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1 | #include "cache.h" | |
2 | #include "commit.h" | |
3 | #include "config.h" | |
4 | #include "run-command.h" | |
5 | #include "strbuf.h" | |
6 | #include "gpg-interface.h" | |
7 | #include "sigchain.h" | |
8 | #include "tempfile.h" | |
9 | ||
10 | static char *configured_signing_key; | |
11 | static enum signature_trust_level configured_min_trust_level = TRUST_UNDEFINED; | |
12 | ||
13 | struct gpg_format { | |
14 | const char *name; | |
15 | const char *program; | |
16 | const char **verify_args; | |
17 | const char **sigs; | |
18 | }; | |
19 | ||
20 | static const char *openpgp_verify_args[] = { | |
21 | "--keyid-format=long", | |
22 | NULL | |
23 | }; | |
24 | static const char *openpgp_sigs[] = { | |
25 | "-----BEGIN PGP SIGNATURE-----", | |
26 | "-----BEGIN PGP MESSAGE-----", | |
27 | NULL | |
28 | }; | |
29 | ||
30 | static const char *x509_verify_args[] = { | |
31 | NULL | |
32 | }; | |
33 | static const char *x509_sigs[] = { | |
34 | "-----BEGIN SIGNED MESSAGE-----", | |
35 | NULL | |
36 | }; | |
37 | ||
38 | static struct gpg_format gpg_format[] = { | |
39 | { .name = "openpgp", .program = "gpg", | |
40 | .verify_args = openpgp_verify_args, | |
41 | .sigs = openpgp_sigs | |
42 | }, | |
43 | { .name = "x509", .program = "gpgsm", | |
44 | .verify_args = x509_verify_args, | |
45 | .sigs = x509_sigs | |
46 | }, | |
47 | }; | |
48 | ||
49 | static struct gpg_format *use_format = &gpg_format[0]; | |
50 | ||
51 | static struct gpg_format *get_format_by_name(const char *str) | |
52 | { | |
53 | int i; | |
54 | ||
55 | for (i = 0; i < ARRAY_SIZE(gpg_format); i++) | |
56 | if (!strcmp(gpg_format[i].name, str)) | |
57 | return gpg_format + i; | |
58 | return NULL; | |
59 | } | |
60 | ||
61 | static struct gpg_format *get_format_by_sig(const char *sig) | |
62 | { | |
63 | int i, j; | |
64 | ||
65 | for (i = 0; i < ARRAY_SIZE(gpg_format); i++) | |
66 | for (j = 0; gpg_format[i].sigs[j]; j++) | |
67 | if (starts_with(sig, gpg_format[i].sigs[j])) | |
68 | return gpg_format + i; | |
69 | return NULL; | |
70 | } | |
71 | ||
72 | void signature_check_clear(struct signature_check *sigc) | |
73 | { | |
74 | FREE_AND_NULL(sigc->payload); | |
75 | FREE_AND_NULL(sigc->gpg_output); | |
76 | FREE_AND_NULL(sigc->gpg_status); | |
77 | FREE_AND_NULL(sigc->signer); | |
78 | FREE_AND_NULL(sigc->key); | |
79 | FREE_AND_NULL(sigc->fingerprint); | |
80 | FREE_AND_NULL(sigc->primary_key_fingerprint); | |
81 | } | |
82 | ||
83 | /* An exclusive status -- only one of them can appear in output */ | |
84 | #define GPG_STATUS_EXCLUSIVE (1<<0) | |
85 | /* The status includes key identifier */ | |
86 | #define GPG_STATUS_KEYID (1<<1) | |
87 | /* The status includes user identifier */ | |
88 | #define GPG_STATUS_UID (1<<2) | |
89 | /* The status includes key fingerprints */ | |
90 | #define GPG_STATUS_FINGERPRINT (1<<3) | |
91 | /* The status includes trust level */ | |
92 | #define GPG_STATUS_TRUST_LEVEL (1<<4) | |
93 | ||
94 | /* Short-hand for standard exclusive *SIG status with keyid & UID */ | |
95 | #define GPG_STATUS_STDSIG (GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID|GPG_STATUS_UID) | |
96 | ||
97 | static struct { | |
98 | char result; | |
99 | const char *check; | |
100 | unsigned int flags; | |
101 | } sigcheck_gpg_status[] = { | |
102 | { 'G', "GOODSIG ", GPG_STATUS_STDSIG }, | |
103 | { 'B', "BADSIG ", GPG_STATUS_STDSIG }, | |
104 | { 'E', "ERRSIG ", GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID }, | |
105 | { 'X', "EXPSIG ", GPG_STATUS_STDSIG }, | |
106 | { 'Y', "EXPKEYSIG ", GPG_STATUS_STDSIG }, | |
107 | { 'R', "REVKEYSIG ", GPG_STATUS_STDSIG }, | |
108 | { 0, "VALIDSIG ", GPG_STATUS_FINGERPRINT }, | |
109 | { 0, "TRUST_", GPG_STATUS_TRUST_LEVEL }, | |
110 | }; | |
111 | ||
112 | static struct { | |
113 | const char *key; | |
114 | enum signature_trust_level value; | |
115 | } sigcheck_gpg_trust_level[] = { | |
116 | { "UNDEFINED", TRUST_UNDEFINED }, | |
117 | { "NEVER", TRUST_NEVER }, | |
118 | { "MARGINAL", TRUST_MARGINAL }, | |
119 | { "FULLY", TRUST_FULLY }, | |
120 | { "ULTIMATE", TRUST_ULTIMATE }, | |
121 | }; | |
122 | ||
123 | static void replace_cstring(char **field, const char *line, const char *next) | |
124 | { | |
125 | free(*field); | |
126 | ||
127 | if (line && next) | |
128 | *field = xmemdupz(line, next - line); | |
129 | else | |
130 | *field = NULL; | |
131 | } | |
132 | ||
133 | static int parse_gpg_trust_level(const char *level, | |
134 | enum signature_trust_level *res) | |
135 | { | |
136 | size_t i; | |
137 | ||
138 | for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_trust_level); i++) { | |
139 | if (!strcmp(sigcheck_gpg_trust_level[i].key, level)) { | |
140 | *res = sigcheck_gpg_trust_level[i].value; | |
141 | return 0; | |
142 | } | |
143 | } | |
144 | return 1; | |
145 | } | |
146 | ||
147 | static void parse_gpg_output(struct signature_check *sigc) | |
148 | { | |
149 | const char *buf = sigc->gpg_status; | |
150 | const char *line, *next; | |
151 | int i, j; | |
152 | int seen_exclusive_status = 0; | |
153 | ||
154 | /* Iterate over all lines */ | |
155 | for (line = buf; *line; line = strchrnul(line+1, '\n')) { | |
156 | while (*line == '\n') | |
157 | line++; | |
158 | if (!*line) | |
159 | break; | |
160 | ||
161 | /* Skip lines that don't start with GNUPG status */ | |
162 | if (!skip_prefix(line, "[GNUPG:] ", &line)) | |
163 | continue; | |
164 | ||
165 | /* Iterate over all search strings */ | |
166 | for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) { | |
167 | if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) { | |
168 | /* | |
169 | * GOODSIG, BADSIG etc. can occur only once for | |
170 | * each signature. Therefore, if we had more | |
171 | * than one then we're dealing with multiple | |
172 | * signatures. We don't support them | |
173 | * currently, and they're rather hard to | |
174 | * create, so something is likely fishy and we | |
175 | * should reject them altogether. | |
176 | */ | |
177 | if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) { | |
178 | if (seen_exclusive_status++) | |
179 | goto error; | |
180 | } | |
181 | ||
182 | if (sigcheck_gpg_status[i].result) | |
183 | sigc->result = sigcheck_gpg_status[i].result; | |
184 | /* Do we have key information? */ | |
185 | if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) { | |
186 | next = strchrnul(line, ' '); | |
187 | replace_cstring(&sigc->key, line, next); | |
188 | /* Do we have signer information? */ | |
189 | if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) { | |
190 | line = next + 1; | |
191 | next = strchrnul(line, '\n'); | |
192 | replace_cstring(&sigc->signer, line, next); | |
193 | } | |
194 | } | |
195 | ||
196 | /* Do we have trust level? */ | |
197 | if (sigcheck_gpg_status[i].flags & GPG_STATUS_TRUST_LEVEL) { | |
198 | /* | |
199 | * GPG v1 and v2 differs in how the | |
200 | * TRUST_ lines are written. Some | |
201 | * trust lines contain no additional | |
202 | * space-separated information for v1. | |
203 | */ | |
204 | size_t trust_size = strcspn(line, " \n"); | |
205 | char *trust = xmemdupz(line, trust_size); | |
206 | ||
207 | if (parse_gpg_trust_level(trust, &sigc->trust_level)) { | |
208 | free(trust); | |
209 | goto error; | |
210 | } | |
211 | free(trust); | |
212 | } | |
213 | ||
214 | /* Do we have fingerprint? */ | |
215 | if (sigcheck_gpg_status[i].flags & GPG_STATUS_FINGERPRINT) { | |
216 | const char *limit; | |
217 | char **field; | |
218 | ||
219 | next = strchrnul(line, ' '); | |
220 | replace_cstring(&sigc->fingerprint, line, next); | |
221 | ||
222 | /* | |
223 | * Skip interim fields. The search is | |
224 | * limited to the same line since only | |
225 | * OpenPGP signatures has a field with | |
226 | * the primary fingerprint. | |
227 | */ | |
228 | limit = strchrnul(line, '\n'); | |
229 | for (j = 9; j > 0; j--) { | |
230 | if (!*next || limit <= next) | |
231 | break; | |
232 | line = next + 1; | |
233 | next = strchrnul(line, ' '); | |
234 | } | |
235 | ||
236 | field = &sigc->primary_key_fingerprint; | |
237 | if (!j) { | |
238 | next = strchrnul(line, '\n'); | |
239 | replace_cstring(field, line, next); | |
240 | } else { | |
241 | replace_cstring(field, NULL, NULL); | |
242 | } | |
243 | } | |
244 | ||
245 | break; | |
246 | } | |
247 | } | |
248 | } | |
249 | return; | |
250 | ||
251 | error: | |
252 | sigc->result = 'E'; | |
253 | /* Clear partial data to avoid confusion */ | |
254 | FREE_AND_NULL(sigc->primary_key_fingerprint); | |
255 | FREE_AND_NULL(sigc->fingerprint); | |
256 | FREE_AND_NULL(sigc->signer); | |
257 | FREE_AND_NULL(sigc->key); | |
258 | } | |
259 | ||
260 | static int verify_signed_buffer(const char *payload, size_t payload_size, | |
261 | const char *signature, size_t signature_size, | |
262 | struct strbuf *gpg_output, | |
263 | struct strbuf *gpg_status) | |
264 | { | |
265 | struct child_process gpg = CHILD_PROCESS_INIT; | |
266 | struct gpg_format *fmt; | |
267 | struct tempfile *temp; | |
268 | int ret; | |
269 | struct strbuf buf = STRBUF_INIT; | |
270 | ||
271 | temp = mks_tempfile_t(".git_vtag_tmpXXXXXX"); | |
272 | if (!temp) | |
273 | return error_errno(_("could not create temporary file")); | |
274 | if (write_in_full(temp->fd, signature, signature_size) < 0 || | |
275 | close_tempfile_gently(temp) < 0) { | |
276 | error_errno(_("failed writing detached signature to '%s'"), | |
277 | temp->filename.buf); | |
278 | delete_tempfile(&temp); | |
279 | return -1; | |
280 | } | |
281 | ||
282 | fmt = get_format_by_sig(signature); | |
283 | if (!fmt) | |
284 | BUG("bad signature '%s'", signature); | |
285 | ||
286 | strvec_push(&gpg.args, fmt->program); | |
287 | strvec_pushv(&gpg.args, fmt->verify_args); | |
288 | strvec_pushl(&gpg.args, | |
289 | "--status-fd=1", | |
290 | "--verify", temp->filename.buf, "-", | |
291 | NULL); | |
292 | ||
293 | if (!gpg_status) | |
294 | gpg_status = &buf; | |
295 | ||
296 | sigchain_push(SIGPIPE, SIG_IGN); | |
297 | ret = pipe_command(&gpg, payload, payload_size, | |
298 | gpg_status, 0, gpg_output, 0); | |
299 | sigchain_pop(SIGPIPE); | |
300 | ||
301 | delete_tempfile(&temp); | |
302 | ||
303 | ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG "); | |
304 | strbuf_release(&buf); /* no matter it was used or not */ | |
305 | ||
306 | return ret; | |
307 | } | |
308 | ||
309 | int check_signature(const char *payload, size_t plen, const char *signature, | |
310 | size_t slen, struct signature_check *sigc) | |
311 | { | |
312 | struct strbuf gpg_output = STRBUF_INIT; | |
313 | struct strbuf gpg_status = STRBUF_INIT; | |
314 | int status; | |
315 | ||
316 | sigc->result = 'N'; | |
317 | sigc->trust_level = -1; | |
318 | ||
319 | status = verify_signed_buffer(payload, plen, signature, slen, | |
320 | &gpg_output, &gpg_status); | |
321 | if (status && !gpg_output.len) | |
322 | goto out; | |
323 | sigc->payload = xmemdupz(payload, plen); | |
324 | sigc->gpg_output = strbuf_detach(&gpg_output, NULL); | |
325 | sigc->gpg_status = strbuf_detach(&gpg_status, NULL); | |
326 | parse_gpg_output(sigc); | |
327 | status |= sigc->result != 'G'; | |
328 | status |= sigc->trust_level < configured_min_trust_level; | |
329 | ||
330 | out: | |
331 | strbuf_release(&gpg_status); | |
332 | strbuf_release(&gpg_output); | |
333 | ||
334 | return !!status; | |
335 | } | |
336 | ||
337 | void print_signature_buffer(const struct signature_check *sigc, unsigned flags) | |
338 | { | |
339 | const char *output = flags & GPG_VERIFY_RAW ? | |
340 | sigc->gpg_status : sigc->gpg_output; | |
341 | ||
342 | if (flags & GPG_VERIFY_VERBOSE && sigc->payload) | |
343 | fputs(sigc->payload, stdout); | |
344 | ||
345 | if (output) | |
346 | fputs(output, stderr); | |
347 | } | |
348 | ||
349 | size_t parse_signed_buffer(const char *buf, size_t size) | |
350 | { | |
351 | size_t len = 0; | |
352 | size_t match = size; | |
353 | while (len < size) { | |
354 | const char *eol; | |
355 | ||
356 | if (get_format_by_sig(buf + len)) | |
357 | match = len; | |
358 | ||
359 | eol = memchr(buf + len, '\n', size - len); | |
360 | len += eol ? eol - (buf + len) + 1 : size - len; | |
361 | } | |
362 | return match; | |
363 | } | |
364 | ||
365 | int parse_signature(const char *buf, size_t size, struct strbuf *payload, struct strbuf *signature) | |
366 | { | |
367 | size_t match = parse_signed_buffer(buf, size); | |
368 | if (match != size) { | |
369 | strbuf_add(payload, buf, match); | |
370 | remove_signature(payload); | |
371 | strbuf_add(signature, buf + match, size - match); | |
372 | return 1; | |
373 | } | |
374 | return 0; | |
375 | } | |
376 | ||
377 | void set_signing_key(const char *key) | |
378 | { | |
379 | free(configured_signing_key); | |
380 | configured_signing_key = xstrdup(key); | |
381 | } | |
382 | ||
383 | int git_gpg_config(const char *var, const char *value, void *cb) | |
384 | { | |
385 | struct gpg_format *fmt = NULL; | |
386 | char *fmtname = NULL; | |
387 | char *trust; | |
388 | int ret; | |
389 | ||
390 | if (!strcmp(var, "user.signingkey")) { | |
391 | if (!value) | |
392 | return config_error_nonbool(var); | |
393 | set_signing_key(value); | |
394 | return 0; | |
395 | } | |
396 | ||
397 | if (!strcmp(var, "gpg.format")) { | |
398 | if (!value) | |
399 | return config_error_nonbool(var); | |
400 | fmt = get_format_by_name(value); | |
401 | if (!fmt) | |
402 | return error("unsupported value for %s: %s", | |
403 | var, value); | |
404 | use_format = fmt; | |
405 | return 0; | |
406 | } | |
407 | ||
408 | if (!strcmp(var, "gpg.mintrustlevel")) { | |
409 | if (!value) | |
410 | return config_error_nonbool(var); | |
411 | ||
412 | trust = xstrdup_toupper(value); | |
413 | ret = parse_gpg_trust_level(trust, &configured_min_trust_level); | |
414 | free(trust); | |
415 | ||
416 | if (ret) | |
417 | return error("unsupported value for %s: %s", var, | |
418 | value); | |
419 | return 0; | |
420 | } | |
421 | ||
422 | if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program")) | |
423 | fmtname = "openpgp"; | |
424 | ||
425 | if (!strcmp(var, "gpg.x509.program")) | |
426 | fmtname = "x509"; | |
427 | ||
428 | if (fmtname) { | |
429 | fmt = get_format_by_name(fmtname); | |
430 | return git_config_string(&fmt->program, var, value); | |
431 | } | |
432 | ||
433 | return 0; | |
434 | } | |
435 | ||
436 | const char *get_signing_key(void) | |
437 | { | |
438 | if (configured_signing_key) | |
439 | return configured_signing_key; | |
440 | return git_committer_info(IDENT_STRICT|IDENT_NO_DATE); | |
441 | } | |
442 | ||
443 | int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key) | |
444 | { | |
445 | struct child_process gpg = CHILD_PROCESS_INIT; | |
446 | int ret; | |
447 | size_t i, j, bottom; | |
448 | struct strbuf gpg_status = STRBUF_INIT; | |
449 | ||
450 | strvec_pushl(&gpg.args, | |
451 | use_format->program, | |
452 | "--status-fd=2", | |
453 | "-bsau", signing_key, | |
454 | NULL); | |
455 | ||
456 | bottom = signature->len; | |
457 | ||
458 | /* | |
459 | * When the username signingkey is bad, program could be terminated | |
460 | * because gpg exits without reading and then write gets SIGPIPE. | |
461 | */ | |
462 | sigchain_push(SIGPIPE, SIG_IGN); | |
463 | ret = pipe_command(&gpg, buffer->buf, buffer->len, | |
464 | signature, 1024, &gpg_status, 0); | |
465 | sigchain_pop(SIGPIPE); | |
466 | ||
467 | ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED "); | |
468 | strbuf_release(&gpg_status); | |
469 | if (ret) | |
470 | return error(_("gpg failed to sign the data")); | |
471 | ||
472 | /* Strip CR from the line endings, in case we are on Windows. */ | |
473 | for (i = j = bottom; i < signature->len; i++) | |
474 | if (signature->buf[i] != '\r') { | |
475 | if (i != j) | |
476 | signature->buf[j] = signature->buf[i]; | |
477 | j++; | |
478 | } | |
479 | strbuf_setlen(signature, j); | |
480 | ||
481 | return 0; | |
482 | } |