[PATCH v7 4/5] merge/pull Check for untrusted good GPG signatures

["Sebastian Götte" <jaseg@physik.tu-berlin.de>]

When --verify-signatures is specified, abort the merge in case a good
GPG signature from an untrusted key is encountered.

Signed-off-by: Sebastian Götte <jaseg@physik-pool.tu-berlin.de>
---
 Documentation/merge-options.txt    |   4 ++--
 builtin/merge.c                    |   2 ++
 commit.c                           |  13 ++++++++-----
 commit.h                           |  10 +++++-----
 gpg-interface.h                    |   1 +
 t/lib-gpg/pubring.gpg              | Bin 1164 -> 2359 bytes
 t/lib-gpg/random_seed              | Bin 600 -> 600 bytes
 t/lib-gpg/secring.gpg              | Bin 1237 -> 3734 bytes
 t/lib-gpg/trustdb.gpg              | Bin 1280 -> 1360 bytes
 t/t7612-merge-verify-signatures.sh |   9 +++++++++
 10 files changed, 27 insertions(+), 12 deletions(-)

diff --git a/Documentation/merge-options.txt b/Documentation/merge-options.txt
index 31f1067..a0f022b 100644
--- a/Documentation/merge-options.txt
+++ b/Documentation/merge-options.txt
@@ -85,8 +85,8 @@ option can be used to override --squash.
 
 --verify-signatures::
 --no-verify-signatures::
-	Verify that the commits being merged have good GPG signatures and abort the
-	merge in case they do not.
+	Verify that the commits being merged have good and trusted GPG signatures
+	and abort the merge in case they do not.
 
 --summary::
 --no-summary::
diff --git a/builtin/merge.c b/builtin/merge.c
index 7a33d03..752e3a9 100644
--- a/builtin/merge.c
+++ b/builtin/merge.c
@@ -1248,6 +1248,8 @@ int cmd_merge(int argc, const char **argv, const char *prefix)
 			switch(signature_check.result){
 				case 'G':
 					break;
+				case 'U':
+					die(_("Commit %s has a good, untrusted GPG signature allegedly by %s."), hex, signature_check.signer);
 				case 'B':
 					die(_("Commit %s has a bad GPG signature allegedly by %s."), hex, signature_check.signer);
 				default: /* 'N' */
diff --git a/commit.c b/commit.c
index eda7f90..bb2d9ad 100644
--- a/commit.c
+++ b/commit.c
@@ -1029,6 +1029,8 @@ static struct {
 } sigcheck_gpg_status[] = {
 	{ 'G', "[GNUPG:] GOODSIG " },
 	{ 'B', "[GNUPG:] BADSIG " },
+	{ 'U', "[GNUPG:] TRUST_NEVER" },
+	{ 'U', "[GNUPG:] TRUST_UNDEFINED" },
 };
 
 static void parse_gpg_output(struct signature_check *sigc)
@@ -1050,11 +1052,12 @@ static void parse_gpg_output(struct signature_check *sigc)
 			found += strlen(sigcheck_gpg_status[i].check);
 		}
 		sigc->result = sigcheck_gpg_status[i].result;
-		sigc->key = xmemdupz(found, 16);
-		found += 17;
-		next = strchrnul(found, '\n');
-		sigc->signer = xmemdupz(found, next - found);
-		break;
+		if (sigc->result != 'U') {
+			sigc->key = xmemdupz(found, 16);
+			found += 17;
+			next = strchrnul(found, '\n');
+			sigc->signer = xmemdupz(found, next - found);
+		}
 	}
 }
 
diff --git a/commit.h b/commit.h
index 8bbcf13..27d9b36 100644
--- a/commit.h
+++ b/commit.h
@@ -232,11 +232,11 @@ extern void print_commit_list(struct commit_list *list,
 			      const char *format_last);
 
 /*
- * Check the signature of the given commit. The result of the check is stored in
- * sig->result, 'G' for a good signature, 'B' for a bad signature and 'N'
- * for no signature at all.
- * This may allocate memory for sig->gpg_output, sig->gpg_status, sig->signer
- * and sig->key.
+ * Check the signature of the given commit. The result of the check is stored
+ * in sig->check_result, 'G' for a good signature, 'U' for a good signature
+ * from an untrusted signer, 'B' for a bad signature and 'N' for no signature
+ * at all.  This may allocate memory for sig->gpg_output, sig->gpg_status,
+ * sig->signer and sig->key.
  */
 extern void check_commit_signature(const struct commit* commit, struct signature_check *sigc);
 
diff --git a/gpg-interface.h b/gpg-interface.h
index 5884aa4..a85cb5b 100644
--- a/gpg-interface.h
+++ b/gpg-interface.h
@@ -6,6 +6,7 @@ struct signature_check {
 	char *gpg_status;
 	char result; /* 0 (not checked),
 		      * N (checked but no further result),
+		      * U (untrusted good),
 		      * G (good)
 		      * B (bad) */
 	char *signer;
diff --git a/t/lib-gpg/pubring.gpg b/t/lib-gpg/pubring.gpg
index 83855fa4e1c6c37afe550c17afa1e7971042ded5..1a3c2d487c2fda9169751a3068fa51e853a1e519 100644
GIT binary patch
delta 1212
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a9*zs=xM)EjeiKg!$s4>o369jT0ssS^s3f2O

delta 7
Ocmdlk)Wf-<hXnu&fC8TY

diff --git a/t/lib-gpg/random_seed b/t/lib-gpg/random_seed
index 8fed1339ed0a744e5663f4a5e6b6ac9bae3d8524..95d249f15fce980f0e8c1a8a18b085b3885708aa 100644
GIT binary patch
literal 600
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diff --git a/t/lib-gpg/secring.gpg b/t/lib-gpg/secring.gpg
index d831cd9eb3eee613d3c0e1a71093ae01ea7347e3..82dca8f80bf170fde5705862c3eeb9d994725042 100644
GIT binary patch
delta 2524
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delta 7
OcmbOxdzEv;RTcmY+5;N^

diff --git a/t/lib-gpg/trustdb.gpg b/t/lib-gpg/trustdb.gpg
index abace962b8bf84be688a6f27e4ebd0ee7052f210..4879ae9a84650a93a4d15bd6560c5d1b89eb4c2f 100644
GIT binary patch
delta 133
zcmZqRy1*sEm|l?1%*@Ej$i%=9=re5@0|Nu&L_y(=>YJDu6*k{umSl_t3LyXw!<BtX
zhEkV><>GE>E=lCnYu&C?*vSl0pomb%%dj-dsEA)Mq*Svt$mH(j_twWhW_@KtD1fp6
DE~Fa=

delta 52
zcmcb>)xagdm|l?1%*@Ej$iTqhmVVlAqM`Uk^-atZ9rz~(oS3|U#hLd&3{VON0Ad;p
ADF6Tf

diff --git a/t/t7612-merge-verify-signatures.sh b/t/t7612-merge-verify-signatures.sh
index 6ccfbf3..20b3cfb 100755
--- a/t/t7612-merge-verify-signatures.sh
+++ b/t/t7612-merge-verify-signatures.sh
@@ -27,6 +27,10 @@ test_expect_success GPG 'create signed commits' '
 	git hash-object -w -t commit forged >forged.commit &&
 	git checkout initial &&
 
+	git checkout -b side-untrusted &&
+	echo 3 >baz && git add baz &&
+	test_tick && git commit -SB7227189 -m "untrusted on side"
+
 	git checkout master
 '
 
@@ -40,6 +44,11 @@ test_expect_success GPG 'merge commit with bad signature with verification' '
 	test_i18ngrep "has a bad GPG signature" mergeerror
 '
 
+test_expect_success GPG 'merge commit with untrusted signature with verification' '
+	test_must_fail git merge --ff-only --verify-signatures side-untrusted 2>mergeerror &&
+	test_i18ngrep "has a good, untrusted GPG signature" mergeerror
+'
+
 test_expect_success GPG 'merge signed commit with verification' '
 	git merge --verbose --ff-only --verify-signatures side-signed >mergeoutput &&
 	test_i18ngrep "has a good GPG signature" mergeoutput
-- 
1.8.1.5