Re: [PATCH v2] credential: clear expired c->credential, unify secret clearing
From: Jeff King <hidden>
Date: 2024-06-05 08:57:40
On Tue, Jun 04, 2024 at 12:29:28PM -0700, Aaron Plattner wrote:
quoted hunk ↗ jump to hunk
@@ -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); }
I'm skeptical of this hunk. The caller will usually have filled in parts
of a credential struct like scheme and host, and then we picked up the
rest from helpers or by prompting the user. Rejecting the credential
should certainly clear the bogus password field and other secrets. But
should it clear the host field?
I think it may be somewhat academic for now because we'll generally exit
the program immediately after rejecting the credential. But occasionally
the topic comes up of retrying auth within a command. So you might have
a loop like this (or knowing our http code, probably some more baroque
equivalent spread across multiple functions):
credential_from_url(&cred, url);
for (int attempt = 0; attempt < 5; attempt++) {
credential_fill(&cred);
switch (do_something(url, &cred)) {
case OK: /* it worked */
return 0;
case AUTH_ERROR:
/* try again */
credential_reject(&cred);
}
}
return -1; /* too many failures */
And in that case you really want to retain the "query" parts of the
credential after the reject. In this toy example you could just move the
url-to-cred parsing into the loop, but in the real world it's often more
complicated.
Arguably even the original code is a bit questionable for this, because
we don't know if the username came from a helper or from the user, or if
it was part of the original URL (e.g., "https://user@example.com/"
should prompt only for the password). But it feels like this hunk is
making it worse.
The rest of the patch made sense to me, though. As would using
credential_clear_secrets() here to replace the equivalent lines.
-Peff