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nspawn: add new --tmpfs= option to mount a tmpfs on specific directories, such as /var

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This commit is contained in:
Lennart Poettering 2014-06-11 00:44:30 +02:00
parent 9339db7187
commit 06c17c39a8
2 changed files with 105 additions and 13 deletions
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24
man/systemd-nspawn.xml
View File

@ -503,6 +503,30 @@
mounts.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--tmpfs=</option></term>
<listitem><para>Mount a tmpfs file
system into the container. Takes a
single absolute path argument that
specifies where to mount the tmpfs
instance to (in which case the
directory access mode will be chosen
as 0755, owned by root/root), or
optionally a colon-separated pair of
path and mount option string, that is
used for mounting (in which case the
kernel default for access mode and
owner will be chosen, unless otherwise
specified). This option is
particularly useful for mounting
directories such as
<filename>/var</filename> as tmpfs, to
allow state-less systems, in
particular when combined with
<option>--read-only</option>.</para></listitem>
</varlistentry>
<varlistentry>
<term><option>--setenv=</option></term>

94
src/nspawn/nspawn.c
View File

@ -146,6 +146,7 @@ static uint64_t arg_retain =
(1ULL << CAP_MKNOD);
static char **arg_bind = NULL;
static char **arg_bind_ro = NULL;
static char **arg_tmpfs = NULL;
static char **arg_setenv = NULL;
static bool arg_quiet = false;
static bool arg_share_system = false;
@ -200,6 +201,7 @@ static int help(void) {
" --bind=PATH[:PATH] Bind mount a file or directory from the host into\n"
" the container\n"
" --bind-ro=PATH[:PATH] Similar, but creates a read-only bind mount\n"
" --tmpfs=PATH:[OPTIONS] Mount an empty tmpfs to the specified directory\n"
" --setenv=NAME=VALUE Pass an environment variable to PID 1\n"
" --share-system Share system namespaces with host\n"
" --register=BOOLEAN Register container as machine\n"
@ -222,6 +224,7 @@ static int parse_argv(int argc, char *argv[]) {
ARG_LINK_JOURNAL,
ARG_BIND,
ARG_BIND_RO,
ARG_TMPFS,
ARG_SETENV,
ARG_SHARE_SYSTEM,
ARG_REGISTER,
@ -247,6 +250,7 @@ static int parse_argv(int argc, char *argv[]) {
{ "link-journal", required_argument, NULL, ARG_LINK_JOURNAL },
{ "bind", required_argument, NULL, ARG_BIND },
{ "bind-ro", required_argument, NULL, ARG_BIND_RO },
{ "tmpfs", required_argument, NULL, ARG_TMPFS },
{ "machine", required_argument, NULL, 'M' },
{ "slice", required_argument, NULL, 'S' },
{ "setenv", required_argument, NULL, ARG_SETENV },
@ -469,6 +473,42 @@ static int parse_argv(int argc, char *argv[]) {
break;
}
case ARG_TMPFS: {
_cleanup_free_ char *a = NULL, *b = NULL;
char *e;
e = strchr(optarg, ':');
if (e) {
a = strndup(optarg, e - optarg);
b = strdup(e + 1);
} else {
a = strdup(optarg);
b = strdup("mode=0755");
}
if (!a || !b)
return log_oom();
if (!path_is_absolute(a)) {
log_error("Invalid tmpfs specification: %s", optarg);
return -EINVAL;
}
r = strv_push(&arg_tmpfs, a);
if (r < 0)
return log_oom();
a = NULL;
r = strv_push(&arg_tmpfs, b);
if (r < 0)
return log_oom();
b = NULL;
break;
}
case ARG_SETENV: {
char **n;
@ -561,17 +601,17 @@ 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", NULL, NULL, MS_BIND, true }, /* Bind mount first */
{ NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
{ "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
{ "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, true },
{ "proc", "/proc", "proc", NULL, MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
{ "/proc/sys", "/proc/sys", NULL, NULL, MS_BIND, true }, /* Bind mount first */
{ NULL, "/proc/sys", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, true }, /* Then, make it r/o */
{ "sysfs", "/sys", "sysfs", NULL, MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV, true },
{ "tmpfs", "/dev", "tmpfs", "mode=755", MS_NOSUID|MS_STRICTATIME, true },
{ "devpts", "/dev/pts", "devpts","newinstance,ptmxmode=0666,mode=620,gid=" STRINGIFY(TTY_GID), MS_NOSUID|MS_NOEXEC, true },
{ "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
{ "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
{ "tmpfs", "/dev/shm", "tmpfs", "mode=1777", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
{ "tmpfs", "/run", "tmpfs", "mode=755", MS_NOSUID|MS_NODEV|MS_STRICTATIME, true },
#ifdef HAVE_SELINUX
{ "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, false }, /* Bind mount first */
{ NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */
{ "/sys/fs/selinux", "/sys/fs/selinux", NULL, NULL, MS_BIND, false }, /* Bind mount first */
{ NULL, "/sys/fs/selinux", NULL, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, false }, /* Then, make it r/o */
#endif
};
@ -640,7 +680,7 @@ static int mount_binds(const char *dest, char **l, bool ro) {
char **x, **y;
STRV_FOREACH_PAIR(x, y, l) {
char *where;
_cleanup_free_ char *where = NULL;
struct stat source_st, dest_st;
int r;
@ -649,12 +689,14 @@ static int mount_binds(const char *dest, char **l, bool ro) {
return -errno;
}
where = strappenda(dest, *y);
where = strappend(dest, *y);
if (!where)
return log_oom();
r = stat(where, &dest_st);
if (r == 0) {
if ((source_st.st_mode & S_IFMT) != (dest_st.st_mode & S_IFMT)) {
log_error("The file types of %s and %s do not match. Refusing bind mount",
*x, where);
log_error("The file types of %s and %s do not match. Refusing bind mount", *x, where);
return -EINVAL;
}
} else if (errno == ENOENT) {
@ -667,6 +709,7 @@ static int mount_binds(const char *dest, char **l, bool ro) {
log_error("Failed to bind mount %s: %m", *x);
return -errno;
}
/* Create the mount point, but be conservative -- refuse to create block
* and char devices. */
if (S_ISDIR(source_st.st_mode))
@ -699,6 +742,27 @@ static int mount_binds(const char *dest, char **l, bool ro) {
return 0;
}
static int mount_tmpfs(const char *dest) {
char **i, **o;
STRV_FOREACH_PAIR(i, o, arg_tmpfs) {
_cleanup_free_ char *where = NULL;
where = strappend(dest, *i);
if (!where)
return log_oom();
mkdir_label(where, 0755);
if (mount("tmpfs", where, "tmpfs", MS_NODEV|MS_STRICTATIME, *o) < 0) {
log_error("tmpfs mount to %s failed: %m", where);
return -errno;
}
}
return 0;
}
static int setup_timezone(const char *dest) {
_cleanup_free_ char *where = NULL, *p = NULL, *q = NULL, *check = NULL, *what = NULL;
char *z, *y;
@ -2998,6 +3062,9 @@ int main(int argc, char *argv[]) {
if (mount_binds(arg_directory, arg_bind_ro, true) < 0)
goto child_fail;
if (mount_tmpfs(arg_directory) < 0)
goto child_fail;
if (setup_kdbus(arg_directory, kdbus_domain) < 0)
goto child_fail;
@ -3248,6 +3315,7 @@ finish:
strv_free(arg_network_macvlan);
strv_free(arg_bind);
strv_free(arg_bind_ro);
strv_free(arg_tmpfs);
return r;
}