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

[Jeff King <peff@peff.net>]

On Tue, Oct 04, 2011 at 08:55:09AM +1100, Nguyen Thai Ngoc Duy wrote:

> 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.

I do think this is an improvement, but I wonder if the verbosity should
be configurable. Then open sites like kernel.org could be friendlier to
their users. Something like this instead:

---
 daemon.c |   21 +++++++++++++++++----
 1 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/daemon.c b/daemon.c
index 4c8346d..ec88fd0 100644
--- a/daemon.c
+++ b/daemon.c
@@ -20,6 +20,7 @@
 static int log_syslog;
 static int verbose;
 static int reuseaddr;
+static int informative_errors;
 
 static const char daemon_usage[] =
 "git daemon [--verbose] [--syslog] [--export-all]\n"
@@ -247,6 +248,14 @@ static int git_daemon_config(const char *var, const char *value, void *cb)
 	return 0;
 }
 
+static int daemon_error(const char *dir, const char *msg)
+{
+	if (!informative_errors)
+		msg = "access denied";
+	packet_write(1, "ERR %s: %s", dir, msg);
+	return -1;
+}
+
 static int run_service(char *dir, struct daemon_service *service)
 {
 	const char *path;
@@ -257,11 +266,11 @@ 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;
+		return daemon_error(dir, "service not enabled");
 	}
 
 	if (!(path = path_ok(dir)))
-		return -1;
+		return daemon_error(dir, "no such repository");
 
 	/*
 	 * Security on the cheap.
@@ -277,7 +286,7 @@ 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;
+		return daemon_error(dir, "repository not exported");
 	}
 
 	if (service->overridable) {
@@ -291,7 +300,7 @@ static int run_service(char *dir, struct daemon_service *service)
 		logerror("'%s': service not enabled for '%s'",
 			 service->name, path);
 		errno = EACCES;
-		return -1;
+		return daemon_error(dir, "service not enabled");
 	}
 
 	/*
@@ -1167,6 +1176,10 @@ int main(int argc, char **argv)
 			make_service_overridable(arg + 18, 0);
 			continue;
 		}
+		if (!prefixcmp(arg, "--informative-errors")) {
+			informative_errors = 1;
+			continue;
+		}
 		if (!strcmp(arg, "--")) {
 			ok_paths = &argv[i+1];
 			break;
-- 
1.7.7.rc2.21.gb9948