Merge branch 'ap/credential-clear-fix' into next

Upon expiration event, we forgot to clear in-core authentication
material other than password (whose support was added recently),
which has been corrected.

* ap/credential-clear-fix:
  credential: clear expired c->credential, unify secret clearing

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;

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 *);