diff options
Diffstat (limited to 'src/nspawn/nspawn-mount.c')
| -rw-r--r-- | src/nspawn/nspawn-mount.c | 191 |
1 files changed, 174 insertions, 17 deletions
diff --git a/src/nspawn/nspawn-mount.c b/src/nspawn/nspawn-mount.c index 85e2c943e3..803caef3dd 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"); } @@ -762,12 +916,15 @@ int mount_cgroups( const char *dest, bool unified_requested, bool userns, uid_t uid_shift, uid_t uid_range, - const char *selinux_apifs_context) { + const char *selinux_apifs_context, + bool use_cgns) { if (unified_requested) return mount_unified_cgroups(dest); - else - return mount_legacy_cgroups(dest, userns, uid_shift, uid_range, selinux_apifs_context); + else if (use_cgns && 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 +992,7 @@ 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 +1028,7 @@ 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) |