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-rw-r--r--src/core/namespace.c232
1 files changed, 181 insertions, 51 deletions
diff --git a/src/core/namespace.c b/src/core/namespace.c
index b453f8dc09..092e08f72c 100644
--- a/src/core/namespace.c
+++ b/src/core/namespace.c
@@ -30,6 +30,7 @@
#include <sys/syscall.h>
#include <limits.h>
#include <linux/fs.h>
+#include <sys/file.h>
#include "strv.h"
#include "util.h"
@@ -37,6 +38,7 @@
#include "namespace.h"
#include "missing.h"
#include "execute.h"
+#include "loopback-setup.h"
typedef enum MountMode {
/* This is ordered by priority! */
@@ -57,6 +59,8 @@ typedef struct BindMount {
static int append_mounts(BindMount **p, char **strv, MountMode mode) {
char **i;
+ assert(p);
+
STRV_FOREACH(i, strv) {
(*p)->ignore = false;
@@ -184,68 +188,50 @@ static int make_read_only(BindMount *m) {
return 0;
}
-int setup_tmpdirs(const char *unit_id,
- char **tmp_dir,
- char **var_tmp_dir) {
- int r = 0;
- _cleanup_free_ char *tmp = NULL, *var = NULL;
-
- assert(tmp_dir);
- assert(var_tmp_dir);
-
- tmp = strjoin("/tmp/systemd-", unit_id, "-XXXXXXX", NULL);
- var = strjoin("/var/tmp/systemd-", unit_id, "-XXXXXXX", NULL);
-
- r = create_tmp_dir(tmp, tmp_dir);
- if (r < 0)
- return r;
-
- r = create_tmp_dir(var, var_tmp_dir);
- if (r == 0)
- return 0;
+int setup_namespace(
+ char** read_write_dirs,
+ char** read_only_dirs,
+ char** inaccessible_dirs,
+ char* tmp_dir,
+ char* var_tmp_dir,
+ unsigned mount_flags) {
- /* failure */
- rmdir(*tmp_dir);
- rmdir(tmp);
- free(*tmp_dir);
- *tmp_dir = NULL;
-
- return r;
-}
-
-int setup_namespace(char** read_write_dirs,
- char** read_only_dirs,
- char** inaccessible_dirs,
- char* tmp_dir,
- char* var_tmp_dir,
- bool private_tmp,
- unsigned mount_flags) {
-
- unsigned n = strv_length(read_write_dirs) +
- strv_length(read_only_dirs) +
- strv_length(inaccessible_dirs) +
- (private_tmp ? 2 : 0);
BindMount *m, *mounts = NULL;
+ unsigned n;
int r = 0;
- if (!mount_flags)
+ if (mount_flags == 0)
mount_flags = MS_SHARED;
if (unshare(CLONE_NEWNS) < 0)
return -errno;
- if (n) {
+ n = !!tmp_dir + !!var_tmp_dir +
+ strv_length(read_write_dirs) +
+ strv_length(read_only_dirs) +
+ strv_length(inaccessible_dirs);
+
+ if (n > 0) {
m = mounts = (BindMount *) alloca(n * sizeof(BindMount));
- if ((r = append_mounts(&m, read_write_dirs, READWRITE)) < 0 ||
- (r = append_mounts(&m, read_only_dirs, READONLY)) < 0 ||
- (r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE)) < 0)
+ r = append_mounts(&m, read_write_dirs, READWRITE);
+ if (r < 0)
+ return r;
+
+ r = append_mounts(&m, read_only_dirs, READONLY);
+ if (r < 0)
+ return r;
+
+ r = append_mounts(&m, inaccessible_dirs, INACCESSIBLE);
+ if (r < 0)
return r;
- if (private_tmp) {
+ if (tmp_dir) {
m->path = "/tmp";
m->mode = PRIVATE_TMP;
m++;
+ }
+ if (var_tmp_dir) {
m->path = "/var/tmp";
m->mode = PRIVATE_VAR_TMP;
m++;
@@ -265,28 +251,172 @@ int setup_namespace(char** read_write_dirs,
for (m = mounts; m < mounts + n; ++m) {
r = apply_mount(m, tmp_dir, var_tmp_dir);
if (r < 0)
- goto undo_mounts;
+ goto fail;
}
for (m = mounts; m < mounts + n; ++m) {
r = make_read_only(m);
if (r < 0)
- goto undo_mounts;
+ goto fail;
}
/* Remount / as the desired mode */
if (mount(NULL, "/", NULL, mount_flags | MS_REC, NULL) < 0) {
r = -errno;
- goto undo_mounts;
+ goto fail;
}
return 0;
-undo_mounts:
- for (m = mounts; m < mounts + n; ++m) {
+fail:
+ for (m = mounts; m < mounts + n; ++m)
if (m->done)
umount2(m->path, MNT_DETACH);
+
+ return r;
+}
+
+static int setup_one_tmp_dir(const char *id, const char *prefix, char **path) {
+ _cleanup_free_ char *x = NULL;
+
+ assert(id);
+ assert(prefix);
+ assert(path);
+
+ x = strjoin(prefix, "/systemd-", id, "-XXXXXX", NULL);
+ if (!x)
+ return -ENOMEM;
+
+ RUN_WITH_UMASK(0077)
+ if (!mkdtemp(x))
+ return -errno;
+
+ RUN_WITH_UMASK(0000) {
+ char *y;
+
+ y = strappenda(x, "/tmp");
+
+ if (mkdir(y, 0777 | S_ISVTX) < 0)
+ return -errno;
}
+ *path = x;
+ x = NULL;
+
+ return 0;
+}
+
+int setup_tmp_dirs(const char *id, char **tmp_dir, char **var_tmp_dir) {
+ char *a, *b;
+ int r;
+
+ assert(id);
+ assert(tmp_dir);
+ assert(var_tmp_dir);
+
+ r = setup_one_tmp_dir(id, "/tmp", &a);
+ if (r < 0)
+ return r;
+
+ r = setup_one_tmp_dir(id, "/var/tmp", &b);
+ if (r < 0) {
+ char *t;
+
+ t = strappenda(a, "/tmp");
+ rmdir(t);
+ rmdir(a);
+
+ free(a);
+ return r;
+ }
+
+ *tmp_dir = a;
+ *var_tmp_dir = b;
+
+ return 0;
+}
+
+int setup_netns(int netns_storage_socket[2]) {
+ _cleanup_close_ int netns = -1;
+ union {
+ struct cmsghdr cmsghdr;
+ uint8_t buf[CMSG_SPACE(sizeof(int))];
+ } control = {};
+ struct msghdr mh = {
+ .msg_control = &control,
+ .msg_controllen = sizeof(control),
+ };
+ struct cmsghdr *cmsg;
+ int r;
+
+ assert(netns_storage_socket);
+ assert(netns_storage_socket[0] >= 0);
+ assert(netns_storage_socket[1] >= 0);
+
+ /* We use the passed socketpair as a storage buffer for our
+ * namespace socket. Whatever process runs this first shall
+ * create a new namespace, all others should just join it. To
+ * serialize that we use a file lock on the socket pair.
+ *
+ * It's a bit crazy, but hey, works great! */
+
+ if (lockf(netns_storage_socket[0], F_LOCK, 0) < 0)
+ return -errno;
+
+ if (recvmsg(netns_storage_socket[0], &mh, MSG_DONTWAIT|MSG_CMSG_CLOEXEC) < 0) {
+ if (errno != EAGAIN) {
+ r = -errno;
+ goto fail;
+ }
+
+ /* Nothing stored yet, so let's create a new namespace */
+
+ if (unshare(CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ loopback_setup();
+
+ netns = open("/proc/self/ns/net", O_RDONLY|O_CLOEXEC|O_NOCTTY);
+ if (netns < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 1;
+ } else {
+ /* Yay, found something, so let's join the namespace */
+
+ for (cmsg = CMSG_FIRSTHDR(&mh); cmsg; cmsg = CMSG_NXTHDR(&mh, cmsg)) {
+ if (cmsg->cmsg_level == SOL_SOCKET && cmsg->cmsg_type == SCM_RIGHTS) {
+ assert(cmsg->cmsg_len == CMSG_LEN(sizeof(int)));
+ netns = *(int*) CMSG_DATA(cmsg);
+ }
+ }
+
+ if (setns(netns, CLONE_NEWNET) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+ r = 0;
+ }
+
+ 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), &netns, sizeof(int));
+ mh.msg_controllen = cmsg->cmsg_len;
+
+ if (sendmsg(netns_storage_socket[1], &mh, MSG_DONTWAIT|MSG_NOSIGNAL) < 0) {
+ r = -errno;
+ goto fail;
+ }
+
+fail:
+ lockf(netns_storage_socket[0], F_ULOCK, 0);
+
return r;
}
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-11-24 17:54:44 +0000