X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fnspawn.c;h=653d7db730a80361b08a2b002415c0cb2e6fcaa6;hb=2096e009a790073a934f5cd07d17024d3b199d0b;hp=f8a190097ae1d0f1433a88833988f2a5b4837d71;hpb=a258bf2648fa5e3005b96203c60b9751807bacf0;p=elogind.git diff --git a/src/nspawn.c b/src/nspawn.c index f8a190097..653d7db73 100644 --- a/src/nspawn.c +++ b/src/nspawn.c @@ -36,6 +36,8 @@ #include #include #include +#include +#include #include "log.h" #include "util.h" @@ -43,15 +45,20 @@ #include "cgroup-util.h" #include "sd-daemon.h" #include "strv.h" +#include "loopback-setup.h" static char *arg_directory = NULL; +static char *arg_user = NULL; +static bool arg_private_network = false; static int help(void) { printf("%s [OPTIONS...] [PATH] [ARGUMENTS...]\n\n" "Spawn a minimal namespace container for debugging, testing and building.\n\n" " -h --help Show this help\n" - " -D --directory=NAME Root directory for the container\n", + " -D --directory=NAME Root directory for the container\n" + " -u --user=USER Run the command under specified user or uid\n" + " --private-network Disable network in container\n", program_invocation_short_name); return 0; @@ -59,10 +66,16 @@ static int help(void) { static int parse_argv(int argc, char *argv[]) { + enum { + ARG_PRIVATE_NETWORK = 0x100 + }; + static const struct option options[] = { - { "help", no_argument, NULL, 'h' }, - { "directory", required_argument, NULL, 'D' }, - { NULL, 0, NULL, 0 } + { "help", no_argument, NULL, 'h' }, + { "directory", required_argument, NULL, 'D' }, + { "user", required_argument, NULL, 'u' }, + { "private-network", no_argument, NULL, ARG_PRIVATE_NETWORK }, + { NULL, 0, NULL, 0 } }; int c; @@ -70,7 +83,7 @@ static int parse_argv(int argc, char *argv[]) { assert(argc >= 0); assert(argv); - while ((c = getopt_long(argc, argv, "+hD:", options, NULL)) >= 0) { + while ((c = getopt_long(argc, argv, "+hD:u:", options, NULL)) >= 0) { switch (c) { @@ -87,6 +100,19 @@ static int parse_argv(int argc, char *argv[]) { break; + case 'u': + free(arg_user); + if (!(arg_user = strdup(optarg))) { + log_error("Failed to duplicate user name."); + return -ENOMEM; + } + + break; + + case ARG_PRIVATE_NETWORK: + arg_private_network = true; + break; + case '?': return -EINVAL; @@ -111,23 +137,25 @@ static int mount_all(const char *dest) { } MountPoint; static const MountPoint mount_table[] = { - { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, - { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */ - { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */ - { "sysfs", "/sys", "sysfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, true }, - { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID, true }, - { "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND, true }, - { "tmpfs", "/dev/.run", "tmpfs", "mode=755", MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true }, + { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */ + { "/proc/sys", "/proc/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */ + { "/sys", "/sys", "bind", NULL, MS_BIND, true }, /* Bind mount first */ + { "/sys", "/sys", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */ + { "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID, true }, + { "/dev/pts", "/dev/pts", "bind", NULL, MS_BIND, true }, + { "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV, true }, #ifdef HAVE_SELINUX - { "selinux", "/selinux", "selinuxfs", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_RDONLY, false }, + { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND, false }, /* Bind mount first */ + { "/sys/fs/selinux", "/sys/fs/selinux", "bind", NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */ #endif }; unsigned k; int r = 0; + char *where; for (k = 0; k < ELEMENTSOF(mount_table); k++) { - char *where; int t; if (asprintf(&where, "%s/%s", dest, mount_table[k].where) < 0) { @@ -139,7 +167,7 @@ static int mount_all(const char *dest) { break; } - if ((t = path_is_mount_point(where)) < 0) { + if ((t = path_is_mount_point(where, false)) < 0) { log_error("Failed to detect whether %s is a mount point: %s", where, strerror(-t)); free(where); @@ -167,6 +195,15 @@ static int mount_all(const char *dest) { free(where); } + /* Fix the timezone, if possible */ + if (asprintf(&where, "%s/%s", dest, "/etc/localtime") >= 0) { + + if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0) + mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL); + + free(where); + } + return r; } @@ -292,7 +329,6 @@ static int copy_devnodes(const char *dest, const char *console) { } finish: - umask(u); return r; @@ -325,7 +361,7 @@ static int drop_capabilities(void) { unsigned long l; - for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l ++) { + for (l = 0; l <= cap_last_cap(); l++) { unsigned i; for (i = 0; i < ELEMENTSOF(retain); i++) @@ -336,12 +372,6 @@ static int drop_capabilities(void) { continue; if (prctl(PR_CAPBSET_DROP, l) < 0) { - - /* If this capability is not known, EINVAL - * will be returned, let's ignore this. */ - if (errno == EINVAL) - continue; - log_error("PR_CAPBSET_DROP failed: %m"); return -errno; } @@ -367,11 +397,11 @@ static int is_os_tree(const char *path) { #define BUFFER_SIZE 1024 static int process_pty(int master, sigset_t *mask) { + char in_buffer[BUFFER_SIZE], out_buffer[BUFFER_SIZE]; size_t in_buffer_full = 0, out_buffer_full = 0; struct epoll_event stdin_ev, stdout_ev, master_ev, signal_ev; bool stdin_readable = false, stdout_writable = false, master_readable = false, master_writable = false; - bool stdin_rhup = false, stdout_whup = false, master_rhup = false, master_whup = false; int ep = -1, signal_fd = -1, r; fd_nonblock(STDIN_FILENO, 1); @@ -415,7 +445,7 @@ static int process_pty(int master, sigset_t *mask) { goto finish; } - do { + for (;;) { struct epoll_event ev[16]; ssize_t k; int i, nfds; @@ -435,30 +465,20 @@ static int process_pty(int master, sigset_t *mask) { for (i = 0; i < nfds; i++) { if (ev[i].data.fd == STDIN_FILENO) { - if (!stdin_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) + if (ev[i].events & (EPOLLIN|EPOLLHUP)) stdin_readable = true; } else if (ev[i].data.fd == STDOUT_FILENO) { - if (ev[i].events & EPOLLHUP) { - stdout_writable = false; - stdout_whup = true; - } - - if (!stdout_whup && (ev[i].events & EPOLLOUT)) + if (ev[i].events & (EPOLLOUT|EPOLLHUP)) stdout_writable = true; } else if (ev[i].data.fd == master) { - /* We don't connect EPOLLHUP to - * master_whup here, since EPOLLHUP - * can happen when noone has opened - * the other side */ - - if (!master_rhup && (ev[i].events & (EPOLLHUP|EPOLLIN))) + if (ev[i].events & (EPOLLIN|EPOLLHUP)) master_readable = true; - if (!master_whup && (ev[i].events & EPOLLOUT)) + if (ev[i].events & (EPOLLOUT|EPOLLHUP)) master_writable = true; } else if (ev[i].data.fd == signal_fd) { @@ -468,11 +488,13 @@ static int process_pty(int master, sigset_t *mask) { if ((n = read(signal_fd, &sfsi, sizeof(sfsi))) != sizeof(sfsi)) { if (n >= 0) { + log_error("Failed to read from signalfd: invalid block size"); r = -EIO; goto finish; } if (errno != EINTR && errno != EAGAIN) { + log_error("Failed to read from signalfd: %m"); r = -errno; goto finish; } @@ -482,11 +504,10 @@ static int process_pty(int master, sigset_t *mask) { struct winsize ws; /* The window size changed, let's forward that. */ - if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) >= 0) ioctl(master, TIOCSWINSZ, &ws); } else { - r = -EINTR; + r = 0; goto finish; } } @@ -502,35 +523,26 @@ static int process_pty(int master, sigset_t *mask) { if ((k = read(STDIN_FILENO, in_buffer + in_buffer_full, BUFFER_SIZE - in_buffer_full)) < 0) { - if (errno == EAGAIN) + if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO) stdin_readable = false; - else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) - k = 0; else { log_error("read(): %m"); + r = -errno; goto finish; } } else in_buffer_full += (size_t) k; - - if (k == 0) { - stdin_rhup = true; - stdin_readable = false; - shutdown(STDIN_FILENO, SHUT_RD); - } } if (master_writable && in_buffer_full > 0) { if ((k = write(master, in_buffer, in_buffer_full)) < 0) { - if (errno == EAGAIN) + if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO) master_writable = false; - else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) { - master_whup = true; - master_writable = false; - } else { + else { log_error("write(): %m"); + r = -errno; goto finish; } @@ -545,34 +557,26 @@ static int process_pty(int master, sigset_t *mask) { if ((k = read(master, out_buffer + out_buffer_full, BUFFER_SIZE - out_buffer_full)) < 0) { - if (errno == EAGAIN) + if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO) master_readable = false; - else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) - k = 0; else { log_error("read(): %m"); + r = -errno; goto finish; } } else out_buffer_full += (size_t) k; - - if (k == 0) { - master_rhup = true; - master_readable = false; - } } if (stdout_writable && out_buffer_full > 0) { if ((k = write(STDOUT_FILENO, out_buffer, out_buffer_full)) < 0) { - if (errno == EAGAIN) + if (errno == EAGAIN || errno == EPIPE || errno == ECONNRESET || errno == EIO) stdout_writable = false; - else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) { - stdout_whup = true; - stdout_writable = false; - } else { + else { log_error("write(): %m"); + r = -errno; goto finish; } @@ -583,19 +587,7 @@ static int process_pty(int master, sigset_t *mask) { } } } - - if (stdin_rhup && in_buffer_full <= 0 && !master_whup) { - master_whup = true; - master_writable = false; - } - - if (master_rhup && out_buffer_full <= 0 && !stdout_whup) { - stdout_whup = true; - stdout_writable = false; - shutdown(STDOUT_FILENO, SHUT_WR); - } - - } while (!stdout_whup || !master_whup); + } finish: if (ep >= 0) @@ -715,7 +707,7 @@ int main(int argc, char *argv[]) { sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1); assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0); - if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS, NULL)) < 0) { + if ((pid = syscall(__NR_clone, SIGCHLD|CLONE_NEWIPC|CLONE_NEWNS|CLONE_NEWPID|CLONE_NEWUTS|(arg_private_network ? CLONE_NEWNET : 0), NULL)) < 0) { log_error("clone() failed: %m"); goto finish; } @@ -724,10 +716,16 @@ int main(int argc, char *argv[]) { /* child */ const char *hn; + const char *home = NULL; + uid_t uid = (uid_t) -1; + gid_t gid = (gid_t) -1; const char *envp[] = { - "HOME=/root", "PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin", - NULL, + "container=systemd-nspawn", /* LXC sets container=lxc, so follow the scheme here */ + NULL, /* TERM */ + NULL, /* HOME */ + NULL, /* USER */ + NULL, /* LOGNAME */ NULL }; @@ -752,6 +750,10 @@ int main(int argc, char *argv[]) { if (prctl(PR_SET_PDEATHSIG, SIGKILL) < 0) goto child_fail; + /* Mark / as private, in case somebody marked it shared */ + if (mount(NULL, "/", NULL, MS_PRIVATE|MS_REC, NULL) < 0) + goto child_fail; + if (mount_all(arg_directory) < 0) goto child_fail; @@ -783,18 +785,60 @@ int main(int argc, char *argv[]) { goto child_fail; } - umask(0002); + umask(0022); + + loopback_setup(); if (drop_capabilities() < 0) goto child_fail; + if (arg_user) { + + if (get_user_creds((const char**)&arg_user, &uid, &gid, &home) < 0) { + log_error("get_user_creds() failed: %m"); + goto child_fail; + } + + if (mkdir_parents(home, 0775) < 0) { + log_error("mkdir_parents() failed: %m"); + goto child_fail; + } + + if (safe_mkdir(home, 0775, uid, gid) < 0) { + log_error("safe_mkdir() failed: %m"); + goto child_fail; + } + + if (initgroups((const char*)arg_user, gid) < 0) { + log_error("initgroups() failed: %m"); + goto child_fail; + } + + if (setresgid(gid, gid, gid) < 0) { + log_error("setregid() failed: %m"); + goto child_fail; + } + + if (setresuid(uid, uid, uid) < 0) { + log_error("setreuid() failed: %m"); + goto child_fail; + } + } + + if ((asprintf((char**)(envp + 3), "HOME=%s", home? home: "/root") < 0) || + (asprintf((char**)(envp + 4), "USER=%s", arg_user? arg_user : "root") < 0) || + (asprintf((char**)(envp + 5), "LOGNAME=%s", arg_user? arg_user : "root") < 0)) { + log_error("Out of memory"); + goto child_fail; + } + if ((hn = file_name_from_path(arg_directory))) sethostname(hn, strlen(hn)); if (argc > optind) execvpe(argv[optind], argv + optind, (char**) envp); else { - chdir("/root"); + chdir(home ? home : "/root"); execle("/bin/bash", "-bash", NULL, (char**) envp); }