On 12.07.21 18:55, Ævar Arnfjörð Bjarmason wrote:
I'll change all the whitespace / comments / style issues with the next
commit. Thanks
+ sigc->result = 'G';
+ sigc->trust_level = TRUST_FULLY;
+
+ next = strchrnul(output, ' '); // 'principal'
+ replace_cstring(&sigc->signer, output, next);
+ output = next + 1;
+ next = strchrnul(output, ' '); // 'with'
+ output = next + 1;
+ next = strchrnul(output, ' '); // KEY Type
+ output = next + 1;
+ next = strchrnul(output, ' '); // 'key'
+ output = next + 1;
FWIW for new code we'd probably use string_list_split() or
string_list_split_in_place() or strbuf_split_buf() or something, but I
see this is following the existing pattern in the file...
I agree. This is my first patch in the git codebase so it takes a bit
getting used to all the available utilities.
+ const char *payload, size_t payload_size,
+ const char *signature, size_t signature_size)
{
- struct child_process gpg = CHILD_PROCESS_INIT;
- struct gpg_format *fmt;
+ struct child_process ssh_keygen = CHILD_PROCESS_INIT;
struct tempfile *temp;
int ret;
- struct strbuf buf = STRBUF_INIT;
+ const char *line;
+ size_t trust_size;
+ char *principal;
+ struct strbuf ssh_keygen_out = STRBUF_INIT;
+ struct strbuf ssh_keygen_err = STRBUF_INIT;
temp = mks_tempfile_t(".git_vtag_tmpXXXXXX");
if (!temp)
@@ -279,29 +342,125 @@ static int verify_signed_buffer(const char *payload, size_t payload_size,
return -1;
}
- fmt = get_format_by_sig(signature);
- if (!fmt)
- BUG("bad signature '%s'", signature);
+ // Find the principal from the signers
+ strvec_pushl(&ssh_keygen.args, fmt->program,
+ "-Y", "find-principals",
+ "-f", get_ssh_allowed_signers(),
+ "-s", temp->filename.buf,
+ NULL);
+ ret = pipe_command(&ssh_keygen, NULL, 0, &ssh_keygen_out, 0, &ssh_keygen_err, 0);
+ if (strstr(ssh_keygen_err.buf, "unknown option")) {
+ error(_("openssh version > 8.2p1 is needed for ssh signature verification (ssh-keygen needs -Y find-principals/verify option)"));
+ }
+ if (ret || !ssh_keygen_out.len) {
+ // We did not find a matching principal in the keyring - Check without validation
+ child_process_init(&ssh_keygen);
+ strvec_pushl(&ssh_keygen.args, fmt->program,
+ "-Y", "check-novalidate",
+ "-n", "git",
+ "-s", temp->filename.buf,
+ NULL);
+ ret = pipe_command(&ssh_keygen, payload, payload_size, &ssh_keygen_out, 0, &ssh_keygen_err, 0);
+ } else {
+ // Check every principal we found (one per line)
+ for (line = ssh_keygen_out.buf; *line; line = strchrnul(line + 1, '\n')) {
Hrm, can't we use strbuf_getline() here with the underlying io_pump API
that pipe_command() uses, instead of slurping it all up, and then
splitting on '\n' ourselves? (I'm not sure)
Sounds good. I'll give it a try.
+ while (*line == '\n')
+ line++;
+ if (!*line)
+ break;
+
+ trust_size = strcspn(line, " \n");
+ principal = xmemdupz(line, trust_size);
+
+ 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",
+ //TODO: sprintf("-Overify-time=%s", commit->date...),
+ "-n", "git",
+ "-f", get_ssh_allowed_signers(),
+ "-I", principal,
+ "-s", temp->filename.buf,
+ NULL);
+
+ if (ssh_revocation_file && file_exists(ssh_revocation_file)) {
+ strvec_pushl(&ssh_keygen.args, "-r", ssh_revocation_file, NULL);
Do we want to silently ignore missing but configured revocation files?
I'll add a warning
+ }
+
+ sigchain_push(SIGPIPE, SIG_IGN);
+ ret = pipe_command(&ssh_keygen, payload, payload_size,
+ &ssh_keygen_out, 0, &ssh_keygen_err, 0);
+ sigchain_pop(SIGPIPE);
+
+ ret &= starts_with(ssh_keygen_out.buf, "Good");
+ if (ret == 0)
+ break;
+ }
+ }
+
+ sigc->payload = xmemdupz(payload, payload_size);
+ strbuf_stripspace(&ssh_keygen_out, 0);
+ strbuf_stripspace(&ssh_keygen_err, 0);
+ strbuf_add(&ssh_keygen_out, ssh_keygen_err.buf, ssh_keygen_err.len);
+ sigc->output = strbuf_detach(&ssh_keygen_out, NULL);
+
+ //sigc->gpg_output = strbuf_detach(&ssh_keygen_err, NULL); // This flip around is broken...
Broken how? And why the commented-out code as part of the patch?
Sorry, i should have removed it. The original code assigned gpg's stdout
to gpg_status and stdout to gpg_output which can be a bit confusing.
- status = verify_signed_buffer(payload, plen, signature, slen,
- &gpg_output, &gpg_status);
- if (status && !gpg_output.len)
- goto out;
- sigc->payload = xmemdupz(payload, plen);
- sigc->gpg_output = strbuf_detach(&gpg_output, NULL);
- sigc->gpg_status = strbuf_detach(&gpg_status, NULL);
- parse_gpg_output(sigc);
+ fmt = get_format_by_sig(signature);
+ if (!fmt)
+ BUG("bad signature '%s'", signature);
So if we run this from receive-pack or whatever we'll BUG() out? I.e. I
think this should be an fsck check or something, but not a BUG(), or
does this not rely on potentially bad object-store state?
The BUG() call is also from the original code. I agree that it should be
handled differently.
Unfortunately this call is also the reason that when trying to verify a
new SSH signature with a current git version you'll get a segfault from
this BUG() :/
I'm not sure if i can do anything about this other than adding a
completely new tag in the commit itself instead of "gpgsig" which might
be quite involved. I haven't looked into that too much yet.
+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;
+
+ /* For SSH Signing this can contain a filename or a public key
+ * For textual representation we usually want a fingerprint
+ */
+ if (istarts_with(signing_key, "ssh-")) {
+ strvec_pushl(&ssh_keygen.args, "ssh-keygen",
+ "-lf", "-",
+ NULL);
+ ret = pipe_command(&ssh_keygen, signing_key, strlen(signing_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]) {
+ return strbuf_detach(fingerprint[1], NULL);
+ }
+ }
+ die_errno(_("failed to get the ssh fingerprint for key '%s'"), signing_key);
+}
Her you declare a ret that's not used at all in the "istarts_with"
branch, and we fall through to die_errno()?
I'll clean up the logic. Thanks
[I stopped reading mostly at this point]
[...]
+# test_expect_success GPGSSH 'detect fudged commit with double signature' '
+# sed -e "/gpgsig/,/END PGP/d" forged1 >double-base &&
+# sed -n -e "/gpgsig/,/END PGP/p" forged1 | \
+# sed -e "s/^$(test_oid header)//;s/^ //" | gpg --dearmor >double-sig1.sig &&
+# gpg -o double-sig2.sig -u 29472784 --detach-sign double-base &&
+# cat double-sig1.sig double-sig2.sig | gpg --enarmor >double-combined.asc &&
+# sed -e "s/^\(-.*\)ARMORED FILE/\1SIGNATURE/;1s/^/$(test_oid header) /;2,\$s/^/ /" \
+# double-combined.asc > double-gpgsig &&
+# sed -e "/committer/r double-gpgsig" double-base >double-commit &&
+# git hash-object -w -t commit double-commit >double-commit.commit &&
+# test_must_fail git verify-commit $(cat double-commit.commit) &&
+# git show --pretty=short --show-signature $(cat double-commit.commit) >double-actual &&
+# grep "BAD signature from" double-actual &&
+# grep "Good signature from" double-actual
+# '
+
+# test_expect_success GPGSSH 'show double signature with custom format' '
+# cat >expect <<-\EOF &&
+# E
+
+
+
+
+# EOF
+# git log -1 --format="%G?%n%GK%n%GS%n%GF%n%GP" $(cat double-commit.commit) >actual &&
+# test_cmp expect actual
+# '
Perhaps you're looking for test_expect_failure for TODO tests?
Yes. Although this test explicitly i'm having a hard time to duplicate
for ssh. I'm still trying to find out if the duplicate signature thing
is actually an issue with ssh.
I think this patch is *way* past the point of benefitting from being
split into a patch series. It grew from ~200 lines added to ~1k.
Sure, I can easily split the patch into seperate commits. But do i
create a v3 patch from this or issue a new pull request?
The diff between v2 & v3 would be quite useless otherwise wouldn't it?
And maybe another beginner contribution question:
When i make changes to a patchset do i put new changes from the review
on top as new commits or do i edit the existing commits?
If so what is the workflow you normally use for this? fixup commits? I
know about those but haven't worked with them before.
Thanks for your help!
