Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 118 insertions, 0 deletions

diff --git a/src/systemctl/systemctl-switch-root.c b/src/systemctl/systemctl-switch-root.c
new file mode 100644
index 0000000..ae4a1a7
--- /dev/null
+++ b/src/systemctl/systemctl-switch-root.c
@@ -0,0 +1,118 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "argv-util.h"
+#include "bus-error.h"
+#include "bus-locator.h"
+#include "chase.h"
+#include "fd-util.h"
+#include "initrd-util.h"
+#include "parse-util.h"
+#include "path-util.h"
+#include "proc-cmdline.h"
+#include "signal-util.h"
+#include "stat-util.h"
+#include "systemctl.h"
+#include "systemctl-switch-root.h"
+#include "systemctl-util.h"
+
+static int same_file_in_root(
+                const char *root,
+                const char *a,
+                const char *b) {
+
+        struct stat sta, stb;
+        int r;
+
+        r = chase_and_stat(a, root, CHASE_PREFIX_ROOT, NULL, &sta);
+        if (r < 0)
+                return r;
+
+        r = chase_and_stat(b, root, CHASE_PREFIX_ROOT, NULL, &stb);
+        if (r < 0)
+                return r;
+
+        return stat_inode_same(&sta, &stb);
+}
+
+int verb_switch_root(int argc, char *argv[], void *userdata) {
+        _cleanup_(sd_bus_error_free) sd_bus_error error = SD_BUS_ERROR_NULL;
+        _cleanup_free_ char *cmdline_init = NULL;
+        const char *root, *init;
+        sd_bus *bus;
+        int r;
+
+        if (arg_transport != BUS_TRANSPORT_LOCAL)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Cannot switch root remotely.");
+
+        if (argc > 3)
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Too many arguments.");
+
+        if (argc >= 2) {
+                root = argv[1];
+
+                if (!path_is_valid(root))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid root path: %s", root);
+
+                if (!path_is_absolute(root))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Root path is not absolute: %s", root);
+
+                r = path_is_root(root);
+                if (r < 0)
+                        return log_error_errno(r, "Failed to check if switch-root directory '%s' is current root: %m", root);
+                if (r > 0)
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Cannot switch to current root directory: %s", root);
+        } else
+                root = "/sysroot";
+
+        if (!in_initrd())
+                return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Not in initrd, refusing switch-root operation.");
+
+        if (argc >= 3)
+                init = argv[2];
+        else {
+                r = proc_cmdline_get_key("init", 0, &cmdline_init);
+                if (r < 0)
+                        log_debug_errno(r, "Failed to parse /proc/cmdline: %m");
+
+                init = cmdline_init;
+        }
+
+        init = empty_to_null(init);
+        if (init) {
+                if (!path_is_valid(init))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Invalid path to init binary: %s", init);
+                if (!path_is_absolute(init))
+                        return log_error_errno(SYNTHETIC_ERRNO(EINVAL), "Path to init binary is not absolute: %s", init);
+
+                /* If the passed init is actually the same as the systemd binary, then let's suppress it. */
+                if (same_file_in_root(root, SYSTEMD_BINARY_PATH, init) > 0)
+                        init = NULL;
+        }
+
+        /* Instruct PID1 to exclude us from its killing spree applied during the transition. Otherwise we
+         * would exit with a failure status even though the switch to the new root has succeed. */
+        assert(saved_argv);
+        assert(saved_argv[0]);
+        saved_argv[0][0] = '@';
+
+        r = acquire_bus(BUS_MANAGER, &bus);
+        if (r < 0)
+                return r;
+
+        /* If we are slow to exit after the root switch, the new systemd instance will send us a signal to
+         * terminate. Just ignore it and exit normally.  This way the unit does not end up as failed. */
+        r = ignore_signals(SIGTERM);
+        if (r < 0)
+                log_warning_errno(r, "Failed to change disposition of SIGTERM to ignore: %m");
+
+        log_debug("Switching root - root: %s; init: %s", root, strna(init));
+
+        r = bus_call_method(bus, bus_systemd_mgr, "SwitchRoot", &error, NULL, "ss", root, init);
+        if (r < 0) {
+                (void) default_signals(SIGTERM);
+
+                return log_error_errno(r, "Failed to switch root: %s", bus_error_message(&error, r));
+        }
+
+        return 0;
+}