[PATCH v2] credential/libsecret: erase matching creds only

["M Hickford via GitGitGadget" <gitgitgadget@gmail.com>]

From: M Hickford <mirth.hickford@gmail.com>

The credential erase request typically includes protocol, host, username
and password.

credential-libsecret erases a stored credential if it matches protocol,
host and username, regardless of password.

This is confusing in the case the stored password differs from that
in the request. This case can occur when multiple credential helpers are
configured.

Only erase credential if stored password matches request (or request
omits password).

This fixes test "helper ... does not erase a password distinct from
input" introduced in aeb21ce22e (credential: avoid erasing distinct
password, 2023-06-13)

Signed-off-by: M Hickford <mirth.hickford@gmail.com>
---
    credential/libsecret: erase more carefully
    
    Patch v2 has a more detailed commit message following
    https://lore.kernel.org/git/xmqqpmax5c4v.fsf@gitster.g/

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1527%2Fhickford%2Ffix-libsecret-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1527/hickford/fix-libsecret-v2
Pull-Request: https://github.com/git/git/pull/1527

Range-diff vs v1:

 1:  dcc429c1afc ! 1:  b5d5c3159ad credential/libsecret: erase matching creds only
     @@ Metadata
       ## Commit message ##
          credential/libsecret: erase matching creds only
      
     -    Fix test "helper ... does not erase a password distinct from input"
     -    introduced in aeb21ce22e (credential: avoid erasing distinct password,
     -    2023-06-13)
     +    The credential erase request typically includes protocol, host, username
     +    and password.
     +
     +    credential-libsecret erases a stored credential if it matches protocol,
     +    host and username, regardless of password.
     +
     +    This is confusing in the case the stored password differs from that
     +    in the request. This case can occur when multiple credential helpers are
     +    configured.
     +
     +    Only erase credential if stored password matches request (or request
     +    omits password).
     +
     +    This fixes test "helper ... does not erase a password distinct from
     +    input" introduced in aeb21ce22e (credential: avoid erasing distinct
     +    password, 2023-06-13)
      
          Signed-off-by: M Hickford <mirth.hickford@gmail.com>
      


 .../libsecret/git-credential-libsecret.c        | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/contrib/credential/libsecret/git-credential-libsecret.c b/contrib/credential/libsecret/git-credential-libsecret.c
index ef681f29d5b..9110714601e 100644
--- a/contrib/credential/libsecret/git-credential-libsecret.c
+++ b/contrib/credential/libsecret/git-credential-libsecret.c
@@ -52,6 +52,8 @@ struct credential_operation {
 
 #define CREDENTIAL_OP_END { NULL, NULL }
 
+static void credential_clear(struct credential *c);
+
 /* ----------------- Secret Service functions ----------------- */
 
 static char *make_label(struct credential *c)
@@ -185,6 +187,7 @@ static int keyring_erase(struct credential *c)
 {
 	GHashTable *attributes = NULL;
 	GError *error = NULL;
+	struct credential existing = CREDENTIAL_INIT;
 
 	/*
 	 * Sanity check that we actually have something to match
@@ -197,6 +200,20 @@ static int keyring_erase(struct credential *c)
 	if (!c->protocol && !c->host && !c->path && !c->username)
 		return EXIT_FAILURE;
 
+	if (c->password) {
+		existing.host = g_strdup(c->host);
+		existing.path = g_strdup(c->path);
+		existing.port = c->port;
+		existing.protocol = g_strdup(c->protocol);
+		existing.username = g_strdup(c->username);
+		keyring_get(&existing);
+		if (existing.password && strcmp(c->password, existing.password)) {
+			credential_clear(&existing);
+			return EXIT_SUCCESS;
+		}
+		credential_clear(&existing);
+	}
+
 	attributes = make_attr_list(c);
 	secret_password_clearv_sync(SECRET_SCHEMA_COMPAT_NETWORK,
 				    attributes,

base-commit: a80be152923a46f04a06bade7bcc72870e46ca09
-- 
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