From: Fabian Stelzer <fs@xxxxxxxxxxxx>
If user.signingkey is not set and a ssh signature is requested we call
gpg.ssh.defaultKeyCommand (typically "ssh-add -L") and use the first key we get
Signed-off-by: Fabian Stelzer <fs@xxxxxxxxxxxx>
---
Documentation/config/gpg.txt | 6 +++
Documentation/config/user.txt | 4 +-
gpg-interface.c | 70 ++++++++++++++++++++++++++++++++++-
3 files changed, 77 insertions(+), 3 deletions(-)
diff --git a/Documentation/config/gpg.txt b/Documentation/config/gpg.txt
index 88531b15f0f..9b95dd280c3 100644
--- a/Documentation/config/gpg.txt
+++ b/Documentation/config/gpg.txt
@@ -33,3 +33,9 @@ gpg.minTrustLevel::
* `marginal`
* `fully`
* `ultimate`
+
+gpg.ssh.defaultKeyCommand:
+ This command that will be run when user.signingkey is not set and a ssh
+ signature is requested. On successful exit a valid ssh public key is
+ expected in the first line of its output. To automatically use the first
+ available key from your ssh-agent set this to "ssh-add -L".
diff --git a/Documentation/config/user.txt b/Documentation/config/user.txt
index 2155128957c..ad78dce9ecb 100644
--- a/Documentation/config/user.txt
+++ b/Documentation/config/user.txt
@@ -40,4 +40,6 @@ user.signingKey::
key (e.g.: "ssh-rsa XXXXXX identifier") or a file which contains it and
corresponds to the private key used for signing. The private key
needs to be available via ssh-agent. Alternatively it can be set to
- a file containing a private key directly.
+ a file containing a private key directly. If not set git will call
+ gpg.ssh.defaultKeyCommand (e.g.: "ssh-add -L") and try to use the first
+ key available.
diff --git a/gpg-interface.c b/gpg-interface.c
index 7ca682ac6d6..3a0cca1b1d2 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -6,8 +6,10 @@
#include "gpg-interface.h"
#include "sigchain.h"
#include "tempfile.h"
+#include "alias.h"
static char *configured_signing_key;
+static const char *ssh_default_key_command;
static enum signature_trust_level configured_min_trust_level = TRUST_UNDEFINED;
struct gpg_format {
@@ -21,6 +23,7 @@ struct gpg_format {
size_t signature_size);
int (*sign_buffer)(struct strbuf *buffer, struct strbuf *signature,
const char *signing_key);
+ const char *(*get_default_key)(void);
};
static const char *openpgp_verify_args[] = {
@@ -56,6 +59,8 @@ static int sign_buffer_gpg(struct strbuf *buffer, struct strbuf *signature,
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 struct gpg_format gpg_format[] = {
{
.name = "openpgp",
@@ -64,6 +69,7 @@ static struct gpg_format gpg_format[] = {
.sigs = openpgp_sigs,
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
+ .get_default_key = NULL,
},
{
.name = "x509",
@@ -72,6 +78,7 @@ static struct gpg_format gpg_format[] = {
.sigs = x509_sigs,
.verify_signed_buffer = verify_gpg_signed_buffer,
.sign_buffer = sign_buffer_gpg,
+ .get_default_key = NULL,
},
{
.name = "ssh",
@@ -79,7 +86,8 @@ static struct gpg_format gpg_format[] = {
.verify_args = ssh_verify_args,
.sigs = ssh_sigs,
.verify_signed_buffer = NULL, /* TODO */
- .sign_buffer = sign_buffer_ssh
+ .sign_buffer = sign_buffer_ssh,
+ .get_default_key = get_default_ssh_signing_key,
},
};
@@ -453,6 +461,12 @@ int git_gpg_config(const char *var, const char *value, void *cb)
return 0;
}
+ if (!strcmp(var, "gpg.ssh.defaultkeycommand")) {
+ if (!value)
+ return config_error_nonbool(var);
+ return git_config_string(&ssh_default_key_command, var, value);
+ }
+
if (!strcmp(var, "gpg.program") || !strcmp(var, "gpg.openpgp.program"))
fmtname = "openpgp";
@@ -470,11 +484,63 @@ int git_gpg_config(const char *var, const char *value, void *cb)
return 0;
}
+/* 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;
+
+ 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] && starts_with(keys[0]->buf, "ssh-")) {
+ 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;
+}
+
const char *get_signing_key(void)
{
if (configured_signing_key)
return configured_signing_key;
- return git_committer_info(IDENT_STRICT|IDENT_NO_DATE);
+ if (use_format->get_default_key) {
+ return use_format->get_default_key();
+ }
+
+ return git_committer_info(IDENT_STRICT | IDENT_NO_DATE);
}
int sign_buffer(struct strbuf *buffer, struct strbuf *signature, const char *signing_key)
--
gitgitgadget
