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.
Update comments in credential.h to mention the new struct fields.
Signed-off-by: Aaron Plattner <aplattner@xxxxxxxxxx>
---
v3: I reverted the behavior change to credential_reject() and just unified
everything to use credential_clear_secrets() instead. We can rework
credential_reject() in a later change if we decide to. So the only behavior
change now should be the expiration case in credential_fill()
I also updated some of the comments in credential.h to mention the new struct
fields.
Thanks for your patience with this series, everyone!
credential.c | 16 ++++++++++------
credential.h | 34 ++++++++++++++++++----------------
2 files changed, 28 insertions(+), 22 deletions(-)
diff --git a/credential.c b/credential.c
index 758528b291..4b1a2b94fe 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 +478,15 @@ 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;
}
@@ -528,9 +533,8 @@ void credential_reject(struct credential *c)
for (i = 0; i < c->helpers.nr; i++)
credential_do(c, c->helpers.items[i].string, "erase");
+ credential_clear_secrets(c);
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;
diff --git a/credential.h b/credential.h
index af8c287ff2..5f9e6ff2ef 100644
--- a/credential.h
+++ b/credential.h
@@ -5,8 +5,8 @@
#include "strvec.h"
/**
- * The credentials API provides an abstracted way of gathering username and
- * password credentials from the user.
+ * The credentials API provides an abstracted way of gathering
+ * authentication credentials from the user.
*
* Typical setup
* -------------
@@ -116,11 +116,12 @@ struct credential_capability {
};
/**
- * This struct represents a single username/password combination
- * along with any associated context. All string fields should be
- * heap-allocated (or NULL if they are not known or not applicable).
- * The meaning of the individual context fields is the same as
- * their counterparts in the helper protocol.
+ * This struct represents a single login credential (typically a
+ * username/password combination) along with any associated
+ * context. All string fields should be heap-allocated (or NULL if
+ * they are not known or not applicable). The meaning of the
+ * individual context fields is the same as their counterparts in
+ * the helper protocol.
*
* This struct should always be initialized with `CREDENTIAL_INIT` or
* `credential_init`.
@@ -207,11 +208,12 @@ void credential_clear(struct credential *);
/**
* Instruct the credential subsystem to fill the username and
- * password fields of the passed credential struct by first
- * consulting helpers, then asking the user. After this function
- * returns, the username and password fields of the credential are
- * guaranteed to be non-NULL. If an error occurs, the function will
- * die().
+ * password (or authtype and credential) fields of the passed
+ * credential struct by first consulting helpers, then asking the
+ * user. After this function returns, either the username and
+ * password fields or the credential field of the credential are
+ * guaranteed to be non-NULL. If an error occurs, the function
+ * will die().
*
* If all_capabilities is set, this is an internal user that is prepared
* to deal with all known capabilities, and we should advertise that fact.
@@ -232,10 +234,10 @@ void credential_approve(struct credential *);
* have been rejected. This will cause the credential subsystem to
* notify any helpers of the rejection (which allows them, for
* example, to purge the invalid credentials from storage). It
- * will also free() the username and password fields of the
- * credential and set them to NULL (readying the credential for
- * another call to `credential_fill`). Any errors from helpers are
- * ignored.
+ * will also free() the username, password, and credential fields
+ * of the credential and set them to NULL (readying the credential
+ * for another call to `credential_fill`). Any errors from helpers
+ * are ignored.
*/
void credential_reject(struct credential *);
--
2.45.2.409.g7b0defb391
