From: Alexei Starovoitov <alexei.starovoitov@gmail.com> To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp> Cc: "Eric W. Biederman" <ebiederm@xmission.com>, Linus Torvalds <torvalds@linux-foundation.org>, Kees Cook <keescook@chromium.org>, Andrew Morton <akpm@linux-foundation.org>, Alexei Starovoitov <ast@kernel.org>, David Miller <davem@davemloft.net>, Al Viro <viro@zeniv.linux.org.uk>, bpf <bpf@vger.kernel.org>, linux-fsdevel <linux-fsdevel@vger.kernel.org>, Daniel Borkmann <daniel@iogearbox.net>, Jakub Kicinski <kuba@kernel.org>, Masahiro Yamada <yamada.masahiro@socionext.com>, Gary Lin <GLin@suse.com>, Bruno Meneguele <bmeneg@redhat.com> Subject: Re: [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Date: Tue, 23 Jun 2020 23:39:40 -0700 Message-ID: <20200624063940.ctzhf4nnh3cjyxqi@ast-mbp.dhcp.thefacebook.com> (raw) In-Reply-To: <5254444e-465e-6dee-287b-bef58526b724@i-love.sakura.ne.jp> On Wed, Jun 24, 2020 at 01:58:33PM +0900, Tetsuo Handa wrote: > On 2020/06/24 13:00, Alexei Starovoitov wrote: > >> However, regarding usermode_blob, although the byte array (which contains code / data) > >> might be initially loaded from the kernel space (which is protected), that byte array > >> is no longer protected (e.g. SIGKILL, strace()) when executed because they are placed > >> in the user address space. Thus, LSM modules (including pathname based security) want > >> to control how that byte array can behave. > > > > It's privileged memory regardless. root can poke into kernel or any process memory. > > LSM is there to restrict processes running as "root". hmm. do you really mean that it's possible for an LSM to restrict CAP_SYS_ADMIN effectively? LSM can certainly provide extra level of foolproof-ness against accidental mistakes, but it's not a security boundary. > Your "root can poke into kernel or any process memory." response is out of step with the times. > > Initial byte array used for usermode blob might be protected because of "part of .rodata or > .init.rodata of kernel module", but that byte array after started in userspace is no longer > protected. > > I don't trust such byte array as "part of kernel module", and I'm asking you how > such byte array does not interfere (or be interfered by) the rest of the system. Could you please explain the attack vector that you see in such scenario? How elf binaries embedded in the kernel modules different from pid 1? If anything can peek into their memory the system is compromised. Say, there are no user blobs in kernel modules. How pid 1 memory is different from all the JITed images? How is it different for all memory regions shared between kernel and user processes? I see an opportunity for an LSM to provide a protection against non-security bugs when system is running trusted apps, but not when arbitrary code can execute under root.
next prev parent reply index Thread overview: 193+ messages / expand[flat|nested] mbox.gz Atom feed top [not found] <20200329005528.xeKtdz2A0%akpm@linux-foundation.org> [not found] ` <13fb3ab7-9ab1-b25f-52f2-40a6ca5655e1@i-love.sakura.ne.jp> [not found] ` <202006051903.C44988B@keescook> 2020-06-06 19:20 ` Eric W. Biederman 2020-06-06 20:19 ` Alexei Starovoitov 2020-06-06 22:33 ` Linus Torvalds 2020-06-07 1:49 ` Alexei Starovoitov 2020-06-07 2:19 ` Linus Torvalds 2020-06-07 16:09 ` Eric W. Biederman 2020-06-08 16:20 ` Alexei Starovoitov 2020-06-08 16:40 ` Greg KH 2020-06-08 18:35 ` Kees Cook 2020-06-09 1:26 ` Alexei Starovoitov 2020-06-09 15:37 ` Kees Cook 2020-06-09 19:51 ` Eric W. Biederman 2020-06-07 2:31 ` Tetsuo Handa 2020-06-08 16:23 ` Alexei Starovoitov 2020-06-08 23:22 ` Tetsuo Handa 2020-06-09 1:28 ` Alexei Starovoitov 2020-06-09 5:29 ` Tetsuo Handa 2020-06-09 22:32 ` Alexei Starovoitov 2020-06-09 23:30 ` Tetsuo Handa 2020-06-10 0:05 ` Alexei Starovoitov 2020-06-10 3:08 ` Tetsuo Handa 2020-06-10 3:32 ` Alexei Starovoitov 2020-06-10 7:30 ` Tetsuo Handa 2020-06-10 16:24 ` Casey Schaufler 2020-06-09 20:02 ` Eric W. Biederman 2020-06-09 23:56 ` Alexei Starovoitov 2020-06-10 21:12 ` Eric W. Biederman 2020-06-11 23:31 ` Alexei Starovoitov 2020-06-12 0:57 ` Tetsuo Handa 2020-06-13 3:38 ` Alexei Starovoitov 2020-06-13 4:22 ` Tetsuo Handa 2020-06-13 14:08 ` Eric W. Biederman 2020-06-13 15:33 ` Alexei Starovoitov 2020-06-13 16:14 ` Alexei Starovoitov 2020-06-14 14:51 ` Eric W. Biederman 2020-06-16 1:55 ` Alexei Starovoitov 2020-06-16 16:21 ` Alexei Starovoitov 2020-06-23 18:04 ` Eric W. Biederman 2020-06-23 18:35 ` Alexei Starovoitov 2020-06-23 18:53 ` Eric W. Biederman 2020-06-23 19:40 ` Alexei Starovoitov 2020-06-24 1:51 ` Tetsuo Handa 2020-06-24 4:00 ` Alexei Starovoitov 2020-06-24 4:58 ` Tetsuo Handa 2020-06-24 6:39 ` Alexei Starovoitov [this message] 2020-06-24 7:05 ` Tetsuo Handa 2020-06-24 15:41 ` Casey Schaufler 2020-06-24 17:54 ` Alexei Starovoitov 2020-06-24 19:48 ` Casey Schaufler 2020-06-24 6:05 ` Alexei Starovoitov 2020-06-24 14:18 ` Alexei Starovoitov 2020-06-24 12:13 ` Eric W. Biederman 2020-06-24 14:26 ` Alexei Starovoitov 2020-06-24 23:14 ` Tetsuo Handa 2020-06-25 1:35 ` Alexei Starovoitov 2020-06-25 6:38 ` Tetsuo Handa 2020-06-25 9:57 ` Greg KH 2020-06-25 11:03 ` Tetsuo Handa 2020-06-25 12:07 ` Greg KH 2020-06-25 14:21 ` Tetsuo Handa 2020-06-25 19:34 ` David Miller 2020-06-26 1:36 ` Linus Torvalds 2020-06-26 1:51 ` Alexei Starovoitov 2020-06-26 4:58 ` Tetsuo Handa 2020-06-26 5:41 ` Alexei Starovoitov 2020-06-26 6:20 ` Tetsuo Handa 2020-06-26 6:39 ` Alexei Starovoitov 2020-06-26 12:51 ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman 2020-06-26 12:53 ` [PATCH 01/14] umh: Capture the pid in umh_pipe_setup Eric W. Biederman 2020-06-26 12:53 ` [PATCH 02/14] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman 2020-06-26 12:54 ` [PATCH 03/14] umh: Rename the user mode driver helpers for clarity Eric W. Biederman 2020-06-26 12:54 ` [PATCH 04/14] umh: Remove call_usermodehelper_setup_file Eric W. Biederman 2020-06-26 12:55 ` [PATCH 05/14] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman 2020-06-26 16:22 ` Tetsuo Handa 2020-06-26 16:45 ` Eric W. Biederman 2020-06-27 1:26 ` Tetsuo Handa 2020-06-27 4:21 ` Eric W. Biederman 2020-06-27 4:36 ` Tetsuo Handa 2020-06-26 12:55 ` [PATCH 06/14] umd: For clarity rename umh_info umd_info Eric W. Biederman 2020-06-26 15:37 ` Kees Cook 2020-06-26 16:31 ` Eric W. Biederman 2020-06-26 12:56 ` [PATCH 07/14] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman 2020-06-26 12:56 ` [PATCH 08/14] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman 2020-06-26 12:57 ` [PATCH 09/14] umh: Stop calling do_execve_file Eric W. Biederman 2020-06-26 12:57 ` [PATCH 10/14] exec: Remove do_execve_file Eric W. Biederman 2020-06-26 12:58 ` [PATCH 11/14] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman 2020-06-26 12:58 ` [PATCH 12/14] umd: Track user space drivers with struct pid Eric W. Biederman 2020-06-26 12:59 ` [PATCH 13/14] bpfilter: Take advantage of the facilities of " Eric W. Biederman 2020-06-26 12:59 ` [PATCH 14/14] umd: Remove exit_umh Eric W. Biederman 2020-06-26 13:48 ` [PATCH 00/14] Make the user mode driver code a better citizen Eric W. Biederman 2020-06-29 19:55 ` [PATCH v2 00/15] " Eric W. Biederman 2020-06-29 19:56 ` [PATCH v2 01/15] umh: Capture the pid in umh_pipe_setup Eric W. Biederman 2020-06-29 19:57 ` [PATCH v2 02/15] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman 2020-06-29 19:57 ` [PATCH v2 03/15] umh: Rename the user mode driver helpers for clarity Eric W. Biederman 2020-06-29 19:59 ` [PATCH v2 04/15] umh: Remove call_usermodehelper_setup_file Eric W. Biederman 2020-06-29 20:00 ` [PATCH v2 05/15] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman 2020-06-30 16:58 ` Linus Torvalds 2020-07-01 17:18 ` Eric W. Biederman 2020-07-01 17:42 ` Alexei Starovoitov 2020-06-29 20:01 ` [PATCH v2 06/15] umd: For clarity rename umh_info umd_info Eric W. Biederman 2020-06-29 20:02 ` [PATCH v2 07/15] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman 2020-06-29 20:03 ` [PATCH v2 08/15] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman 2020-06-29 20:03 ` [PATCH v2 09/15] umh: Stop calling do_execve_file Eric W. Biederman 2020-06-29 20:04 ` [PATCH v2 10/15] exec: Remove do_execve_file Eric W. Biederman 2020-06-30 5:43 ` Christoph Hellwig 2020-06-30 12:14 ` Eric W. Biederman 2020-06-30 13:38 ` Christoph Hellwig 2020-06-30 14:28 ` Eric W. Biederman 2020-06-30 16:55 ` Alexei Starovoitov 2020-06-29 20:05 ` [PATCH v2 11/15] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman 2020-06-29 20:06 ` [PATCH v2 12/15] umd: Track user space drivers with struct pid Eric W. Biederman 2020-06-29 20:06 ` [PATCH v2 13/15] bpfilter: Take advantage of the facilities of " Eric W. Biederman 2020-06-29 20:07 ` [PATCH v2 14/15] umd: Remove exit_umh Eric W. Biederman 2020-06-29 20:08 ` [PATCH v2 15/15] umd: Stop using split_argv Eric W. Biederman 2020-06-29 22:12 ` [PATCH v2 00/15] Make the user mode driver code a better citizen Alexei Starovoitov 2020-06-30 1:13 ` Eric W. Biederman 2020-06-30 6:16 ` Tetsuo Handa 2020-06-30 12:29 ` Eric W. Biederman 2020-06-30 13:21 ` Tetsuo Handa 2020-07-02 13:08 ` Eric W. Biederman 2020-07-02 13:40 ` Tetsuo Handa 2020-07-02 16:02 ` Eric W. Biederman 2020-07-03 13:19 ` Tetsuo Handa 2020-07-03 22:25 ` Eric W. Biederman 2020-07-04 6:57 ` Tetsuo Handa 2020-07-08 4:46 ` Eric W. Biederman 2020-06-30 16:52 ` Alexei Starovoitov 2020-07-01 17:12 ` Eric W. Biederman 2020-07-02 16:40 ` [PATCH v3 00/16] " Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 01/16] umh: Capture the pid in umh_pipe_setup Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 02/16] umh: Move setting PF_UMH into umh_pipe_setup Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 03/16] umh: Rename the user mode driver helpers for clarity Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 04/16] umh: Remove call_usermodehelper_setup_file Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 05/16] umh: Separate the user mode driver and the user mode helper support Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 06/16] umd: For clarity rename umh_info umd_info Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 07/16] umd: Rename umd_info.cmdline umd_info.driver_name Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 08/16] umd: Transform fork_usermode_blob into fork_usermode_driver Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 09/16] umh: Stop calling do_execve_file Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 10/16] exec: Remove do_execve_file Eric W. Biederman 2020-07-08 6:35 ` Luis Chamberlain 2020-07-08 12:41 ` Luis Chamberlain 2020-07-08 13:08 ` Eric W. Biederman 2020-07-08 13:32 ` Luis Chamberlain 2020-07-12 21:02 ` Pavel Machek 2020-07-02 16:41 ` [PATCH v3 11/16] bpfilter: Move bpfilter_umh back into init data Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 12/16] umd: Track user space drivers with struct pid Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 13/16] exit: Factor thread_group_exited out of pidfd_poll Eric W. Biederman 2020-07-03 20:30 ` Alexei Starovoitov 2020-07-03 21:37 ` Eric W. Biederman 2020-07-04 0:03 ` Alexei Starovoitov 2020-07-04 15:50 ` Christian Brauner 2020-07-07 17:09 ` Eric W. Biederman 2020-07-08 0:05 ` Daniel Borkmann 2020-07-08 3:50 ` Eric W. Biederman 2020-07-04 16:00 ` Christian Brauner 2020-07-02 16:41 ` [PATCH v3 14/16] bpfilter: Take advantage of the facilities of struct pid Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 15/16] umd: Remove exit_umh Eric W. Biederman 2020-07-02 16:41 ` [PATCH v3 16/16] umd: Stop using split_argv Eric W. Biederman 2020-07-02 23:51 ` [PATCH v3 00/16] Make the user mode driver code a better citizen Tetsuo Handa 2020-07-09 22:05 ` [merged][PATCH " Eric W. Biederman 2020-07-14 19:42 ` Alexei Starovoitov 2020-07-08 5:20 ` [PATCH v2 00/15] " Luis Chamberlain 2020-06-26 14:10 ` [PATCH 00/14] " Greg Kroah-Hartman 2020-06-26 16:40 ` Alexei Starovoitov 2020-06-26 17:17 ` Eric W. Biederman 2020-06-26 18:22 ` Alexei Starovoitov 2020-06-27 11:38 ` Tetsuo Handa 2020-06-27 12:59 ` Eric W. Biederman 2020-06-27 13:57 ` Tetsuo Handa 2020-06-28 19:44 ` Alexei Starovoitov 2020-06-29 2:20 ` Tetsuo Handa 2020-06-29 20:19 ` Eric W. Biederman 2020-06-30 6:28 ` Tetsuo Handa 2020-06-30 12:32 ` Eric W. Biederman 2020-06-30 16:48 ` Alexei Starovoitov 2020-06-30 21:54 ` Tetsuo Handa 2020-06-30 21:57 ` Alexei Starovoitov 2020-06-30 22:58 ` Tetsuo Handa 2020-06-25 12:56 ` [RFC][PATCH] net/bpfilter: Remove this broken and apparently unmantained Stephen Smalley 2020-06-25 13:25 ` Greg Kroah-Hartman 2020-06-25 14:26 ` Stephen Smalley 2020-06-25 14:36 ` Stephen Smalley 2020-06-25 15:21 ` Tetsuo Handa 2020-06-25 16:03 ` Stephen Smalley 2020-06-25 16:06 ` Casey Schaufler 2020-06-26 11:30 ` Eric W. Biederman 2020-06-07 5:58 ` Eric W. Biederman 2020-06-07 11:56 ` Eric W. Biederman 2020-06-08 16:35 ` Alexei Starovoitov 2020-06-08 16:33 ` Alexei Starovoitov 2020-06-06 20:43 ` Matthew Wilcox 2020-06-07 15:51 ` Eric W. Biederman 2020-06-07 1:13 ` Tetsuo Handa
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