From: Andrew Lutomirski <luto@mit.edu> To: Will Drewry <wad@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org>, linux-kernel@vger.kernel.org, keescook@chromium.org, john.johansen@canonical.com, serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org, khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, olofj@chromium.org, mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net, alan@lxorguk.ukuu.org.uk Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Date: Thu, 12 Jan 2012 17:41:33 -0800 [thread overview] Message-ID: <CAObL_7Fr-yV33jobSa3g_WqVJar-5x5oQM0t8GJxcLFsuBhLtg@mail.gmail.com> (raw) In-Reply-To: <CABqD9hZCpFM4fN9p3vmnGeLVbvoDtTgbiovz=RsSkjH6sv=xBQ@mail.gmail.com> On Thu, Jan 12, 2012 at 5:37 PM, Will Drewry <wad@chromium.org> wrote: > On Thu, Jan 12, 2012 at 7:11 PM, Andrew Lutomirski <luto@mit.edu> wrote: >> (Also, preventing dropping of privileges will probably make a patch >> more complicted -- I'll have to find and update all the places that >> allow dropping privileges.) > > An alternative approach might be that the restricted bit drops all > privileges that allows privilege changes in either direction. E.g., > - set restricted bit > -- adds a check anywhere MNT_NOSUID is > -- sets securebit to SECURE_NOROOT|..LOCKED > -- drops CAP_SETUID, CAP_DAC_OVERRIDE, ... > -- set the caps bounding set to the minimum the restricted bit allows > > That may deviate from the intent (by re-using caps), but it could keep some > of the privilege transition checking code the same. I'm not sure it'll be much of a simplification. The entire patch is 45 lines right now :) I'll test it and send it out. FWIW, though, it breaks apparmor (intentionally). Can any of you either explain what *should* happen or (better) volunteer to fix it? It should be about three lines of code for someone who understands what's going on. I don't have an apparmor system, so I can't really test it. --Andy > > Just a thought, > will
WARNING: multiple messages have this Message-ID (diff)
From: Andrew Lutomirski <luto@mit.edu> To: Will Drewry <wad@chromium.org> Cc: Linus Torvalds <torvalds@linux-foundation.org>, linux-kernel@vger.kernel.org, keescook@chromium.org, john.johansen@canonical.com, serge.hallyn@canonical.com, coreyb@linux.vnet.ibm.com, pmoore@redhat.com, eparis@redhat.com, djm@mindrot.org, segoon@openwall.com, rostedt@goodmis.org, jmorris@namei.org, scarybeasts@gmail.com, avi@redhat.com, penberg@cs.helsinki.fi, viro@zeniv.linux.org.uk, mingo@elte.hu, akpm@linux-foundation.org, khilman@ti.com, borislav.petkov@amd.com, amwang@redhat.com, oleg@redhat.com, ak@linux.intel.com, eric.dumazet@gmail.com, gregkh@suse.de, dhowells@redhat.com, daniel.lezcano@free.fr, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, olofj@chromium.org, mhalcrow@google.com, dlaor@redhat.com, corbet@lwn.net, alan@lxorguk.ukuu.org.uk Subject: Re: [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Date: Thu, 12 Jan 2012 17:41:33 -0800 [thread overview] Message-ID: <CAObL_7Fr-yV33jobSa3g_WqVJar-5x5oQM0t8GJxcLFsuBhLtg@mail.gmail.com> (raw) In-Reply-To: <CABqD9hZCpFM4fN9p3vmnGeLVbvoDtTgbiovz=RsSkjH6sv=xBQ@mail.gmail.com> On Thu, Jan 12, 2012 at 5:37 PM, Will Drewry <wad@chromium.org> wrote: > On Thu, Jan 12, 2012 at 7:11 PM, Andrew Lutomirski <luto@mit.edu> wrote: >> (Also, preventing dropping of privileges will probably make a patch >> more complicted -- I'll have to find and update all the places that >> allow dropping privileges.) > > An alternative approach might be that the restricted bit drops all > privileges that allows privilege changes in either direction. E.g., > - set restricted bit > -- adds a check anywhere MNT_NOSUID is > -- sets securebit to SECURE_NOROOT|..LOCKED > -- drops CAP_SETUID, CAP_DAC_OVERRIDE, ... > -- set the caps bounding set to the minimum the restricted bit allows > > That may deviate from the intent (by re-using caps), but it could keep some > of the privilege transition checking code the same. I'm not sure it'll be much of a simplification. The entire patch is 45 lines right now :) I'll test it and send it out. FWIW, though, it breaks apparmor (intentionally). Can any of you either explain what *should* happen or (better) volunteer to fix it? It should be about three lines of code for someone who understands what's going on. I don't have an apparmor system, so I can't really test it. --Andy > > Just a thought, > will -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2012-01-13 1:41 UTC|newest] Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-01-12 23:38 [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Will Drewry 2012-01-12 23:38 ` [PATCH v3 2/3] seccomp_filters: system call filtering using BPF Will Drewry 2012-01-13 0:51 ` Randy Dunlap 2012-01-12 23:59 ` Will Drewry 2012-01-12 23:59 ` Will Drewry 2012-01-13 1:35 ` Randy Dunlap 2012-01-13 17:39 ` Eric Paris 2012-01-13 18:50 ` Will Drewry 2012-01-13 18:50 ` Will Drewry 2012-01-12 23:38 ` [PATCH v3 3/3] Documentation: prctl/seccomp_filter Will Drewry 2012-01-15 1:52 ` Randy Dunlap 2012-01-16 1:41 ` Will Drewry 2012-01-17 23:29 ` Eric Paris 2012-01-17 23:29 ` Eric Paris 2012-01-17 23:54 ` Will Drewry 2012-01-12 23:47 ` [PATCH PLACEHOLDER 1/3] fs/exec: "always_unprivileged" patch Linus Torvalds 2012-01-13 0:03 ` Will Drewry 2012-01-13 0:42 ` Andrew Lutomirski 2012-01-13 0:57 ` Linus Torvalds 2012-01-13 0:57 ` Linus Torvalds 2012-01-13 1:11 ` Andrew Lutomirski 2012-01-13 1:11 ` Andrew Lutomirski 2012-01-13 1:17 ` Linus Torvalds 2012-01-14 13:30 ` Jamie Lokier 2012-01-14 19:21 ` Will Drewry 2012-01-14 19:21 ` Will Drewry 2012-01-14 20:22 ` Linus Torvalds 2012-01-14 21:04 ` Andrew Lutomirski 2012-01-15 20:16 ` Casey Schaufler 2012-01-15 20:59 ` Andrew Lutomirski 2012-01-15 21:32 ` Casey Schaufler 2012-01-15 21:32 ` Casey Schaufler 2012-01-15 22:07 ` Andrew Lutomirski 2012-01-16 2:04 ` Will Drewry 2012-01-16 2:04 ` Will Drewry 2012-01-18 3:12 ` Eric W. Biederman 2012-01-18 3:12 ` Eric W. Biederman 2012-01-16 2:41 ` Casey Schaufler 2012-01-16 2:41 ` Casey Schaufler 2012-01-16 7:45 ` Andrew Lutomirski 2012-01-16 18:02 ` Casey Schaufler 2012-01-16 18:02 ` Casey Schaufler 2012-01-13 1:37 ` Will Drewry 2012-01-13 1:41 ` Andrew Lutomirski [this message] 2012-01-13 1:41 ` Andrew Lutomirski 2012-01-13 2:09 ` Kees Cook 2012-01-13 2:09 ` Kees Cook
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