0 ? "" : "/", !ns || strcmp(ns, "") == 0 ? "" : ns); if (ret < 0 || (size_t)ret >= __NS_PATH_LEN) { errno = EFBIG; return -1; } return open(path, O_RDONLY | O_CLOEXEC); } int lxc_switch_uid_gid(uid_t uid, gid_t gid) { if (setgid(gid) < 0) { SYSERROR("Failed to switch to gid %d.", gid); return -errno; } NOTICE("Switched to gid %d.", gid); if (setuid(uid) < 0) { SYSERROR("Failed to switch to uid %d.", uid); return -errno; } NOTICE("Switched to uid %d.", uid); return 0; } /* Simple covenience function which enables uniform logging. */ int lxc_setgroups(int size, gid_t list[]) { if (setgroups(size, list) < 0) { SYSERROR("Failed to setgroups()."); return -errno; } NOTICE("Dropped additional groups."); return 0; } static int lxc_get_unused_loop_dev_legacy(char *loop_name) { struct dirent *dp; struct loop_info64 lo64; DIR *dir; int dfd = -1, fd = -1, ret = -1; dir = opendir("/dev"); if (!dir) return -1; while ((dp = readdir(dir))) { if (strncmp(dp->d_name, "loop", 4) != 0) continue; dfd = dirfd(dir); if (dfd < 0) continue; fd = openat(dfd, dp->d_name, O_RDWR); if (fd < 0) continue; ret = ioctl(fd, LOOP_GET_STATUS64, &lo64); if (ret < 0) { if (ioctl(fd, LOOP_GET_STATUS64, &lo64) == 0 || errno != ENXIO) { close(fd); fd = -1; continue; } } ret = snprintf(loop_name, LO_NAME_SIZE, "/dev/%s", dp->d_name); if (ret < 0 || ret >= LO_NAME_SIZE) { close(fd); fd = -1; continue; } break; } closedir(dir); if (fd < 0) return -1; return fd; } static int lxc_get_unused_loop_dev(char *name_loop) { int loop_nr, ret; int fd_ctl = -1, fd_tmp = -1; fd_ctl = open("/dev/loop-control", O_RDWR | O_CLOEXEC); if (fd_ctl < 0) return -ENODEV; loop_nr = ioctl(fd_ctl, LOOP_CTL_GET_FREE); if (loop_nr < 0) goto on_error; ret = snprintf(name_loop, LO_NAME_SIZE, "/dev/loop%d", loop_nr); if (ret < 0 || ret >= LO_NAME_SIZE) goto on_error; fd_tmp = open(name_loop, O_RDWR | O_CLOEXEC); if (fd_tmp < 0) goto on_error; on_error: close(fd_ctl); return fd_tmp; } int lxc_prepare_loop_dev(const char *source, char *loop_dev, int flags) { int ret; struct loop_info64 lo64; int fd_img = -1, fret = -1, fd_loop = -1; fd_loop = lxc_get_unused_loop_dev(loop_dev); if (fd_loop < 0) { if (fd_loop == -ENODEV) fd_loop = lxc_get_unused_loop_dev_legacy(loop_dev); else goto on_error; } fd_img = open(source, O_RDWR | O_CLOEXEC); if (fd_img < 0) goto on_error; ret = ioctl(fd_loop, LOOP_SET_FD, fd_img); if (ret < 0) goto on_error; memset(&lo64, 0, sizeof(lo64)); lo64.lo_flags = flags; ret = ioctl(fd_loop, LOOP_SET_STATUS64, &lo64); if (ret < 0) goto on_error; fret = 0; on_error: if (fd_img >= 0) close(fd_img); if (fret < 0 && fd_loop >= 0) { close(fd_loop); fd_loop = -1; } return fd_loop; } int lxc_unstack_mountpoint(const char *path, bool lazy) { int ret; int umounts = 0; pop_stack: ret = umount2(path, lazy ? MNT_DETACH : 0); if (ret < 0) { /* We consider anything else than EINVAL deadly to prevent going * into an infinite loop. (The other alternative is constantly * parsing /proc/self/mountinfo which is yucky and probably * racy.) */ if (errno != EINVAL) return -errno; } else { /* Just stop counting when this happens. That'd just be so * stupid that we won't even bother trying to report back the * correct value anymore. */ if (umounts != INT_MAX) umounts++; /* We succeeded in umounting. Make sure that there's no other * mountpoint stacked underneath. */ goto pop_stack; } return umounts; } int run_command(char *buf, size_t buf_size, int (*child_fn)(void *), void *args) { pid_t child; int ret, fret, pipefd[2]; ssize_t bytes; /* Make sure our callers do not receive uninitialized memory. */ if (buf_size > 0 && buf) buf[0] = '\0'; if (pipe(pipefd) < 0) { SYSERROR("failed to create pipe"); return -1; } child = lxc_raw_clone(0); if (child < 0) { close(pipefd[0]); close(pipefd[1]); SYSERROR("failed to create new process"); return -1; } if (child == 0) { /* Close the read-end of the pipe. */ close(pipefd[0]); /* Redirect std{err,out} to write-end of the * pipe. */ ret = dup2(pipefd[1], STDOUT_FILENO); if (ret >= 0) ret = dup2(pipefd[1], STDERR_FILENO); /* Close the write-end of the pipe. */ close(pipefd[1]); if (ret < 0) { SYSERROR("failed to duplicate std{err,out} file descriptor"); _exit(EXIT_FAILURE); } /* Does not return. */ child_fn(args); ERROR("failed to exec command"); _exit(EXIT_FAILURE); } /* close the write-end of the pipe */ close(pipefd[1]); if (buf && buf_size > 0) { bytes = lxc_read_nointr(pipefd[0], buf, buf_size - 1); if (bytes > 0) buf[bytes - 1] = '\0'; } fret = wait_for_pid(child); /* close the read-end of the pipe */ close(pipefd[0]); return fret; } bool lxc_nic_exists(char *nic) { #define __LXC_SYS_CLASS_NET_LEN 15 + IFNAMSIZ + 1 char path[__LXC_SYS_CLASS_NET_LEN]; int ret; struct stat sb; if (!strcmp(nic, "none")) return true; ret = snprintf(path, __LXC_SYS_CLASS_NET_LEN, "/sys/class/net/%s", nic); if (ret < 0 || (size_t)ret >= __LXC_SYS_CLASS_NET_LEN) return false; ret = stat(path, &sb); if (ret < 0) return false; return true; } uint64_t lxc_find_next_power2(uint64_t n) { /* 0 is not valid input. We return 0 to the caller since 0 is not a * valid power of two. */ if (n == 0) return 0; if (!(n & (n - 1))) return n; while (n & (n - 1)) n = n & (n - 1); n = n << 1; return n; } int lxc_set_death_signal(int signal) { int ret; pid_t ppid; ret = prctl(PR_SET_PDEATHSIG, prctl_arg(signal), prctl_arg(0), prctl_arg(0), prctl_arg(0)); /* Check whether we have been orphaned. */ ppid = (pid_t)syscall(SYS_getppid); if (ppid == 1) { pid_t self; self = lxc_raw_getpid(); ret = kill(self, SIGKILL); if (ret < 0) return -1; } if (ret < 0) { SYSERROR("Failed to set PR_SET_PDEATHSIG to %d", signal); return -1; } return 0; } int fd_cloexec(int fd, bool cloexec) { int oflags, nflags; oflags = fcntl(fd, F_GETFD, 0); if (oflags < 0) return -errno; if (cloexec) nflags = oflags | FD_CLOEXEC; else nflags = oflags & ~FD_CLOEXEC; if (nflags == oflags) return 0; if (fcntl(fd, F_SETFD, nflags) < 0) return -errno; return 0; } int recursive_destroy(char *dirname) { int ret; struct dirent *direntp; DIR *dir; int r = 0; dir = opendir(dirname); if (!dir) return -1; while ((direntp = readdir(dir))) { char *pathname; struct stat mystat; if (!strcmp(direntp->d_name, ".") || !strcmp(direntp->d_name, "..")) continue; pathname = must_make_path(dirname, direntp->d_name, NULL); ret = lstat(pathname, &mystat); if (ret < 0) { if (!r) WARN("Failed to stat \"%s\"", pathname); r = -1; goto next; } if (!S_ISDIR(mystat.st_mode)) goto next; ret = recursive_destroy(pathname); if (ret < 0) r = -1; next: free(pathname); } ret = rmdir(dirname); if (ret < 0) { if (!r) SYSWARN("Failed to delete \"%s\"", dirname); r = -1; } ret = closedir(dir); if (ret < 0) { if (!r) SYSWARN("Failed to delete \"%s\"", dirname); r = -1; } return r; }