From: Jann Horn <jannh@google.com> To: Kees Cook <keescook@chromium.org> Cc: Kernel Hardening <kernel-hardening@lists.openwall.com>, John Wood <john.wood@gmx.com>, Matthew Wilcox <willy@infradead.org>, Jonathan Corbet <corbet@lwn.net>, Alexander Viro <viro@zeniv.linux.org.uk>, Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>, Juri Lelli <juri.lelli@redhat.com>, Vincent Guittot <vincent.guittot@linaro.org>, Dietmar Eggemann <dietmar.eggemann@arm.com>, Steven Rostedt <rostedt@goodmis.org>, Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>, Luis Chamberlain <mcgrof@kernel.org>, Iurii Zaikin <yzaikin@google.com>, James Morris <jmorris@namei.org>, "Serge E. Hallyn" <serge@hallyn.com>, linux-doc@vger.kernel.org, kernel list <linux-kernel@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, linux-security-module <linux-security-module@vger.kernel.org> Subject: Re: [RFC PATCH 5/6] security/fbfam: Detect a fork brute force attack Date: Fri, 11 Sep 2020 02:01:56 +0200 [thread overview] Message-ID: <CAG48ez2fP7yupg6Th+Hg0tL3o06p2PR1HtQcvy4Ro+Q5T2Nfkw@mail.gmail.com> (raw) In-Reply-To: <202009101634.52ED6751AD@keescook> On Fri, Sep 11, 2020 at 1:49 AM Kees Cook <keescook@chromium.org> wrote: > On Thu, Sep 10, 2020 at 01:21:06PM -0700, Kees Cook wrote: > > From: John Wood <john.wood@gmx.com> > > > > To detect a fork brute force attack it is necessary to compute the > > crashing rate of the application. This calculation is performed in each > > fatal fail of a task, or in other words, when a core dump is triggered. > > If this rate shows that the application is crashing quickly, there is a > > clear signal that an attack is happening. > > > > Since the crashing rate is computed in milliseconds per fault, if this > > rate goes under a certain threshold a warning is triggered. > > > > Signed-off-by: John Wood <john.wood@gmx.com> > > --- > > fs/coredump.c | 2 ++ > > include/fbfam/fbfam.h | 2 ++ > > security/fbfam/fbfam.c | 39 +++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 43 insertions(+) > > > > diff --git a/fs/coredump.c b/fs/coredump.c > > index 76e7c10edfc0..d4ba4e1828d5 100644 > > --- a/fs/coredump.c > > +++ b/fs/coredump.c > > @@ -51,6 +51,7 @@ > > #include "internal.h" > > > > #include <trace/events/sched.h> > > +#include <fbfam/fbfam.h> > > > > int core_uses_pid; > > unsigned int core_pipe_limit; > > @@ -825,6 +826,7 @@ void do_coredump(const kernel_siginfo_t *siginfo) > > fail_creds: > > put_cred(cred); > > fail: > > + fbfam_handle_attack(siginfo->si_signo); > > I don't think this is the right place for detecting a crash -- isn't > this only for the "dumping core" condition? In other words, don't you > want to do this in get_signal()'s "fatal" block? (i.e. very close to the > do_coredump, but without the "should I dump?" check?) > > Hmm, but maybe I'm wrong? It looks like you're looking at noticing the > process taking a signal from SIG_KERNEL_COREDUMP_MASK ? > > (Better yet: what are fatal conditions that do NOT match > SIG_KERNEL_COREDUMP_MASK, and should those be covered?) > > Regardless, *this* looks like the only place without an LSM hook. And it > doesn't seem unreasonable to add one here. I assume it would probably > just take the siginfo pointer, which is also what you're checking. Good point, making this an LSM might be a good idea. > e.g. for include/linux/lsm_hook_defs.h: > > LSM_HOOK(int, 0, task_coredump, const kernel_siginfo_t *siginfo); I guess it should probably be an LSM_RET_VOID hook? And since, as you said, it's not really semantically about core dumping, maybe it should be named task_fatal_signal or something like that.
next prev parent reply other threads:[~2020-09-11 0:02 UTC|newest] Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-09-10 20:21 [RESEND][RFC PATCH 0/6] Fork brute force attack mitigation (fbfam) Kees Cook 2020-09-10 20:21 ` [RFC PATCH 1/6] security/fbfam: Add a Kconfig to enable the fbfam feature Kees Cook 2020-09-10 21:21 ` Jann Horn 2020-09-10 21:21 ` Jann Horn 2020-09-17 17:32 ` John Wood 2020-09-10 23:18 ` Kees Cook 2020-09-17 18:40 ` John Wood 2020-09-17 22:05 ` Kees Cook 2020-09-18 14:50 ` John Wood 2020-09-10 20:21 ` [RFC PATCH 2/6] security/fbfam: Add the api to manage statistics Kees Cook 2020-09-10 23:23 ` Kees Cook 2020-09-10 20:21 ` [RFC PATCH 3/6] security/fbfam: Use " Kees Cook 2020-09-10 20:27 ` Jann Horn 2020-09-10 20:27 ` Jann Horn 2020-09-10 23:33 ` Kees Cook 2020-09-29 23:47 ` Steven Rostedt 2020-09-29 23:49 ` Steven Rostedt 2020-10-03 9:52 ` John Wood 2020-09-10 20:21 ` [RFC PATCH 4/6] security/fbfam: Add a new sysctl to control the crashing rate threshold Kees Cook 2020-09-10 23:14 ` Kees Cook 2020-09-13 14:33 ` John Wood 2020-09-10 20:21 ` [RFC PATCH 5/6] security/fbfam: Detect a fork brute force attack Kees Cook 2020-09-10 21:10 ` Jann Horn 2020-09-10 21:10 ` Jann Horn 2020-09-13 17:54 ` John Wood 2020-09-14 19:42 ` Jann Horn 2020-09-14 19:42 ` Jann Horn 2020-09-15 18:44 ` John Wood 2020-09-10 23:49 ` Kees Cook 2020-09-11 0:01 ` Jann Horn [this message] 2020-09-11 0:01 ` Jann Horn 2020-09-13 16:56 ` John Wood 2020-09-14 19:39 ` Jann Horn 2020-09-14 19:39 ` Jann Horn 2020-09-15 17:36 ` John Wood 2020-09-10 20:21 ` [RFC PATCH 6/6] security/fbfam: Mitigate " Kees Cook 2020-09-10 20:55 ` Jann Horn 2020-09-10 20:55 ` Jann Horn 2020-09-10 23:56 ` Kees Cook 2020-09-11 0:20 ` Jann Horn 2020-09-11 0:20 ` Jann Horn 2020-09-18 16:02 ` John Wood 2020-09-18 21:35 ` Kees Cook 2020-09-19 8:01 ` John Wood 2020-09-10 20:39 ` [RESEND][RFC PATCH 0/6] Fork brute force attack mitigation (fbfam) Jann Horn 2020-09-10 20:39 ` Jann Horn 2020-09-10 23:58 ` Kees Cook 2020-09-11 14:48 ` John Wood 2020-09-12 7:55 ` Kees Cook 2020-09-12 12:24 ` John Wood 2020-09-12 0:03 ` James Morris 2020-09-12 7:56 ` Kees Cook 2020-09-12 9:36 ` John Wood 2020-09-12 14:47 ` Mel Gorman 2020-09-12 20:48 ` Ondrej Mosnacek 2020-09-12 20:48 ` Ondrej Mosnacek 2020-09-13 7:24 ` John Wood 2020-09-13 7:24 ` John Wood
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=CAG48ez2fP7yupg6Th+Hg0tL3o06p2PR1HtQcvy4Ro+Q5T2Nfkw@mail.gmail.com \ --to=jannh@google.com \ --cc=bsegall@google.com \ --cc=corbet@lwn.net \ --cc=dietmar.eggemann@arm.com \ --cc=jmorris@namei.org \ --cc=john.wood@gmx.com \ --cc=juri.lelli@redhat.com \ --cc=keescook@chromium.org \ --cc=kernel-hardening@lists.openwall.com \ --cc=linux-doc@vger.kernel.org \ --cc=linux-fsdevel@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-security-module@vger.kernel.org \ --cc=mcgrof@kernel.org \ --cc=mgorman@suse.de \ --cc=mingo@redhat.com \ --cc=peterz@infradead.org \ --cc=rostedt@goodmis.org \ --cc=serge@hallyn.com \ --cc=vincent.guittot@linaro.org \ --cc=viro@zeniv.linux.org.uk \ --cc=willy@infradead.org \ --cc=yzaikin@google.com \ --subject='Re: [RFC PATCH 5/6] security/fbfam: Detect a fork brute force attack' \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.