[PATCH v2] osxkeychain: avoid incorrectly skipping store operation

From: Koji Nakamaru <koji.nakamaru@gree.net>

git-credential-osxkeychain skips storing a credential if its "get" action sets "state[]=osxkeychain:seen=1". This behavior was introduced in e1ab45b2 (osxkeychain: state to skip unnecessary store operations, 2024-05-15), which appeared in v2.46.

However, this state[] persists even if a credential returned by "git-credential-osxkeychain get" is invalid and a subsequent helper's "get" operation returns a valid credential. Another subsequent helper (such as [1]) may expect git-credential-osxkeychain to store the valid credential, but the "store" operation is incorrectly skipped because it only checks "state[]=osxkeychain:seen=1".

To solve this issue, "state[]=osxkeychain:seen" needs to contain enough information to identify whether the current "store" input matches the output from the previous "get" operation (and not a credential from another helper).

Set "state[]=osxkeychain:seen" to a value encoding the credential output by "get", and compare it with a value encoding the credential input by "store".

[1]: https://github.com/hickford/git-credential-oauth

Reported-by: Petter Sælen <petter@saelen.eu>
Helped-by: Junio C Hamano <gitster@pobox.com>
Helped-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Koji Nakamaru <koji.nakamaru@gree.net>
---
    osxkeychain: avoid incorrectly skipping store operation
    
    Changes since v1:
    
     * Use functions provided by wrapper.h and strbuf.h instead of
       self-defined ones.
     * Adjust Makefile and meson.build to use these functions.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1999%2FKojiNakamaru%2Ffix%2Fosxkeychain-state-seen-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1999/KojiNakamaru/fix/osxkeychain-state-seen-v2
Pull-Request: https://github.com/gitgitgadget/git/pull/1999

Range-diff vs v1:

 1:  b14045b4de ! 1:  dd36d290ff osxkeychain: avoid incorrectly skipping store operation
     @@ Commit message
      
          Reported-by: Petter Sælen <petter@saelen.eu>
          Helped-by: Junio C Hamano <gitster@pobox.com>
     +    Helped-by: brian m. carlson <sandals@crustytoothpaste.net>
          Signed-off-by: Koji Nakamaru <koji.nakamaru@gree.net>
      
     + ## contrib/credential/osxkeychain/Makefile ##
     +@@
     + # The default target of this Makefile is...
     + all:: git-credential-osxkeychain
     + 
     ++include ../../../config.mak.uname
     + -include ../../../config.mak.autogen
     + -include ../../../config.mak
     + 
     ++ifdef ZLIB_NG
     ++	BASIC_CFLAGS += -DHAVE_ZLIB_NG
     ++        ifdef ZLIB_NG_PATH
     ++		BASIC_CFLAGS += -I$(ZLIB_NG_PATH)/include
     ++		EXTLIBS += $(call libpath_template,$(ZLIB_NG_PATH)/$(lib))
     ++        endif
     ++	EXTLIBS += -lz-ng
     ++else
     ++        ifdef ZLIB_PATH
     ++		BASIC_CFLAGS += -I$(ZLIB_PATH)/include
     ++		EXTLIBS += $(call libpath_template,$(ZLIB_PATH)/$(lib))
     ++        endif
     ++	EXTLIBS += -lz
     ++endif
     ++ifndef NO_ICONV
     ++        ifdef NEEDS_LIBICONV
     ++                ifdef ICONVDIR
     ++			BASIC_CFLAGS += -I$(ICONVDIR)/include
     ++			ICONV_LINK = $(call libpath_template,$(ICONVDIR)/$(lib))
     ++                else
     ++			ICONV_LINK =
     ++                endif
     ++                ifdef NEEDS_LIBINTL_BEFORE_LIBICONV
     ++			ICONV_LINK += -lintl
     ++                endif
     ++		EXTLIBS += $(ICONV_LINK) -liconv
     ++        endif
     ++endif
     ++ifndef LIBC_CONTAINS_LIBINTL
     ++	EXTLIBS += -lintl
     ++endif
     ++
     + prefix ?= /usr/local
     + gitexecdir ?= $(prefix)/libexec/git-core
     + 
     + CC ?= gcc
     +-CFLAGS ?= -g -O2 -Wall
     ++CFLAGS ?= -g -O2 -Wall -I../../.. $(BASIC_CFLAGS)
     ++LDFLAGS ?= $(BASIC_LDFLAGS) $(EXTLIBS)
     + INSTALL ?= install
     + RM ?= rm -f
     + 
     + %.o: %.c
     + 	$(CC) $(CFLAGS) $(CPPFLAGS) -o $@ -c $<
     + 
     +-git-credential-osxkeychain: git-credential-osxkeychain.o
     ++git-credential-osxkeychain: git-credential-osxkeychain.o ../../../libgit.a
     + 	$(CC) $(CFLAGS) -o $@ $^ $(LDFLAGS) \
     + 		-framework Security -framework CoreFoundation
     + 
     +@@ contrib/credential/osxkeychain/Makefile: install: git-credential-osxkeychain
     + 	$(INSTALL) -d -m 755 $(DESTDIR)$(gitexecdir)
     + 	$(INSTALL) -m 755 $< $(DESTDIR)$(gitexecdir)
     + 
     ++../../../libgit.a:
     ++	cd ../../..; make libgit.a
     ++
     + clean:
     + 	$(RM) git-credential-osxkeychain git-credential-osxkeychain.o
     + 
     +
       ## contrib/credential/osxkeychain/git-credential-osxkeychain.c ##
     +@@
     + #include <string.h>
     + #include <stdlib.h>
     + #include <Security/Security.h>
     ++#include "git-compat-util.h"
     ++#include "strbuf.h"
     ++#include "wrapper.h"
     + 
     + #define ENCODING kCFStringEncodingUTF8
     + static CFStringRef protocol; /* Stores constant strings - not memory managed */
      @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static CFStringRef username;
       static CFDataRef password;
       static CFDataRef password_expiry_utc;
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static CFStringRef
       
       static void clear_credential(void)
       {
     -@@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void die(const char *err, ...)
     - 	exit(1);
     - }
     +@@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void clear_credential(void)
       
     -+/*
     -+ * NOTE: We could use functions in strbuf.h and/or wrapper.h, but those
     -+ * introduce significant dependencies. Therefore, we define simplified
     -+ * versions here to keep this code self-contained.
     -+ */
     -+
     - static void *xmalloc(size_t len)
     - {
     - 	void *ret = malloc(len);
     -@@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void *xmalloc(size_t len)
     - 	return ret;
     - }
     + #define STRING_WITH_LENGTH(s) s, sizeof(s) - 1
       
     -+static void *xcalloc(size_t count, size_t size)
     -+{
     -+	void *ret = calloc(count, size);
     -+	if (!ret)
     -+		die("Out of memory");
     -+	return ret;
     -+}
     -+
     -+static void *xrealloc(void *ptr, size_t size)
     -+{
     -+	void *ret = realloc(ptr, size);
     -+	if (!ret)
     -+		die("Out of memory");
     -+	return ret;
     -+}
     -+
     -+static char *xstrdup(const char *str)
     -+{
     -+	char *ret = strdup(str);
     -+	if (!ret)
     -+		die("Out of memory");
     -+	return ret;
     -+}
     -+
     +-__attribute__((format (printf, 1, 2), __noreturn__))
     +-static void die(const char *err, ...)
     +-{
     +-	char msg[4096];
     +-	va_list params;
     +-	va_start(params, err);
     +-	vsnprintf(msg, sizeof(msg), err, params);
     +-	fprintf(stderr, "%s\n", msg);
     +-	va_end(params);
     +-	clear_credential();
     +-	exit(1);
     +-}
     +-
     +-static void *xmalloc(size_t len)
     +-{
     +-	void *ret = malloc(len);
     +-	if (!ret)
     +-		die("Out of memory");
     +-	return ret;
     +-}
     +-
       static CFDictionaryRef create_dictionary(CFAllocatorRef allocator, ...)
       {
       	va_list args;
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void write_i
       	putchar('\n');
       }
       
     -+struct sb {
     -+	char *buf;
     -+	int size;
     -+};
     -+
     -+static void sb_init(struct sb *sb)
     -+{
     -+	sb->size = 1024;
     -+	sb->buf = xcalloc(sb->size, 1);
     -+}
     -+
     -+static void sb_release(struct sb *sb)
     -+{
     -+	if (sb->buf) {
     -+		free(sb->buf);
     -+		sb->buf = NULL;
     -+		sb->size = 0;
     -+	}
     -+}
     -+
     -+static void sb_add(struct sb *sb, const char *s, int n)
     -+{
     -+	int len = strlen(sb->buf);
     -+	int size = sb->size;
     -+	if (size < len + n + 1) {
     -+		sb->size = len + n + 1;
     -+		sb->buf = xrealloc(sb->buf, sb->size);
     -+	}
     -+	strncat(sb->buf, s, n);
     -+	sb->buf[len + n] = '\0';
     -+}
     -+
     -+static void write_item_sb(struct sb *sb, const char *what, const char *buf, int n)
     ++static void write_item_strbuf(struct strbuf *sb, const char *what, const char *buf, int n)
      +{
      +	char s[32];
      +
     -+	sprintf(s, "__%s=", what);
     -+	sb_add(sb, s, strlen(s));
     -+	sb_add(sb, buf, n);
     ++	xsnprintf(s, sizeof(s), "__%s=", what);
     ++	strbuf_add(sb, s, strlen(s));
     ++	strbuf_add(sb, buf, n);
      +}
      +
     -+static void write_item_sb_cfstring(struct sb *sb, const char *what, CFStringRef ref)
     ++static void write_item_strbuf_cfstring(struct strbuf *sb, const char *what, CFStringRef ref)
      +{
      +	char *buf;
      +	int len;
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void write_i
      +	len = CFStringGetMaximumSizeForEncoding(CFStringGetLength(ref), ENCODING) + 1;
      +	buf = xmalloc(len);
      +	if (CFStringGetCString(ref, buf, len, ENCODING))
     -+		write_item_sb(sb, what, buf, strlen(buf));
     ++		write_item_strbuf(sb, what, buf, strlen(buf));
      +	free(buf);
      +}
      +
     -+static void write_item_sb_cfnumber(struct sb *sb, const char *what, CFNumberRef ref)
     ++static void write_item_strbuf_cfnumber(struct strbuf *sb, const char *what, CFNumberRef ref)
      +{
      +	short n;
      +	char buf[32];
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void write_i
      +		return;
      +	if (!CFNumberGetValue(ref, kCFNumberShortType, &n))
      +		return;
     -+	sprintf(buf, "%d", n);
     -+	write_item_sb(sb, what, buf, strlen(buf));
     ++	xsnprintf(buf, sizeof(buf), "%d", n);
     ++	write_item_strbuf(sb, what, buf, strlen(buf));
      +}
      +
     -+static void write_item_sb_cfdata(struct sb *sb, const char *what, CFDataRef ref)
     ++static void write_item_strbuf_cfdata(struct strbuf *sb, const char *what, CFDataRef ref)
      +{
      +	char *buf;
      +	int len;
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static void write_i
      +	if (!buf || strlen(buf) == 0)
      +		return;
      +	len = CFDataGetLength(ref);
     -+	write_item_sb(sb, what, buf, len);
     ++	write_item_strbuf(sb, what, buf, len);
      +}
      +
     -+static void encode_state_seen(struct sb *sb)
     ++static void encode_state_seen(struct strbuf *sb)
      +{
     -+	sb_add(sb, "osxkeychain:seen=", strlen("osxkeychain:seen="));
     -+	write_item_sb_cfstring(sb, "host", host);
     -+	write_item_sb_cfnumber(sb, "port", port);
     -+	write_item_sb_cfstring(sb, "path", path);
     -+	write_item_sb_cfstring(sb, "username", username);
     -+	write_item_sb_cfdata(sb, "password", password);
     ++	strbuf_add(sb, "osxkeychain:seen=", strlen("osxkeychain:seen="));
     ++	write_item_strbuf_cfstring(sb, "host", host);
     ++	write_item_strbuf_cfnumber(sb, "port", port);
     ++	write_item_strbuf_cfstring(sb, "path", path);
     ++	write_item_strbuf_cfstring(sb, "username", username);
     ++	write_item_strbuf_cfdata(sb, "password", password);
      +}
      +
       static void find_username_in_item(CFDictionaryRef item)
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static OSStatus fin
       	write_item("capability[]", "state", strlen("state"));
      -	write_item("state[]", "osxkeychain:seen=1", strlen("osxkeychain:seen=1"));
      +	{
     -+		struct sb sb;
     ++		struct strbuf sb;
      +
     -+		sb_init(&sb);
     ++		strbuf_init(&sb, 1024);
      +		encode_state_seen(&sb);
      +		write_item("state[]", sb.buf, strlen(sb.buf));
     -+		sb_release(&sb);
     ++		strbuf_release(&sb);
      +	}
       
       out:
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: static OSStatus add
       		return -1;
       
      +	if (state_seen) {
     -+		struct sb sb;
     ++		struct strbuf sb;
      +
     -+		sb_init(&sb);
     ++		strbuf_init(&sb, 1024);
      +		encode_state_seen(&sb);
      +		if (!strcmp(state_seen, sb.buf)) {
     -+			sb_release(&sb);
     ++			strbuf_release(&sb);
      +			return errSecSuccess;
      +		}
     -+		sb_release(&sb);
     ++		strbuf_release(&sb);
      +	}
      +
       	data = CFDataCreateMutableCopy(kCFAllocatorDefault, 0, password);
     @@ contrib/credential/osxkeychain/git-credential-osxkeychain.c: int main(int argc,
      +
       	return 0;
       }
     +
     + ## contrib/credential/osxkeychain/meson.build ##
     +@@
     + executable('git-credential-osxkeychain',
     +   sources: 'git-credential-osxkeychain.c',
     +   dependencies: [
     ++    libgit,
     +     dependency('CoreFoundation'),
     +     dependency('Security'),
     +   ],

 contrib/credential/osxkeychain/Makefile       |  41 +++++-
 .../osxkeychain/git-credential-osxkeychain.c  | 120 ++++++++++++++----
 contrib/credential/osxkeychain/meson.build    |   1 +
 3 files changed, 132 insertions(+), 30 deletions(-)