Re: regression: "96b9e0e3 config: treat user and xdg config permission problems as errors" busted git-daemon

[Jeff King <peff@peff.net>]

On Thu, Apr 11, 2013 at 08:35:46AM -0700, Junio C Hamano wrote:

> > Yeah, I think the bug here is that git-daemon should be setting $HOME
> > when it switches privileges with --user. Does this patch fix it for you?
> [...]
> Yeah, that sounds like the obvious fix to me.

Here it is with a commit message.

-- >8 --
Subject: [PATCH] daemon: set HOME when we switch to --user

If git-daemon is invoked with the "--user foo" option, we
setuid and setgid to the "foo" user. However, we do not
currently touch $HOME or any other environment variables.

This means that a git-daemon (and its git subprocesses)
invoked as root will look at ~root/.gitconfig,
~root/.config/git, etc. This is probably not what the admin
expected; it would make more sense to load user-wide config
from ~foo.

Traditionally this wasn't that big a deal, as most sites do
not put config in either homedir (they would use the
system-wide /etc/gitconfig if they wanted global config).
However, since 96b9e0e (config: treat user and xdg config
permission problems as errors, 2012-10-13), it is now an
error to try to read from an inaccessible config file (which
a file in ~root is very likely to be), meaning that
git-daemon will not run at all in such a case.

We can fix this by setting HOME appropriately when we switch
users. Note that this is a regression for any site that uses
--user but depends on putting config in the $HOME of the
user invoking git-daemon. Since the original behavior was
never documented, and the new behavior is much more
sensible, we can consider this a bugfix.

Reported-by: Mike Galbraith <bitbucket@online.de>
Signed-off-by: Jeff King <peff@peff.net>
---
I don't have any problem calling this a bugfix and claiming that anyone
who was depending on the original behavior is stupid and wrong. But it
should probably get a prominent slot in the ReleaseNotes.

 daemon.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/daemon.c b/daemon.c
index 6aeddcb..a4451fd 100644
--- a/daemon.c
+++ b/daemon.c
@@ -1091,6 +1091,7 @@ static void drop_privileges(struct credentials *cred)
 	if (cred && (initgroups(cred->pass->pw_name, cred->gid) ||
 	    setgid (cred->gid) || setuid(cred->pass->pw_uid)))
 		die("cannot drop privileges");
+	setenv("HOME", cred->pass->pw_dir, 1);
 }
 
 static struct credentials *prepare_credentials(const char *user_name,
-- 
1.8.2.rc0.33.gd915649