[PATCH v2 0/5] Wildcard matching for credentials

[PATCH v2 0/5] Wildcard matching for credentials

[brian m. carlson]

This series introduces wildcard matching (that is, urlmatch support) for
credential config options, just like for the http options.  This is
helpful in corporate environments where custom credentials should be
used across a wide variety of subdomains.

Changes from v1:
* Add a variety of additional tests in patch 3.
* Switch to using the last matching config option for
  credential.username like we do everywhere else.
* Use all matching config keys, as we did before.
* Skip calling git_default_config.
* Fix percent-encoding handling and add a function to handle that.

brian m. carlson (5):
  mailmap: add an additional email address for brian m. carlson
  t1300: add test for urlmatch with multiple wildcards
  t0300: add tests for some additional cases
  credential: use the last matching username in the config
  credential: allow wildcard patterns when matching config

 .mailmap                         |   1 +
 Documentation/gitcredentials.txt |   4 +-
 credential.c                     |  75 +++++++++++++-----
 credential.h                     |   3 +-
 strbuf.c                         |  15 ++++
 strbuf.h                         |   6 ++
 t/t0300-credentials.sh           | 128 +++++++++++++++++++++++++++++++
 t/t1300-config.sh                |   6 ++
 urlmatch.c                       |   4 +-
 urlmatch.h                       |   9 +++
 10 files changed, 228 insertions(+), 23 deletions(-)

[PATCH v2 1/5] mailmap: add an additional email address for brian m. carlson

[brian m. carlson]

From: brian m. carlson <bk2204@github.com>

To more accurately track the provenance of contributions, brian uses a
work email address for commits created at work. Add this email address
to .mailmap so that contributions are properly attributed to the same
person.

Signed-off-by: brian m. carlson <bk2204@github.com>
---
 .mailmap | 1 +
 1 file changed, 1 insertion(+)

diff --git a/.mailmap b/.mailmap
index 73fd92e192..bde7aba756 100644
--- a/.mailmap
+++ b/.mailmap
@@ -31,6 +31,7 @@ Brandon Casey <drafnel@gmail.com> <casey@nrlssc.navy.mil>
 Brandon Williams <bwilliams.eng@gmail.com> <bmwill@google.com>
 brian m. carlson <sandals@crustytoothpaste.net>
 brian m. carlson <sandals@crustytoothpaste.net> <sandals@crustytoothpaste.ath.cx>
+brian m. carlson <sandals@crustytoothpaste.net> <bk2204@github.com>
 Bryan Larsen <bryan@larsen.st> <bryan.larsen@gmail.com>
 Bryan Larsen <bryan@larsen.st> <bryanlarsen@yahoo.com>
 Cheng Renquan <crquan@gmail.com>

[PATCH v2 2/5] t1300: add test for urlmatch with multiple wildcards

[brian m. carlson]

From: brian m. carlson <bk2204@github.com>

Our urlmatch code handles multiple wildcards, but we don't currently
have a test that checks this code path. Add a test that we handle this
case correctly to avoid any regressions.

Signed-off-by: brian m. carlson <bk2204@github.com>
---
 t/t1300-config.sh | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/t/t1300-config.sh b/t/t1300-config.sh
index 5464c46c18..97ebfe1f9d 100755
--- a/t/t1300-config.sh
+++ b/t/t1300-config.sh
@@ -1408,6 +1408,8 @@ test_expect_success 'urlmatch favors more specific URLs' '
 		cookieFile = /tmp/wildcard.txt
 	[http "https://*.example.com/wildcardwithsubdomain"]
 		cookieFile = /tmp/wildcardwithsubdomain.txt
+	[http "https://*.example.*"]
+		cookieFile = /tmp/multiwildcard.txt
 	[http "https://trailing.example.com"]
 		cookieFile = /tmp/trailing.txt
 	[http "https://user@*.example.com/"]
@@ -1454,6 +1456,10 @@ test_expect_success 'urlmatch favors more specific URLs' '
 
 	echo http.cookiefile /tmp/sub.txt >expect &&
 	git config --get-urlmatch HTTP https://user@sub.example.com >actual &&
+	test_cmp expect actual &&
+
+	echo http.cookiefile /tmp/multiwildcard.txt >expect &&
+	git config --get-urlmatch HTTP https://wildcard.example.org >actual &&
 	test_cmp expect actual
 '
 

[PATCH v2 3/5] t0300: add tests for some additional cases

[brian m. carlson]

From: brian m. carlson <bk2204@github.com>

There are some tricky cases in our credential helpers that we don't have
test cases for.  To help prevent regressions, let's add some for these
cases:

* If there are multiple configured credential helpers, one without a
  path and one with a path, we want to invoke both of them.
* If there are percent-encoded values in the URL, we handle them
  properly.
* And finally, if there is a username in the remote URL, we want to
  honor that over what the configuration tells us.

Finally, there's an additional case that we'd like to test for as well,
but that currently fails.  In all other situations in our configuration,
we pick the last configuration setting that's provided.  However, we
fail to do that for credential.username, where we pick the first setting
instead.  Let's add a failing test that we have the consistent behavior
here, since that's the documented, expected behavior.

Signed-off-by: brian m. carlson <bk2204@github.com>
---
 t/t0300-credentials.sh | 108 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)

diff --git a/t/t0300-credentials.sh b/t/t0300-credentials.sh
index 82eaaea0f4..4593a0cd3d 100755
--- a/t/t0300-credentials.sh
+++ b/t/t0300-credentials.sh
@@ -240,6 +240,57 @@ test_expect_success 'do not match configured credential' '
 	EOF
 '
 
+test_expect_success 'match multiple configured helpers' '
+	test_config credential.helper "verbatim \"\" \"\"" &&
+	test_config credential.https://example.com.helper "$HELPER" &&
+	check fill <<-\EOF
+	protocol=https
+	host=example.com
+	path=repo.git
+	--
+	protocol=https
+	host=example.com
+	username=foo
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.com
+	EOF
+'
+
+test_expect_success 'match multiple configured helpers with URLs' '
+	test_config credential.https://example.com/repo.git.helper "verbatim \"\" \"\"" &&
+	test_config credential.https://example.com.helper "$HELPER" &&
+	check fill <<-\EOF
+	protocol=https
+	host=example.com
+	path=repo.git
+	--
+	protocol=https
+	host=example.com
+	username=foo
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.com
+	EOF
+'
+
+test_expect_success 'match percent-encoded values' '
+	test_config credential.https://example.com/%2566.git.helper "$HELPER" &&
+	check fill <<-\EOF
+	url=https://example.com/%2566.git
+	--
+	protocol=https
+	host=example.com
+	username=foo
+	password=bar
+	--
+	EOF
+'
+
 test_expect_success 'pull username from config' '
 	test_config credential.https://example.com.username foo &&
 	check fill <<-\EOF
@@ -255,6 +306,63 @@ test_expect_success 'pull username from config' '
 	EOF
 '
 
+test_expect_success 'honors username from URL over helper (URL)' '
+	test_config credential.https://example.com.username bob &&
+	test_config credential.https://example.com.helper "verbatim \"\" bar" &&
+	check fill <<-\EOF
+	url=https://alice@example.com
+	--
+	protocol=https
+	host=example.com
+	username=alice
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.com
+	verbatim: username=alice
+	EOF
+'
+
+test_expect_success 'honors username from URL over helper (components)' '
+	test_config credential.https://example.com.username bob &&
+	test_config credential.https://example.com.helper "verbatim \"\" bar" &&
+	check fill <<-\EOF
+	protocol=https
+	host=example.com
+	username=alice
+	--
+	protocol=https
+	host=example.com
+	username=alice
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.com
+	verbatim: username=alice
+	EOF
+'
+
+test_expect_failure 'last matching username wins' '
+	test_config credential.https://example.com/path.git.username bob &&
+	test_config credential.https://example.com.username alice &&
+	test_config credential.https://example.com.helper "verbatim \"\" bar" &&
+	check fill <<-\EOF
+	url=https://example.com/path.git
+	--
+	protocol=https
+	host=example.com
+	username=alice
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.com
+	verbatim: username=alice
+	EOF
+'
+
 test_expect_success 'http paths can be part of context' '
 	check fill "verbatim foo bar" <<-\EOF &&
 	protocol=https

[PATCH v2 4/5] credential: use the last matching username in the config

[brian m. carlson]

From: brian m. carlson <bk2204@github.com>

Everywhere else in the codebase, we use the rule that the last matching
configuration option is the one that takes effect.  This is helpful
because it allows more specific configuration settings (e.g., per-repo
configuration) to override less specific settings (e.g., per-user
configuration).

However, in the credential code, we didn't honor this setting, and
instead picked the first setting we had, and stuck with it.  This was
likely to ensure we picked the value from the URL, which we want to
honor over the configuration.

It's possible to do both, though, so let's check if the value is the one
we've gotten over our protocol connection, which if present will have
come from the URL, and keep it if so.  Otherwise, let's overwrite the
value with the latest version we've got from the configuration, so we
keep the last configuration value.

Signed-off-by: brian m. carlson <bk2204@github.com>
---
 credential.c           | 9 ++++++++-
 credential.h           | 3 ++-
 t/t0300-credentials.sh | 2 +-
 3 files changed, 11 insertions(+), 3 deletions(-)

diff --git a/credential.c b/credential.c
index 62be651b03..5701e32792 100644
--- a/credential.c
+++ b/credential.c
@@ -71,8 +71,10 @@ static int credential_config_callback(const char *var, const char *value,
 		else
 			string_list_clear(&c->helpers, 0);
 	} else if (!strcmp(key, "username")) {
-		if (!c->username)
+		if (!c->username_from_proto) {
+			free(c->username);
 			c->username = xstrdup(value);
+		}
 	}
 	else if (!strcmp(key, "usehttppath"))
 		c->use_http_path = git_config_bool(var, value);
@@ -163,6 +165,7 @@ int credential_read(struct credential *c, FILE *fp)
 		if (!strcmp(key, "username")) {
 			free(c->username);
 			c->username = xstrdup(value);
+			c->username_from_proto = 1;
 		} else if (!strcmp(key, "password")) {
 			free(c->password);
 			c->password = xstrdup(value);
@@ -349,10 +352,14 @@ void credential_from_url(struct credential *c, const char *url)
 	else if (!colon || at <= colon) {
 		/* Case (2) */
 		c->username = url_decode_mem(cp, at - cp);
+		if (c->username && *c->username)
+			c->username_from_proto = 1;
 		host = at + 1;
 	} else {
 		/* Case (3) */
 		c->username = url_decode_mem(cp, colon - cp);
+		if (c->username && *c->username)
+			c->username_from_proto = 1;
 		c->password = url_decode_mem(colon + 1, at - (colon + 1));
 		host = at + 1;
 	}
diff --git a/credential.h b/credential.h
index a5a3ee9bb8..fec7815dd0 100644
--- a/credential.h
+++ b/credential.h
@@ -118,7 +118,8 @@ struct credential {
 	unsigned approved:1,
 		 configured:1,
 		 quit:1,
-		 use_http_path:1;
+		 use_http_path:1,
+		 username_from_proto:1;
 
 	char *username;
 	char *password;
diff --git a/t/t0300-credentials.sh b/t/t0300-credentials.sh
index 4593a0cd3d..8f87599056 100755
--- a/t/t0300-credentials.sh
+++ b/t/t0300-credentials.sh
@@ -344,7 +344,7 @@ test_expect_success 'honors username from URL over helper (components)' '
 	EOF
 '
 
-test_expect_failure 'last matching username wins' '
+test_expect_success 'last matching username wins' '
 	test_config credential.https://example.com/path.git.username bob &&
 	test_config credential.https://example.com.username alice &&
 	test_config credential.https://example.com.helper "verbatim \"\" bar" &&

[PATCH v2 5/5] credential: allow wildcard patterns when matching config

[brian m. carlson]

From: brian m. carlson <bk2204@github.com>

In some cases, a user will want to use a specific credential helper for
a wildcard pattern, such as https://*.corp.example.com.  We have code
that handles this already with the urlmatch code, so let's use that
instead of our custom code.

Since the urlmatch code is a superset of our current matching in terms
of capabilities, there shouldn't be any cases of things that matched
previously that don't match now.  However, in addition to wildcard
matching, we now use partial path matching, which can cause slightly
different behavior in the case that a helper applies to the prefix
(considering path components) of the remote URL.  While different, this
is probably the behavior people were wanting anyway.

Since we're using the urlmatch code, we need to encode the components
we've gotten into a URL to match, so add a function to percent-encode
data and format the URL with it.  We now also no longer need to the
custom code to match URLs, so let's remove it.

Additionally, the urlmatch code always looks for the best match, whereas
we want all matches for credential helpers to preserve existing
behavior.  Let's add an optional field, select_fn, that lets us control
which items we want (in this case, all of them) and default it to the
best-match code that already exists for other users.

Signed-off-by: brian m. carlson <bk2204@github.com>
---
 Documentation/gitcredentials.txt |  4 +-
 credential.c                     | 66 +++++++++++++++++++++++---------
 strbuf.c                         | 15 ++++++++
 strbuf.h                         |  6 +++
 t/t0300-credentials.sh           | 20 ++++++++++
 urlmatch.c                       |  4 +-
 urlmatch.h                       |  9 +++++
 7 files changed, 103 insertions(+), 21 deletions(-)

diff --git a/Documentation/gitcredentials.txt b/Documentation/gitcredentials.txt
index 5b9d14fb1f..1814d2d23c 100644
--- a/Documentation/gitcredentials.txt
+++ b/Documentation/gitcredentials.txt
@@ -131,7 +131,9 @@ context would not match:
 because the hostnames differ. Nor would it match `foo.example.com`; Git
 compares hostnames exactly, without considering whether two hosts are part of
 the same domain. Likewise, a config entry for `http://example.com` would not
-match: Git compares the protocols exactly.
+match: Git compares the protocols exactly.  However, you may use wildcards in
+the domain name and other pattern matching techniques as with the `http.<url>.*`
+options.
 
 If the "pattern" URL does include a path component, then this too must match
 exactly: the context `https://example.com/bar/baz.git` will match a config
diff --git a/credential.c b/credential.c
index 5701e32792..77dfde44e3 100644
--- a/credential.c
+++ b/credential.c
@@ -6,6 +6,7 @@
 #include "url.h"
 #include "prompt.h"
 #include "sigchain.h"
+#include "urlmatch.h"
 
 void credential_init(struct credential *c)
 {
@@ -40,7 +41,7 @@ static int credential_config_callback(const char *var, const char *value,
 				      void *data)
 {
 	struct credential *c = data;
-	const char *key, *dot;
+	const char *key;
 
 	if (!skip_prefix(var, "credential.", &key))
 		return 0;
@@ -48,23 +49,6 @@ static int credential_config_callback(const char *var, const char *value,
 	if (!value)
 		return config_error_nonbool(var);
 
-	dot = strrchr(key, '.');
-	if (dot) {
-		struct credential want = CREDENTIAL_INIT;
-		char *url = xmemdupz(key, dot - key);
-		int matched;
-
-		credential_from_url(&want, url);
-		matched = credential_match(&want, c);
-
-		credential_clear(&want);
-		free(url);
-
-		if (!matched)
-			return 0;
-		key = dot + 1;
-	}
-
 	if (!strcmp(key, "helper")) {
 		if (*value)
 			string_list_append(&c->helpers, value);
@@ -89,11 +73,38 @@ static int proto_is_http(const char *s)
 	return !strcmp(s, "https") || !strcmp(s, "http");
 }
 
+static void credential_describe(struct credential *c, struct strbuf *out);
+static void credential_format(struct credential *c, struct strbuf *out);
+
+static int select_all(const struct urlmatch_item *a,
+		      const struct urlmatch_item *b)
+{
+	return 0;
+}
+
 static void credential_apply_config(struct credential *c)
 {
+	char *normalized_url;
+	struct urlmatch_config config = { STRING_LIST_INIT_DUP };
+	struct strbuf url = STRBUF_INIT;
+
 	if (c->configured)
 		return;
-	git_config(credential_config_callback, c);
+
+	config.section = "credential";
+	config.key = NULL;
+	config.collect_fn = credential_config_callback;
+	config.cascade_fn = NULL;
+	config.select_fn = select_all;
+	config.cb = c;
+
+	credential_format(c, &url);
+	normalized_url = url_normalize(url.buf, &config.url);
+
+	git_config(urlmatch_config_entry, &config);
+	free(normalized_url);
+	strbuf_release(&url);
+
 	c->configured = 1;
 
 	if (!c->use_http_path && proto_is_http(c->protocol)) {
@@ -114,6 +125,23 @@ static void credential_describe(struct credential *c, struct strbuf *out)
 		strbuf_addf(out, "/%s", c->path);
 }
 
+static void credential_format(struct credential *c, struct strbuf *out)
+{
+	if (!c->protocol)
+		return;
+	strbuf_addf(out, "%s://", c->protocol);
+	if (c->username && *c->username) {
+		strbuf_add_percentencode(out, c->username);
+		strbuf_addch(out, '@');
+	}
+	if (c->host)
+		strbuf_addstr(out, c->host);
+	if (c->path) {
+		strbuf_addch(out, '/');
+		strbuf_add_percentencode(out, c->path);
+	}
+}
+
 static char *credential_ask_one(const char *what, struct credential *c,
 				int flags)
 {
diff --git a/strbuf.c b/strbuf.c
index f19da55b07..bb0065ccaf 100644
--- a/strbuf.c
+++ b/strbuf.c
@@ -479,6 +479,21 @@ void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src)
 	}
 }
 
+#define URL_UNSAFE_CHARS " <>\"%{}|\\^`:/?#[]@!$&'()*+,;="
+
+void strbuf_add_percentencode(struct strbuf *dst, const char *src)
+{
+	size_t i, len = strlen(src);
+
+	for (i = 0; i < len; i++) {
+		unsigned char ch = src[i];
+		if (ch <= 0x1F || ch >= 0x7F || strchr(URL_UNSAFE_CHARS, ch))
+			strbuf_addf(dst, "%%%02X", (unsigned char)ch);
+		else
+			strbuf_addch(dst, ch);
+	}
+}
+
 size_t strbuf_fread(struct strbuf *sb, size_t size, FILE *f)
 {
 	size_t res;
diff --git a/strbuf.h b/strbuf.h
index aae7ac3a82..ce8e49c0b2 100644
--- a/strbuf.h
+++ b/strbuf.h
@@ -378,6 +378,12 @@ size_t strbuf_expand_dict_cb(struct strbuf *sb,
  */
 void strbuf_addbuf_percentquote(struct strbuf *dst, const struct strbuf *src);
 
+/**
+ * Append the contents of a string to a strbuf, percent-encoding any characters
+ * that are needed to be encoded for a URL.
+ */
+void strbuf_add_percentencode(struct strbuf *dst, const char *src);
+
 /**
  * Append the given byte size as a human-readable string (i.e. 12.23 KiB,
  * 3.50 MiB).
diff --git a/t/t0300-credentials.sh b/t/t0300-credentials.sh
index 8f87599056..39f097ea9e 100755
--- a/t/t0300-credentials.sh
+++ b/t/t0300-credentials.sh
@@ -397,6 +397,26 @@ test_expect_success 'http paths can be part of context' '
 	EOF
 '
 
+test_expect_success 'context uses urlmatch' '
+	test_config "credential.https://*.org.useHttpPath" true &&
+	check fill "verbatim foo bar" <<-\EOF
+	protocol=https
+	host=example.org
+	path=foo.git
+	--
+	protocol=https
+	host=example.org
+	path=foo.git
+	username=foo
+	password=bar
+	--
+	verbatim: get
+	verbatim: protocol=https
+	verbatim: host=example.org
+	verbatim: path=foo.git
+	EOF
+'
+
 test_expect_success 'helpers can abort the process' '
 	test_must_fail git \
 		-c credential.helper="!f() { echo quit=1; }; f" \
diff --git a/urlmatch.c b/urlmatch.c
index 3e42bd7504..29272a5c4f 100644
--- a/urlmatch.c
+++ b/urlmatch.c
@@ -557,6 +557,8 @@ int urlmatch_config_entry(const char *var, const char *value, void *cb)
 	const char *key, *dot;
 	struct strbuf synthkey = STRBUF_INIT;
 	int retval;
+	int (*select_fn)(const struct urlmatch_item *a, const struct urlmatch_item *b) =
+		collect->select_fn ? collect->select_fn : cmp_matches;
 
 	if (!skip_prefix(var, collect->section, &key) || *(key++) != '.') {
 		if (collect->cascade_fn)
@@ -587,7 +589,7 @@ int urlmatch_config_entry(const char *var, const char *value, void *cb)
 	if (!item->util) {
 		item->util = xcalloc(1, sizeof(matched));
 	} else {
-		if (cmp_matches(&matched, item->util) < 0)
+		if (select_fn(&matched, item->util) < 0)
 			 /*
 			  * Our match is worse than the old one,
 			  * we cannot use it.
diff --git a/urlmatch.h b/urlmatch.h
index eed5f29235..2407520731 100644
--- a/urlmatch.h
+++ b/urlmatch.h
@@ -50,6 +50,15 @@ struct urlmatch_config {
 	void *cb;
 	int (*collect_fn)(const char *var, const char *value, void *cb);
 	int (*cascade_fn)(const char *var, const char *value, void *cb);
+	/*
+	 * Compare the two matches, the one just discovered and the existing
+	 * best match and return a negative value if the found item is to be
+	 * rejected or a non-negative value if it is to be accepted.  If this
+	 * field is set to NULL, use the default comparison technique, which
+	 * checks to ses if found is better (according to the urlmatch
+	 * specificity rules) than existing.
+	 */
+	int (*select_fn)(const struct urlmatch_item *found, const struct urlmatch_item *existing);
 };
 
 int urlmatch_config_entry(const char *var, const char *value, void *cb);

Re: [PATCH v2 5/5] credential: allow wildcard patterns when matching config

[Junio C Hamano]

"brian m. carlson" <sandals@crustytoothpaste.net> writes:

> From: brian m. carlson <bk2204@github.com>
>
> In some cases, a user will want to use a specific credential helper for
> a wildcard pattern, such as https://*.corp.example.com.  We have code
> that handles this already with the urlmatch code, so let's use that
> instead of our custom code.

Quite nice.  Will queue the whole series.

Thanks.

Re: [PATCH v2 0/5] Wildcard matching for credentials

[Jeff King]

On Thu, Feb 20, 2020 at 02:24:08AM +0000, brian m. carlson wrote:

> This series introduces wildcard matching (that is, urlmatch support) for
> credential config options, just like for the http options.  This is
> helpful in corporate environments where custom credentials should be
> used across a wide variety of subdomains.
> 
> Changes from v1:
> * Add a variety of additional tests in patch 3.
> * Switch to using the last matching config option for
>   credential.username like we do everywhere else.
> * Use all matching config keys, as we did before.
> * Skip calling git_default_config.
> * Fix percent-encoding handling and add a function to handle that.

Thanks, this addresses all of my concerns, and I'm really happy to see
all the new tests covering various bits from our discussion. Really
cleanly done.

-Peff