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Date: Mon, 10 Jul 2017 15:07:44 +0200 From: Phil Sutter <phil@....cc> To: Matteo Croce <mcroce@...hat.com> Cc: netdev@...r.kernel.org, Stephen Hemminger <stephen@...workplumber.org> Subject: Re: [PATCH] netns: avoid directory traversal (was: ip netns: Make sure netns name is sane) Hi Matteo, On Mon, Jul 10, 2017 at 02:08:31PM +0200, Matteo Croce wrote: > I noticed that your patch still leaves an uncovered scenario, the one where the > namespace name is "." or "..". > Calling 'ip netns del ..' will remove /var/run which is a symlink to /run on > most systems causing some daemons, eg. dbus, to fail. Oh, indeed. My patch even checks the name for 'ip netns add' only! > ip netns doesn't validate input, allowing creation and deletion of files > relatives to /var/run/netns. > This patch denies creation or deletion of namespaces with names contaning > "/" or that matches exactly "." or "..". You might want to have a look at --scissors option to git-am for a more elegant way of sending a reply with attached patch. [...] > int do_netns(int argc, char **argv) > { > netns_nsid_socket_init(); > @@ -775,6 +780,11 @@ int do_netns(int argc, char **argv) > return netns_list(0, NULL); > } > > + if (argc > 1 && invalid_name(argv[1])) { > + fprintf(stderr, "Invalid netns name \"%s\"\n", argv[1]); > + exit(-1); > + } Maybe worth noting, this assumes argv[1] will be used for the netns name which doesn't hold for 'ip netns identify' command. It doesn't matter though, since netns_identify() enforces the parameter to be either "self" or a decimal number. Yet, in future a new subcommand might be added which requires this check to be refactored. Thanks, Phil
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