diff options
Diffstat (limited to 'src/veritysetup/veritysetup-generator.c')
| -rw-r--r-- | src/veritysetup/veritysetup-generator.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/src/veritysetup/veritysetup-generator.c b/src/veritysetup/veritysetup-generator.c new file mode 100644 index 0000000..7c807c8 --- /dev/null +++ b/src/veritysetup/veritysetup-generator.c @@ -0,0 +1,230 @@ +/* SPDX-License-Identifier: LGPL-2.1-or-later */ + +#include <errno.h> +#include <stdbool.h> +#include <stdlib.h> +#include <sys/stat.h> +#include <unistd.h> + +#include "alloc-util.h" +#include "fd-util.h" +#include "fileio.h" +#include "fstab-util.h" +#include "generator.h" +#include "hexdecoct.h" +#include "id128-util.h" +#include "main-func.h" +#include "mkdir.h" +#include "parse-util.h" +#include "path-util.h" +#include "proc-cmdline.h" +#include "specifier.h" +#include "string-util.h" +#include "unit-name.h" + +#define SYSTEMD_VERITYSETUP_SERVICE "systemd-veritysetup@root.service" + +static const char *arg_dest = NULL; +static bool arg_enabled = true; +static char *arg_root_hash = NULL; +static char *arg_data_what = NULL; +static char *arg_hash_what = NULL; + +STATIC_DESTRUCTOR_REGISTER(arg_root_hash, freep); +STATIC_DESTRUCTOR_REGISTER(arg_data_what, freep); +STATIC_DESTRUCTOR_REGISTER(arg_hash_what, freep); + +static int create_device(void) { + _cleanup_free_ char *u = NULL, *v = NULL, *d = NULL, *e = NULL, *u_escaped = NULL, *v_escaped = NULL, *root_hash_escaped = NULL; + _cleanup_fclose_ FILE *f = NULL; + const char *to; + int r; + + /* If all three pieces of information are missing, then verity is turned off */ + if (!arg_root_hash && !arg_data_what && !arg_hash_what) + return 0; + + /* if one of them is missing however, the data is simply incomplete and this is an error */ + if (!arg_root_hash) + log_error("Verity information incomplete, root hash unspecified."); + if (!arg_data_what) + log_error("Verity information incomplete, root data device unspecified."); + if (!arg_hash_what) + log_error("Verity information incomplete, root hash device unspecified."); + + if (!arg_root_hash || !arg_data_what || !arg_hash_what) + return -EINVAL; + + log_debug("Using root verity data device %s,\n" + " hash device %s,\n" + " and root hash %s.", arg_data_what, arg_hash_what, arg_root_hash); + + u = fstab_node_to_udev_node(arg_data_what); + if (!u) + return log_oom(); + v = fstab_node_to_udev_node(arg_hash_what); + if (!v) + return log_oom(); + + u_escaped = specifier_escape(u); + if (!u_escaped) + return log_oom(); + v_escaped = specifier_escape(v); + if (!v_escaped) + return log_oom(); + + r = unit_name_from_path(u, ".device", &d); + if (r < 0) + return log_error_errno(r, "Failed to generate unit name: %m"); + r = unit_name_from_path(v, ".device", &e); + if (r < 0) + return log_error_errno(r, "Failed to generate unit name: %m"); + + root_hash_escaped = specifier_escape(arg_root_hash); + if (!root_hash_escaped) + return log_oom(); + + r = generator_open_unit_file(arg_dest, NULL, SYSTEMD_VERITYSETUP_SERVICE, &f); + if (r < 0) + return r; + + fprintf(f, + "[Unit]\n" + "Description=Integrity Protection Setup for %%I\n" + "Documentation=man:systemd-veritysetup-generator(8) man:systemd-veritysetup@.service(8)\n" + "SourcePath=/proc/cmdline\n" + "DefaultDependencies=no\n" + "Conflicts=umount.target\n" + "BindsTo=%s %s\n" + "IgnoreOnIsolate=true\n" + "After=cryptsetup-pre.target systemd-udevd-kernel.socket %s %s\n" + "Before=cryptsetup.target umount.target\n" + "\n[Service]\n" + "Type=oneshot\n" + "RemainAfterExit=yes\n" + "ExecStart=" ROOTLIBEXECDIR "/systemd-veritysetup attach root '%s' '%s' '%s'\n" + "ExecStop=" ROOTLIBEXECDIR "/systemd-veritysetup detach root\n", + d, e, + d, e, + u_escaped, v_escaped, root_hash_escaped); + + r = fflush_and_check(f); + if (r < 0) + return log_error_errno(r, "Failed to write file unit "SYSTEMD_VERITYSETUP_SERVICE": %m"); + + to = strjoina(arg_dest, "/cryptsetup.target.requires/" SYSTEMD_VERITYSETUP_SERVICE); + + (void) mkdir_parents(to, 0755); + if (symlink("../" SYSTEMD_VERITYSETUP_SERVICE, to) < 0) + return log_error_errno(errno, "Failed to create symlink %s: %m", to); + + return 0; +} + +static int parse_proc_cmdline_item(const char *key, const char *value, void *data) { + int r; + + if (proc_cmdline_key_streq(key, "systemd.verity")) { + + r = value ? parse_boolean(value) : 1; + if (r < 0) + log_warning("Failed to parse verity= kernel command line switch %s. Ignoring.", value); + else + arg_enabled = r; + + } else if (proc_cmdline_key_streq(key, "roothash")) { + + if (proc_cmdline_value_missing(key, value)) + return 0; + + r = free_and_strdup(&arg_root_hash, value); + if (r < 0) + return log_oom(); + + } else if (proc_cmdline_key_streq(key, "systemd.verity_root_data")) { + + if (proc_cmdline_value_missing(key, value)) + return 0; + + r = free_and_strdup(&arg_data_what, value); + if (r < 0) + return log_oom(); + + } else if (proc_cmdline_key_streq(key, "systemd.verity_root_hash")) { + + if (proc_cmdline_value_missing(key, value)) + return 0; + + r = free_and_strdup(&arg_hash_what, value); + if (r < 0) + return log_oom(); + } + + return 0; +} + +static int determine_devices(void) { + _cleanup_free_ void *m = NULL; + sd_id128_t root_uuid, verity_uuid; + char ids[ID128_UUID_STRING_MAX]; + size_t l; + int r; + + /* Try to automatically derive the root data and hash device paths from the root hash */ + + if (!arg_root_hash) + return 0; + + if (arg_data_what && arg_hash_what) + return 0; + + r = unhexmem(arg_root_hash, strlen(arg_root_hash), &m, &l); + if (r < 0) + return log_error_errno(r, "Failed to parse root hash: %s", arg_root_hash); + if (l < sizeof(sd_id128_t)) { + log_debug("Root hash is shorter than 128 bits (32 characters), ignoring for discovering verity partition."); + return 0; + } + + if (!arg_data_what) { + memcpy(&root_uuid, m, sizeof(root_uuid)); + + arg_data_what = path_join("/dev/disk/by-partuuid", id128_to_uuid_string(root_uuid, ids)); + if (!arg_data_what) + return log_oom(); + } + + if (!arg_hash_what) { + memcpy(&verity_uuid, (uint8_t*) m + l - sizeof(verity_uuid), sizeof(verity_uuid)); + + arg_hash_what = path_join("/dev/disk/by-partuuid", id128_to_uuid_string(verity_uuid, ids)); + if (!arg_hash_what) + return log_oom(); + } + + return 1; +} + +static int run(const char *dest, const char *dest_early, const char *dest_late) { + int r; + + assert_se(arg_dest = dest); + + r = proc_cmdline_parse(parse_proc_cmdline_item, NULL, PROC_CMDLINE_STRIP_RD_PREFIX); + if (r < 0) + return log_warning_errno(r, "Failed to parse kernel command line: %m"); + + /* For now we only support the root device on verity. Later on we might want to add support for /etc/veritytab + * or similar to define additional mappings */ + + if (!arg_enabled) + return 0; + + r = determine_devices(); + if (r < 0) + return r; + + return create_device(); +} + +DEFINE_MAIN_GENERATOR_FUNCTION(run); |