credential/wincred: store oauth_refresh_token

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.hickford@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/contrib/credential/wincred/git-credential-wincred.c b/contrib/credential/wincred/git-credential-wincred.c
index 96f10613aee29b7c360b25308927564df1551388..f8968ec8648c9dfec1ecf614b4131aa7205a2504 100644 (file)
--- 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)
 {
@@ -128,6 +128,11 @@ 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;
@@ -137,9 +142,24 @@ static void get_credential(void)
                if (match_cred(creds[i])) {
                        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")) {
@@ -158,16 +178,26 @@ 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;
@@ -182,6 +212,8 @@ static void store_credential(void)
        cred.TargetAlias = NULL;
        cred.UserName = wusername;
 
+       free(secret);
+
        if (!CredWriteW(&cred, 0))
                die("CredWrite failed");
 }
@@ -253,6 +285,8 @@ 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