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git/gpg-interface.c

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#define USE_THE_REPOSITORY_VARIABLE
#include "git-compat-util.h"
#include "commit.h"
#include "config.h"
#include "date.h"
#include "gettext.h"
#include "run-command.h"
#include "strbuf.h"
#include "dir.h"
#include "ident.h"
#include "gpg-interface.h"
#include "path.h"
#include "sigchain.h"
#include "tempfile.h"
#include "alias.h"
static int git_gpg_config(const char *, const char *,
const struct config_context *, void *);
static void gpg_interface_lazy_init(void)
{
static int done;
if (done)
return;
done = 1;
git_config(git_gpg_config, NULL);
}
static char *configured_signing_key;
static char *ssh_default_key_command;
static char *ssh_allowed_signers;
static char *ssh_revocation_file;
static enum signature_trust_level configured_min_trust_level = TRUST_UNDEFINED;
struct gpg_format {
const char *name;
const char *program;
const char **verify_args;
const char **sigs;
int (*verify_signed_buffer)(struct signature_check *sigc,
struct gpg_format *fmt,
const char *signature,
size_t signature_size);
int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key);
const char *(*get_default_key)(void);
const char *(*get_key_id)(void);
};
static const char *openpgp_verify_args[] = {
"--keyid-format=long",
NULL
};
static const char *openpgp_sigs[] = {
"-----BEGIN PGP SIGNATURE-----",
"-----BEGIN PGP MESSAGE-----",
NULL
};
static const char *x509_verify_args[] = {
NULL
};
static const char *x509_sigs[] = {
"-----BEGIN SIGNED MESSAGE-----",
NULL
};
static const char *ssh_verify_args[] = { NULL };
static const char *ssh_sigs[] = {
"-----BEGIN SSH SIGNATURE-----",
NULL
};
static int verify_gpg_signed_buffer(struct signature_check *sigc,
struct gpg_format *fmt,
const char *signature,
size_t signature_size);
static int verify_ssh_signed_buffer(struct signature_check *sigc,
struct gpg_format *fmt,
const char *signature,
size_t signature_size);
static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key);
static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key);
static const char *get_default_ssh_signing_key(void);
static const char *get_ssh_key_id(void);
static struct gpg_format gpg_format[] = {
{
.name = "openpgp",
.program = "gpg",
.verify_args = openpgp_verify_args,
.sigs = openpgp_sigs,
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
.get_default_key = NULL,
.get_key_id = NULL,
},
{
.name = "x509",
.program = "gpgsm",
.verify_args = x509_verify_args,
.sigs = x509_sigs,
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
.get_default_key = NULL,
.get_key_id = NULL,
},
{
.name = "ssh",
.program = "ssh-keygen",
.verify_args = ssh_verify_args,
.sigs = ssh_sigs,
.verify_signed_buffer = verify_ssh_signed_buffer,
.sign_buffer = sign_buffer_ssh,
.get_default_key = get_default_ssh_signing_key,
.get_key_id = get_ssh_key_id,
},
};
static struct gpg_format *use_format = &gpg_format[0];
static struct gpg_format *get_format_by_name(const char *str)
{
int i;
for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
if (!strcmp(gpg_format[i].name, str))
return gpg_format + i;
return NULL;
}
static struct gpg_format *get_format_by_sig(const char *sig)
{
int i, j;
for (i = 0; i < ARRAY_SIZE(gpg_format); i++)
for (j = 0; gpg_format[i].sigs[j]; j++)
if (starts_with(sig, gpg_format[i].sigs[j]))
return gpg_format + i;
return NULL;
}
void signature_check_clear(struct signature_check *sigc)
{
FREE_AND_NULL(sigc->payload);
FREE_AND_NULL(sigc->output);
FREE_AND_NULL(sigc->gpg_status);
FREE_AND_NULL(sigc->signer);
FREE_AND_NULL(sigc->key);
FREE_AND_NULL(sigc->fingerprint);
FREE_AND_NULL(sigc->primary_key_fingerprint);
}
/* An exclusive status -- only one of them can appear in output */
#define GPG_STATUS_EXCLUSIVE (1<<0)
/* The status includes key identifier */
#define GPG_STATUS_KEYID (1<<1)
/* The status includes user identifier */
#define GPG_STATUS_UID (1<<2)
/* The status includes key fingerprints */
#define GPG_STATUS_FINGERPRINT (1<<3)
/* The status includes trust level */
#define GPG_STATUS_TRUST_LEVEL (1<<4)
/* Short-hand for standard exclusive *SIG status with keyid & UID */
#define GPG_STATUS_STDSIG (GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID|GPG_STATUS_UID)
static struct {
char result;
const char *check;
unsigned int flags;
} sigcheck_gpg_status[] = {
{ 'G', "GOODSIG ", GPG_STATUS_STDSIG },
{ 'B', "BADSIG ", GPG_STATUS_STDSIG },
{ 'E', "ERRSIG ", GPG_STATUS_EXCLUSIVE|GPG_STATUS_KEYID },
{ 'X', "EXPSIG ", GPG_STATUS_STDSIG },
{ 'Y', "EXPKEYSIG ", GPG_STATUS_STDSIG },
{ 'R', "REVKEYSIG ", GPG_STATUS_STDSIG },
{ 0, "VALIDSIG ", GPG_STATUS_FINGERPRINT },
{ 0, "TRUST_", GPG_STATUS_TRUST_LEVEL },
};
/* Keep the order same as enum signature_trust_level */
static struct sigcheck_gpg_trust_level {
const char *key;
const char *display_key;
enum signature_trust_level value;
} sigcheck_gpg_trust_level[] = {
{ "UNDEFINED", "undefined", TRUST_UNDEFINED },
{ "NEVER", "never", TRUST_NEVER },
{ "MARGINAL", "marginal", TRUST_MARGINAL },
{ "FULLY", "fully", TRUST_FULLY },
{ "ULTIMATE", "ultimate", TRUST_ULTIMATE },
};
static void replace_cstring(char **field, const char *line, const char *next)
{
free(*field);
if (line && next)
*field = xmemdupz(line, next - line);
else
*field = NULL;
}
static int parse_gpg_trust_level(const char *level,
enum signature_trust_level *res)
{
size_t i;
for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_trust_level); i++) {
if (!strcmp(sigcheck_gpg_trust_level[i].key, level)) {
*res = sigcheck_gpg_trust_level[i].value;
return 0;
}
}
return 1;
}
static void parse_gpg_output(struct signature_check *sigc)
{
const char *buf = sigc->gpg_status;
const char *line, *next;
int i, j;
int seen_exclusive_status = 0;
/* Iterate over all lines */
for (line = buf; *line; line = strchrnul(line+1, '\n')) {
while (*line == '\n')
line++;
if (!*line)
break;
/* Skip lines that don't start with GNUPG status */
if (!skip_prefix(line, "[GNUPG:] ", &line))
continue;
/* Iterate over all search strings */
for (i = 0; i < ARRAY_SIZE(sigcheck_gpg_status); i++) {
if (skip_prefix(line, sigcheck_gpg_status[i].check, &line)) {
/*
* GOODSIG, BADSIG etc. can occur only once for
* each signature. Therefore, if we had more
* than one then we're dealing with multiple
* signatures. We don't support them
* currently, and they're rather hard to
* create, so something is likely fishy and we
* should reject them altogether.
*/
if (sigcheck_gpg_status[i].flags & GPG_STATUS_EXCLUSIVE) {
if (seen_exclusive_status++)
goto error;
}
if (sigcheck_gpg_status[i].result)
sigc->result = sigcheck_gpg_status[i].result;
/* Do we have key information? */
if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) {
next = strchrnul(line, ' ');
replace_cstring(&sigc->key, line, next);
/* Do we have signer information? */
if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) {
line = next + 1;
next = strchrnul(line, '\n');
replace_cstring(&sigc->signer, line, next);
}
}
/* Do we have trust level? */
if (sigcheck_gpg_status[i].flags & GPG_STATUS_TRUST_LEVEL) {
/*
* GPG v1 and v2 differs in how the
* TRUST_ lines are written. Some
* trust lines contain no additional
* space-separated information for v1.
*/
size_t trust_size = strcspn(line, " \n");
char *trust = xmemdupz(line, trust_size);
if (parse_gpg_trust_level(trust, &sigc->trust_level)) {
free(trust);
goto error;
}
free(trust);
}
/* Do we have fingerprint? */
if (sigcheck_gpg_status[i].flags & GPG_STATUS_FINGERPRINT) {
const char *limit;
char **field;
next = strchrnul(line, ' ');
replace_cstring(&sigc->fingerprint, line, next);
/*
* Skip interim fields. The search is
* limited to the same line since only
* OpenPGP signatures has a field with
* the primary fingerprint.
*/
limit = strchrnul(line, '\n');
for (j = 9; j > 0; j--) {
if (!*next || limit <= next)
break;
line = next + 1;
next = strchrnul(line, ' ');
}
field = &sigc->primary_key_fingerprint;
if (!j) {
next = strchrnul(line, '\n');
replace_cstring(field, line, next);
} else {
replace_cstring(field, NULL, NULL);
}
}
break;
}
}
}
return;
error:
sigc->result = 'E';
/* Clear partial data to avoid confusion */
FREE_AND_NULL(sigc->primary_key_fingerprint);
FREE_AND_NULL(sigc->fingerprint);
FREE_AND_NULL(sigc->signer);
FREE_AND_NULL(sigc->key);
}
static int verify_gpg_signed_buffer(struct signature_check *sigc,
struct gpg_format *fmt,
const char *signature,
size_t signature_size)
{
struct child_process gpg = CHILD_PROCESS_INIT;
struct tempfile *temp;
int ret;
struct strbuf gpg_stdout = STRBUF_INIT;
struct strbuf gpg_stderr = STRBUF_INIT;
temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
if (!temp)
return error_errno(_("could not create temporary file"));
if (write_in_full(temp->fd, signature, signature_size) < 0 ||
close_tempfile_gently(temp) < 0) {
error_errno(_("failed writing detached signature to '%s'"),
temp->filename.buf);
delete_tempfile(&temp);
return -1;
}
strvec_push(&gpg.args, fmt->program);
strvec_pushv(&gpg.args, fmt->verify_args);
strvec_pushl(&gpg.args,
"--status-fd=1",
"--verify", temp->filename.buf, "-",
NULL);
sigchain_push(SIGPIPE, SIG_IGN);
ret = pipe_command(&gpg, sigc->payload, sigc->payload_len, &gpg_stdout, 0,
&gpg_stderr, 0);
sigchain_pop(SIGPIPE);
delete_tempfile(&temp);
ret |= !strstr(gpg_stdout.buf, "\n[GNUPG:] GOODSIG ");
sigc->output = strbuf_detach(&gpg_stderr, NULL);
sigc->gpg_status = strbuf_detach(&gpg_stdout, NULL);
parse_gpg_output(sigc);
strbuf_release(&gpg_stdout);
strbuf_release(&gpg_stderr);
return ret;
}
static void parse_ssh_output(struct signature_check *sigc)
{
const char *line, *principal, *search;
char *to_free;
char *key = NULL;
/*
* ssh-keygen output should be:
* Good "git" signature for PRINCIPAL with RSA key SHA256:FINGERPRINT
*
* or for valid but unknown keys:
* Good "git" signature with RSA key SHA256:FINGERPRINT
*
* Note that "PRINCIPAL" can contain whitespace, "RSA" and
* "SHA256" part could be a different token that names of
* the algorithms used, and "FINGERPRINT" is a hexadecimal
* string. By finding the last occurence of " with ", we can
* reliably parse out the PRINCIPAL.
*/
sigc->result = 'B';
sigc->trust_level = TRUST_NEVER;
line = to_free = xmemdupz(sigc->output, strcspn(sigc->output, "\n"));
if (skip_prefix(line, "Good \"git\" signature for ", &line)) {
/* Search for the last "with" to get the full principal */
principal = line;
do {
search = strstr(line, " with ");
if (search)
line = search + 1;
} while (search != NULL);
if (line == principal)
goto cleanup;
/* Valid signature and known principal */
sigc->result = 'G';
sigc->trust_level = TRUST_FULLY;
sigc->signer = xmemdupz(principal, line - principal - 1);
} else if (skip_prefix(line, "Good \"git\" signature with ", &line)) {
/* Valid signature, but key unknown */
sigc->result = 'G';
sigc->trust_level = TRUST_UNDEFINED;
} else {
goto cleanup;
}
key = strstr(line, "key ");
if (key) {
sigc->fingerprint = xstrdup(strstr(line, "key ") + 4);
sigc->key = xstrdup(sigc->fingerprint);
} else {
/*
* Output did not match what we expected
* Treat the signature as bad
*/
sigc->result = 'B';
}
cleanup:
free(to_free);
}
static int verify_ssh_signed_buffer(struct signature_check *sigc,
struct gpg_format *fmt,
const char *signature,
size_t signature_size)
{
struct child_process ssh_keygen = CHILD_PROCESS_INIT;
struct tempfile *buffer_file;
int ret = -1;
const char *line;
char *principal;
struct strbuf ssh_principals_out = STRBUF_INIT;
struct strbuf ssh_principals_err = STRBUF_INIT;
struct strbuf ssh_keygen_out = STRBUF_INIT;
struct strbuf ssh_keygen_err = STRBUF_INIT;
struct strbuf verify_time = STRBUF_INIT;
const struct date_mode verify_date_mode = {
.type = DATE_STRFTIME,
.strftime_fmt = "%Y%m%d%H%M%S",
/* SSH signing key validity has no timezone information - Use the local timezone */
.local = 1,
};
if (!ssh_allowed_signers) {
error(_("gpg.ssh.allowedSignersFile needs to be configured and exist for ssh signature verification"));
return -1;
}
buffer_file = mks_tempfile_t(".git_vtag_tmpXXXXXX");
if (!buffer_file)
return error_errno(_("could not create temporary file"));
if (write_in_full(buffer_file->fd, signature, signature_size) < 0 ||
close_tempfile_gently(buffer_file) < 0) {
error_errno(_("failed writing detached signature to '%s'"),
buffer_file->filename.buf);
delete_tempfile(&buffer_file);
return -1;
}
if (sigc->payload_timestamp)
strbuf_addf(&verify_time, "-Overify-time=%s",
show_date(sigc->payload_timestamp, 0, verify_date_mode));
/* Find the principal from the signers */
strvec_pushl(&ssh_keygen.args, fmt->program,
"-Y", "find-principals",
"-f", ssh_allowed_signers,
"-s", buffer_file->filename.buf,
verify_time.buf,
NULL);
ret = pipe_command(&ssh_keygen, NULL, 0, &ssh_principals_out, 0,
&ssh_principals_err, 0);
if (ret && strstr(ssh_principals_err.buf, "usage:")) {
error(_("ssh-keygen -Y find-principals/verify is needed for ssh signature verification (available in openssh version 8.2p1+)"));
goto out;
}
if (ret || !ssh_principals_out.len) {
/*
* We did not find a matching principal in the allowedSigners
* Check without validation
*/
child_process_init(&ssh_keygen);
strvec_pushl(&ssh_keygen.args, fmt->program,
"-Y", "check-novalidate",
"-n", "git",
"-s", buffer_file->filename.buf,
verify_time.buf,
NULL);
pipe_command(&ssh_keygen, sigc->payload, sigc->payload_len,
&ssh_keygen_out, 0, &ssh_keygen_err, 0);
/*
* Fail on unknown keys
* we still call check-novalidate to display the signature info
*/
ret = -1;
} else {
/* Check every principal we found (one per line) */
const char *next;
for (line = ssh_principals_out.buf;
*line;
line = next) {
const char *end_of_text;
next = end_of_text = strchrnul(line, '\n');
/* Did we find a LF, and did we have CR before it? */
if (*end_of_text &&
line < end_of_text &&
end_of_text[-1] == '\r')
end_of_text--;
/* Unless we hit NUL, skip over the LF we found */
if (*next)
next++;
/* Not all lines are data. Skip empty ones */
if (line == end_of_text)
continue;
/* We now know we have an non-empty line. Process it */
principal = xmemdupz(line, end_of_text - line);
child_process_init(&ssh_keygen);
strbuf_release(&ssh_keygen_out);
strbuf_release(&ssh_keygen_err);
strvec_push(&ssh_keygen.args, fmt->program);
/*
* We found principals
* Try with each until we find a match
*/
strvec_pushl(&ssh_keygen.args, "-Y", "verify",
"-n", "git",
"-f", ssh_allowed_signers,
"-I", principal,
"-s", buffer_file->filename.buf,
verify_time.buf,
NULL);
if (ssh_revocation_file) {
if (file_exists(ssh_revocation_file)) {
strvec_pushl(&ssh_keygen.args, "-r",
ssh_revocation_file, NULL);
} else {
warning(_("ssh signing revocation file configured but not found: %s"),
ssh_revocation_file);
}
}
sigchain_push(SIGPIPE, SIG_IGN);
ret = pipe_command(&ssh_keygen, sigc->payload, sigc->payload_len,
&ssh_keygen_out, 0, &ssh_keygen_err, 0);
sigchain_pop(SIGPIPE);
FREE_AND_NULL(principal);
if (!ret)
ret = !starts_with(ssh_keygen_out.buf, "Good");
if (!ret)
break;
}
}
strbuf_stripspace(&ssh_keygen_out, NULL);
strbuf_stripspace(&ssh_keygen_err, NULL);
/* Add stderr outputs to show the user actual ssh-keygen errors */
strbuf_add(&ssh_keygen_out, ssh_principals_err.buf, ssh_principals_err.len);
strbuf_add(&ssh_keygen_out, ssh_keygen_err.buf, ssh_keygen_err.len);
sigc->output = strbuf_detach(&ssh_keygen_out, NULL);
sigc->gpg_status = xstrdup(sigc->output);
parse_ssh_output(sigc);
out:
if (buffer_file)
delete_tempfile(&buffer_file);
strbuf_release(&ssh_principals_out);
strbuf_release(&ssh_principals_err);
strbuf_release(&ssh_keygen_out);
strbuf_release(&ssh_keygen_err);
strbuf_release(&verify_time);
return ret;
}
static int parse_payload_metadata(struct signature_check *sigc)
{
const char *ident_line = NULL;
size_t ident_len;
struct ident_split ident;
const char *signer_header;
switch (sigc->payload_type) {
case SIGNATURE_PAYLOAD_COMMIT:
signer_header = "committer";
break;
case SIGNATURE_PAYLOAD_TAG:
signer_header = "tagger";
break;
case SIGNATURE_PAYLOAD_UNDEFINED:
case SIGNATURE_PAYLOAD_PUSH_CERT:
/* Ignore payloads we don't want to parse */
return 0;
default:
BUG("invalid value for sigc->payload_type");
}
ident_line = find_commit_header(sigc->payload, signer_header, &ident_len);
if (!ident_line || !ident_len)
return 1;
if (split_ident_line(&ident, ident_line, ident_len))
return 1;
if (!sigc->payload_timestamp && ident.date_begin && ident.date_end)
sigc->payload_timestamp = parse_timestamp(ident.date_begin, NULL, 10);
return 0;
}
int check_signature(struct signature_check *sigc,
const char *signature, size_t slen)
{
struct gpg_format *fmt;
int status;
gpg_interface_lazy_init();
sigc->result = 'N';
sigc->trust_level = TRUST_UNDEFINED;
fmt = get_format_by_sig(signature);
if (!fmt)
die(_("bad/incompatible signature '%s'"), signature);
if (parse_payload_metadata(sigc))
return 1;
status = fmt->verify_signed_buffer(sigc, fmt, signature, slen);
if (status && !sigc->output)
return !!status;
status |= sigc->result != 'G';
status |= sigc->trust_level < configured_min_trust_level;
return !!status;
}
void print_signature_buffer(const struct signature_check *sigc, unsigned flags)
{
const char *output = flags & GPG_VERIFY_RAW ? sigc->gpg_status :
sigc->output;
if (flags & GPG_VERIFY_VERBOSE && sigc->payload)
fwrite(sigc->payload, 1, sigc->payload_len, stdout);
if (output)
fputs(output, stderr);
}
size_t parse_signed_buffer(const char *buf, size_t size)
{
size_t len = 0;
size_t match = size;
while (len < size) {
const char *eol;
if (get_format_by_sig(buf + len))
match = len;
eol = memchr(buf + len, '\n', size - len);
len += eol ? eol - (buf + len) + 1 : size - len;
}
return match;
}
int parse_signature(const char *buf, size_t size, struct strbuf *payload, struct strbuf *signature)
{
size_t match = parse_signed_buffer(buf, size);
if (match != size) {
strbuf_add(payload, buf, match);
remove_signature(payload);
strbuf_add(signature, buf + match, size - match);
return 1;
}
return 0;
}
void set_signing_key(const char *key)
{
gpg_interface_lazy_init();
free(configured_signing_key);
configured_signing_key = xstrdup(key);
}
static int git_gpg_config(const char *var, const char *value,
const struct config_context *ctx UNUSED,
void *cb UNUSED)
{
struct gpg_format *fmt = NULL;
const char *fmtname = NULL;
char *trust;
int ret;
if (!strcmp(var, "user.signingkey")) {
if (!value)
return config_error_nonbool(var);
set_signing_key(value);
return 0;
}
if (!strcmp(var, "gpg.format")) {
if (!value)
return config_error_nonbool(var);
fmt = get_format_by_name(value);
if (!fmt)
return error(_("invalid value for '%s': '%s'"),
var, value);
use_format = fmt;
return 0;
}
if (!strcmp(var, "gpg.mintrustlevel")) {
if (!value)
return config_error_nonbool(var);
trust = xstrdup_toupper(value);
ret = parse_gpg_trust_level(trust, &configured_min_trust_level);
free(trust);
if (ret)
return error(_("invalid value for '%s': '%s'"),
var, value);
return 0;
}
if (!strcmp(var, "gpg.ssh.defaultkeycommand"))
return git_config_string(&ssh_default_key_command, var, value);
if (!strcmp(var, "gpg.ssh.allowedsignersfile"))
return git_config_pathname(&ssh_allowed_signers, var, value);
if (!strcmp(var, "gpg.ssh.revocationfile"))
return git_config_pathname(&ssh_revocation_file, var, value);
if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
fmtname = "openpgp";
if (!strcmp(var, "gpg.x509.program"))
fmtname = "x509";
if (!strcmp(var, "gpg.ssh.program"))
fmtname = "ssh";
if (fmtname) {
fmt = get_format_by_name(fmtname);
return git_config_string((char **) &fmt->program, var, value);
}
return 0;
}
/*
* Returns 1 if `string` contains a literal ssh key, 0 otherwise
* `key` will be set to the start of the actual key if a prefix is present.
*/
static int is_literal_ssh_key(const char *string, const char **key)
{
if (skip_prefix(string, "key::", key))
return 1;
if (starts_with(string, "ssh-")) {
*key = string;
return 1;
}
return 0;
}
static char *get_ssh_key_fingerprint(const char *signing_key)
{
struct child_process ssh_keygen = CHILD_PROCESS_INIT;
int ret = -1;
struct strbuf fingerprint_stdout = STRBUF_INIT;
struct strbuf **fingerprint;
char *fingerprint_ret;
const char *literal_key = NULL;
/*
* With SSH Signing this can contain a filename or a public key
* For textual representation we usually want a fingerprint
*/
if (is_literal_ssh_key(signing_key, &literal_key)) {
strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf", "-", NULL);
ret = pipe_command(&ssh_keygen, literal_key,
strlen(literal_key), &fingerprint_stdout, 0,
NULL, 0);
} else {
strvec_pushl(&ssh_keygen.args, "ssh-keygen", "-lf",
configured_signing_key, NULL);
ret = pipe_command(&ssh_keygen, NULL, 0, &fingerprint_stdout, 0,
NULL, 0);
}
if (!!ret)
die_errno(_("failed to get the ssh fingerprint for key '%s'"),
signing_key);
fingerprint = strbuf_split_max(&fingerprint_stdout, ' ', 3);
if (!fingerprint[1])
die_errno(_("failed to get the ssh fingerprint for key '%s'"),
signing_key);
fingerprint_ret = strbuf_detach(fingerprint[1], NULL);
strbuf_list_free(fingerprint);
strbuf_release(&fingerprint_stdout);
return fingerprint_ret;
}
/* Returns the first public key from an ssh-agent to use for signing */
static const char *get_default_ssh_signing_key(void)
{
struct child_process ssh_default_key = CHILD_PROCESS_INIT;
int ret = -1;
struct strbuf key_stdout = STRBUF_INIT, key_stderr = STRBUF_INIT;
struct strbuf **keys;
char *key_command = NULL;
const char **argv;
int n;
char *default_key = NULL;
const char *literal_key = NULL;
if (!ssh_default_key_command)
die(_("either user.signingkey or gpg.ssh.defaultKeyCommand needs to be configured"));
key_command = xstrdup(ssh_default_key_command);
n = split_cmdline(key_command, &argv);
if (n < 0)
die("malformed build-time gpg.ssh.defaultKeyCommand: %s",
split_cmdline_strerror(n));
strvec_pushv(&ssh_default_key.args, argv);
ret = pipe_command(&ssh_default_key, NULL, 0, &key_stdout, 0,
&key_stderr, 0);
if (!ret) {
keys = strbuf_split_max(&key_stdout, '\n', 2);
if (keys[0] && is_literal_ssh_key(keys[0]->buf, &literal_key)) {
/*
* We only use `is_literal_ssh_key` here to check validity
* The prefix will be stripped when the key is used.
*/
default_key = strbuf_detach(keys[0], NULL);
} else {
warning(_("gpg.ssh.defaultKeyCommand succeeded but returned no keys: %s %s"),
key_stderr.buf, key_stdout.buf);
}
strbuf_list_free(keys);
} else {
warning(_("gpg.ssh.defaultKeyCommand failed: %s %s"),
key_stderr.buf, key_stdout.buf);
}
free(key_command);
free(argv);
strbuf_release(&key_stdout);
return default_key;
}
static const char *get_ssh_key_id(void) {
return get_ssh_key_fingerprint(get_signing_key());
}
/* Returns a textual but unique representation of the signing key */
const char *get_signing_key_id(void)
{
gpg_interface_lazy_init();
if (use_format->get_key_id) {
return use_format->get_key_id();
}
/* GPG/GPGSM only store a key id on this variable */
return get_signing_key();
}
const char *get_signing_key(void)
{
gpg_interface_lazy_init();
if (configured_signing_key)
return configured_signing_key;
if (use_format->get_default_key) {
return use_format->get_default_key();
}
return git_committer_info(IDENT_STRICT | IDENT_NO_DATE);
}
const char *gpg_trust_level_to_str(enum signature_trust_level level)
{
struct sigcheck_gpg_trust_level *trust;
if (level < 0 || level >= ARRAY_SIZE(sigcheck_gpg_trust_level))
BUG("invalid trust level requested %d", level);
trust = &sigcheck_gpg_trust_level[level];
if (trust->value != level)
BUG("sigcheck_gpg_trust_level[] unsorted");
return sigcheck_gpg_trust_level[level].display_key;
}
int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
{
gpg_interface_lazy_init();
return use_format->sign_buffer(buffer, signature, signing_key);
}
/*
* Strip CR from the line endings, in case we are on Windows.
* NEEDSWORK: make it trim only CRs before LFs and rename
*/
static void remove_cr_after(struct strbuf *buffer, size_t offset)
{
size_t i, j;
for (i = j = offset; i < buffer->len; i++) {
if (buffer->buf[i] != '\r') {
if (i != j)
buffer->buf[j] = buffer->buf[i];
j++;
}
}
strbuf_setlen(buffer, j);
}
static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key)
{
struct child_process gpg = CHILD_PROCESS_INIT;
int ret;
size_t bottom;
const char *cp;
struct strbuf gpg_status = STRBUF_INIT;
strvec_pushl(&gpg.args,
use_format->program,
"--status-fd=2",
"-bsau", signing_key,
NULL);
bottom = signature->len;
/*
* 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);
ret = pipe_command(&gpg, buffer->buf, buffer->len,
signature, 1024, &gpg_status, 0);
sigchain_pop(SIGPIPE);
for (cp = gpg_status.buf;
cp && (cp = strstr(cp, "[GNUPG:] SIG_CREATED "));
cp++) {
if (cp == gpg_status.buf || cp[-1] == '\n')
break; /* found */
}
ret |= !cp;
if (ret) {
error(_("gpg failed to sign the data:\n%s"),
gpg_status.len ? gpg_status.buf : "(no gpg output)");
strbuf_release(&gpg_status);
return -1;
}
strbuf_release(&gpg_status);
/* Strip CR from the line endings, in case we are on Windows. */
remove_cr_after(signature, bottom);
return 0;
}
static int sign_buffer_ssh(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key)
{
struct child_process signer = CHILD_PROCESS_INIT;
int ret = -1;
size_t bottom, keylen;
struct strbuf signer_stderr = STRBUF_INIT;
struct tempfile *key_file = NULL, *buffer_file = NULL;
char *ssh_signing_key_file = NULL;
struct strbuf ssh_signature_filename = STRBUF_INIT;
const char *literal_key = NULL;
int literal_ssh_key = 0;
if (!signing_key || signing_key[0] == '\0')
return error(
_("user.signingKey needs to be set for ssh signing"));
if (is_literal_ssh_key(signing_key, &literal_key)) {
/* A literal ssh key */
literal_ssh_key = 1;
key_file = mks_tempfile_t(".git_signing_key_tmpXXXXXX");
if (!key_file)
return error_errno(
_("could not create temporary file"));
keylen = strlen(literal_key);
if (write_in_full(key_file->fd, literal_key, keylen) < 0 ||
close_tempfile_gently(key_file) < 0) {
error_errno(_("failed writing ssh signing key to '%s'"),
key_file->filename.buf);
goto out;
}
ssh_signing_key_file = strbuf_detach(&key_file->filename, NULL);
} else {
/* We assume a file */
ssh_signing_key_file = interpolate_path(signing_key, 1);
}
buffer_file = mks_tempfile_t(".git_signing_buffer_tmpXXXXXX");
if (!buffer_file) {
error_errno(_("could not create temporary file"));
goto out;
}
if (write_in_full(buffer_file->fd, buffer->buf, buffer->len) < 0 ||
close_tempfile_gently(buffer_file) < 0) {
error_errno(_("failed writing ssh signing key buffer to '%s'"),
buffer_file->filename.buf);
goto out;
}
strvec_pushl(&signer.args, use_format->program,
"-Y", "sign",
"-n", "git",
"-f", ssh_signing_key_file,
NULL);
if (literal_ssh_key)
strvec_push(&signer.args, "-U");
strvec_push(&signer.args, buffer_file->filename.buf);
sigchain_push(SIGPIPE, SIG_IGN);
ret = pipe_command(&signer, NULL, 0, NULL, 0, &signer_stderr, 0);
sigchain_pop(SIGPIPE);
if (ret) {
if (strstr(signer_stderr.buf, "usage:"))
error(_("ssh-keygen -Y sign is needed for ssh signing (available in openssh version 8.2p1+)"));
ret = error("%s", signer_stderr.buf);
goto out;
}
bottom = signature->len;
strbuf_addbuf(&ssh_signature_filename, &buffer_file->filename);
strbuf_addstr(&ssh_signature_filename, ".sig");
if (strbuf_read_file(signature, ssh_signature_filename.buf, 0) < 0) {
ret = error_errno(
_("failed reading ssh signing data buffer from '%s'"),
ssh_signature_filename.buf);
goto out;
}
/* Strip CR from the line endings, in case we are on Windows. */
remove_cr_after(signature, bottom);
out:
if (key_file)
delete_tempfile(&key_file);
if (buffer_file)
delete_tempfile(&buffer_file);
if (ssh_signature_filename.len)
unlink_or_warn(ssh_signature_filename.buf);
strbuf_release(&signer_stderr);
strbuf_release(&ssh_signature_filename);
FREE_AND_NULL(ssh_signing_key_file);
return ret;
}
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