When a struct credential expires, credential_fill() clears c->password
so that clients don't try to use it later. However, a struct cred that
uses an alternate authtype won't have a password, but might have a
credential stored in c->credential.
This is a problem, for example, when an OAuth2 bearer token is used. In
the system I'm using, the OAuth2 configuration generates and caches a
bearer token that is valid for an hour. After the token expires, git
needs to call back into the credential helper to use a stored refresh
token to get a new bearer token. But if c->credential is still non-NULL,
git will instead try to use the expired token and fail with an error:
fatal: Authentication failed for 'https://<oauth2-enabled-server>/repository'
And on the server:
[auth_openidc:error] [client <ip>:34012] oidc_proto_validate_exp: "exp" validation failure (1717522989): JWT expired 224 seconds ago
Fix this by clearing both c->password and c->credential for an expired
struct credential. While we're at it, use credential_clear_secrets()
wherever both c->password and c->credential are being cleared, and use
the full credential_clear() in credential_reject() after the credential
has been erased from all of the helpers.
v2: Unify secret clearing into credential_clear_secrets(), use
credential_clear() in credential_reject(), add a comment about why we
can't use credential_clear() in credential_fill().
Signed-off-by: Aaron Plattner <aplattner@xxxxxxxxxx>
---
credential.c | 19 +++++++++----------
1 file changed, 9 insertions(+), 10 deletions(-)
diff --git a/credential.c b/credential.c
index 758528b291..72c6f46b02 100644
--- a/credential.c
+++ b/credential.c
@@ -20,12 +20,11 @@ void credential_init(struct credential *c)
void credential_clear(struct credential *c)
{
+ credential_clear_secrets(c);
free(c->protocol);
free(c->host);
free(c->path);
free(c->username);
- free(c->password);
- free(c->credential);
free(c->oauth_refresh_token);
free(c->authtype);
string_list_clear(&c->helpers, 0);
@@ -479,9 +478,14 @@ void credential_fill(struct credential *c, int all_capabilities)
for (i = 0; i < c->helpers.nr; i++) {
credential_do(c, c->helpers.items[i].string, "get");
+
if (c->password_expiry_utc < time(NULL)) {
- /* Discard expired password */
- FREE_AND_NULL(c->password);
+ /*
+ * Don't use credential_clear() here: callers such as
+ * cmd_credential() expect to still be able to call
+ * credential_write() on a struct credential whose secrets have expired.
+ */
+ credential_clear_secrets(c);
/* Reset expiry to maintain consistency */
c->password_expiry_utc = TIME_MAX;
}
@@ -528,12 +532,7 @@ void credential_reject(struct credential *c)
for (i = 0; i < c->helpers.nr; i++)
credential_do(c, c->helpers.items[i].string, "erase");
- FREE_AND_NULL(c->username);
- FREE_AND_NULL(c->password);
- FREE_AND_NULL(c->credential);
- FREE_AND_NULL(c->oauth_refresh_token);
- c->password_expiry_utc = TIME_MAX;
- c->approved = 0;
+ credential_clear(c);
}
static int check_url_component(const char *url, int quiet,
--
2.45.2.410.gb47f57dd90.dirty
