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-rw-r--r--src/basic/cgroup-util.c14
-rw-r--r--src/basic/cgroup-util.h2
-rw-r--r--src/basic/missing.h4
-rw-r--r--src/nspawn/nspawn-mount.c188
-rw-r--r--src/nspawn/nspawn.c41
5 files changed, 221 insertions, 28 deletions
diff --git a/src/basic/cgroup-util.c b/src/basic/cgroup-util.c
index 472e24b7a3..302b958d0d 100644
--- a/src/basic/cgroup-util.c
+++ b/src/basic/cgroup-util.c
@@ -134,6 +134,20 @@ int cg_read_event(const char *controller, const char *path, const char *event,
return -ENOENT;
}
+bool cg_ns_supported(void) {
+ static thread_local int enabled = -1;
+
+ if (enabled >= 0)
+ return enabled;
+
+ if (access("/proc/self/ns/cgroup", F_OK) == 0)
+ enabled = 1;
+ else
+ enabled = 0;
+
+ return enabled;
+}
+
int cg_enumerate_subgroups(const char *controller, const char *path, DIR **_d) {
_cleanup_free_ char *fs = NULL;
int r;
diff --git a/src/basic/cgroup-util.h b/src/basic/cgroup-util.h
index 14ebde5fc9..ec5c715987 100644
--- a/src/basic/cgroup-util.h
+++ b/src/basic/cgroup-util.h
@@ -222,6 +222,8 @@ int cg_mask_supported(CGroupMask *ret);
int cg_kernel_controllers(Set *controllers);
+bool cg_ns_supported(void);
+
int cg_unified(void);
void cg_unified_flush(void);
diff --git a/src/basic/missing.h b/src/basic/missing.h
index b1272f8799..f8e096605e 100644
--- a/src/basic/missing.h
+++ b/src/basic/missing.h
@@ -445,6 +445,10 @@ struct btrfs_ioctl_quota_ctl_args {
#define CGROUP2_SUPER_MAGIC 0x63677270
#endif
+#ifndef CLONE_NEWCGROUP
+#define CLONE_NEWCGROUP 0x02000000
+#endif
+
#ifndef TMPFS_MAGIC
#define TMPFS_MAGIC 0x01021994
#endif
diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c
index 85e2c943e3..ac93357ef4 100644
--- a/src/nspawn/nspawn-mount.c
+++ b/src/nspawn/nspawn-mount.c
@@ -23,6 +23,8 @@
#include "alloc-util.h"
#include "cgroup-util.h"
#include "escape.h"
+#include "fd-util.h"
+#include "fileio.h"
#include "fs-util.h"
#include "label.h"
#include "mkdir.h"
@@ -181,13 +183,15 @@ int tmpfs_mount_parse(CustomMount **l, unsigned *n, const char *s) {
static int tmpfs_patch_options(
const char *options,
- bool userns, uid_t uid_shift, uid_t uid_range,
+ bool userns,
+ uid_t uid_shift, uid_t uid_range,
+ bool patch_ids,
const char *selinux_apifs_context,
char **ret) {
char *buf = NULL;
- if (userns && uid_shift != 0) {
+ if ((userns && uid_shift != 0) || patch_ids) {
assert(uid_shift != UID_INVALID);
if (options)
@@ -218,7 +222,13 @@ static int tmpfs_patch_options(
}
#endif
+ if (!buf && options) {
+ buf = strdup(options);
+ if (!buf)
+ return -ENOMEM;
+ }
*ret = buf;
+
return !!buf;
}
@@ -271,7 +281,15 @@ int mount_sysfs(const char *dest) {
return log_error_errno(errno, "Failed to remove %s: %m", full);
x = prefix_roota(top, "/fs/kdbus");
- (void) mkdir(x, 0755);
+ (void) mkdir_p(x, 0755);
+
+ /* Create mountpoint for cgroups. Otherwise we are not allowed since we
+ * remount /sys read-only.
+ */
+ if (cg_ns_supported()) {
+ x = prefix_roota(top, "/fs/cgroup");
+ (void) mkdir_p(x, 0755);
+ }
if (mount(NULL, top, NULL, MS_BIND|MS_RDONLY|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_REMOUNT, NULL) < 0)
return log_error_errno(errno, "Failed to make %s read-only: %m", top);
@@ -349,7 +367,7 @@ int mount_all(const char *dest,
o = mount_table[k].options;
if (streq_ptr(mount_table[k].type, "tmpfs")) {
- r = tmpfs_patch_options(o, use_userns, uid_shift, uid_range, selinux_apifs_context, &options);
+ r = tmpfs_patch_options(o, use_userns, uid_shift, uid_range, false, selinux_apifs_context, &options);
if (r < 0)
return log_oom();
if (r > 0)
@@ -486,7 +504,7 @@ static int mount_tmpfs(
if (r < 0 && r != -EEXIST)
return log_error_errno(r, "Creating mount point for tmpfs %s failed: %m", where);
- r = tmpfs_patch_options(m->options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+ r = tmpfs_patch_options(m->options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf);
if (r < 0)
return log_oom();
options = r > 0 ? buf : m->options;
@@ -601,6 +619,48 @@ int mount_custom(
return 0;
}
+/* Retrieve existing subsystems. This function is called in a new cgroup
+ * namespace.
+ */
+static int get_controllers(Set *subsystems) {
+ _cleanup_fclose_ FILE *f = NULL;
+ char line[LINE_MAX];
+
+ assert(subsystems);
+
+ f = fopen("/proc/self/cgroup", "re");
+ if (!f)
+ return errno == ENOENT ? -ESRCH : -errno;
+
+ FOREACH_LINE(line, f, return -errno) {
+ int r;
+ char *e, *l, *p;
+
+ truncate_nl(line);
+
+ l = strchr(line, ':');
+ if (!l)
+ continue;
+
+ l++;
+ e = strchr(l, ':');
+ if (!e)
+ continue;
+
+ *e = 0;
+
+ if (streq(l, "") || streq(l, "name=systemd"))
+ continue;
+
+ p = strdup(l);
+ r = set_consume(subsystems, p);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controller, const char *hierarchy, bool read_only) {
char *to;
int r;
@@ -629,11 +689,107 @@ static int mount_legacy_cgroup_hierarchy(const char *dest, const char *controlle
return 1;
}
-static int mount_legacy_cgroups(
- const char *dest,
+/* Mount a legacy cgroup hierarchy when cgroup namespaces are supported. */
+static int mount_legacy_cgns_supported(
bool userns, uid_t uid_shift, uid_t uid_range,
const char *selinux_apifs_context) {
+ _cleanup_set_free_free_ Set *controllers = NULL;
+ const char *cgroup_root = "/sys/fs/cgroup", *c;
+ int r;
+ (void) mkdir_p(cgroup_root, 0755);
+
+ /* Mount a tmpfs to /sys/fs/cgroup if it's not mounted there yet. */
+ r = path_is_mount_point(cgroup_root, AT_SYMLINK_FOLLOW);
+ if (r < 0)
+ return log_error_errno(r, "Failed to determine if /sys/fs/cgroup is already mounted: %m");
+ if (r == 0) {
+ _cleanup_free_ char *options = NULL;
+
+ /* When cgroup namespaces are enabled and user namespaces are
+ * used then the mount of the cgroupfs is done *inside* the new
+ * user namespace. We're root in the new user namespace and the
+ * kernel will happily translate our uid/gid to the correct
+ * uid/gid as seen from e.g. /proc/1/mountinfo. So we simply
+ * pass uid 0 and not uid_shift to tmpfs_patch_options().
+ */
+ r = tmpfs_patch_options("mode=755", userns, 0, uid_range, true, selinux_apifs_context, &options);
+ if (r < 0)
+ return log_oom();
+
+ if (mount("tmpfs", cgroup_root, "tmpfs", MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME, options) < 0)
+ return log_error_errno(errno, "Failed to mount /sys/fs/cgroup: %m");
+ }
+
+ if (cg_unified() > 0)
+ goto skip_controllers;
+
+ controllers = set_new(&string_hash_ops);
+ if (!controllers)
+ return log_oom();
+
+ r = get_controllers(controllers);
+ if (r < 0)
+ return log_error_errno(r, "Failed to determine cgroup controllers: %m");
+
+ for (;;) {
+ _cleanup_free_ const char *controller = NULL;
+
+ controller = set_steal_first(controllers);
+ if (!controller)
+ break;
+
+ r = mount_legacy_cgroup_hierarchy("", controller, controller, !userns);
+ if (r < 0)
+ return r;
+
+ /* When multiple hierarchies are co-mounted, make their
+ * constituting individual hierarchies a symlink to the
+ * co-mount.
+ */
+ c = controller;
+ for (;;) {
+ _cleanup_free_ char *target = NULL, *tok = NULL;
+
+ r = extract_first_word(&c, &tok, ",", 0);
+ if (r < 0)
+ return log_error_errno(r, "Failed to extract co-mounted cgroup controller: %m");
+ if (r == 0)
+ break;
+
+ target = prefix_root("/sys/fs/cgroup", tok);
+ if (!target)
+ return log_oom();
+
+ if (streq(controller, tok))
+ break;
+
+ r = symlink_idempotent(controller, target);
+ if (r == -EINVAL)
+ return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m");
+ if (r < 0)
+ return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m");
+ }
+ }
+
+skip_controllers:
+ r = mount_legacy_cgroup_hierarchy("", "none,name=systemd,xattr", "systemd", false);
+ if (r < 0)
+ return r;
+
+ if (!userns) {
+ if (mount(NULL, cgroup_root, NULL, MS_REMOUNT|MS_NOSUID|MS_NOEXEC|MS_NODEV|MS_STRICTATIME|MS_RDONLY, "mode=755") < 0)
+ return log_error_errno(errno, "Failed to remount %s read-only: %m", cgroup_root);
+ }
+
+ return 0;
+}
+
+/* Mount legacy cgroup hierarchy when cgroup namespaces are unsupported. */
+static int mount_legacy_cgns_unsupported(
+ const char *dest,
+ bool userns, uid_t uid_shift, uid_t uid_range,
+ const char *selinux_apifs_context) {
_cleanup_set_free_free_ Set *controllers = NULL;
const char *cgroup_root;
int r;
@@ -649,7 +805,7 @@ static int mount_legacy_cgroups(
if (r == 0) {
_cleanup_free_ char *options = NULL;
- r = tmpfs_patch_options("mode=755", userns, uid_shift, uid_range, selinux_apifs_context, &options);
+ r = tmpfs_patch_options("mode=755", userns, uid_shift, uid_range, false, selinux_apifs_context, &options);
if (r < 0)
return log_oom();
@@ -708,10 +864,8 @@ static int mount_legacy_cgroups(
return r;
r = symlink_idempotent(combined, target);
- if (r == -EINVAL) {
- log_error("Invalid existing symlink for combined hierarchy");
- return r;
- }
+ if (r == -EINVAL)
+ return log_error_errno(r, "Invalid existing symlink for combined hierarchy: %m");
if (r < 0)
return log_error_errno(r, "Failed to create symlink for combined hierarchy: %m");
}
@@ -766,8 +920,10 @@ int mount_cgroups(
if (unified_requested)
return mount_unified_cgroups(dest);
- else
- return mount_legacy_cgroups(dest, userns, uid_shift, uid_range, selinux_apifs_context);
+ else if (cg_ns_supported())
+ return mount_legacy_cgns_supported(userns, uid_shift, uid_range, selinux_apifs_context);
+
+ return mount_legacy_cgns_unsupported(dest, userns, uid_shift, uid_range, selinux_apifs_context);
}
int mount_systemd_cgroup_writable(
@@ -835,7 +991,7 @@ int setup_volatile_state(
return log_error_errno(errno, "Failed to create %s: %m", directory);
options = "mode=755";
- r = tmpfs_patch_options(options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+ r = tmpfs_patch_options(options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf);
if (r < 0)
return log_oom();
if (r > 0)
@@ -871,7 +1027,7 @@ int setup_volatile(
return log_error_errno(errno, "Failed to create temporary directory: %m");
options = "mode=755";
- r = tmpfs_patch_options(options, userns, uid_shift, uid_range, selinux_apifs_context, &buf);
+ r = tmpfs_patch_options(options, userns, uid_shift, uid_range, false, selinux_apifs_context, &buf);
if (r < 0)
return log_oom();
if (r > 0)
diff --git a/src/nspawn/nspawn.c b/src/nspawn/nspawn.c
index b1c012a9e4..d5093a6d17 100644
--- a/src/nspawn/nspawn.c
+++ b/src/nspawn/nspawn.c
@@ -2589,9 +2589,24 @@ static int inner_child(
return -ESRCH;
}
- r = mount_systemd_cgroup_writable("", arg_unified_cgroup_hierarchy);
- if (r < 0)
- return r;
+ if (cg_ns_supported()) {
+ r = unshare(CLONE_NEWCGROUP);
+ if (r < 0)
+ return log_error_errno(errno, "Failed to unshare cgroup namespace");
+ r = mount_cgroups(
+ "",
+ arg_unified_cgroup_hierarchy,
+ arg_userns_mode != USER_NAMESPACE_NO,
+ arg_uid_shift,
+ arg_uid_range,
+ arg_selinux_apifs_context);
+ if (r < 0)
+ return r;
+ } else {
+ r = mount_systemd_cgroup_writable("", arg_unified_cgroup_hierarchy);
+ if (r < 0)
+ return r;
+ }
r = reset_uid_gid();
if (r < 0)
@@ -2973,15 +2988,17 @@ static int outer_child(
if (r < 0)
return r;
- r = mount_cgroups(
- directory,
- arg_unified_cgroup_hierarchy,
- arg_userns_mode != USER_NAMESPACE_NO,
- arg_uid_shift,
- arg_uid_range,
- arg_selinux_apifs_context);
- if (r < 0)
- return r;
+ if (!cg_ns_supported()) {
+ r = mount_cgroups(
+ directory,
+ arg_unified_cgroup_hierarchy,
+ arg_userns_mode != USER_NAMESPACE_NO,
+ arg_uid_shift,
+ arg_uid_range,
+ arg_selinux_apifs_context);
+ if (r < 0)
+ return r;
+ }
r = mount_move_root(directory);
if (r < 0)
generated by cgit v1.2.3-54-g00ecf (git 2.45.2) at 2024-12-03 00:11:00 +0000