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nspawn: fake /dev/kmsg and /proc/kmsg as fifo

This commit is contained in:
Lennart Poettering 2012-04-13 16:51:33 +02:00
parent a417efcd33
commit e58a12770c
2 changed files with 174 additions and 59 deletions
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1
src/journal/journald.c
View File

@ -2479,7 +2479,6 @@ static int open_proc_kmsg(Server *s) {
if (!s->import_proc_kmsg)
return 0;
s->proc_kmsg_fd = open("/proc/kmsg", O_RDONLY|O_CLOEXEC|O_NONBLOCK|O_NOCTTY);
if (s->proc_kmsg_fd < 0) {
log_warning("Failed to open /proc/kmsg, ignoring: %m");

232
src/nspawn/nspawn.c
View File

@ -213,32 +213,39 @@ static int mount_all(const char *dest) {
free(where);
}
/* Fix the timezone, if possible */
if (asprintf(&where, "%s/etc/localtime", dest) >= 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);
}
if (asprintf(&where, "%s/etc/timezone", dest) >= 0) {
if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
}
if (asprintf(&where, "%s/proc/kmsg", dest) >= 0) {
mount("/dev/null", where, "bind", MS_BIND, NULL);
free(where);
}
return r;
}
static int copy_devnodes(const char *dest, const char *console) {
static int setup_timezone(const char *dest) {
char *where;
assert(dest);
/* Fix the timezone, if possible */
if (asprintf(&where, "%s/etc/localtime", dest) < 0) {
log_error("Out of memory");
return -ENOMEM;
}
if (mount("/etc/localtime", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/localtime", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
if (asprintf(&where, "%s/etc/timezone", dest) < 0) {
log_error("Out of memory");
return -ENOMEM;
}
if (mount("/etc/timezone", where, "bind", MS_BIND, NULL) >= 0)
mount("/etc/timezone", where, "bind", MS_BIND|MS_REMOUNT|MS_RDONLY, NULL);
free(where);
return 0;
}
static int copy_devnodes(const char *dest) {
static const char devnodes[] =
"null\0"
@ -248,22 +255,19 @@ static int copy_devnodes(const char *dest, const char *console) {
"urandom\0"
"tty\0"
"ptmx\0"
"kmsg\0"
"rtc0\0";
const char *d;
int r = 0, k;
int r = 0;
mode_t u;
struct stat st;
char *from = NULL, *to = NULL;
assert(dest);
assert(console);
u = umask(0000);
NULSTR_FOREACH(d, devnodes) {
from = to = NULL;
struct stat st;
char *from = NULL, *to = NULL;
asprintf(&from, "/dev/%s", d);
asprintf(&to, "%s/dev/%s", dest, d);
@ -307,30 +311,43 @@ static int copy_devnodes(const char *dest, const char *console) {
free(to);
}
umask(u);
return r;
}
static int setup_dev_console(const char *dest, const char *console) {
struct stat st;
char *to = NULL;
int r;
mode_t u;
assert(dest);
assert(console);
u = umask(0000);
if (stat(console, &st) < 0) {
log_error("Failed to stat %s: %m", console);
if (r == 0)
r = -errno;
r = -errno;
goto finish;
} else if (!S_ISCHR(st.st_mode)) {
log_error("/dev/console is not a char device.");
if (r == 0)
r = -EIO;
r = -EIO;
goto finish;
}
r = chmod_and_chown(console, 0600, 0, 0);
if (r < 0) {
log_error("Failed to correct access mode for TTY: %s", strerror(-r));
goto finish;
}
if (asprintf(&to, "%s/dev/console", dest) < 0) {
log_error("Out of memory");
if (r == 0)
r = -ENOMEM;
goto finish;
r = -ENOMEM;
goto finish;
}
/* We need to bind mount the right tty to /dev/console since
@ -340,26 +357,106 @@ static int copy_devnodes(const char *dest, const char *console) {
* doesn't actually matter here, since we mount it over
* anyway). */
if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0)
log_error("mknod for /dev/console failed: %m");
if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
log_error("bind mount for /dev/console failed: %m");
if (r == 0)
r = -errno;
if (mknod(to, (st.st_mode & ~07777) | 0600, st.st_rdev) < 0) {
log_error("mknod() for /dev/console failed: %m");
r = -errno;
goto finish;
}
free(to);
if ((k = chmod_and_chown(console, 0600, 0, 0)) < 0) {
log_error("Failed to correct access mode for TTY: %s", strerror(-k));
if (r == 0)
r = k;
if (mount(console, to, "bind", MS_BIND, NULL) < 0) {
log_error("Bind mount for /dev/console failed: %m");
r = -errno;
goto finish;
}
finish:
free(to);
umask(u);
return r;
}
static int setup_kmsg(const char *dest, int kmsg_socket) {
char *from = NULL, *to = NULL;
int r, fd, k;
mode_t u;
union {
struct cmsghdr cmsghdr;
uint8_t buf[CMSG_SPACE(sizeof(int))];
} control;
struct msghdr mh;
struct cmsghdr *cmsg;
assert(dest);
assert(kmsg_socket >= 0);
u = umask(0000);
if (asprintf(&from, "%s/dev/kmsg", dest) < 0) {
log_error("Out of memory");
r = -ENOMEM;
goto finish;
}
if (asprintf(&to, "%s/proc/kmsg", dest) < 0) {
log_error("Out of memory");
r = -ENOMEM;
goto finish;
}
if (mkfifo(from, 0600) < 0) {
log_error("mkfifo() for /dev/kmsg failed: %m");
r = -errno;
goto finish;
}
r = chmod_and_chown(from, 0600, 0, 0);
if (r < 0) {
log_error("Failed to correct access mode for /dev/kmsg: %s", strerror(-r));
goto finish;
}
if (mount(from, to, "bind", MS_BIND, NULL) < 0) {
log_error("Bind mount for /proc/kmsg failed: %m");
r = -errno;
goto finish;
}
fd = open(from, O_RDWR|O_NDELAY|O_CLOEXEC);
if (fd < 0) {
log_error("Failed to open fifo: %m");
r = -errno;
goto finish;
}
zero(mh);
zero(control);
mh.msg_control = &control;
mh.msg_controllen = sizeof(control);
cmsg = CMSG_FIRSTHDR(&mh);
cmsg->cmsg_level = SOL_SOCKET;
cmsg->cmsg_type = SCM_RIGHTS;
cmsg->cmsg_len = CMSG_LEN(sizeof(int));
memcpy(CMSG_DATA(cmsg), &fd, sizeof(int));
mh.msg_controllen = cmsg->cmsg_len;
/* Store away the fd in the socket, so that it stays open as
* long as we run the child */
k = sendmsg(kmsg_socket, &mh, MSG_DONTWAIT|MSG_NOSIGNAL);
close_nointr_nofail(fd);
if (k < 0) {
log_error("Failed to send FIFO fd: %m");
r = -errno;
goto finish;
}
finish:
free(from);
free(to);
umask(u);
return r;
@ -639,6 +736,7 @@ int main(int argc, char *argv[]) {
sigset_t mask;
bool saved_attr_valid = false;
struct winsize ws;
int kmsg_socket_pair[2] = { -1, -1 };
log_parse_environment();
log_open();
@ -740,6 +838,11 @@ int main(int argc, char *argv[]) {
goto finish;
}
if (socketpair(AF_UNIX, SOCK_DGRAM|SOCK_NONBLOCK|SOCK_CLOEXEC, 0, kmsg_socket_pair) < 0) {
log_error("Failed to create kmsg socket pair");
goto finish;
}
assert_se(sigemptyset(&mask) == 0);
sigset_add_many(&mask, SIGCHLD, SIGWINCH, SIGTERM, SIGINT, -1);
assert_se(sigprocmask(SIG_BLOCK, &mask, NULL) == 0);
@ -779,7 +882,7 @@ int main(int argc, char *argv[]) {
close_nointr(STDOUT_FILENO);
close_nointr(STDERR_FILENO);
close_all_fds(NULL, 0);
close_all_fds(&kmsg_socket_pair[1], 1);
reset_all_signal_handlers();
@ -799,7 +902,18 @@ int main(int argc, char *argv[]) {
if (mount_all(arg_directory) < 0)
goto child_fail;
if (copy_devnodes(arg_directory, console) < 0)
if (copy_devnodes(arg_directory) < 0)
goto child_fail;
if (setup_dev_console(arg_directory, console) < 0)
goto child_fail;
if (setup_kmsg(arg_directory, kmsg_socket_pair[1]) < 0)
goto child_fail;
close_nointr_nofail(kmsg_socket_pair[1]);
if (setup_timezone(arg_directory) < 0)
goto child_fail;
if (chdir(arg_directory) < 0) {
@ -910,6 +1024,8 @@ finish:
if (master >= 0)
close_nointr_nofail(master);
close_pipe(kmsg_socket_pair);
if (oldcg)
cg_attach(SYSTEMD_CGROUP_CONTROLLER, oldcg, 0);