aboutsummaryrefslogtreecommitdiff
path: root/gpg-interface.c
blob: 1ef73fb7dfedd8cd5d3444433218ff177a63111b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
#include "cache.h"
#include "run-command.h"
#include "strbuf.h"
#include "gpg-interface.h"
#include "sigchain.h"

static char *configured_signing_key;
static const char *gpg_program = "gpg";

void signature_check_clear(struct signature_check *sigc)
{
	free(sigc->payload);
	free(sigc->gpg_output);
	free(sigc->gpg_status);
	free(sigc->signer);
	free(sigc->key);
	sigc->payload = NULL;
	sigc->gpg_output = NULL;
	sigc->gpg_status = NULL;
	sigc->signer = NULL;
	sigc->key = NULL;
}

void set_signing_key(const char *key)
{
	free(configured_signing_key);
	configured_signing_key = xstrdup(key);
}

int git_gpg_config(const char *var, const char *value, void *cb)
{
	if (!strcmp(var, "user.signingkey")) {
		set_signing_key(value);
	}
	if (!strcmp(var, "gpg.program")) {
		if (!value)
			return config_error_nonbool(var);
		gpg_program = xstrdup(value);
	}
	return 0;
}

const char *get_signing_key(void)
{
	if (configured_signing_key)
		return configured_signing_key;
	return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
}

/*
 * Create a detached signature for the contents of "buffer" and append
 * it after "signature"; "buffer" and "signature" can be the same
 * strbuf instance, which would cause the detached signature appended
 * at the end.
 */
int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
{
	struct child_process gpg = CHILD_PROCESS_INIT;
	const char *args[4];
	ssize_t len;
	size_t i, j, bottom;

	gpg.argv = args;
	gpg.in = -1;
	gpg.out = -1;
	args[0] = gpg_program;
	args[1] = "-bsau";
	args[2] = signing_key;
	args[3] = NULL;

	if (start_command(&gpg))
		return error(_("could not run gpg."));

	/*
	 * When the username signingkey is bad, program could be terminated
	 * because gpg exits without reading and then write gets SIGPIPE.
	 */
	sigchain_push(SIGPIPE, SIG_IGN);

	if (write_in_full(gpg.in, buffer->buf, buffer->len) != buffer->len) {
		close(gpg.in);
		close(gpg.out);
		finish_command(&gpg);
		return error(_("gpg did not accept the data"));
	}
	close(gpg.in);

	bottom = signature->len;
	len = strbuf_read(signature, gpg.out, 1024);
	close(gpg.out);

	sigchain_pop(SIGPIPE);

	if (finish_command(&gpg) || !len || len < 0)
		return error(_("gpg failed to sign the data"));

	/* Strip CR from the line endings, in case we are on Windows. */
	for (i = j = bottom; i < signature->len; i++)
		if (signature->buf[i] != '\r') {
			if (i != j)
				signature->buf[j] = signature->buf[i];
			j++;
		}
	strbuf_setlen(signature, j);

	return 0;
}

/*
 * Run "gpg" to see if the payload matches the detached signature.
 * gpg_output, when set, receives the diagnostic output from GPG.
 * gpg_status, when set, receives the status output from GPG.
 */
int verify_signed_buffer(const char *payload, size_t payload_size,
			 const char *signature, size_t signature_size,
			 struct strbuf *gpg_output, struct strbuf *gpg_status)
{
	struct child_process gpg = CHILD_PROCESS_INIT;
	const char *args_gpg[] = {NULL, "--status-fd=1", "--verify", "FILE", "-", NULL};
	char path[PATH_MAX];
	int fd, ret;
	struct strbuf buf = STRBUF_INIT;
	struct strbuf *pbuf = &buf;

	args_gpg[0] = gpg_program;
	fd = git_mkstemp(path, PATH_MAX, ".git_vtag_tmpXXXXXX");
	if (fd < 0)
		return error(_("could not create temporary file '%s': %s"),
			     path, strerror(errno));
	if (write_in_full(fd, signature, signature_size) < 0)
		return error(_("failed writing detached signature to '%s': %s"),
			     path, strerror(errno));
	close(fd);

	gpg.argv = args_gpg;
	gpg.in = -1;
	gpg.out = -1;
	if (gpg_output)
		gpg.err = -1;
	args_gpg[3] = path;
	if (start_command(&gpg)) {
		unlink(path);
		return error(_("could not run gpg."));
	}

	write_in_full(gpg.in, payload, payload_size);
	close(gpg.in);

	if (gpg_output) {
		strbuf_read(gpg_output, gpg.err, 0);
		close(gpg.err);
	}
	if (gpg_status)
		pbuf = gpg_status;
	strbuf_read(pbuf, gpg.out, 0);
	close(gpg.out);

	ret = finish_command(&gpg);

	unlink_or_warn(path);

	ret |= !strstr(pbuf->buf, "\n[GNUPG:] GOODSIG ");
	strbuf_release(&buf); /* no matter it was used or not */

	return ret;
}