Re: [PATCH] Allow aliases to expand to shell commands

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Feb 10, 2007, 20:34 UTC
Message-ID: <Pine.LNX.4.63.0702102129110.22628@wbgn013.biozentrum.uni-wuerzburg.de>
In-Reply-To: <20070210181357.GE25607@thunk.org>

Hi,

On Sat, 10 Feb 2007, Theodore Tso wrote:

Show 11 quoted lines

> diff --git a/git.c b/git.c
> index c43d4ff..fc08396 100644
> --- a/git.c
> +++ b/git.c
> @@ -159,6 +159,16 @@ static int handle_alias(int *argcp, const char ***argv)
>  	alias_command = (*argv)[0];
>  	git_config(git_alias_config);
>  	if (alias_string) {
> +		if (alias_string[0] == '!') {
> +			trace_printf("trace: alias to shell cmd: %s => %s\n",
> +				     alias_command, alias_string+1);

Here, you add 1 to alias string (though I would put spaces around the plus, but that's really a nit).

Show 6 quoted lines

> +			ret = system(alias_string+1);
> +			if (ret >= 0 && WIFEXITED(ret) && 
> +			    WEXITSTATUS(ret) != 127)
> +				exit(WEXITSTATUS(ret));
> +			die("Failed to run '%s' when expanding alias '%s'\n", 
> +			    alias_string, alias_command);

So, shouldn't you here, too?

It made me feel a little uneasy that we can execute _any_ command now, but I can only find one way to exploit this, when an attacker does not have shell access anyway: git-shell.

Ciao, Dscho