Sync with maint
[git] / gpg-interface.c
1 #include "cache.h"
2 #include "run-command.h"
3 #include "strbuf.h"
4 #include "gpg-interface.h"
5 #include "sigchain.h"
6
7 static char *configured_signing_key;
8 static const char *gpg_program = "gpg";
9
10 #define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
11 #define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
12
13 void signature_check_clear(struct signature_check *sigc)
14 {
15         free(sigc->payload);
16         free(sigc->gpg_output);
17         free(sigc->gpg_status);
18         free(sigc->signer);
19         free(sigc->key);
20         sigc->payload = NULL;
21         sigc->gpg_output = NULL;
22         sigc->gpg_status = NULL;
23         sigc->signer = NULL;
24         sigc->key = NULL;
25 }
26
27 static struct {
28         char result;
29         const char *check;
30 } sigcheck_gpg_status[] = {
31         { 'G', "\n[GNUPG:] GOODSIG " },
32         { 'B', "\n[GNUPG:] BADSIG " },
33         { 'U', "\n[GNUPG:] TRUST_NEVER" },
34         { 'U', "\n[GNUPG:] TRUST_UNDEFINED" },
35 };
36
37 void parse_gpg_output(struct signature_check *sigc)
38 {
39         const char *buf = sigc->gpg_status;
40         int i;
41
42         /* Iterate over all search strings */
43         for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
44                 const char *found, *next;
45
46                 if (!skip_prefix(buf, sigcheck_gpg_status[i].check + 1, &found)) {
47                         found = strstr(buf, sigcheck_gpg_status[i].check);
48                         if (!found)
49                                 continue;
50                         found += strlen(sigcheck_gpg_status[i].check);
51                 }
52                 sigc->result = sigcheck_gpg_status[i].result;
53                 /* The trust messages are not followed by key/signer information */
54                 if (sigc->result != 'U') {
55                         sigc->key = xmemdupz(found, 16);
56                         found += 17;
57                         next = strchrnul(found, '\n');
58                         sigc->signer = xmemdupz(found, next - found);
59                 }
60         }
61 }
62
63 int check_signature(const char *payload, size_t plen, const char *signature,
64         size_t slen, struct signature_check *sigc)
65 {
66         struct strbuf gpg_output = STRBUF_INIT;
67         struct strbuf gpg_status = STRBUF_INIT;
68         int status;
69
70         sigc->result = 'N';
71
72         status = verify_signed_buffer(payload, plen, signature, slen,
73                                       &gpg_output, &gpg_status);
74         if (status && !gpg_output.len)
75                 goto out;
76         sigc->payload = xmemdupz(payload, plen);
77         sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
78         sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
79         parse_gpg_output(sigc);
80
81  out:
82         strbuf_release(&gpg_status);
83         strbuf_release(&gpg_output);
84
85         return sigc->result != 'G' && sigc->result != 'U';
86 }
87
88 void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
89 {
90         const char *output = flags & GPG_VERIFY_RAW ?
91                 sigc->gpg_status : sigc->gpg_output;
92
93         if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
94                 fputs(sigc->payload, stdout);
95
96         if (output)
97                 fputs(output, stderr);
98 }
99
100 /*
101  * Look at GPG signed content (e.g. a signed tag object), whose
102  * payload is followed by a detached signature on it.  Return the
103  * offset where the embedded detached signature begins, or the end of
104  * the data when there is no such signature.
105  */
106 size_t parse_signature(const char *buf, unsigned long size)
107 {
108         char *eol;
109         size_t len = 0;
110         while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
111                         !starts_with(buf + len, PGP_MESSAGE)) {
112                 eol = memchr(buf + len, '\n', size - len);
113                 len += eol ? eol - (buf + len) + 1 : size - len;
114         }
115         return len;
116 }
117
118 void set_signing_key(const char *key)
119 {
120         free(configured_signing_key);
121         configured_signing_key = xstrdup(key);
122 }
123
124 int git_gpg_config(const char *var, const char *value, void *cb)
125 {
126         if (!strcmp(var, "user.signingkey")) {
127                 set_signing_key(value);
128         }
129         if (!strcmp(var, "gpg.program")) {
130                 if (!value)
131                         return config_error_nonbool(var);
132                 gpg_program = xstrdup(value);
133         }
134         return 0;
135 }
136
137 const char *get_signing_key(void)
138 {
139         if (configured_signing_key)
140                 return configured_signing_key;
141         return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
142 }
143
144 /*
145  * Create a detached signature for the contents of "buffer" and append
146  * it after "signature"; "buffer" and "signature" can be the same
147  * strbuf instance, which would cause the detached signature appended
148  * at the end.
149  */
150 int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
151 {
152         struct child_process gpg = CHILD_PROCESS_INIT;
153         const char *args[4];
154         ssize_t len;
155         size_t i, j, bottom;
156
157         gpg.argv = args;
158         gpg.in = -1;
159         gpg.out = -1;
160         args[0] = gpg_program;
161         args[1] = "-bsau";
162         args[2] = signing_key;
163         args[3] = NULL;
164
165         if (start_command(&gpg))
166                 return error(_("could not run gpg."));
167
168         /*
169          * When the username signingkey is bad, program could be terminated
170          * because gpg exits without reading and then write gets SIGPIPE.
171          */
172         sigchain_push(SIGPIPE, SIG_IGN);
173
174         if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
175                 close(gpg.in);
176                 close(gpg.out);
177                 finish_command(&gpg);
178                 return error(_("gpg did not accept the data"));
179         }
180         close(gpg.in);
181
182         bottom = signature->len;
183         len = strbuf_read(signature, gpg.out, 1024);
184         close(gpg.out);
185
186         sigchain_pop(SIGPIPE);
187
188         if (finish_command(&gpg) || !len || len < 0)
189                 return error(_("gpg failed to sign the data"));
190
191         /* Strip CR from the line endings, in case we are on Windows. */
192         for (i = j = bottom; i < signature->len; i++)
193                 if (signature->buf[i] != '\r') {
194                         if (i != j)
195                                 signature->buf[j] = signature->buf[i];
196                         j++;
197                 }
198         strbuf_setlen(signature, j);
199
200         return 0;
201 }
202
203 /*
204  * Run "gpg" to see if the payload matches the detached signature.
205  * gpg_output, when set, receives the diagnostic output from GPG.
206  * gpg_status, when set, receives the status output from GPG.
207  */
208 int verify_signed_buffer(const char *payload, size_t payload_size,
209                          const char *signature, size_t signature_size,
210                          struct strbuf *gpg_output, struct strbuf *gpg_status)
211 {
212         struct child_process gpg = CHILD_PROCESS_INIT;
213         const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
214         char path[PATH_MAX];
215         int fd, ret;
216         struct strbuf buf = STRBUF_INIT;
217         struct strbuf *pbuf = &buf;
218
219         args_gpg[0] = gpg_program;
220         fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
221         if (fd < 0)
222                 return error(_("could not create temporary file '%s': %s"),
223                              path, strerror(errno));
224         if (write_in_full(fd, signature, signature_size) < 0)
225                 return error(_("failed writing detached signature to '%s': %s"),
226                              path, strerror(errno));
227         close(fd);
228
229         gpg.argv = args_gpg;
230         gpg.in = -1;
231         gpg.out = -1;
232         if (gpg_output)
233                 gpg.err = -1;
234         args_gpg[3] = path;
235         if (start_command(&gpg)) {
236                 unlink(path);
237                 return error(_("could not run gpg."));
238         }
239
240         write_in_full(gpg.in, payload, payload_size);
241         close(gpg.in);
242
243         if (gpg_output) {
244                 strbuf_read(gpg_output, gpg.err, 0);
245                 close(gpg.err);
246         }
247         if (gpg_status)
248                 pbuf = gpg_status;
249         strbuf_read(pbuf, gpg.out, 0);
250         close(gpg.out);
251
252         ret = finish_command(&gpg);
253
254         unlink_or_warn(path);
255
256         ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
257         strbuf_release(&buf); /* no matter it was used or not */
258
259         return ret;
260 }