diff options
Diffstat (limited to '')
| -rw-r--r-- | src/systemctl/systemctl-switch-root.c | 118 |
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; +} |