builtin-check.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * Copyright (C) 2015-2017 Josh Poimboeuf <jpoimboe@redhat.com>
  4 */
  5
  6#include <subcmd/parse-options.h>
  7#include <string.h>
  8#include <stdlib.h>
  9#include <fcntl.h>
 10#include <unistd.h>
 11#include <errno.h>
 12#include <sys/stat.h>
 13#include <sys/sendfile.h>
 14#include <objtool/builtin.h>
 15#include <objtool/objtool.h>
 16#include <objtool/warn.h>
 17
 18#define ORIG_SUFFIX ".orig"
 19
 20int orig_argc;
 21static char **orig_argv;
 22const char *objname;
 23struct opts opts;
 24
 25static const char * const check_usage[] = {
 26	"objtool <actions> [<options>] file.o",
 27	NULL,
 28};
 29
 30static const char * const env_usage[] = {
 31	"OBJTOOL_ARGS=\"<options>\"",
 32	NULL,
 33};
 34
 35static int parse_dump(const struct option *opt, const char *str, int unset)
 36{
 37	if (!str || !strcmp(str, "orc")) {
 38		opts.dump_orc = true;
 39		return 0;
 40	}
 41
 42	return -1;
 43}
 44
 45static int parse_hacks(const struct option *opt, const char *str, int unset)
 46{
 47	bool found = false;
 48
 49	/*
 50	 * Use strstr() as a lazy method of checking for comma-separated
 51	 * options.
 52	 *
 53	 * No string provided == enable all options.
 54	 */
 55
 56	if (!str || strstr(str, "jump_label")) {
 57		opts.hack_jump_label = true;
 58		found = true;
 59	}
 60
 61	if (!str || strstr(str, "noinstr")) {
 62		opts.hack_noinstr = true;
 63		found = true;
 64	}
 65
 66	if (!str || strstr(str, "skylake")) {
 67		opts.hack_skylake = true;
 68		found = true;
 69	}
 70
 71	return found ? 0 : -1;
 72}
 73
 74static const struct option check_options[] = {
 75	OPT_GROUP("Actions:"),
 76	OPT_BOOLEAN(0,		 "checksum", &opts.checksum, "generate per-function checksums"),
 77	OPT_BOOLEAN(0,		 "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"),
 78	OPT_STRING_OPTARG('d',	 "disas", &opts.disas, "function-pattern", "disassemble functions", "*"),
 79	OPT_CALLBACK_OPTARG('h', "hacks", NULL, NULL, "jump_label,noinstr,skylake", "patch toolchain bugs/limitations", parse_hacks),
 80	OPT_BOOLEAN('i',	 "ibt", &opts.ibt, "validate and annotate IBT"),
 81	OPT_BOOLEAN('m',	 "mcount", &opts.mcount, "annotate mcount/fentry calls for ftrace"),
 82	OPT_BOOLEAN(0,		 "noabs", &opts.noabs, "reject absolute references in allocatable sections"),
 83	OPT_BOOLEAN('n',	 "noinstr", &opts.noinstr, "validate noinstr rules"),
 84	OPT_BOOLEAN(0,		 "orc", &opts.orc, "generate ORC metadata"),
 85	OPT_BOOLEAN('r',	 "retpoline", &opts.retpoline, "validate and annotate retpoline usage"),
 86	OPT_BOOLEAN(0,		 "rethunk", &opts.rethunk, "validate and annotate rethunk usage"),
 87	OPT_BOOLEAN(0,		 "unret", &opts.unret, "validate entry unret placement"),
 88	OPT_INTEGER(0,		 "prefix", &opts.prefix, "generate prefix symbols"),
 89	OPT_BOOLEAN('l',	 "sls", &opts.sls, "validate straight-line-speculation mitigations"),
 90	OPT_BOOLEAN('s',	 "stackval", &opts.stackval, "validate frame pointer rules"),
 91	OPT_BOOLEAN('t',	 "static-call", &opts.static_call, "annotate static calls"),
 92	OPT_BOOLEAN('u',	 "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"),
 93	OPT_CALLBACK_OPTARG(0,	 "dump", NULL, NULL, "orc", "dump metadata", parse_dump),
 94
 95	OPT_GROUP("Options:"),
 96	OPT_BOOLEAN(0,		 "backtrace", &opts.backtrace, "unwind on error"),
 97	OPT_BOOLEAN(0,		 "backup", &opts.backup, "create backup (.orig) file on warning/error"),
 98	OPT_STRING(0,		 "debug-checksum", &opts.debug_checksum,  "funcs", "enable checksum debug output"),
 99	OPT_BOOLEAN(0,		 "dry-run", &opts.dryrun, "don't write modifications"),
100	OPT_BOOLEAN(0,		 "link", &opts.link, "object is a linked object"),
101	OPT_BOOLEAN(0,		 "module", &opts.module, "object is part of a kernel module"),
102	OPT_BOOLEAN(0,		 "mnop", &opts.mnop, "nop out mcount call sites"),
103	OPT_BOOLEAN(0,		 "no-unreachable", &opts.no_unreachable, "skip 'unreachable instruction' warnings"),
104	OPT_STRING('o',		 "output", &opts.output, "file", "output file name"),
105	OPT_BOOLEAN(0,		 "sec-address", &opts.sec_address, "print section addresses in warnings"),
106	OPT_BOOLEAN(0,		 "stats", &opts.stats, "print statistics"),
107	OPT_STRING(0,		 "trace", &opts.trace, "func", "trace function validation"),
108	OPT_BOOLEAN('v',	 "verbose", &opts.verbose, "verbose warnings"),
109	OPT_BOOLEAN(0,		 "werror", &opts.werror, "return error on warnings"),
110	OPT_BOOLEAN(0,		 "wide", &opts.wide, "wide output"),
111
112	OPT_END(),
113};
114
115int cmd_parse_options(int argc, const char **argv, const char * const usage[])
116{
117	const char *envv[16] = { };
118	char *env;
119	int envc;
120
121	env = getenv("OBJTOOL_ARGS");
122	if (env) {
123		envv[0] = "OBJTOOL_ARGS";
124		for (envc = 1; envc < ARRAY_SIZE(envv); ) {
125			envv[envc++] = env;
126			env = strchr(env, ' ');
127			if (!env)
128				break;
129			*env = '\0';
130			env++;
131		}
132
133		parse_options(envc, envv, check_options, env_usage, 0);
134	}
135
136	env = getenv("OBJTOOL_VERBOSE");
137	if (env && !strcmp(env, "1"))
138		opts.verbose = true;
139
140	argc = parse_options(argc, argv, check_options, usage, 0);
141	if (argc != 1)
142		usage_with_options(usage, check_options);
143	return argc;
144}
145
146static bool opts_valid(void)
147{
148	if (opts.mnop && !opts.mcount) {
149		ERROR("--mnop requires --mcount");
150		return false;
151	}
152
153	if (opts.noinstr && !opts.link) {
154		ERROR("--noinstr requires --link");
155		return false;
156	}
157
158	if (opts.ibt && !opts.link) {
159		ERROR("--ibt requires --link");
160		return false;
161	}
162
163	if (opts.unret && !opts.link) {
164		ERROR("--unret requires --link");
165		return false;
166	}
167
168#ifndef BUILD_KLP
169	if (opts.checksum) {
170		ERROR("--checksum not supported; install xxhash-devel/libxxhash-dev (version >= 0.8) and recompile");
171		return false;
172	}
173#endif
174
175	if (opts.debug_checksum && !opts.checksum) {
176		ERROR("--debug-checksum requires --checksum");
177		return false;
178	}
179
180	if (opts.checksum		||
181	    opts.disas			||
182	    opts.hack_jump_label	||
183	    opts.hack_noinstr		||
184	    opts.ibt			||
185	    opts.mcount			||
186	    opts.noabs			||
187	    opts.noinstr		||
188	    opts.orc			||
189	    opts.retpoline		||
190	    opts.rethunk		||
191	    opts.sls			||
192	    opts.stackval		||
193	    opts.static_call		||
194	    opts.uaccess) {
195		if (opts.dump_orc) {
196			ERROR("--dump can't be combined with other actions");
197			return false;
198		}
199
200		return true;
201	}
202
203	if (opts.dump_orc)
204		return true;
205
206	ERROR("At least one action required");
207	return false;
208}
209
210static int copy_file(const char *src, const char *dst)
211{
212	size_t to_copy, copied;
213	int dst_fd, src_fd;
214	struct stat stat;
215	off_t offset = 0;
216
217	src_fd = open(src, O_RDONLY);
218	if (src_fd == -1) {
219		ERROR("can't open %s for reading: %s", src, strerror(errno));
220		return 1;
221	}
222
223	dst_fd = open(dst, O_WRONLY | O_CREAT | O_TRUNC, 0400);
224	if (dst_fd == -1) {
225		ERROR("can't open %s for writing: %s", dst, strerror(errno));
226		return 1;
227	}
228
229	if (fstat(src_fd, &stat) == -1) {
230		ERROR_GLIBC("fstat");
231		return 1;
232	}
233
234	if (fchmod(dst_fd, stat.st_mode) == -1) {
235		ERROR_GLIBC("fchmod");
236		return 1;
237	}
238
239	for (to_copy = stat.st_size; to_copy > 0; to_copy -= copied) {
240		copied = sendfile(dst_fd, src_fd, &offset, to_copy);
241		if (copied == -1) {
242			ERROR_GLIBC("sendfile");
243			return 1;
244		}
245	}
246
247	close(dst_fd);
248	close(src_fd);
249	return 0;
250}
251
252static void save_argv(int argc, const char **argv)
253{
254	orig_argv = calloc(argc, sizeof(char *));
255	if (!orig_argv) {
256		ERROR_GLIBC("calloc");
257		exit(1);
258	}
259
260	for (int i = 0; i < argc; i++) {
261		orig_argv[i] = strdup(argv[i]);
262		if (!orig_argv[i]) {
263			ERROR_GLIBC("strdup(%s)", argv[i]);
264			exit(1);
265		}
266	}
267}
268
269int make_backup(void)
270{
271	char *backup;
272
273	/*
274	 * Make a backup before kbuild deletes the file so the error
275	 * can be recreated without recompiling or relinking.
276	 */
277	backup = malloc(strlen(objname) + strlen(ORIG_SUFFIX) + 1);
278	if (!backup) {
279		ERROR_GLIBC("malloc");
280		return 1;
281	}
282
283	strcpy(backup, objname);
284	strcat(backup, ORIG_SUFFIX);
285	if (copy_file(objname, backup))
286		return 1;
287
288	/*
289	 * Print the cmdline args to make it easier to recreate.
290	 */
291
292	fprintf(stderr, "%s", orig_argv[0]);
293
294	for (int i = 1; i < orig_argc; i++) {
295		char *arg = orig_argv[i];
296
297		/* Modify the printed args to use the backup */
298		if (!opts.output && !strcmp(arg, objname))
299			fprintf(stderr, " %s -o %s", backup, objname);
300		else
301			fprintf(stderr, " %s", arg);
302	}
303
304	fprintf(stderr, "\n");
305	return 0;
306}
307
308int objtool_run(int argc, const char **argv)
309{
310	struct objtool_file *file;
311	int ret = 0;
312
313	orig_argc = argc;
314	save_argv(argc, argv);
315
316	cmd_parse_options(argc, argv, check_usage);
317
318	if (!opts_valid())
319		return 1;
320
321	objname = argv[0];
322
323	if (opts.dump_orc)
324		return orc_dump(objname);
325
326	if (!opts.dryrun && opts.output) {
327		/* copy original .o file to output file */
328		if (copy_file(objname, opts.output))
329			return 1;
330
331		/* from here on, work directly on the output file */
332		objname = opts.output;
333	}
334
335	file = objtool_open_read(objname);
336	if (!file)
337		return 1;
338
339	if (!opts.link && has_multiple_files(file->elf)) {
340		ERROR("Linked object requires --link");
341		return 1;
342	}
343
344	ret = check(file);
345	if (ret)
346		return ret;
347
348	if (!opts.dryrun && file->elf->changed && elf_write(file->elf))
349		return 1;
350
351	return elf_close(file->elf);
352}