Merge branch 'jk/merge-subtree-heuristics'
[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
140  out:
141         strbuf_release(&gpg_status);
142         strbuf_release(&gpg_output);
143
144         return sigc->result != 'G' && sigc->result != 'U';
145 }
146
147 void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
148 {
149         const char *output = flags & GPG_VERIFY_RAW ?
150                 sigc->gpg_status : sigc->gpg_output;
151
152         if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
153                 fputs(sigc->payload, stdout);
154
155         if (output)
156                 fputs(output, stderr);
157 }
158
159 size_t parse_signature(const char *buf, size_t size)
160 {
161         size_t len = 0;
162         size_t match = size;
163         while (len < size) {
164                 const char *eol;
165
166                 if (get_format_by_sig(buf + len))
167                         match = len;
168
169                 eol = memchr(buf + len, '\n', size - len);
170                 len += eol ? eol - (buf + len) + 1 : size - len;
171         }
172         return match;
173 }
174
175 void set_signing_key(const char *key)
176 {
177         free(configured_signing_key);
178         configured_signing_key = xstrdup(key);
179 }
180
181 int git_gpg_config(const char *var, const char *value, void *cb)
182 {
183         struct gpg_format *fmt = NULL;
184         char *fmtname = NULL;
185
186         if (!strcmp(var, "user.signingkey")) {
187                 if (!value)
188                         return config_error_nonbool(var);
189                 set_signing_key(value);
190                 return 0;
191         }
192
193         if (!strcmp(var, "gpg.format")) {
194                 if (!value)
195                         return config_error_nonbool(var);
196                 fmt = get_format_by_name(value);
197                 if (!fmt)
198                         return error("unsupported value for %s: %s",
199                                      var, value);
200                 use_format = fmt;
201                 return 0;
202         }
203
204         if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
205                 fmtname = "openpgp";
206
207         if (!strcmp(var, "gpg.x509.program"))
208                 fmtname = "x509";
209
210         if (fmtname) {
211                 fmt = get_format_by_name(fmtname);
212                 return git_config_string(&fmt->program, var, value);
213         }
214
215         return 0;
216 }
217
218 const char *get_signing_key(void)
219 {
220         if (configured_signing_key)
221                 return configured_signing_key;
222         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
223 }
224
225 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
226 {
227         struct child_process gpg = CHILD_PROCESS_INIT;
228         int ret;
229         size_t i, j, bottom;
230         struct strbuf gpg_status = STRBUF_INIT;
231
232         argv_array_pushl(&gpg.args,
233                          use_format->program,
234                          "--status-fd=2",
235                          "-bsau", signing_key,
236                          NULL);
237
238         bottom = signature->len;
239
240         /*
241          * When the username signingkey is bad, program could be terminated
242          * because gpg exits without reading and then write gets SIGPIPE.
243          */
244         sigchain_push(SIGPIPE, SIG_IGN);
245         ret = pipe_command(&gpg, buffer->buf, buffer->len,
246                            signature, 1024, &gpg_status, 0);
247         sigchain_pop(SIGPIPE);
248
249         ret |= !strstr(gpg_status.buf, "\n[GNUPG:] SIG_CREATED ");
250         strbuf_release(&gpg_status);
251         if (ret)
252                 return error(_("gpg failed to sign the data"));
253
254         /* Strip CR from the line endings, in case we are on Windows. */
255         for (i = j = bottom; i < signature->len; i++)
256                 if (signature->buf[i] != '\r') {
257                         if (i != j)
258                                 signature->buf[j] = signature->buf[i];
259                         j++;
260                 }
261         strbuf_setlen(signature, j);
262
263         return 0;
264 }
265
266 int verify_signed_buffer(const char *payload, size_t payload_size,
267                          const char *signature, size_t signature_size,
268                          struct strbuf *gpg_output, struct strbuf *gpg_status)
269 {
270         struct child_process gpg = CHILD_PROCESS_INIT;
271         struct gpg_format *fmt;
272         struct tempfile *temp;
273         int ret;
274         struct strbuf buf = STRBUF_INIT;
275
276         temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
277         if (!temp)
278                 return error_errno(_("could not create temporary file"));
279         if (write_in_full(temp->fd, signature, signature_size) < 0 ||
280             close_tempfile_gently(temp) < 0) {
281                 error_errno(_("failed writing detached signature to '%s'"),
282                             temp->filename.buf);
283                 delete_tempfile(&temp);
284                 return -1;
285         }
286
287         fmt = get_format_by_sig(signature);
288         if (!fmt)
289                 BUG("bad signature '%s'", signature);
290
291         argv_array_push(&gpg.args, fmt->program);
292         argv_array_pushv(&gpg.args, fmt->verify_args);
293         argv_array_pushl(&gpg.args,
294                          "--status-fd=1",
295                          "--verify", temp->filename.buf, "-",
296                          NULL);
297
298         if (!gpg_status)
299                 gpg_status = &buf;
300
301         sigchain_push(SIGPIPE, SIG_IGN);
302         ret = pipe_command(&gpg, payload, payload_size,
303                            gpg_status, 0, gpg_output, 0);
304         sigchain_pop(SIGPIPE);
305
306         delete_tempfile(&temp);
307
308         ret |= !strstr(gpg_status->buf, "\n[GNUPG:] GOODSIG ");
309         strbuf_release(&buf); /* no matter it was used or not */
310
311         return ret;
312 }