From: Daniel Borkmann <daniel@iogearbox.net> To: Alexei Starovoitov <alexei.starovoitov@gmail.com>, joeyli <jlee@suse.com> Cc: Andy Lutomirski <luto@kernel.org>, David Howells <dhowells@redhat.com>, Ard Biesheuvel <ard.biesheuvel@linaro.org>, James Morris <jmorris@namei.org>, One Thousand Gnomes <gnomes@lxorguk.ukuu.org.uk>, Linus Torvalds <torvalds@linux-foundation.org>, Matthew Garrett <mjg59@google.com>, Greg KH <gregkh@linuxfoundation.org>, LKML <linux-kernel@vger.kernel.org>, Justin Forbes <jforbes@redhat.com>, linux-man <linux-man@vger.kernel.org>, LSM List <linux-security-module@vger.kernel.org>, Linux API <linux-api@vger.kernel.org>, Kees Cook <keescook@chromium.org>, linux-efi <linux-efi@vger.kernel.org> Subject: Re: [GIT PULL] Kernel lockdown for secure boot Date: Mon, 9 Apr 2018 10:14:15 +0200 [thread overview] Message-ID: <9040da29-2803-5c00-d47c-ae676a86b65c@iogearbox.net> (raw) In-Reply-To: <20180409034008.dyte7k5kgkbjh5is@ast-mbp.dhcp.thefacebook.com> On 04/09/2018 05:40 AM, Alexei Starovoitov wrote: > On Sun, Apr 08, 2018 at 04:07:42PM +0800, joeyli wrote: [...] >>> If the only thing that folks are paranoid about is reading >>> arbitrary kernel memory with bpf_probe_read() helper >>> then preferred patch would be to disable it during verification >>> when in lockdown mode >> >> Sorry for I didn't fully understand your idea... >> Do you mean that using bpf verifier to filter out bpf program that >> uses bpf_probe_read()? > > Take a look bpf_get_trace_printk_proto(). > Similarly we can add bpf_get_probe_read_proto() that > will return NULL if lockdown is on. > Then programs with bpf_probe_read() will be rejected by the verifier. Fully agree with the above. For the two helpers, something like the below would be sufficient to reject progs at verification time. diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d88e96d..51a6c2e 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -117,6 +117,11 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; +static const struct bpf_func_proto *bpf_get_probe_read_proto(void) +{ + return kernel_is_locked_down("BPF") ? NULL : &bpf_probe_read_proto; +} + BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { @@ -282,6 +287,9 @@ static const struct bpf_func_proto bpf_trace_printk_proto = { const struct bpf_func_proto *bpf_get_trace_printk_proto(void) { + if (kernel_is_locked_down("BPF")) + return NULL; + /* * this program might be calling bpf_trace_printk, * so allocate per-cpu printk buffers @@ -535,7 +543,7 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_map_delete_elem: return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: - return &bpf_probe_read_proto; + return bpf_get_probe_read_proto(); case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call:
WARNING: multiple messages have this Message-ID (diff)
From: daniel@iogearbox.net (Daniel Borkmann) To: linux-security-module@vger.kernel.org Subject: [GIT PULL] Kernel lockdown for secure boot Date: Mon, 9 Apr 2018 10:14:15 +0200 [thread overview] Message-ID: <9040da29-2803-5c00-d47c-ae676a86b65c@iogearbox.net> (raw) In-Reply-To: <20180409034008.dyte7k5kgkbjh5is@ast-mbp.dhcp.thefacebook.com> On 04/09/2018 05:40 AM, Alexei Starovoitov wrote: > On Sun, Apr 08, 2018 at 04:07:42PM +0800, joeyli wrote: [...] >>> If the only thing that folks are paranoid about is reading >>> arbitrary kernel memory with bpf_probe_read() helper >>> then preferred patch would be to disable it during verification >>> when in lockdown mode >> >> Sorry for I didn't fully understand your idea... >> Do you mean that using bpf verifier to filter out bpf program that >> uses bpf_probe_read()? > > Take a look bpf_get_trace_printk_proto(). > Similarly we can add bpf_get_probe_read_proto() that > will return NULL if lockdown is on. > Then programs with bpf_probe_read() will be rejected by the verifier. Fully agree with the above. For the two helpers, something like the below would be sufficient to reject progs at verification time. diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index d88e96d..51a6c2e 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -117,6 +117,11 @@ static const struct bpf_func_proto bpf_probe_read_proto = { .arg3_type = ARG_ANYTHING, }; +static const struct bpf_func_proto *bpf_get_probe_read_proto(void) +{ + return kernel_is_locked_down("BPF") ? NULL : &bpf_probe_read_proto; +} + BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src, u32, size) { @@ -282,6 +287,9 @@ static const struct bpf_func_proto bpf_trace_printk_proto = { const struct bpf_func_proto *bpf_get_trace_printk_proto(void) { + if (kernel_is_locked_down("BPF")) + return NULL; + /* * this program might be calling bpf_trace_printk, * so allocate per-cpu printk buffers @@ -535,7 +543,7 @@ tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_map_delete_elem: return &bpf_map_delete_elem_proto; case BPF_FUNC_probe_read: - return &bpf_probe_read_proto; + return bpf_get_probe_read_proto(); case BPF_FUNC_ktime_get_ns: return &bpf_ktime_get_ns_proto; case BPF_FUNC_tail_call: -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2018-04-09 8:14 UTC|newest] Thread overview: 250+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-04-04 2:34 [GIT PULL] Kernel lockdown for secure boot Alexei Starovoitov 2018-04-04 2:34 ` Alexei Starovoitov 2018-04-04 4:31 ` Matthew Garrett 2018-04-04 4:31 ` Matthew Garrett 2018-04-08 7:44 ` joeyli 2018-04-08 7:44 ` joeyli 2018-04-08 8:07 ` joeyli 2018-04-08 8:07 ` joeyli 2018-04-09 3:40 ` Alexei Starovoitov 2018-04-09 3:40 ` Alexei Starovoitov 2018-04-09 8:14 ` Daniel Borkmann [this message] 2018-04-09 8:14 ` Daniel Borkmann 2018-04-09 13:55 ` joeyli 2018-04-09 13:55 ` joeyli -- strict thread matches above, loose matches on Subject: below -- 2018-03-30 23:29 David Howells 2018-03-30 23:29 ` David Howells 2018-03-31 0:46 ` James Morris 2018-03-31 0:46 ` James Morris 2018-04-03 0:37 ` Andy Lutomirski 2018-04-03 0:37 ` Andy Lutomirski 2018-04-03 0:59 ` Kees Cook 2018-04-03 0:59 ` Kees Cook 2018-04-03 1:47 ` Andy Lutomirski 2018-04-03 1:47 ` Andy Lutomirski 2018-04-03 7:06 ` David Howells 2018-04-03 7:06 ` David Howells 2018-04-03 15:11 ` Andy Lutomirski 2018-04-03 15:11 ` Andy Lutomirski 2018-04-03 15:41 ` Alexei Starovoitov 2018-04-03 15:41 ` Alexei Starovoitov 2018-04-03 16:26 ` Andy Lutomirski 2018-04-03 16:26 ` Andy Lutomirski 2018-04-03 16:29 ` Matthew Garrett 2018-04-03 16:29 ` Matthew Garrett 2018-04-03 16:45 ` Andy Lutomirski 2018-04-03 16:45 ` Andy Lutomirski 2018-04-03 18:45 ` Kees Cook 2018-04-03 18:45 ` Kees Cook 2018-04-03 19:01 ` Andy Lutomirski 2018-04-03 19:01 ` Andy Lutomirski 2018-04-03 19:07 ` Kees Cook 2018-04-03 19:07 ` Kees Cook 2018-04-03 19:29 ` Matthew Garrett 2018-04-03 19:29 ` Matthew Garrett 2018-04-03 21:51 ` Andy Lutomirski 2018-04-03 21:51 ` Andy Lutomirski 2018-04-04 18:42 ` Peter Jones 2018-04-04 18:42 ` Peter Jones 2018-04-04 20:01 ` Thomas Gleixner 2018-04-04 20:01 ` Thomas Gleixner 2018-04-04 20:18 ` Matthew Garrett 2018-04-04 20:18 ` Matthew Garrett 2018-04-05 18:47 ` Andy Lutomirski 2018-04-05 18:47 ` Andy Lutomirski 2018-04-06 4:42 ` Peter Dolding 2018-04-06 4:42 ` Peter Dolding 2018-04-03 17:16 ` David Howells 2018-04-03 17:16 ` David Howells 2018-04-03 19:01 ` Andy Lutomirski 2018-04-03 19:01 ` Andy Lutomirski 2018-04-03 19:49 ` David Howells 2018-04-03 19:49 ` David Howells 2018-04-03 21:58 ` Andy Lutomirski 2018-04-03 21:58 ` Andy Lutomirski 2018-04-03 22:32 ` David Howells 2018-04-03 22:32 ` David Howells 2018-04-03 22:39 ` Andy Lutomirski 2018-04-03 22:39 ` Andy Lutomirski 2018-04-03 22:46 ` Linus Torvalds 2018-04-03 22:46 ` Linus Torvalds 2018-04-03 22:51 ` Matthew Garrett 2018-04-03 22:51 ` Matthew Garrett 2018-04-03 22:53 ` Andy Lutomirski 2018-04-03 22:53 ` Andy Lutomirski 2018-04-03 23:08 ` Justin Forbes 2018-04-03 23:09 ` Matthew Garrett 2018-04-03 23:09 ` Matthew Garrett 2018-04-03 23:08 ` Linus Torvalds 2018-04-03 23:08 ` Linus Torvalds 2018-04-03 23:10 ` Linus Torvalds 2018-04-03 23:10 ` Linus Torvalds 2018-04-03 23:17 ` Matthew Garrett 2018-04-03 23:17 ` Matthew Garrett 2018-04-03 23:26 ` Linus Torvalds 2018-04-03 23:26 ` Linus Torvalds 2018-04-03 23:39 ` Linus Torvalds 2018-04-03 23:39 ` Linus Torvalds 2018-04-03 23:47 ` Matthew Garrett 2018-04-03 23:47 ` Matthew Garrett 2018-04-04 0:02 ` Linus Torvalds 2018-04-04 0:02 ` Linus Torvalds 2018-04-04 0:04 ` Matthew Garrett 2018-04-04 0:04 ` Matthew Garrett 2018-04-04 0:08 ` Linus Torvalds 2018-04-04 0:08 ` Linus Torvalds 2018-04-04 0:12 ` Matthew Garrett 2018-04-04 0:12 ` Matthew Garrett 2018-04-05 14:58 ` Alan Cox 2018-04-05 14:58 ` Alan Cox 2018-04-04 0:22 ` David Howells 2018-04-04 0:22 ` David Howells 2018-04-04 0:22 ` David Howells 2018-04-05 17:59 ` Alan Cox 2018-04-05 17:59 ` Alan Cox 2018-04-05 18:03 ` Matthew Garrett 2018-04-05 18:03 ` Matthew Garrett 2018-04-03 23:45 ` Matthew Garrett 2018-04-03 23:45 ` Matthew Garrett 2018-04-03 23:55 ` Linus Torvalds 2018-04-03 23:55 ` Linus Torvalds 2018-04-03 23:59 ` Matthew Garrett 2018-04-03 23:59 ` Matthew Garrett 2018-04-04 0:06 ` Linus Torvalds 2018-04-04 0:06 ` Linus Torvalds 2018-04-04 0:10 ` Matthew Garrett 2018-04-04 0:10 ` Matthew Garrett 2018-04-04 0:15 ` Linus Torvalds 2018-04-04 0:15 ` Linus Torvalds 2018-04-04 0:16 ` Matthew Garrett 2018-04-04 0:16 ` Matthew Garrett 2018-04-04 0:18 ` Andy Lutomirski 2018-04-04 0:18 ` Andy Lutomirski 2018-04-04 0:19 ` Matthew Garrett 2018-04-04 0:19 ` Matthew Garrett 2018-04-04 9:04 ` Greg Kroah-Hartman 2018-04-04 9:04 ` Greg Kroah-Hartman 2018-04-04 0:25 ` Linus Torvalds 2018-04-04 0:25 ` Linus Torvalds 2018-04-04 0:33 ` Linus Torvalds 2018-04-04 0:33 ` Linus Torvalds 2018-04-04 0:46 ` Matthew Garrett 2018-04-04 0:46 ` Matthew Garrett 2018-04-04 0:56 ` Linus Torvalds 2018-04-04 0:56 ` Linus Torvalds 2018-04-04 1:13 ` Matthew Garrett 2018-04-04 1:13 ` Matthew Garrett 2018-04-04 1:43 ` Linus Torvalds 2018-04-04 1:43 ` Linus Torvalds 2018-04-04 4:30 ` Matthew Garrett 2018-04-04 4:30 ` Matthew Garrett 2018-04-04 12:57 ` Theodore Y. Ts'o 2018-04-04 12:57 ` Theodore Y. Ts'o 2018-04-04 13:02 ` Greg Kroah-Hartman 2018-04-04 13:02 ` Greg Kroah-Hartman 2018-04-04 13:34 ` Theodore Y. Ts'o 2018-04-04 13:34 ` Theodore Y. Ts'o 2018-04-04 13:57 ` Greg Kroah-Hartman 2018-04-04 13:57 ` Greg Kroah-Hartman 2018-04-04 13:29 ` Mike Galbraith 2018-04-04 13:29 ` Mike Galbraith 2018-04-04 16:20 ` Matthew Garrett 2018-04-04 16:20 ` Matthew Garrett 2018-04-08 22:00 ` Pavel Machek 2018-04-04 13:33 ` David Howells 2018-04-04 13:33 ` David Howells 2018-04-04 13:52 ` Theodore Y. Ts'o 2018-04-04 13:52 ` Theodore Y. Ts'o 2018-04-04 16:22 ` Matthew Garrett 2018-04-04 16:22 ` Matthew Garrett 2018-04-04 16:39 ` Andy Lutomirski 2018-04-04 16:39 ` Andy Lutomirski 2018-04-04 16:42 ` Matthew Garrett 2018-04-04 16:42 ` Matthew Garrett 2018-04-04 16:46 ` Justin Forbes 2018-04-04 16:46 ` Justin Forbes 2018-04-05 0:05 ` Peter Dolding 2018-04-05 0:05 ` Peter Dolding 2018-04-05 0:20 ` Matthew Garrett 2018-04-05 0:20 ` Matthew Garrett 2018-04-04 13:57 ` David Howells 2018-04-04 13:57 ` David Howells 2018-04-04 16:09 ` Linus Torvalds 2018-04-04 16:09 ` Linus Torvalds 2018-04-04 16:17 ` Matthew Garrett 2018-04-04 16:17 ` Matthew Garrett 2018-04-04 6:56 ` Peter Dolding 2018-04-04 6:56 ` Peter Dolding 2018-04-04 16:26 ` Matthew Garrett 2018-04-04 16:26 ` Matthew Garrett 2018-04-05 1:28 ` Peter Dolding 2018-04-05 1:28 ` Peter Dolding 2018-04-04 1:30 ` Justin Forbes 2018-04-04 1:58 ` Linus Torvalds 2018-04-04 1:58 ` Linus Torvalds 2018-04-04 1:36 ` Justin Forbes 2018-04-04 1:36 ` Justin Forbes 2018-04-04 0:17 ` Jann Horn 2018-04-04 0:17 ` Jann Horn 2018-04-04 0:23 ` Andy Lutomirski 2018-04-04 0:23 ` Andy Lutomirski 2018-04-04 8:05 ` David Howells 2018-04-04 8:05 ` David Howells 2018-04-04 8:05 ` David Howells 2018-04-04 14:35 ` Andy Lutomirski 2018-04-04 14:35 ` Andy Lutomirski 2018-04-04 14:44 ` David Howells 2018-04-04 14:44 ` David Howells 2018-04-04 14:44 ` David Howells 2018-04-04 15:43 ` Eric W. Biederman 2018-04-04 15:43 ` Eric W. Biederman 2018-04-03 23:56 ` David Howells 2018-04-03 23:56 ` David Howells 2018-04-03 23:56 ` David Howells 2018-04-03 23:58 ` Linus Torvalds 2018-04-03 23:58 ` Linus Torvalds 2018-04-03 23:39 ` David Howells 2018-04-03 23:39 ` David Howells 2018-04-03 23:48 ` Andy Lutomirski 2018-04-03 23:48 ` Andy Lutomirski 2018-04-08 8:23 ` Pavel Machek 2018-04-03 23:12 ` David Howells 2018-04-03 23:12 ` David Howells 2018-04-03 23:27 ` Linus Torvalds 2018-04-03 23:27 ` Linus Torvalds 2018-04-03 23:42 ` Andy Lutomirski 2018-04-03 23:42 ` Andy Lutomirski 2018-04-03 20:53 ` Linus Torvalds 2018-04-03 20:53 ` Linus Torvalds 2018-04-03 20:54 ` Matthew Garrett 2018-04-03 20:54 ` Matthew Garrett 2018-04-03 21:01 ` Linus Torvalds 2018-04-03 21:01 ` Linus Torvalds 2018-04-03 21:08 ` Matthew Garrett 2018-04-03 21:08 ` Matthew Garrett 2018-04-03 21:21 ` Al Viro 2018-04-03 21:21 ` Al Viro 2018-04-03 21:37 ` Matthew Garrett 2018-04-03 21:37 ` Matthew Garrett 2018-04-03 21:26 ` Linus Torvalds 2018-04-03 21:26 ` Linus Torvalds 2018-04-03 21:32 ` Matthew Garrett 2018-04-03 21:32 ` Matthew Garrett 2018-04-08 8:10 ` Pavel Machek 2018-03-31 10:20 ` David Howells 2018-03-31 10:20 ` David Howells 2018-04-03 13:25 ` Ard Biesheuvel 2018-04-03 13:25 ` Ard Biesheuvel 2018-04-03 21:48 ` James Morris 2018-04-03 21:48 ` James Morris 2018-04-05 17:53 ` Alan Cox 2018-04-05 17:53 ` Alan Cox 2017-10-26 16:37 David Howells 2017-10-26 16:37 ` David Howells 2017-10-26 16:37 ` David Howells 2017-10-26 18:22 ` Mimi Zohar 2017-10-26 18:22 ` Mimi Zohar 2017-10-26 18:22 ` Mimi Zohar 2017-10-26 19:20 ` James Morris 2017-10-26 19:20 ` James Morris 2017-10-26 19:20 ` James Morris
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