Merge branch 'tg/rerere'
[git] / gpg-interface.c
1 #include "cache.h"
2 #include "config.h"
3 #include "run-command.h"
4 #include "strbuf.h"
5 #include "gpg-interface.h"
6 #include "sigchain.h"
7 #include "tempfile.h"
8
9 static char *configured_signing_key;
10 struct gpg_format {
11         const char *name;
12         const char *program;
13         const char **verify_args;
14         const char **sigs;
15 };
16
17 static const char *openpgp_verify_args[] = {
18         "--keyid-format=long",
19         NULL
20 };
21 static const char *openpgp_sigs[] = {
22         "-----BEGIN PGP SIGNATURE-----",
23         "-----BEGIN PGP MESSAGE-----",
24         NULL
25 };
26
27 static const char *x509_verify_args[] = {
28         NULL
29 };
30 static const char *x509_sigs[] = {
31         "-----BEGIN SIGNED MESSAGE-----",
32         NULL
33 };
34
35 static struct gpg_format gpg_format[] = {
36         { .name = "openpgp", .program = "gpg",
37           .verify_args = openpgp_verify_args,
38           .sigs = openpgp_sigs
39         },
40         { .name = "x509", .program = "gpgsm",
41           .verify_args = x509_verify_args,
42           .sigs = x509_sigs
43         },
44 };
45
46 static struct gpg_format *use_format = &gpg_format[0];
47
48 static struct gpg_format *get_format_by_name(const char *str)
49 {
50         int i;
51
52         for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
53                 if (!strcmp(gpg_format[i].name, str))
54                         return gpg_format + i;
55         return NULL;
56 }
57
58 static struct gpg_format *get_format_by_sig(const char *sig)
59 {
60         int i, j;
61
62         for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
63                 for (j = 0; gpg_format[i].sigs[j]; j++)
64                         if (starts_with(sig, gpg_format[i].sigs[j]))
65                                 return gpg_format + i;
66         return NULL;
67 }
68
69 void signature_check_clear(struct signature_check *sigc)
70 {
71         FREE_AND_NULL(sigc->payload);
72         FREE_AND_NULL(sigc->gpg_output);
73         FREE_AND_NULL(sigc->gpg_status);
74         FREE_AND_NULL(sigc->signer);
75         FREE_AND_NULL(sigc->key);
76 }
77
78 static struct {
79         char result;
80         const char *check;
81 } sigcheck_gpg_status[] = {
82         { 'G', "\n[GNUPG:] GOODSIG " },
83         { 'B', "\n[GNUPG:] BADSIG " },
84         { 'U', "\n[GNUPG:] TRUST_NEVER" },
85         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
86         { 'E', "\n[GNUPG:] ERRSIG "},
87         { 'X', "\n[GNUPG:] EXPSIG "},
88         { 'Y', "\n[GNUPG:] EXPKEYSIG "},
89         { 'R', "\n[GNUPG:] REVKEYSIG "},
90 };
91
92 static void parse_gpg_output(struct signature_check *sigc)
93 {
94         const char *buf = sigc->gpg_status;
95         int i;
96
97         /* Iterate over all search strings */
98         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
99                 const char *found, *next;
100
101                 if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
102                         found = strstr(buf, sigcheck_gpg_status[i].check);
103                         if (!found)
104                                 continue;
105                         found += strlen(sigcheck_gpg_status[i].check);
106                 }
107                 sigc->result = sigcheck_gpg_status[i].result;
108                 /* The trust messages are not followed by key/signer information */
109                 if (sigc->result != 'U') {
110                         next = strchrnul(found, ' ');
111                         sigc->key = xmemdupz(found, next - found);
112                         /* The ERRSIG message is not followed by signer information */
113                         if (*next && sigc-> result != 'E') {
114                                 found = next + 1;
115                                 next = strchrnul(found, '\n');
116                                 sigc->signer = xmemdupz(found, next - found);
117                         }
118                 }
119         }
120 }
121
122 int check_signature(const char *payload, size_t plen, const char *signature,
123         size_t slen, struct signature_check *sigc)
124 {
125         struct strbuf gpg_output = STRBUF_INIT;
126         struct strbuf gpg_status = STRBUF_INIT;
127         int status;
128
129         sigc->result = 'N';
130
131         status = verify_signed_buffer(payload, plen, signature, slen,
132                                       &gpg_output, &gpg_status);
133         if (status && !gpg_output.len)
134                 goto out;
135         sigc->payload = xmemdupz(payload, plen);
136         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
137         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
138         parse_gpg_output(sigc);
139         status |= sigc->result != 'G' && sigc->result != 'U';
140
141  out:
142         strbuf_release(&gpg_status);
143         strbuf_release(&gpg_output);
144
145         return !!status;
146 }
147
148 void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
149 {
150         const char *output = flags & GPG_VERIFY_RAW ?
151                 sigc->gpg_status : sigc->gpg_output;
152
153         if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
154                 fputs(sigc->payload, stdout);
155
156         if (output)
157                 fputs(output, stderr);
158 }
159
160 size_t parse_signature(const char *buf, size_t size)
161 {
162         size_t len = 0;
163         size_t match = size;
164         while (len < size) {
165                 const char *eol;
166
167                 if (get_format_by_sig(buf + len))
168                         match = len;
169
170                 eol = memchr(buf + len, '\n', size - len);
171                 len += eol ? eol - (buf + len) + 1 : size - len;
172         }
173         return match;
174 }
175
176 void set_signing_key(const char *key)
177 {
178         free(configured_signing_key);
179         configured_signing_key = xstrdup(key);
180 }
181
182 int git_gpg_config(const char *var, const char *value, void *cb)
183 {
184         struct gpg_format *fmt = NULL;
185         char *fmtname = NULL;
186
187         if (!strcmp(var, "user.signingkey")) {
188                 if (!value)
189                         return config_error_nonbool(var);
190                 set_signing_key(value);
191                 return 0;
192         }
193
194         if (!strcmp(var, "gpg.format")) {
195                 if (!value)
196                         return config_error_nonbool(var);
197                 fmt = get_format_by_name(value);
198                 if (!fmt)
199                         return error("unsupported value for %s: %s",
200                                      var, value);
201                 use_format = fmt;
202                 return 0;
203         }
204
205         if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
206                 fmtname = "openpgp";
207
208         if (!strcmp(var, "gpg.x509.program"))
209                 fmtname = "x509";
210
211         if (fmtname) {
212                 fmt = get_format_by_name(fmtname);
213                 return git_config_string(&fmt->program, var, value);
214         }
215
216         return 0;
217 }
218
219 const char *get_signing_key(void)
220 {
221         if (configured_signing_key)
222                 return configured_signing_key;
223         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
224 }
225
226 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
227 {
228         struct child_process gpg = CHILD_PROCESS_INIT;
229         int ret;
230         size_t i, j, bottom;
231         struct strbuf gpg_status = STRBUF_INIT;
232
233         argv_array_pushl(&gpg.args,
234                          use_format->program,
235                          "--status-fd=2",
236                          "-bsau", signing_key,
237                          NULL);
238
239         bottom = signature->len;
240
241         /*
242          * When the username signingkey is bad, program could be terminated
243          * because gpg exits without reading and then write gets SIGPIPE.
244          */
245         sigchain_push(SIGPIPE, SIG_IGN);
246         ret = pipe_command(&gpg, buffer->buf, buffer->len,
247                            signature, 1024, &gpg_status, 0);
248         sigchain_pop(SIGPIPE);
249
250         ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
251         strbuf_release(&gpg_status);
252         if (ret)
253                 return error(_("gpg failed to sign the data"));
254
255         /* Strip CR from the line endings, in case we are on Windows. */
256         for (i = j = bottom; i < signature->len; i++)
257                 if (signature->buf[i] != '\r') {
258                         if (i != j)
259                                 signature->buf[j] = signature->buf[i];
260                         j++;
261                 }
262         strbuf_setlen(signature, j);
263
264         return 0;
265 }
266
267 int verify_signed_buffer(const char *payload, size_t payload_size,
268                          const char *signature, size_t signature_size,
269                          struct strbuf *gpg_output, struct strbuf *gpg_status)
270 {
271         struct child_process gpg = CHILD_PROCESS_INIT;
272         struct gpg_format *fmt;
273         struct tempfile *temp;
274         int ret;
275         struct strbuf buf = STRBUF_INIT;
276
277         temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
278         if (!temp)
279                 return error_errno(_("could not create temporary file"));
280         if (write_in_full(temp->fd, signature, signature_size) < 0 ||
281             close_tempfile_gently(temp) < 0) {
282                 error_errno(_("failed writing detached signature to '%s'"),
283                             temp->filename.buf);
284                 delete_tempfile(&temp);
285                 return -1;
286         }
287
288         fmt = get_format_by_sig(signature);
289         if (!fmt)
290                 BUG("bad signature '%s'", signature);
291
292         argv_array_push(&gpg.args, fmt->program);
293         argv_array_pushv(&gpg.args, fmt->verify_args);
294         argv_array_pushl(&gpg.args,
295                          "--status-fd=1",
296                          "--verify", temp->filename.buf, "-",
297                          NULL);
298
299         if (!gpg_status)
300                 gpg_status = &buf;
301
302         sigchain_push(SIGPIPE, SIG_IGN);
303         ret = pipe_command(&gpg, payload, payload_size,
304                            gpg_status, 0, gpg_output, 0);
305         sigchain_pop(SIGPIPE);
306
307         delete_tempfile(&temp);
308
309         ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
310         strbuf_release(&buf); /* no matter it was used or not */
311
312         return ret;
313 }