verify-commit: add test for exit status on untrusted signature
[git/git.git] / gpg-interface.c
CommitLineData
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1#include "cache.h"
2#include "run-command.h"
3#include "strbuf.h"
4#include "gpg-interface.h"
5#include "sigchain.h"
6
7static char *configured_signing_key;
0c5e70f0 8static const char *gpg_program = "gpg";
2f47eae2 9
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10#define PGP_SIGNATURE "-----BEGIN PGP SIGNATURE-----"
11#define PGP_MESSAGE "-----BEGIN PGP MESSAGE-----"
12
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13void signature_check_clear(struct signature_check *sigc)
14{
71c214c8 15 free(sigc->payload);
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16 free(sigc->gpg_output);
17 free(sigc->gpg_status);
18 free(sigc->signer);
19 free(sigc->key);
71c214c8 20 sigc->payload = NULL;
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21 sigc->gpg_output = NULL;
22 sigc->gpg_status = NULL;
23 sigc->signer = NULL;
24 sigc->key = NULL;
25}
26
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27static 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
37void 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
a4cc18f2 63void 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
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86/*
87 * Look at GPG signed content (e.g. a signed tag object), whose
88 * payload is followed by a detached signature on it. Return the
89 * offset where the embedded detached signature begins, or the end of
90 * the data when there is no such signature.
91 */
92size_t parse_signature(const char *buf, unsigned long size)
93{
94 char *eol;
95 size_t len = 0;
96 while (len < size && !starts_with(buf + len, PGP_SIGNATURE) &&
97 !starts_with(buf + len, PGP_MESSAGE)) {
98 eol = memchr(buf + len, '\n', size - len);
99 len += eol ? eol - (buf + len) + 1 : size - len;
100 }
101 return len;
102}
103
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104void set_signing_key(const char *key)
105{
106 free(configured_signing_key);
107 configured_signing_key = xstrdup(key);
108}
109
110int git_gpg_config(const char *var, const char *value, void *cb)
111{
112 if (!strcmp(var, "user.signingkey")) {
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113 set_signing_key(value);
114 }
115 if (!strcmp(var, "gpg.program")) {
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116 if (!value)
117 return config_error_nonbool(var);
0c5e70f0 118 gpg_program = xstrdup(value);
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119 }
120 return 0;
121}
122
123const char *get_signing_key(void)
124{
125 if (configured_signing_key)
126 return configured_signing_key;
f9bc573f 127 return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
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128}
129
130/*
131 * Create a detached signature for the contents of "buffer" and append
132 * it after "signature"; "buffer" and "signature" can be the same
133 * strbuf instance, which would cause the detached signature appended
134 * at the end.
135 */
136int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
137{
d3180279 138 struct child_process gpg = CHILD_PROCESS_INIT;
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139 const char *args[4];
140 ssize_t len;
141 size_t i, j, bottom;
142
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143 gpg.argv = args;
144 gpg.in = -1;
145 gpg.out = -1;
0c5e70f0 146 args[0] = gpg_program;
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147 args[1] = "-bsau";
148 args[2] = signing_key;
149 args[3] = NULL;
150
151 if (start_command(&gpg))
152 return error(_("could not run gpg."));
153
154 /*
155 * When the username signingkey is bad, program could be terminated
156 * because gpg exits without reading and then write gets SIGPIPE.
157 */
158 sigchain_push(SIGPIPE, SIG_IGN);
159
160 if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
161 close(gpg.in);
162 close(gpg.out);
163 finish_command(&gpg);
164 return error(_("gpg did not accept the data"));
165 }
166 close(gpg.in);
167
168 bottom = signature->len;
169 len = strbuf_read(signature, gpg.out, 1024);
170 close(gpg.out);
171
172 sigchain_pop(SIGPIPE);
173
174 if (finish_command(&gpg) || !len || len < 0)
175 return error(_("gpg failed to sign the data"));
176
177 /* Strip CR from the line endings, in case we are on Windows. */
178 for (i = j = bottom; i < signature->len; i++)
179 if (signature->buf[i] != '\r') {
180 if (i != j)
181 signature->buf[j] = signature->buf[i];
182 j++;
183 }
184 strbuf_setlen(signature, j);
185
186 return 0;
187}
188
189/*
190 * Run "gpg" to see if the payload matches the detached signature.
e3f55e07 191 * gpg_output, when set, receives the diagnostic output from GPG.
b60b7566 192 * gpg_status, when set, receives the status output from GPG.
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193 */
194int verify_signed_buffer(const char *payload, size_t payload_size,
195 const char *signature, size_t signature_size,
9cc4ac8f 196 struct strbuf *gpg_output, struct strbuf *gpg_status)
2f47eae2 197{
d3180279 198 struct child_process gpg = CHILD_PROCESS_INIT;
b60b7566 199 const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
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200 char path[PATH_MAX];
201 int fd, ret;
b60b7566 202 struct strbuf buf = STRBUF_INIT;
9cc4ac8f 203 struct strbuf *pbuf = &buf;
2f47eae2 204
0c5e70f0 205 args_gpg[0] = gpg_program;
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206 fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
207 if (fd < 0)
4c9a4182 208 return error(_("could not create temporary file '%s': %s"),
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209 path, strerror(errno));
210 if (write_in_full(fd, signature, signature_size) < 0)
4c9a4182 211 return error(_("failed writing detached signature to '%s': %s"),
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212 path, strerror(errno));
213 close(fd);
214
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215 gpg.argv = args_gpg;
216 gpg.in = -1;
b60b7566 217 gpg.out = -1;
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218 if (gpg_output)
219 gpg.err = -1;
b60b7566 220 args_gpg[3] = path;
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221 if (start_command(&gpg)) {
222 unlink(path);
4c9a4182 223 return error(_("could not run gpg."));
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224 }
225
226 write_in_full(gpg.in, payload, payload_size);
227 close(gpg.in);
228
7dac3f83 229 if (gpg_output) {
2f47eae2 230 strbuf_read(gpg_output, gpg.err, 0);
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231 close(gpg.err);
232 }
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233 if (gpg_status)
234 pbuf = gpg_status;
235 strbuf_read(pbuf, gpg.out, 0);
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236 close(gpg.out);
237
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238 ret = finish_command(&gpg);
239
240 unlink_or_warn(path);
241
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242 ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
243 strbuf_release(&buf); /* no matter it was used or not */
b60b7566 244
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245 return ret;
246}