Re: [PATCH] daemon: return "access denied" if a service is not allowed

The message is chosen to avoid leaking information, yet let users know
that they are deliberately not allowed to use the service, not a fault
in service configuration or the service itself.

Signed-off-by: Nguyễn Thái Ngọc Duy <redacted>
---
 OK let's try again. I don't send ERR when faults happen in
 service->fn() (eventually run_service_command) because

  - if it's start_command(), it's likely due to service configuration
    fault (wrong --exec-path..)

  - if it's finish_command(), the service may have run and sent
    something back to users. We may break the protocol by sending ERR

 daemon.c |   12 ++++++++----
 1 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/daemon.c b/daemon.c
index 4c8346d..f0cae24 100644
--- a/daemon.c
+++ b/daemon.c

@@ -257,11 +257,11 @@ static int run_service(char *dir, struct daemon_service *service)
 	if (!enabled && !service->overridable) {
 		logerror("'%s': service not enabled.", service->name);
 		errno = EACCES;
-		return -1;
+		goto failed;
 	}
 
 	if (!(path = path_ok(dir)))
-		return -1;
+		goto failed;
 
 	/*
 	 * Security on the cheap.

@@ -277,7 +277,7 @@ static int run_service(char *dir, struct daemon_service *service)
 	if (!export_all_trees && access("git-daemon-export-ok", F_OK)) {
 		logerror("'%s': repository not exported.", path);
 		errno = EACCES;
-		return -1;
+		goto failed;
 	}
 
 	if (service->overridable) {

@@ -291,7 +291,7 @@ static int run_service(char *dir, struct daemon_service *service)
 		logerror("'%s': service not enabled for '%s'",
 			 service->name, path);
 		errno = EACCES;
-		return -1;
+		goto failed;
 	}
 
 	/*

@@ -301,6 +301,10 @@ static int run_service(char *dir, struct daemon_service *service)
 	signal(SIGTERM, SIG_IGN);
 
 	return service->fn();
+
+failed:
+	packet_write(1, "ERR %s: access denied", dir);
+	return -1;
 }