|
@@ -1,1006 +0,0 @@
|
|
|
-
|
|
|
-#define _GNU_SOURCE
|
|
|
-#include <endian.h>
|
|
|
-#include <errno.h>
|
|
|
-#include <fcntl.h>
|
|
|
-#include <grp.h>
|
|
|
-#include <sched.h>
|
|
|
-#include <setjmp.h>
|
|
|
-#include <signal.h>
|
|
|
-#include <stdarg.h>
|
|
|
-#include <stdbool.h>
|
|
|
-#include <stdint.h>
|
|
|
-#include <stdio.h>
|
|
|
-#include <stdlib.h>
|
|
|
-#include <stdbool.h>
|
|
|
-#include <string.h>
|
|
|
-#include <unistd.h>
|
|
|
-
|
|
|
-#include <sys/ioctl.h>
|
|
|
-#include <sys/prctl.h>
|
|
|
-#include <sys/socket.h>
|
|
|
-#include <sys/types.h>
|
|
|
-#include <sys/wait.h>
|
|
|
-
|
|
|
-#include <linux/limits.h>
|
|
|
-#include <linux/netlink.h>
|
|
|
-#include <linux/types.h>
|
|
|
-
|
|
|
-/* Get all of the CLONE_NEW* flags. */
|
|
|
-#include "namespace.h"
|
|
|
-
|
|
|
-/* Synchronisation values. */
|
|
|
-enum sync_t {
|
|
|
- SYNC_USERMAP_PLS = 0x40, /* Request parent to map our users. */
|
|
|
- SYNC_USERMAP_ACK = 0x41, /* Mapping finished by the parent. */
|
|
|
- SYNC_RECVPID_PLS = 0x42, /* Tell parent we're sending the PID. */
|
|
|
- SYNC_RECVPID_ACK = 0x43, /* PID was correctly received by parent. */
|
|
|
- SYNC_GRANDCHILD = 0x44, /* The grandchild is ready to run. */
|
|
|
- SYNC_CHILD_READY = 0x45, /* The child or grandchild is ready to return. */
|
|
|
-
|
|
|
- /* XXX: This doesn't help with segfaults and other such issues. */
|
|
|
- SYNC_ERR = 0xFF, /* Fatal error, no turning back. The error code follows. */
|
|
|
-};
|
|
|
-
|
|
|
-/*
|
|
|
- * Synchronisation value for cgroup namespace setup.
|
|
|
- * The same constant is defined in process_linux.go as "createCgroupns".
|
|
|
- */
|
|
|
-#define CREATECGROUPNS 0x80
|
|
|
-
|
|
|
-/* longjmp() arguments. */
|
|
|
-#define JUMP_PARENT 0x00
|
|
|
-#define JUMP_CHILD 0xA0
|
|
|
-#define JUMP_INIT 0xA1
|
|
|
-
|
|
|
-/* JSON buffer. */
|
|
|
-#define JSON_MAX 4096
|
|
|
-
|
|
|
-/* Assume the stack grows down, so arguments should be above it. */
|
|
|
-struct clone_t {
|
|
|
- /*
|
|
|
- * Reserve some space for clone() to locate arguments
|
|
|
- * and retcode in this place
|
|
|
- */
|
|
|
- char stack[4096] __attribute__ ((aligned(16)));
|
|
|
- char stack_ptr[0];
|
|
|
-
|
|
|
- /* There's two children. This is used to execute the different code. */
|
|
|
- jmp_buf *env;
|
|
|
- int jmpval;
|
|
|
-};
|
|
|
-
|
|
|
-struct nlconfig_t {
|
|
|
- char *data;
|
|
|
-
|
|
|
- /* Process settings. */
|
|
|
- uint32_t cloneflags;
|
|
|
- char *oom_score_adj;
|
|
|
- size_t oom_score_adj_len;
|
|
|
-
|
|
|
- /* User namespace settings. */
|
|
|
- char *uidmap;
|
|
|
- size_t uidmap_len;
|
|
|
- char *gidmap;
|
|
|
- size_t gidmap_len;
|
|
|
- char *namespaces;
|
|
|
- size_t namespaces_len;
|
|
|
- uint8_t is_setgroup;
|
|
|
-
|
|
|
- /* Rootless container settings. */
|
|
|
- uint8_t is_rootless_euid; /* boolean */
|
|
|
- char *uidmappath;
|
|
|
- size_t uidmappath_len;
|
|
|
- char *gidmappath;
|
|
|
- size_t gidmappath_len;
|
|
|
-};
|
|
|
-
|
|
|
-/*
|
|
|
- * List of netlink message types sent to us as part of bootstrapping the init.
|
|
|
- * These constants are defined in libcontainer/message_linux.go.
|
|
|
- */
|
|
|
-#define INIT_MSG 62000
|
|
|
-#define CLONE_FLAGS_ATTR 27281
|
|
|
-#define NS_PATHS_ATTR 27282
|
|
|
-#define UIDMAP_ATTR 27283
|
|
|
-#define GIDMAP_ATTR 27284
|
|
|
-#define SETGROUP_ATTR 27285
|
|
|
-#define OOM_SCORE_ADJ_ATTR 27286
|
|
|
-#define ROOTLESS_EUID_ATTR 27287
|
|
|
-#define UIDMAPPATH_ATTR 27288
|
|
|
-#define GIDMAPPATH_ATTR 27289
|
|
|
-
|
|
|
-/*
|
|
|
- * Use the raw syscall for versions of glibc which don't include a function for
|
|
|
- * it, namely (glibc 2.12).
|
|
|
- */
|
|
|
-#if __GLIBC__ == 2 && __GLIBC_MINOR__ < 14
|
|
|
-# define _GNU_SOURCE
|
|
|
-# include "syscall.h"
|
|
|
-# if !defined(SYS_setns) && defined(__NR_setns)
|
|
|
-# define SYS_setns __NR_setns
|
|
|
-# endif
|
|
|
-
|
|
|
-#ifndef SYS_setns
|
|
|
-# error "setns(2) syscall not supported by glibc version"
|
|
|
-#endif
|
|
|
-
|
|
|
-int setns(int fd, int nstype)
|
|
|
-{
|
|
|
- return syscall(SYS_setns, fd, nstype);
|
|
|
-}
|
|
|
-#endif
|
|
|
-
|
|
|
-/* XXX: This is ugly. */
|
|
|
-static int syncfd = -1;
|
|
|
-
|
|
|
-/* TODO(cyphar): Fix this so it correctly deals with syncT. */
|
|
|
-#define bail(fmt, ...) \
|
|
|
- do { \
|
|
|
- int ret = __COUNTER__ + 1; \
|
|
|
- fprintf(stderr, "nsenter: " fmt ": %m\n", ##__VA_ARGS__); \
|
|
|
- if (syncfd >= 0) { \
|
|
|
- enum sync_t s = SYNC_ERR; \
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) \
|
|
|
- fprintf(stderr, "nsenter: failed: write(s)"); \
|
|
|
- if (write(syncfd, &ret, sizeof(ret)) != sizeof(ret)) \
|
|
|
- fprintf(stderr, "nsenter: failed: write(ret)"); \
|
|
|
- } \
|
|
|
- exit(ret); \
|
|
|
- } while(0)
|
|
|
-
|
|
|
-static int write_file(char *data, size_t data_len, char *pathfmt, ...)
|
|
|
-{
|
|
|
- int fd, len, ret = 0;
|
|
|
- char path[PATH_MAX];
|
|
|
-
|
|
|
- va_list ap;
|
|
|
- va_start(ap, pathfmt);
|
|
|
- len = vsnprintf(path, PATH_MAX, pathfmt, ap);
|
|
|
- va_end(ap);
|
|
|
- if (len < 0)
|
|
|
- return -1;
|
|
|
-
|
|
|
- fd = open(path, O_RDWR);
|
|
|
- if (fd < 0) {
|
|
|
- return -1;
|
|
|
- }
|
|
|
-
|
|
|
- len = write(fd, data, data_len);
|
|
|
- if (len != data_len) {
|
|
|
- ret = -1;
|
|
|
- goto out;
|
|
|
- }
|
|
|
-
|
|
|
- out:
|
|
|
- close(fd);
|
|
|
- return ret;
|
|
|
-}
|
|
|
-
|
|
|
-enum policy_t {
|
|
|
- SETGROUPS_DEFAULT = 0,
|
|
|
- SETGROUPS_ALLOW,
|
|
|
- SETGROUPS_DENY,
|
|
|
-};
|
|
|
-
|
|
|
-/* This *must* be called before we touch gid_map. */
|
|
|
-static void update_setgroups(int pid, enum policy_t setgroup)
|
|
|
-{
|
|
|
- char *policy;
|
|
|
-
|
|
|
- switch (setgroup) {
|
|
|
- case SETGROUPS_ALLOW:
|
|
|
- policy = "allow";
|
|
|
- break;
|
|
|
- case SETGROUPS_DENY:
|
|
|
- policy = "deny";
|
|
|
- break;
|
|
|
- case SETGROUPS_DEFAULT:
|
|
|
- default:
|
|
|
- /* Nothing to do. */
|
|
|
- return;
|
|
|
- }
|
|
|
-
|
|
|
- if (write_file(policy, strlen(policy), "/proc/%d/setgroups", pid) < 0) {
|
|
|
- /*
|
|
|
- * If the kernel is too old to support /proc/pid/setgroups,
|
|
|
- * open(2) or write(2) will return ENOENT. This is fine.
|
|
|
- */
|
|
|
- if (errno != ENOENT)
|
|
|
- bail("failed to write '%s' to /proc/%d/setgroups", policy, pid);
|
|
|
- }
|
|
|
-}
|
|
|
-
|
|
|
-static int try_mapping_tool(const char *app, int pid, char *map, size_t map_len)
|
|
|
-{
|
|
|
- int child;
|
|
|
-
|
|
|
- /*
|
|
|
- * If @app is NULL, execve will segfault. Just check it here and bail (if
|
|
|
- * we're in this path, the caller is already getting desperate and there
|
|
|
- * isn't a backup to this failing). This usually would be a configuration
|
|
|
- * or programming issue.
|
|
|
- */
|
|
|
- if (!app)
|
|
|
- bail("mapping tool not present");
|
|
|
-
|
|
|
- child = fork();
|
|
|
- if (child < 0)
|
|
|
- bail("failed to fork");
|
|
|
-
|
|
|
- if (!child) {
|
|
|
-#define MAX_ARGV 20
|
|
|
- char *argv[MAX_ARGV];
|
|
|
- char *envp[] = { NULL };
|
|
|
- char pid_fmt[16];
|
|
|
- int argc = 0;
|
|
|
- char *next;
|
|
|
-
|
|
|
- snprintf(pid_fmt, 16, "%d", pid);
|
|
|
-
|
|
|
- argv[argc++] = (char *)app;
|
|
|
- argv[argc++] = pid_fmt;
|
|
|
- /*
|
|
|
- * Convert the map string into a list of argument that
|
|
|
- * newuidmap/newgidmap can understand.
|
|
|
- */
|
|
|
-
|
|
|
- while (argc < MAX_ARGV) {
|
|
|
- if (*map == '\0') {
|
|
|
- argv[argc++] = NULL;
|
|
|
- break;
|
|
|
- }
|
|
|
- argv[argc++] = map;
|
|
|
- next = strpbrk(map, "\n ");
|
|
|
- if (next == NULL)
|
|
|
- break;
|
|
|
- *next++ = '\0';
|
|
|
- map = next + strspn(next, "\n ");
|
|
|
- }
|
|
|
-
|
|
|
- execve(app, argv, envp);
|
|
|
- bail("failed to execv");
|
|
|
- } else {
|
|
|
- int status;
|
|
|
-
|
|
|
- while (true) {
|
|
|
- if (waitpid(child, &status, 0) < 0) {
|
|
|
- if (errno == EINTR)
|
|
|
- continue;
|
|
|
- bail("failed to waitpid");
|
|
|
- }
|
|
|
- if (WIFEXITED(status) || WIFSIGNALED(status))
|
|
|
- return WEXITSTATUS(status);
|
|
|
- }
|
|
|
- }
|
|
|
-
|
|
|
- return -1;
|
|
|
-}
|
|
|
-
|
|
|
-static void update_uidmap(const char *path, int pid, char *map, size_t map_len)
|
|
|
-{
|
|
|
- if (map == NULL || map_len <= 0)
|
|
|
- return;
|
|
|
-
|
|
|
- if (write_file(map, map_len, "/proc/%d/uid_map", pid) < 0) {
|
|
|
- if (errno != EPERM)
|
|
|
- bail("failed to update /proc/%d/uid_map", pid);
|
|
|
- if (try_mapping_tool(path, pid, map, map_len))
|
|
|
- bail("failed to use newuid map on %d", pid);
|
|
|
- }
|
|
|
-}
|
|
|
-
|
|
|
-static void update_gidmap(const char *path, int pid, char *map, size_t map_len)
|
|
|
-{
|
|
|
- if (map == NULL || map_len <= 0)
|
|
|
- return;
|
|
|
-
|
|
|
- if (write_file(map, map_len, "/proc/%d/gid_map", pid) < 0) {
|
|
|
- if (errno != EPERM)
|
|
|
- bail("failed to update /proc/%d/gid_map", pid);
|
|
|
- if (try_mapping_tool(path, pid, map, map_len))
|
|
|
- bail("failed to use newgid map on %d", pid);
|
|
|
- }
|
|
|
-}
|
|
|
-
|
|
|
-static void update_oom_score_adj(char *data, size_t len)
|
|
|
-{
|
|
|
- if (data == NULL || len <= 0)
|
|
|
- return;
|
|
|
-
|
|
|
- if (write_file(data, len, "/proc/self/oom_score_adj") < 0)
|
|
|
- bail("failed to update /proc/self/oom_score_adj");
|
|
|
-}
|
|
|
-
|
|
|
-/* A dummy function that just jumps to the given jumpval. */
|
|
|
-static int child_func(void *arg) __attribute__ ((noinline));
|
|
|
-static int child_func(void *arg)
|
|
|
-{
|
|
|
- struct clone_t *ca = (struct clone_t *)arg;
|
|
|
- longjmp(*ca->env, ca->jmpval);
|
|
|
-}
|
|
|
-
|
|
|
-static int clone_parent(jmp_buf *env, int jmpval) __attribute__ ((noinline));
|
|
|
-static int clone_parent(jmp_buf *env, int jmpval)
|
|
|
-{
|
|
|
- struct clone_t ca = {
|
|
|
- .env = env,
|
|
|
- .jmpval = jmpval,
|
|
|
- };
|
|
|
-
|
|
|
- return clone(child_func, ca.stack_ptr, CLONE_PARENT | SIGCHLD, &ca);
|
|
|
-}
|
|
|
-
|
|
|
-/*
|
|
|
- * Gets the init pipe fd from the environment, which is used to read the
|
|
|
- * bootstrap data and tell the parent what the new pid is after we finish
|
|
|
- * setting up the environment.
|
|
|
- */
|
|
|
-static int initpipe(void)
|
|
|
-{
|
|
|
- int pipenum;
|
|
|
- char *initpipe, *endptr;
|
|
|
-
|
|
|
- initpipe = getenv("_LIBCONTAINER_INITPIPE");
|
|
|
- if (initpipe == NULL || *initpipe == '\0')
|
|
|
- return -1;
|
|
|
-
|
|
|
- pipenum = strtol(initpipe, &endptr, 10);
|
|
|
- if (*endptr != '\0')
|
|
|
- bail("unable to parse _LIBCONTAINER_INITPIPE");
|
|
|
-
|
|
|
- return pipenum;
|
|
|
-}
|
|
|
-
|
|
|
-/* Returns the clone(2) flag for a namespace, given the name of a namespace. */
|
|
|
-static int nsflag(char *name)
|
|
|
-{
|
|
|
- if (!strcmp(name, "cgroup"))
|
|
|
- return CLONE_NEWCGROUP;
|
|
|
- else if (!strcmp(name, "ipc"))
|
|
|
- return CLONE_NEWIPC;
|
|
|
- else if (!strcmp(name, "mnt"))
|
|
|
- return CLONE_NEWNS;
|
|
|
- else if (!strcmp(name, "net"))
|
|
|
- return CLONE_NEWNET;
|
|
|
- else if (!strcmp(name, "pid"))
|
|
|
- return CLONE_NEWPID;
|
|
|
- else if (!strcmp(name, "user"))
|
|
|
- return CLONE_NEWUSER;
|
|
|
- else if (!strcmp(name, "uts"))
|
|
|
- return CLONE_NEWUTS;
|
|
|
-
|
|
|
- /* If we don't recognise a name, fallback to 0. */
|
|
|
- return 0;
|
|
|
-}
|
|
|
-
|
|
|
-static uint32_t readint32(char *buf)
|
|
|
-{
|
|
|
- return *(uint32_t *) buf;
|
|
|
-}
|
|
|
-
|
|
|
-static uint8_t readint8(char *buf)
|
|
|
-{
|
|
|
- return *(uint8_t *) buf;
|
|
|
-}
|
|
|
-
|
|
|
-static void nl_parse(int fd, struct nlconfig_t *config)
|
|
|
-{
|
|
|
- size_t len, size;
|
|
|
- struct nlmsghdr hdr;
|
|
|
- char *data, *current;
|
|
|
-
|
|
|
- /* Retrieve the netlink header. */
|
|
|
- len = read(fd, &hdr, NLMSG_HDRLEN);
|
|
|
- if (len != NLMSG_HDRLEN)
|
|
|
- bail("invalid netlink header length %zu", len);
|
|
|
-
|
|
|
- if (hdr.nlmsg_type == NLMSG_ERROR)
|
|
|
- bail("failed to read netlink message");
|
|
|
-
|
|
|
- if (hdr.nlmsg_type != INIT_MSG)
|
|
|
- bail("unexpected msg type %d", hdr.nlmsg_type);
|
|
|
-
|
|
|
- /* Retrieve data. */
|
|
|
- size = NLMSG_PAYLOAD(&hdr, 0);
|
|
|
- current = data = malloc(size);
|
|
|
- if (!data)
|
|
|
- bail("failed to allocate %zu bytes of memory for nl_payload", size);
|
|
|
-
|
|
|
- len = read(fd, data, size);
|
|
|
- if (len != size)
|
|
|
- bail("failed to read netlink payload, %zu != %zu", len, size);
|
|
|
-
|
|
|
- /* Parse the netlink payload. */
|
|
|
- config->data = data;
|
|
|
- while (current < data + size) {
|
|
|
- struct nlattr *nlattr = (struct nlattr *)current;
|
|
|
- size_t payload_len = nlattr->nla_len - NLA_HDRLEN;
|
|
|
-
|
|
|
- /* Advance to payload. */
|
|
|
- current += NLA_HDRLEN;
|
|
|
-
|
|
|
- /* Handle payload. */
|
|
|
- switch (nlattr->nla_type) {
|
|
|
- case CLONE_FLAGS_ATTR:
|
|
|
- config->cloneflags = readint32(current);
|
|
|
- break;
|
|
|
- case ROOTLESS_EUID_ATTR:
|
|
|
- config->is_rootless_euid = readint8(current); /* boolean */
|
|
|
- break;
|
|
|
- case OOM_SCORE_ADJ_ATTR:
|
|
|
- config->oom_score_adj = current;
|
|
|
- config->oom_score_adj_len = payload_len;
|
|
|
- break;
|
|
|
- case NS_PATHS_ATTR:
|
|
|
- config->namespaces = current;
|
|
|
- config->namespaces_len = payload_len;
|
|
|
- break;
|
|
|
- case UIDMAP_ATTR:
|
|
|
- config->uidmap = current;
|
|
|
- config->uidmap_len = payload_len;
|
|
|
- break;
|
|
|
- case GIDMAP_ATTR:
|
|
|
- config->gidmap = current;
|
|
|
- config->gidmap_len = payload_len;
|
|
|
- break;
|
|
|
- case UIDMAPPATH_ATTR:
|
|
|
- config->uidmappath = current;
|
|
|
- config->uidmappath_len = payload_len;
|
|
|
- break;
|
|
|
- case GIDMAPPATH_ATTR:
|
|
|
- config->gidmappath = current;
|
|
|
- config->gidmappath_len = payload_len;
|
|
|
- break;
|
|
|
- case SETGROUP_ATTR:
|
|
|
- config->is_setgroup = readint8(current);
|
|
|
- break;
|
|
|
- default:
|
|
|
- bail("unknown netlink message type %d", nlattr->nla_type);
|
|
|
- }
|
|
|
-
|
|
|
- current += NLA_ALIGN(payload_len);
|
|
|
- }
|
|
|
-}
|
|
|
-
|
|
|
-void nl_free(struct nlconfig_t *config)
|
|
|
-{
|
|
|
- free(config->data);
|
|
|
-}
|
|
|
-
|
|
|
-void join_namespaces(char *nslist)
|
|
|
-{
|
|
|
- int num = 0, i;
|
|
|
- char *saveptr = NULL;
|
|
|
- char *namespace = strtok_r(nslist, ",", &saveptr);
|
|
|
- struct namespace_t {
|
|
|
- int fd;
|
|
|
- int ns;
|
|
|
- char type[PATH_MAX];
|
|
|
- char path[PATH_MAX];
|
|
|
- } *namespaces = NULL;
|
|
|
-
|
|
|
- if (!namespace || !strlen(namespace) || !strlen(nslist))
|
|
|
- bail("ns paths are empty");
|
|
|
-
|
|
|
- /*
|
|
|
- * We have to open the file descriptors first, since after
|
|
|
- * we join the mnt namespace we might no longer be able to
|
|
|
- * access the paths.
|
|
|
- */
|
|
|
- do {
|
|
|
- int fd;
|
|
|
- char *path;
|
|
|
- struct namespace_t *ns;
|
|
|
-
|
|
|
- /* Resize the namespace array. */
|
|
|
- namespaces = realloc(namespaces, ++num * sizeof(struct namespace_t));
|
|
|
- if (!namespaces)
|
|
|
- bail("failed to reallocate namespace array");
|
|
|
- ns = &namespaces[num - 1];
|
|
|
-
|
|
|
- /* Split 'ns:path'. */
|
|
|
- path = strstr(namespace, ":");
|
|
|
- if (!path)
|
|
|
- bail("failed to parse %s", namespace);
|
|
|
- *path++ = '\0';
|
|
|
-
|
|
|
- fd = open(path, O_RDONLY);
|
|
|
- if (fd < 0)
|
|
|
- bail("failed to open %s", path);
|
|
|
-
|
|
|
- ns->fd = fd;
|
|
|
- ns->ns = nsflag(namespace);
|
|
|
- strncpy(ns->path, path, PATH_MAX - 1);
|
|
|
- ns->path[PATH_MAX - 1] = '\0';
|
|
|
- } while ((namespace = strtok_r(NULL, ",", &saveptr)) != NULL);
|
|
|
-
|
|
|
- /*
|
|
|
- * The ordering in which we join namespaces is important. We should
|
|
|
- * always join the user namespace *first*. This is all guaranteed
|
|
|
- * from the container_linux.go side of this, so we're just going to
|
|
|
- * follow the order given to us.
|
|
|
- */
|
|
|
-
|
|
|
- for (i = 0; i < num; i++) {
|
|
|
- struct namespace_t ns = namespaces[i];
|
|
|
-
|
|
|
- if (setns(ns.fd, ns.ns) < 0)
|
|
|
- bail("failed to setns to %s", ns.path);
|
|
|
-
|
|
|
- close(ns.fd);
|
|
|
- }
|
|
|
-
|
|
|
- free(namespaces);
|
|
|
-}
|
|
|
-
|
|
|
-/* Defined in cloned_binary.c. */
|
|
|
-extern int ensure_cloned_binary(void);
|
|
|
-
|
|
|
-void nsexec(void)
|
|
|
-{
|
|
|
- int pipenum;
|
|
|
- jmp_buf env;
|
|
|
- int sync_child_pipe[2], sync_grandchild_pipe[2];
|
|
|
- struct nlconfig_t config = { 0 };
|
|
|
-
|
|
|
- /*
|
|
|
- * If we don't have an init pipe, just return to the go routine.
|
|
|
- * We'll only get an init pipe for start or exec.
|
|
|
- */
|
|
|
- pipenum = initpipe();
|
|
|
- if (pipenum == -1)
|
|
|
- return;
|
|
|
-
|
|
|
- /*
|
|
|
- * We need to re-exec if we are not in a cloned binary. This is necessary
|
|
|
- * to ensure that containers won't be able to access the host binary
|
|
|
- * through /proc/self/exe. See CVE-2019-5736.
|
|
|
- */
|
|
|
- if (ensure_cloned_binary() < 0)
|
|
|
- bail("could not ensure we are a cloned binary");
|
|
|
-
|
|
|
- /* Parse all of the netlink configuration. */
|
|
|
- nl_parse(pipenum, &config);
|
|
|
-
|
|
|
- /* Set oom_score_adj. This has to be done before !dumpable because
|
|
|
- * /proc/self/oom_score_adj is not writeable unless you're an privileged
|
|
|
- * user (if !dumpable is set). All children inherit their parent's
|
|
|
- * oom_score_adj value on fork(2) so this will always be propagated
|
|
|
- * properly.
|
|
|
- */
|
|
|
- update_oom_score_adj(config.oom_score_adj, config.oom_score_adj_len);
|
|
|
-
|
|
|
- /*
|
|
|
- * Make the process non-dumpable, to avoid various race conditions that
|
|
|
- * could cause processes in namespaces we're joining to access host
|
|
|
- * resources (or potentially execute code).
|
|
|
- *
|
|
|
- * However, if the number of namespaces we are joining is 0, we are not
|
|
|
- * going to be switching to a different security context. Thus setting
|
|
|
- * ourselves to be non-dumpable only breaks things (like rootless
|
|
|
- * containers), which is the recommendation from the kernel folks.
|
|
|
- */
|
|
|
- if (config.namespaces) {
|
|
|
- if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) < 0)
|
|
|
- bail("failed to set process as non-dumpable");
|
|
|
- }
|
|
|
-
|
|
|
- /* Pipe so we can tell the child when we've finished setting up. */
|
|
|
- if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sync_child_pipe) < 0)
|
|
|
- bail("failed to setup sync pipe between parent and child");
|
|
|
-
|
|
|
- /*
|
|
|
- * We need a new socketpair to sync with grandchild so we don't have
|
|
|
- * race condition with child.
|
|
|
- */
|
|
|
- if (socketpair(AF_LOCAL, SOCK_STREAM, 0, sync_grandchild_pipe) < 0)
|
|
|
- bail("failed to setup sync pipe between parent and grandchild");
|
|
|
-
|
|
|
- /* TODO: Currently we aren't dealing with child deaths properly. */
|
|
|
-
|
|
|
- /*
|
|
|
- * Okay, so this is quite annoying.
|
|
|
- *
|
|
|
- * In order for this unsharing code to be more extensible we need to split
|
|
|
- * up unshare(CLONE_NEWUSER) and clone() in various ways. The ideal case
|
|
|
- * would be if we did clone(CLONE_NEWUSER) and the other namespaces
|
|
|
- * separately, but because of SELinux issues we cannot really do that. But
|
|
|
- * we cannot just dump the namespace flags into clone(...) because several
|
|
|
- * usecases (such as rootless containers) require more granularity around
|
|
|
- * the namespace setup. In addition, some older kernels had issues where
|
|
|
- * CLONE_NEWUSER wasn't handled before other namespaces (but we cannot
|
|
|
- * handle this while also dealing with SELinux so we choose SELinux support
|
|
|
- * over broken kernel support).
|
|
|
- *
|
|
|
- * However, if we unshare(2) the user namespace *before* we clone(2), then
|
|
|
- * all hell breaks loose.
|
|
|
- *
|
|
|
- * The parent no longer has permissions to do many things (unshare(2) drops
|
|
|
- * all capabilities in your old namespace), and the container cannot be set
|
|
|
- * up to have more than one {uid,gid} mapping. This is obviously less than
|
|
|
- * ideal. In order to fix this, we have to first clone(2) and then unshare.
|
|
|
- *
|
|
|
- * Unfortunately, it's not as simple as that. We have to fork to enter the
|
|
|
- * PID namespace (the PID namespace only applies to children). Since we'll
|
|
|
- * have to double-fork, this clone_parent() call won't be able to get the
|
|
|
- * PID of the _actual_ init process (without doing more synchronisation than
|
|
|
- * I can deal with at the moment). So we'll just get the parent to send it
|
|
|
- * for us, the only job of this process is to update
|
|
|
- * /proc/pid/{setgroups,uid_map,gid_map}.
|
|
|
- *
|
|
|
- * And as a result of the above, we also need to setns(2) in the first child
|
|
|
- * because if we join a PID namespace in the topmost parent then our child
|
|
|
- * will be in that namespace (and it will not be able to give us a PID value
|
|
|
- * that makes sense without resorting to sending things with cmsg).
|
|
|
- *
|
|
|
- * This also deals with an older issue caused by dumping cloneflags into
|
|
|
- * clone(2): On old kernels, CLONE_PARENT didn't work with CLONE_NEWPID, so
|
|
|
- * we have to unshare(2) before clone(2) in order to do this. This was fixed
|
|
|
- * in upstream commit 1f7f4dde5c945f41a7abc2285be43d918029ecc5, and was
|
|
|
- * introduced by 40a0d32d1eaffe6aac7324ca92604b6b3977eb0e. As far as we're
|
|
|
- * aware, the last mainline kernel which had this bug was Linux 3.12.
|
|
|
- * However, we cannot comment on which kernels the broken patch was
|
|
|
- * backported to.
|
|
|
- *
|
|
|
- * -- Aleksa "what has my life come to?" Sarai
|
|
|
- */
|
|
|
-
|
|
|
- switch (setjmp(env)) {
|
|
|
- /*
|
|
|
- * Stage 0: We're in the parent. Our job is just to create a new child
|
|
|
- * (stage 1: JUMP_CHILD) process and write its uid_map and
|
|
|
- * gid_map. That process will go on to create a new process, then
|
|
|
- * it will send us its PID which we will send to the bootstrap
|
|
|
- * process.
|
|
|
- */
|
|
|
- case JUMP_PARENT:{
|
|
|
- int len;
|
|
|
- pid_t child, first_child = -1;
|
|
|
- bool ready = false;
|
|
|
-
|
|
|
- /* For debugging. */
|
|
|
- prctl(PR_SET_NAME, (unsigned long)"runc:[0:PARENT]", 0, 0, 0);
|
|
|
-
|
|
|
- /* Start the process of getting a container. */
|
|
|
- child = clone_parent(&env, JUMP_CHILD);
|
|
|
- if (child < 0)
|
|
|
- bail("unable to fork: child_func");
|
|
|
-
|
|
|
- /*
|
|
|
- * State machine for synchronisation with the children.
|
|
|
- *
|
|
|
- * Father only return when both child and grandchild are
|
|
|
- * ready, so we can receive all possible error codes
|
|
|
- * generated by children.
|
|
|
- */
|
|
|
- while (!ready) {
|
|
|
- enum sync_t s;
|
|
|
- int ret;
|
|
|
-
|
|
|
- syncfd = sync_child_pipe[1];
|
|
|
- close(sync_child_pipe[0]);
|
|
|
-
|
|
|
- if (read(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with child: next state");
|
|
|
-
|
|
|
- switch (s) {
|
|
|
- case SYNC_ERR:
|
|
|
- /* We have to mirror the error code of the child. */
|
|
|
- if (read(syncfd, &ret, sizeof(ret)) != sizeof(ret))
|
|
|
- bail("failed to sync with child: read(error code)");
|
|
|
-
|
|
|
- exit(ret);
|
|
|
- case SYNC_USERMAP_PLS:
|
|
|
- /*
|
|
|
- * Enable setgroups(2) if we've been asked to. But we also
|
|
|
- * have to explicitly disable setgroups(2) if we're
|
|
|
- * creating a rootless container for single-entry mapping.
|
|
|
- * i.e. config.is_setgroup == false.
|
|
|
- * (this is required since Linux 3.19).
|
|
|
- *
|
|
|
- * For rootless multi-entry mapping, config.is_setgroup shall be true and
|
|
|
- * newuidmap/newgidmap shall be used.
|
|
|
- */
|
|
|
-
|
|
|
- if (config.is_rootless_euid && !config.is_setgroup)
|
|
|
- update_setgroups(child, SETGROUPS_DENY);
|
|
|
-
|
|
|
- /* Set up mappings. */
|
|
|
- update_uidmap(config.uidmappath, child, config.uidmap, config.uidmap_len);
|
|
|
- update_gidmap(config.gidmappath, child, config.gidmap, config.gidmap_len);
|
|
|
-
|
|
|
- s = SYNC_USERMAP_ACK;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with child: write(SYNC_USERMAP_ACK)");
|
|
|
- }
|
|
|
- break;
|
|
|
- case SYNC_RECVPID_PLS:{
|
|
|
- first_child = child;
|
|
|
-
|
|
|
- /* Get the init_func pid. */
|
|
|
- if (read(syncfd, &child, sizeof(child)) != sizeof(child)) {
|
|
|
- kill(first_child, SIGKILL);
|
|
|
- bail("failed to sync with child: read(childpid)");
|
|
|
- }
|
|
|
-
|
|
|
- /* Send ACK. */
|
|
|
- s = SYNC_RECVPID_ACK;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(first_child, SIGKILL);
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with child: write(SYNC_RECVPID_ACK)");
|
|
|
- }
|
|
|
-
|
|
|
- /* Send the init_func pid back to our parent.
|
|
|
- *
|
|
|
- * Send the init_func pid and the pid of the first child back to our parent.
|
|
|
- * We need to send both back because we can't reap the first child we created (CLONE_PARENT).
|
|
|
- * It becomes the responsibility of our parent to reap the first child.
|
|
|
- */
|
|
|
- len = dprintf(pipenum, "{\"pid\": %d, \"pid_first\": %d}\n", child, first_child);
|
|
|
- if (len < 0) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("unable to generate JSON for child pid");
|
|
|
- }
|
|
|
- }
|
|
|
- break;
|
|
|
- case SYNC_CHILD_READY:
|
|
|
- ready = true;
|
|
|
- break;
|
|
|
- default:
|
|
|
- bail("unexpected sync value: %u", s);
|
|
|
- }
|
|
|
- }
|
|
|
-
|
|
|
- /* Now sync with grandchild. */
|
|
|
-
|
|
|
- ready = false;
|
|
|
- while (!ready) {
|
|
|
- enum sync_t s;
|
|
|
- int ret;
|
|
|
-
|
|
|
- syncfd = sync_grandchild_pipe[1];
|
|
|
- close(sync_grandchild_pipe[0]);
|
|
|
-
|
|
|
- s = SYNC_GRANDCHILD;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with child: write(SYNC_GRANDCHILD)");
|
|
|
- }
|
|
|
-
|
|
|
- if (read(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with child: next state");
|
|
|
-
|
|
|
- switch (s) {
|
|
|
- case SYNC_ERR:
|
|
|
- /* We have to mirror the error code of the child. */
|
|
|
- if (read(syncfd, &ret, sizeof(ret)) != sizeof(ret))
|
|
|
- bail("failed to sync with child: read(error code)");
|
|
|
-
|
|
|
- exit(ret);
|
|
|
- case SYNC_CHILD_READY:
|
|
|
- ready = true;
|
|
|
- break;
|
|
|
- default:
|
|
|
- bail("unexpected sync value: %u", s);
|
|
|
- }
|
|
|
- }
|
|
|
- exit(0);
|
|
|
- }
|
|
|
-
|
|
|
- /*
|
|
|
- * Stage 1: We're in the first child process. Our job is to join any
|
|
|
- * provided namespaces in the netlink payload and unshare all
|
|
|
- * of the requested namespaces. If we've been asked to
|
|
|
- * CLONE_NEWUSER, we will ask our parent (stage 0) to set up
|
|
|
- * our user mappings for us. Then, we create a new child
|
|
|
- * (stage 2: JUMP_INIT) for PID namespace. We then send the
|
|
|
- * child's PID to our parent (stage 0).
|
|
|
- */
|
|
|
- case JUMP_CHILD:{
|
|
|
- pid_t child;
|
|
|
- enum sync_t s;
|
|
|
-
|
|
|
- /* We're in a child and thus need to tell the parent if we die. */
|
|
|
- syncfd = sync_child_pipe[0];
|
|
|
- close(sync_child_pipe[1]);
|
|
|
-
|
|
|
- /* For debugging. */
|
|
|
- prctl(PR_SET_NAME, (unsigned long)"runc:[1:CHILD]", 0, 0, 0);
|
|
|
-
|
|
|
- /*
|
|
|
- * We need to setns first. We cannot do this earlier (in stage 0)
|
|
|
- * because of the fact that we forked to get here (the PID of
|
|
|
- * [stage 2: JUMP_INIT]) would be meaningless). We could send it
|
|
|
- * using cmsg(3) but that's just annoying.
|
|
|
- */
|
|
|
- if (config.namespaces)
|
|
|
- join_namespaces(config.namespaces);
|
|
|
-
|
|
|
- /*
|
|
|
- * Deal with user namespaces first. They are quite special, as they
|
|
|
- * affect our ability to unshare other namespaces and are used as
|
|
|
- * context for privilege checks.
|
|
|
- *
|
|
|
- * We don't unshare all namespaces in one go. The reason for this
|
|
|
- * is that, while the kernel documentation may claim otherwise,
|
|
|
- * there are certain cases where unsharing all namespaces at once
|
|
|
- * will result in namespace objects being owned incorrectly.
|
|
|
- * Ideally we should just fix these kernel bugs, but it's better to
|
|
|
- * be safe than sorry, and fix them separately.
|
|
|
- *
|
|
|
- * A specific case of this is that the SELinux label of the
|
|
|
- * internal kern-mount that mqueue uses will be incorrect if the
|
|
|
- * UTS namespace is cloned before the USER namespace is mapped.
|
|
|
- * I've also heard of similar problems with the network namespace
|
|
|
- * in some scenarios. This also mirrors how LXC deals with this
|
|
|
- * problem.
|
|
|
- */
|
|
|
- if (config.cloneflags & CLONE_NEWUSER) {
|
|
|
- if (unshare(CLONE_NEWUSER) < 0)
|
|
|
- bail("failed to unshare user namespace");
|
|
|
- config.cloneflags &= ~CLONE_NEWUSER;
|
|
|
-
|
|
|
- /*
|
|
|
- * We don't have the privileges to do any mapping here (see the
|
|
|
- * clone_parent rant). So signal our parent to hook us up.
|
|
|
- */
|
|
|
-
|
|
|
- /* Switching is only necessary if we joined namespaces. */
|
|
|
- if (config.namespaces) {
|
|
|
- if (prctl(PR_SET_DUMPABLE, 1, 0, 0, 0) < 0)
|
|
|
- bail("failed to set process as dumpable");
|
|
|
- }
|
|
|
- s = SYNC_USERMAP_PLS;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with parent: write(SYNC_USERMAP_PLS)");
|
|
|
-
|
|
|
- /* ... wait for mapping ... */
|
|
|
-
|
|
|
- if (read(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with parent: read(SYNC_USERMAP_ACK)");
|
|
|
- if (s != SYNC_USERMAP_ACK)
|
|
|
- bail("failed to sync with parent: SYNC_USERMAP_ACK: got %u", s);
|
|
|
- /* Switching is only necessary if we joined namespaces. */
|
|
|
- if (config.namespaces) {
|
|
|
- if (prctl(PR_SET_DUMPABLE, 0, 0, 0, 0) < 0)
|
|
|
- bail("failed to set process as dumpable");
|
|
|
- }
|
|
|
-
|
|
|
- /* Become root in the namespace proper. */
|
|
|
- if (setresuid(0, 0, 0) < 0)
|
|
|
- bail("failed to become root in user namespace");
|
|
|
- }
|
|
|
- /*
|
|
|
- * Unshare all of the namespaces. Now, it should be noted that this
|
|
|
- * ordering might break in the future (especially with rootless
|
|
|
- * containers). But for now, it's not possible to split this into
|
|
|
- * CLONE_NEWUSER + [the rest] because of some RHEL SELinux issues.
|
|
|
- *
|
|
|
- * Note that we don't merge this with clone() because there were
|
|
|
- * some old kernel versions where clone(CLONE_PARENT | CLONE_NEWPID)
|
|
|
- * was broken, so we'll just do it the long way anyway.
|
|
|
- */
|
|
|
- if (unshare(config.cloneflags & ~CLONE_NEWCGROUP) < 0)
|
|
|
- bail("failed to unshare namespaces");
|
|
|
-
|
|
|
- /*
|
|
|
- * TODO: What about non-namespace clone flags that we're dropping here?
|
|
|
- *
|
|
|
- * We fork again because of PID namespace, setns(2) or unshare(2) don't
|
|
|
- * change the PID namespace of the calling process, because doing so
|
|
|
- * would change the caller's idea of its own PID (as reported by getpid()),
|
|
|
- * which would break many applications and libraries, so we must fork
|
|
|
- * to actually enter the new PID namespace.
|
|
|
- */
|
|
|
- child = clone_parent(&env, JUMP_INIT);
|
|
|
- if (child < 0)
|
|
|
- bail("unable to fork: init_func");
|
|
|
-
|
|
|
- /* Send the child to our parent, which knows what it's doing. */
|
|
|
- s = SYNC_RECVPID_PLS;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with parent: write(SYNC_RECVPID_PLS)");
|
|
|
- }
|
|
|
- if (write(syncfd, &child, sizeof(child)) != sizeof(child)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with parent: write(childpid)");
|
|
|
- }
|
|
|
-
|
|
|
- /* ... wait for parent to get the pid ... */
|
|
|
-
|
|
|
- if (read(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with parent: read(SYNC_RECVPID_ACK)");
|
|
|
- }
|
|
|
- if (s != SYNC_RECVPID_ACK) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with parent: SYNC_RECVPID_ACK: got %u", s);
|
|
|
- }
|
|
|
-
|
|
|
- s = SYNC_CHILD_READY;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s)) {
|
|
|
- kill(child, SIGKILL);
|
|
|
- bail("failed to sync with parent: write(SYNC_CHILD_READY)");
|
|
|
- }
|
|
|
-
|
|
|
- /* Our work is done. [Stage 2: JUMP_INIT] is doing the rest of the work. */
|
|
|
- exit(0);
|
|
|
- }
|
|
|
-
|
|
|
- /*
|
|
|
- * Stage 2: We're the final child process, and the only process that will
|
|
|
- * actually return to the Go runtime. Our job is to just do the
|
|
|
- * final cleanup steps and then return to the Go runtime to allow
|
|
|
- * init_linux.go to run.
|
|
|
- */
|
|
|
- case JUMP_INIT:{
|
|
|
- /*
|
|
|
- * We're inside the child now, having jumped from the
|
|
|
- * start_child() code after forking in the parent.
|
|
|
- */
|
|
|
- enum sync_t s;
|
|
|
-
|
|
|
- /* We're in a child and thus need to tell the parent if we die. */
|
|
|
- syncfd = sync_grandchild_pipe[0];
|
|
|
- close(sync_grandchild_pipe[1]);
|
|
|
- close(sync_child_pipe[0]);
|
|
|
- close(sync_child_pipe[1]);
|
|
|
-
|
|
|
- /* For debugging. */
|
|
|
- prctl(PR_SET_NAME, (unsigned long)"runc:[2:INIT]", 0, 0, 0);
|
|
|
-
|
|
|
- if (read(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with parent: read(SYNC_GRANDCHILD)");
|
|
|
- if (s != SYNC_GRANDCHILD)
|
|
|
- bail("failed to sync with parent: SYNC_GRANDCHILD: got %u", s);
|
|
|
-
|
|
|
- if (setsid() < 0)
|
|
|
- bail("setsid failed");
|
|
|
-
|
|
|
- if (setuid(0) < 0)
|
|
|
- bail("setuid failed");
|
|
|
-
|
|
|
- if (setgid(0) < 0)
|
|
|
- bail("setgid failed");
|
|
|
-
|
|
|
- if (!config.is_rootless_euid && config.is_setgroup) {
|
|
|
- if (setgroups(0, NULL) < 0)
|
|
|
- bail("setgroups failed");
|
|
|
- }
|
|
|
-
|
|
|
- /* ... wait until our topmost parent has finished cgroup setup in p.manager.Apply() ... */
|
|
|
- if (config.cloneflags & CLONE_NEWCGROUP) {
|
|
|
- uint8_t value;
|
|
|
- if (read(pipenum, &value, sizeof(value)) != sizeof(value))
|
|
|
- bail("read synchronisation value failed");
|
|
|
- if (value == CREATECGROUPNS) {
|
|
|
- if (unshare(CLONE_NEWCGROUP) < 0)
|
|
|
- bail("failed to unshare cgroup namespace");
|
|
|
- } else
|
|
|
- bail("received unknown synchronisation value");
|
|
|
- }
|
|
|
-
|
|
|
- s = SYNC_CHILD_READY;
|
|
|
- if (write(syncfd, &s, sizeof(s)) != sizeof(s))
|
|
|
- bail("failed to sync with patent: write(SYNC_CHILD_READY)");
|
|
|
-
|
|
|
- /* Close sync pipes. */
|
|
|
- close(sync_grandchild_pipe[0]);
|
|
|
-
|
|
|
- /* Free netlink data. */
|
|
|
- nl_free(&config);
|
|
|
-
|
|
|
- /* Finish executing, let the Go runtime take over. */
|
|
|
- return;
|
|
|
- }
|
|
|
- default:
|
|
|
- bail("unexpected jump value");
|
|
|
- }
|
|
|
-
|
|
|
- /* Should never be reached. */
|
|
|
- bail("should never be reached");
|
|
|
-}
|