[PATCH v3] credential/wincred: store oauth_refresh_token

[M Hickford via GitGitGadget]

From: M Hickford <mirth.h...@gmail.com>

a5c7656 (credential: new attribute oauth_refresh_token) introduced
a new confidential credential attribute and added support to
credential-cache. Later 0ce02e2f (credential/libsecret: store new
attributes, 2023-06-16) added support in credential-libsecret.

To add support in credential-wincred, we encode the new attribute in the
CredentialBlob, separated by newline:

hunter2
oauth_refresh_token=xyzzy

This is extensible and backwards compatible. The credential protocol
already assumes that attribute values do not contain newlines.

This fixes test "helper (wincred) gets oauth_refresh_token" when
t0303-credential-external.sh is run with
GIT_TEST_CREDENTIAL_HELPER=wincred. This test was added in a5c76569e7
(credential: new attribute oauth_refresh_token, 2023-04-21).

Alternatives considered: store oauth_refresh_token in a wincred
attribute. This would be insecure because wincred assumes attribute
values to be non-confidential.

Signed-off-by: M Hickford <mirth.h...@gmail.com>
---
credential/wincred: store oauth_refresh_token

Patch v3 fixes a maybe-uninitialized warning.

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1534%2Fhickford%2Fwincred-refresh-v3
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1534/hickford/wincred-refresh-v3
Pull-Request: https://github.com/gitgitgadget/git/pull/1534

Range-diff vs v2:

1: 12f092f45b1 ! 1: a324c3aac41 credential/wincred: store oauth_refresh_token
@@ Commit message
credential/wincred: store oauth_refresh_token

a5c7656 (credential: new attribute oauth_refresh_token) introduced
- a new confidential credential attribute for helpers to store.
+ a new confidential credential attribute and added support to
+ credential-cache. Later 0ce02e2f (credential/libsecret: store new
+ attributes, 2023-06-16) added support in credential-libsecret.

- We encode the new attribute in the CredentialBlob, separated by
- newline:
+ To add support in credential-wincred, we encode the new attribute in the
+ CredentialBlob, separated by newline:

hunter2
oauth_refresh_token=xyzzy
@@ contrib/credential/wincred/git-credential-wincred.c: static void get_credential(
+ }
+ line = wcstok_s(NULL, L"\r\n", &remaining_lines);
+ }
++ free(secret);
+ } else {
+ write_item("password",
+ (LPCWSTR)creds[i]->CredentialBlob,
@@ contrib/credential/wincred/git-credential-wincred.c: static void get_credential(
for (int j = 0; j < creds[i]->AttributeCount; j++) {
attr = creds[i]->Attributes + j;
if (!wcscmp(attr->Keyword, L"git_password_expiry_utc")) {
-@@ contrib/credential/wincred/git-credential-wincred.c: static void get_credential(void)
- break;
- }
- }
-+ free(secret);
- break;
- }
-
@@ contrib/credential/wincred/git-credential-wincred.c: static void store_credential(void)
{
CREDENTIALW cred;


.../wincred/git-credential-wincred.c | 46 ++++++++++++++++---
1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/contrib/credential/wincred/git-credential-wincred.c b/contrib/credential/wincred/git-credential-wincred.c
index 4cd56c42e24..4be0d58cd89 100644
--- a/contrib/credential/wincred/git-credential-wincred.c
+++ b/contrib/credential/wincred/git-credential-wincred.c
@@ -35,7 +35,7 @@ static void *xmalloc(size_t size)
}

static WCHAR *wusername, *password, *protocol, *host, *path, target[1024],
- *password_expiry_utc;
+ *password_expiry_utc, *oauth_refresh_token;

static void write_item(const char *what, LPCWSTR wbuf, int wlen)
{
@@ -140,6 +140,11 @@ static void get_credential(void)
DWORD num_creds;
int i;
CREDENTIAL_ATTRIBUTEW *attr;
+ WCHAR *secret;
+ WCHAR *line;
+ WCHAR *remaining_lines;
+ WCHAR *part;
+ WCHAR *remaining_parts;

if (!CredEnumerateW(L"git:*", 0, &num_creds, &creds))
return;
@@ -149,9 +154,24 @@ static void get_credential(void)
if (match_cred(creds[i], 0)) {
write_item("username", creds[i]->UserName,
creds[i]->UserName ? wcslen(creds[i]->UserName) : 0);
- write_item("password",
- (LPCWSTR)creds[i]->CredentialBlob,
- creds[i]->CredentialBlobSize / sizeof(WCHAR));
+ if (creds[i]->CredentialBlobSize > 0) {
+ secret = xmalloc(creds[i]->CredentialBlobSize);
+ wcsncpy_s(secret, creds[i]->CredentialBlobSize, (LPCWSTR)creds[i]->CredentialBlob, creds[i]->CredentialBlobSize / sizeof(WCHAR));
+ line = wcstok_s(secret, L"\r\n", &remaining_lines);
+ write_item("password", line, line ? wcslen(line) : 0);
+ while(line != NULL) {
+ part = wcstok_s(line, L"=", &remaining_parts);
+ if (!wcscmp(part, L"oauth_refresh_token")) {
+ write_item("oauth_refresh_token", remaining_parts, remaining_parts ? wcslen(remaining_parts) : 0);
+ }
+ line = wcstok_s(NULL, L"\r\n", &remaining_lines);
+ }
+ free(secret);
+ } else {
+ write_item("password",
+ (LPCWSTR)creds[i]->CredentialBlob,
+ creds[i]->CredentialBlobSize / sizeof(WCHAR));
+ }
for (int j = 0; j < creds[i]->AttributeCount; j++) {
attr = creds[i]->Attributes + j;
if (!wcscmp(attr->Keyword, L"git_password_expiry_utc")) {
@@ -170,16 +190,26 @@ static void store_credential(void)
{
CREDENTIALW cred;
CREDENTIAL_ATTRIBUTEW expiry_attr;
+ WCHAR *secret;
+ int wlen;

if (!wusername || !password)
return;

+ if (oauth_refresh_token) {
+ wlen = _scwprintf(L"%s\r\noauth_refresh_token=%s", password, oauth_refresh_token);
+ secret = xmalloc(sizeof(WCHAR) * wlen);
+ _snwprintf_s(secret, sizeof(WCHAR) * wlen, wlen, L"%s\r\noauth_refresh_token=%s", password, oauth_refresh_token);
+ } else {
+ secret = _wcsdup(password);
+ }
+
cred.Flags = 0;
cred.Type = CRED_TYPE_GENERIC;
cred.TargetName = target;
cred.Comment = L"saved by git-credential-wincred";
- cred.CredentialBlobSize = (wcslen(password)) * sizeof(WCHAR);
- cred.CredentialBlob = (LPVOID)password;
+ cred.CredentialBlobSize = wcslen(secret) * sizeof(WCHAR);
+ cred.CredentialBlob = (LPVOID)_wcsdup(secret);
cred.Persist = CRED_PERSIST_LOCAL_MACHINE;
cred.AttributeCount = 0;
cred.Attributes = NULL;
@@ -194,6 +224,8 @@ static void store_credential(void)
cred.TargetAlias = NULL;
cred.UserName = wusername;

+ free(secret);
+
if (!CredWriteW(&cred, 0))
die("CredWrite failed");
}
@@ -265,6 +297,8 @@ static void read_credential(void)
password = utf8_to_utf16_dup(v);
else if (!strcmp(buf, "password_expiry_utc"))
password_expiry_utc = utf8_to_utf16_dup(v);
+ else if (!strcmp(buf, "oauth_refresh_token"))
+ oauth_refresh_token = utf8_to_utf16_dup(v);
/*
* Ignore other lines; we don't know what they mean, but
* this future-proofs us when later versions of git do

base-commit: b50a608ba20348cb3dfc16a696816d51780e3f0f
--
gitgitgadget