+++ /dev/null
-/* lxcfs
- *
- * Copyright © 2014-2016 Canonical, Inc
- * Author: Serge Hallyn <serge.hallyn@ubuntu.com>
- *
- * See COPYING file for details.
- */
-
-#ifndef _GNU_SOURCE
-#define _GNU_SOURCE
-#endif
-
-#ifndef FUSE_USE_VERSION
-#define FUSE_USE_VERSION 26
-#endif
-
-#define _FILE_OFFSET_BITS 64
-
-#include <dirent.h>
-#include <errno.h>
-#include <fcntl.h>
-#include <fuse.h>
-#include <inttypes.h>
-#include <libgen.h>
-#include <pthread.h>
-#include <sched.h>
-#include <stdarg.h>
-#include <stdbool.h>
-#include <stdint.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <time.h>
-#include <unistd.h>
-#include <wait.h>
-#include <linux/magic.h>
-#include <linux/sched.h>
-#include <sys/epoll.h>
-#include <sys/mman.h>
-#include <sys/mount.h>
-#include <sys/param.h>
-#include <signal.h>
-#include <sys/socket.h>
-#include <sys/syscall.h>
-#include <sys/sysinfo.h>
-#include <sys/vfs.h>
-
-#include "bindings.h"
-#include "config.h"
-#include "cgroup_fuse.h"
-#include "cgroups/cgroup.h"
-#include "cgroups/cgroup_utils.h"
-#include "memory_utils.h"
-#include "proc_cpuview.h"
-#include "utils.h"
-
-static bool can_use_pidfd;
-
-/* Define pivot_root() if missing from the C library */
-#ifndef HAVE_PIVOT_ROOT
-static int pivot_root(const char *new_root, const char *put_old)
-{
-#ifdef __NR_pivot_root
- return syscall(__NR_pivot_root, new_root, put_old);
-#else
- errno = ENOSYS;
- return -1;
-#endif
-}
-#else
-extern int pivot_root(const char *new_root, const char *put_old);
-#endif
-
-/*
- * A table caching which pid is init for a pid namespace.
- * When looking up which pid is init for $qpid, we first
- * 1. Stat /proc/$qpid/ns/pid.
- * 2. Check whether the ino_t is in our store.
- * a. if not, fork a child in qpid's ns to send us
- * ucred.pid = 1, and read the initpid. Cache
- * initpid and creation time for /proc/initpid
- * in a new store entry.
- * b. if so, verify that /proc/initpid still matches
- * what we have saved. If not, clear the store
- * entry and go back to a. If so, return the
- * cached initpid.
- */
-struct pidns_init_store {
- ino_t ino; /* inode number for /proc/$pid/ns/pid */
- pid_t initpid; /* the pid of nit in that ns */
- int init_pidfd;
- long int ctime; /* the time at which /proc/$initpid was created */
- struct pidns_init_store *next;
- long int lastcheck;
-};
-
-/* lol - look at how they are allocated in the kernel */
-#define PIDNS_HASH_SIZE 4096
-#define HASH(x) ((x) % PIDNS_HASH_SIZE)
-
-static struct pidns_init_store *pidns_hash_table[PIDNS_HASH_SIZE];
-static pthread_mutex_t pidns_store_mutex = PTHREAD_MUTEX_INITIALIZER;
-
-static void lock_mutex(pthread_mutex_t *l)
-{
- int ret;
-
- ret = pthread_mutex_lock(l);
- if (ret)
- log_exit("%s - returned %d\n", strerror(ret), ret);
-}
-
-struct cgroup_ops *cgroup_ops;
-
-static void unlock_mutex(pthread_mutex_t *l)
-{
- int ret;
-
- ret = pthread_mutex_unlock(l);
- if (ret)
- log_exit("%s - returned %d\n", strerror(ret), ret);
-}
-
-static void store_lock(void)
-{
- lock_mutex(&pidns_store_mutex);
-}
-
-static void store_unlock(void)
-{
- unlock_mutex(&pidns_store_mutex);
-}
-
-/* /proc/ = 6
- * +
- * <pid-as-str> = INTTYPE_TO_STRLEN(pid_t)
- * +
- * \0 = 1
- */
-#define LXCFS_PROC_PID_LEN \
- (STRLITERALLEN("/proc/") + INTTYPE_TO_STRLEN(uint64_t) + +1)
-
-/* Must be called under store_lock */
-static bool initpid_still_valid(struct pidns_init_store *entry)
-{
- bool valid = true;
-
- if (entry->init_pidfd >= 0) {
- if (pidfd_send_signal(entry->init_pidfd, 0, NULL, 0))
- valid = false;
- } else {
- struct stat st;
- char path[LXCFS_PROC_PID_LEN];
-
- snprintf(path, sizeof(path), "/proc/%d", entry->initpid);
-
- if (stat(path, &st) || entry->ctime != st.st_ctime)
- valid = false;
- }
-
- return valid;
-}
-
-/* Must be called under store_lock */
-static void remove_initpid(struct pidns_init_store *entry)
-{
- struct pidns_init_store *it;
- int ino_hash;
-
- lxcfs_debug("Removing cached entry for pid %d from init pid cache",
- entry->initpid);
-
- ino_hash = HASH(entry->ino);
- if (pidns_hash_table[ino_hash] == entry) {
- pidns_hash_table[ino_hash] = entry->next;
- close_prot_errno_disarm(entry->init_pidfd);
- free_disarm(entry);
- return;
- }
-
- it = pidns_hash_table[ino_hash];
- while (it) {
- if (it->next == entry) {
- it->next = entry->next;
- close_prot_errno_disarm(entry->init_pidfd);
- free_disarm(entry);
- return;
- }
- it = it->next;
- }
-}
-
-#define PURGE_SECS 5
-/* Must be called under store_lock */
-static void prune_initpid_store(void)
-{
- static long int last_prune = 0;
- long int now, threshold;
-
- if (!last_prune) {
- last_prune = time(NULL);
- return;
- }
-
- now = time(NULL);
- if (now < last_prune + PURGE_SECS)
- return;
-
- lxcfs_debug("Pruning init pid cache");
-
- last_prune = now;
- threshold = now - 2 * PURGE_SECS;
-
- for (int i = 0; i < PIDNS_HASH_SIZE; i++) {
- for (struct pidns_init_store *entry = pidns_hash_table[i], *prev = NULL; entry;) {
- if (entry->lastcheck < threshold) {
- struct pidns_init_store *cur = entry;
-
- lxcfs_debug("Removed cache entry for pid %d to init pid cache", cur->initpid);
-
- if (prev)
- prev->next = entry->next;
- else
- pidns_hash_table[i] = entry->next;
- entry = entry->next;
- close_prot_errno_disarm(cur->init_pidfd);
- free_disarm(cur);
- } else {
- prev = entry;
- entry = entry->next;
- }
- }
- }
-}
-
-/* Must be called under store_lock */
-static void save_initpid(struct stat *sb, pid_t pid)
-{
- __do_free struct pidns_init_store *entry = NULL;
- __do_close_prot_errno int pidfd = -EBADF;
- char path[LXCFS_PROC_PID_LEN];
- struct lxcfs_opts *opts = fuse_get_context()->private_data;
- struct stat st;
- int ino_hash;
-
- if (opts->use_pidfd && can_use_pidfd) {
- pidfd = pidfd_open(pid, 0);
- if (pidfd < 0)
- return;
- }
-
- snprintf(path, sizeof(path), "/proc/%d", pid);
- if (stat(path, &st))
- return;
-
- entry = malloc(sizeof(*entry));
- if (entry)
- return;
-
- ino_hash = HASH(entry->ino);
- *entry = (struct pidns_init_store){
- .ino = sb->st_ino,
- .initpid = pid,
- .ctime = st.st_ctime,
- .next = pidns_hash_table[ino_hash],
- .lastcheck = time(NULL),
- .init_pidfd = move_fd(pidfd),
- };
- pidns_hash_table[ino_hash] = move_ptr(entry);
-
- lxcfs_debug("Added cache entry %d for pid %d to init pid cache", ino_hash, pid);
-}
-
-/*
- * Given the stat(2) info for a nsfd pid inode, lookup the init_pid_store
- * entry for the inode number and creation time. Verify that the init pid
- * is still valid. If not, remove it. Return the entry if valid, NULL
- * otherwise.
- * Must be called under store_lock
- */
-static struct pidns_init_store *lookup_verify_initpid(struct stat *sb)
-{
- struct pidns_init_store *entry = pidns_hash_table[HASH(sb->st_ino)];
-
- while (entry) {
- if (entry->ino == sb->st_ino) {
- if (initpid_still_valid(entry)) {
- entry->lastcheck = time(NULL);
- return entry;
- }
-
- remove_initpid(entry);
- return NULL;
- }
- entry = entry->next;
- }
-
- return NULL;
-}
-
-static int send_creds_clone_wrapper(void *arg)
-{
- struct ucred cred;
- char v;
- int sock = *(int *)arg;
-
- /* we are the child */
- cred.uid = 0;
- cred.gid = 0;
- cred.pid = 1;
- v = '1';
- if (send_creds(sock, &cred, v, true) != SEND_CREDS_OK)
- return 1;
- return 0;
-}
-
-/*
- * Let's use the "standard stack limit" (i.e. glibc thread size default) for
- * stack sizes: 8MB.
- */
-#define __LXCFS_STACK_SIZE (8 * 1024 * 1024)
-static pid_t lxcfs_clone(int (*fn)(void *), void *arg, int flags)
-{
- pid_t ret;
- void *stack;
-
- stack = malloc(__LXCFS_STACK_SIZE);
- if (!stack)
- return ret_errno(ENOMEM);
-
-#ifdef __ia64__
- ret = __clone2(fn, stack, __LXCFS_STACK_SIZE, flags | SIGCHLD, arg, NULL);
-#else
- ret = clone(fn, stack + __LXCFS_STACK_SIZE, flags | SIGCHLD, arg, NULL);
-#endif
- return ret;
-}
-
-#define LXCFS_PROC_PID_NS_LEN \
- (STRLITERALLEN("/proc/") + INTTYPE_TO_STRLEN(uint64_t) + \
- STRLITERALLEN("/ns/pid") + 1)
-
-/*
- * clone a task which switches to @task's namespace and writes '1'.
- * over a unix sock so we can read the task's reaper's pid in our
- * namespace
- *
- * Note: glibc's fork() does not respect pidns, which can lead to failed
- * assertions inside glibc (and thus failed forks) if the child's pid in
- * the pidns and the parent pid outside are identical. Using clone prevents
- * this issue.
- */
-static void write_task_init_pid_exit(int sock, pid_t target)
-{
- __do_close_prot_errno int fd = -EBADF;
- char path[LXCFS_PROC_PID_NS_LEN];
- pid_t pid;
-
- snprintf(path, sizeof(path), "/proc/%d/ns/pid", (int)target);
- fd = open(path, O_RDONLY | O_CLOEXEC);
- if (fd < 0)
- log_exit("write_task_init_pid_exit open of ns/pid");
-
- if (setns(fd, 0))
- log_exit("Failed to setns to pid namespace of process %d", target);
-
- pid = lxcfs_clone(send_creds_clone_wrapper, &sock, 0);
- if (pid < 0)
- _exit(EXIT_FAILURE);
-
- if (pid != 0) {
- if (!wait_for_pid(pid))
- _exit(EXIT_FAILURE);
-
- _exit(EXIT_SUCCESS);
- }
-}
-
-static pid_t get_init_pid_for_task(pid_t task)
-{
- char v = '0';
- pid_t pid_ret = -1;
- pid_t pid;
- int sock[2];
- struct ucred cred;
-
- if (socketpair(AF_UNIX, SOCK_DGRAM, 0, sock) < 0)
- return -1;
-
- pid = fork();
- if (pid < 0)
- goto out;
-
- if (pid == 0) {
- close(sock[1]);
- write_task_init_pid_exit(sock[0], task);
- _exit(EXIT_SUCCESS);
- }
-
- if (!recv_creds(sock[1], &cred, &v))
- goto out;
-
- pid_ret = cred.pid;
-
-out:
- close(sock[0]);
- close(sock[1]);
- if (pid > 0)
- wait_for_pid(pid);
-
- return pid_ret;
-}
-
-pid_t lookup_initpid_in_store(pid_t pid)
-{
- pid_t answer = 0;
- char path[LXCFS_PROC_PID_NS_LEN];
- struct stat st;
- struct pidns_init_store *entry;
-
- snprintf(path, sizeof(path), "/proc/%d/ns/pid", pid);
-
- store_lock();
- if (stat(path, &st))
- goto out;
-
- entry = lookup_verify_initpid(&st);
- if (entry) {
- answer = entry->initpid;
- goto out;
- }
-
- answer = get_init_pid_for_task(pid);
- if (answer > 0)
- save_initpid(&st, answer);
-
-out:
- /*
- * Prune at the end in case we're returning the value we were about to
- * return.
- */
- prune_initpid_store();
-
- store_unlock();
-
- return answer;
-}
-
-/*
- * Functions needed to setup cgroups in the __constructor__.
- */
-
-static bool umount_if_mounted(void)
-{
- if (umount2(BASEDIR, MNT_DETACH) < 0 && errno != EINVAL) {
- lxcfs_error("Failed to unmount %s: %s.\n", BASEDIR, strerror(errno));
- return false;
- }
- return true;
-}
-
-/* __typeof__ should be safe to use with all compilers. */
-typedef __typeof__(((struct statfs *)NULL)->f_type) fs_type_magic;
-static bool has_fs_type(const struct statfs *fs, fs_type_magic magic_val)
-{
- return (fs->f_type == (fs_type_magic)magic_val);
-}
-
-/*
- * 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.
- */
-static bool is_on_ramfs(void)
-{
- __do_free char *line = NULL;
- __do_fclose FILE *f = NULL;
- size_t len = 0;
-
- f = fopen("/proc/self/mountinfo", "re");
- if (!f)
- return false;
-
- while (getline(&line, &len, f) != -1) {
- int i;
- char *p, *p2;
-
- 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)
- return true;
- }
- }
-
- return false;
-}
-
-static int pivot_enter()
-{
- __do_close_prot_errno int oldroot = -EBADF, newroot = -EBADF;
-
- oldroot = open("/", O_DIRECTORY | O_RDONLY);
- if (oldroot < 0)
- return log_error_errno(-1, errno,
- "Failed to open old root for fchdir");
-
- newroot = open(ROOTDIR, O_DIRECTORY | O_RDONLY);
- if (newroot < 0)
- return log_error_errno(-1, errno,
- "Failed to open new root for fchdir");
-
- /* change into new root fs */
- if (fchdir(newroot) < 0)
- return log_error_errno(-1,
- errno, "Failed to change directory to new rootfs: %s",
- ROOTDIR);
-
- /* pivot_root into our new root fs */
- if (pivot_root(".", ".") < 0)
- return log_error_errno(-1, errno,
- "pivot_root() syscall failed: %s",
- strerror(errno));
-
- /*
- * At this point the old-root is mounted on top of our new-root.
- * To unmounted it we must not be chdir'd into it, so escape back
- * to the old-root.
- */
- if (fchdir(oldroot) < 0)
- return log_error_errno(-1, errno, "Failed to enter old root");
-
- if (umount2(".", MNT_DETACH) < 0)
- return log_error_errno(-1, errno, "Failed to detach old root");
-
- if (fchdir(newroot) < 0)
- return log_error_errno(-1, errno, "Failed to re-enter new root");
-
- return 0;
-}
-
-static int chroot_enter()
-{
- if (mount(ROOTDIR, "/", NULL, MS_REC | MS_BIND, NULL)) {
- lxcfs_error("Failed to recursively bind-mount %s into /.", ROOTDIR);
- return -1;
- }
-
- if (chroot(".") < 0) {
- lxcfs_error("Call to chroot() failed: %s.\n", strerror(errno));
- return -1;
- }
-
- if (chdir("/") < 0) {
- lxcfs_error("Failed to change directory: %s.\n", strerror(errno));
- return -1;
- }
-
- return 0;
-}
-
-static int permute_and_enter(void)
-{
- struct statfs sb;
-
- if (statfs("/", &sb) < 0) {
- lxcfs_error("%s\n", "Could not stat / mountpoint.");
- return -1;
- }
-
- /* has_fs_type() is not reliable. When the ramfs is a tmpfs it will
- * likely report TMPFS_MAGIC. Hence, when it reports no we still check
- * /proc/1/mountinfo. */
- if (has_fs_type(&sb, RAMFS_MAGIC) || is_on_ramfs())
- return chroot_enter();
-
- if (pivot_enter() < 0) {
- lxcfs_error("%s\n", "Could not perform pivot root.");
- return -1;
- }
-
- return 0;
-}
-
-/* Prepare our new clean root. */
-static int permute_prepare(void)
-{
- if (mkdir(ROOTDIR, 0700) < 0 && errno != EEXIST) {
- lxcfs_error("%s\n", "Failed to create directory for new root.");
- return -1;
- }
-
- if (mount("/", ROOTDIR, NULL, MS_BIND, 0) < 0) {
- lxcfs_error("Failed to bind-mount / for new root: %s.\n", strerror(errno));
- return -1;
- }
-
- if (mount(RUNTIME_PATH, ROOTDIR RUNTIME_PATH, NULL, MS_BIND, 0) < 0) {
- lxcfs_error("Failed to bind-mount /run into new root: %s.\n", strerror(errno));
- return -1;
- }
-
- if (mount(BASEDIR, ROOTDIR BASEDIR, NULL, MS_REC | MS_MOVE, 0) < 0) {
- printf("Failed to move " BASEDIR " into new root: %s.\n", strerror(errno));
- return -1;
- }
-
- return 0;
-}
-
-/* Calls chroot() on ramfs, pivot_root() in all other cases. */
-static bool permute_root(void)
-{
- /* Prepare new root. */
- if (permute_prepare() < 0)
- return false;
-
- /* Pivot into new root. */
- if (permute_and_enter() < 0)
- return false;
-
- return true;
-}
-
-static bool cgfs_prepare_mounts(void)
-{
- if (!mkdir_p(BASEDIR, 0700)) {
- lxcfs_error("%s\n", "Failed to create lxcfs cgroup mountpoint.");
- return false;
- }
-
- if (!umount_if_mounted()) {
- lxcfs_error("%s\n", "Failed to clean up old lxcfs cgroup mountpoint.");
- return false;
- }
-
- if (unshare(CLONE_NEWNS) < 0) {
- lxcfs_error("Failed to unshare mount namespace: %s.\n", strerror(errno));
- return false;
- }
-
- cgroup_ops->mntns_fd = preserve_ns(getpid(), "mnt");
- if (cgroup_ops->mntns_fd < 0) {
- lxcfs_error("Failed to preserve mount namespace: %s.\n", strerror(errno));
- return false;
- }
-
- if (mount(NULL, "/", NULL, MS_REC | MS_PRIVATE, 0) < 0) {
- lxcfs_error("Failed to remount / private: %s.\n", strerror(errno));
- return false;
- }
-
- if (mount("tmpfs", BASEDIR, "tmpfs", 0, "size=100000,mode=700") < 0) {
- lxcfs_error("%s\n", "Failed to mount tmpfs over lxcfs cgroup mountpoint.");
- return false;
- }
-
- return true;
-}
-
-static bool cgfs_mount_hierarchies(void)
-{
- if (!mkdir_p(BASEDIR DEFAULT_CGROUP_MOUNTPOINT, 0755))
- return false;
-
- if (!cgroup_ops->mount(cgroup_ops, BASEDIR))
- return false;
-
- for (struct hierarchy **h = cgroup_ops->hierarchies; h && *h; h++) {
- __do_free char *path = must_make_path(BASEDIR, (*h)->mountpoint, NULL);
- (*h)->fd = open(path, O_DIRECTORY | O_CLOEXEC | O_NOFOLLOW);
- if ((*h)->fd < 0)
- return false;
- }
-
- return true;
-}
-
-static bool cgfs_setup_controllers(void)
-{
- if (!cgfs_prepare_mounts())
- return false;
-
- if (!cgfs_mount_hierarchies()) {
- lxcfs_error("%s\n", "Failed to set up private lxcfs cgroup mounts.");
- return false;
- }
-
- if (!permute_root())
- return false;
-
- return true;
-}
-
-static void __attribute__((constructor)) lxcfs_init(void)
-{
- __do_close_prot_errno int init_ns = -EBADF, pidfd = -EBADF;
- int i = 0;
- pid_t pid;
- char *cret;
- char cwd[MAXPATHLEN];
-
- cgroup_ops = cgroup_init();
- if (!cgroup_ops)
- log_exit("Failed to initialize cgroup support");
-
- /* Preserve initial namespace. */
- pid = getpid();
- init_ns = preserve_ns(pid, "mnt");
- if (init_ns < 0)
- log_exit("Failed to preserve initial mount namespace");
-
- cret = getcwd(cwd, MAXPATHLEN);
- if (!cret)
- log_exit("%s - Could not retrieve current working directory", strerror(errno));
-
- /* This function calls unshare(CLONE_NEWNS) our initial mount namespace
- * to privately mount lxcfs cgroups. */
- if (!cgfs_setup_controllers())
- log_exit("Failed to setup private cgroup mounts for lxcfs");
-
- if (setns(init_ns, 0) < 0)
- log_exit("%s - Failed to switch back to initial mount namespace", strerror(errno));
-
- if (!cret || chdir(cwd) < 0)
- log_exit("%s - Could not change back to original working directory", strerror(errno));
-
- if (!init_cpuview())
- log_exit("Failed to init CPU view");
-
- fprintf(stderr, "mount namespace: %d\n", cgroup_ops->mntns_fd);
- fprintf(stderr, "hierarchies:\n");
-
- for (struct hierarchy **h = cgroup_ops->hierarchies; h && *h; h++, i++) {
- __do_free char *controllers = lxc_string_join(",", (const char **)(*h)->controllers, false);
- fprintf(stderr, " %2d: fd: %3d: %s\n", i, (*h)->fd, controllers ?: "");
- }
-
- pidfd = pidfd_open(pid, 0);
- if (pidfd >= 0 && pidfd_send_signal(pidfd, 0, NULL, 0) == 0) {
- can_use_pidfd = true;
- lxcfs_error("Kernel supports pidfds");
- }
-}
-
-static void __attribute__((destructor)) lxcfs_exit(void)
-{
- lxcfs_debug("%s\n", "Running destructor for liblxcfs");
- free_cpuview();
- cgroup_exit(cgroup_ops);
-}
projects / mirror_lxcfs.git / blobdiff