From: Kees Cook <keescook@chromium.org>
To: Dominik Czarnota <dominik.czarnota@trailofbits.com>
Cc: Kees Cook <keescook@chromium.org>, Jessica Yu <jeyu@kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Martin KaFai Lau <kafai@fb.com>, Song Liu <songliubraving@fb.com>,
Yonghong Song <yhs@fb.com>, Andrii Nakryiko <andriin@fb.com>,
KP Singh <kpsingh@chromium.org>,
"Naveen N. Rao" <naveen.n.rao@linux.ibm.com>,
Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>,
"David S. Miller" <davem@davemloft.net>,
Masami Hiramatsu <mhiramat@kernel.org>,
Jakub Kicinski <kuba@kernel.org>,
"Steven Rostedt (VMware)" <rostedt@goodmis.org>,
Dmitry Safonov <0x7f454c46@gmail.com>,
Will Deacon <will@kernel.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Marc Zyngier <maz@kernel.org>,
Masahiro Yamada <masahiroy@kernel.org>,
Al Viro <viro@zeniv.linux.org.uk>,
Matteo Croce <mcroce@redhat.com>,
Edward Cree <ecree@solarflare.com>,
Nicolas Dichtel <nicolas.dichtel@6wind.com>,
Alexander Lobakin <alobakin@dlink.ru>,
Thomas Richter <tmricht@linux.ibm.com>,
Ingo Molnar <mingo@kernel.org>,
netdev@vger.kernel.org, bpf@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: [PATCH 0/5] Refactor kallsyms_show_value() users for correct cred
Date: Thu, 2 Jul 2020 16:26:33 -0700 [thread overview]
Message-ID: <20200702232638.2946421-1-keescook@chromium.org> (raw)
Hi,
I'm not sure who should carry this tree (me? Greg? akpm? Linus?), but
it fixes a kernel address exposure bug reported by Dominik Czarnota,
where /sys/modules/*/sections/* contents were visible to uid-0 without
CAP_SYSLOG (e.g. in containers):
This is correct, with CAP_SYSLOG:
# cat /sys/module/*/sections/.*text
0xffffffffc0458000
...
This is broken:
# capsh --drop=CAP_SYSLOG -- -c "cat /sys/module/*/sections/.*text"
0xffffffffc0458000
...
Fixing this required refactoring of several internals, and in the process
uncovered other users of kallsyms_show_value() that were doing checks
during "read" context instead of "open" context. This fixes all of these
cases by plumbing the file->f_cred through to their ultimate checks via
kallsyms_show_value()'s new cred argument.
Testing, reviews, and acks appreciated. :)
Thanks!
-Kees
Kees Cook (5):
kallsyms: Refactor kallsyms_show_value() to take cred
module: Refactor section attr into bin attribute
module: Do not expose section addresses to non-CAP_SYSLOG
kprobes: Do not expose probe addresses to non-CAP_SYSLOG
bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok()
include/linux/filter.h | 4 +--
include/linux/kallsyms.h | 5 ++--
kernel/bpf/syscall.c | 37 +++++++++++++++------------
kernel/kallsyms.c | 17 ++++++++-----
kernel/kprobes.c | 4 +--
kernel/module.c | 51 ++++++++++++++++++++------------------
net/core/sysctl_net_core.c | 2 +-
7 files changed, 67 insertions(+), 53 deletions(-)
--
2.25.1
next reply other threads:[~2020-07-02 23:27 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-02 23:26 Kees Cook [this message]
2020-07-02 23:26 ` [PATCH 1/5] kallsyms: Refactor kallsyms_show_value() to take cred Kees Cook
2020-07-02 23:26 ` [PATCH 2/5] module: Refactor section attr into bin attribute Kees Cook
2020-07-03 6:02 ` Greg Kroah-Hartman
2020-07-03 15:29 ` Kees Cook
2020-07-08 16:10 ` Jessica Yu
2020-07-02 23:26 ` [PATCH 3/5] module: Do not expose section addresses to non-CAP_SYSLOG Kees Cook
2020-07-08 16:12 ` Jessica Yu
2020-07-02 23:26 ` [PATCH 4/5] kprobes: Do not expose probe " Kees Cook
2020-07-03 1:00 ` Linus Torvalds
2020-07-03 15:13 ` Kees Cook
2020-07-03 15:50 ` Kees Cook
2020-07-05 20:10 ` Linus Torvalds
2020-07-05 20:19 ` Kees Cook
2020-07-10 14:09 ` Masami Hiramatsu
2020-07-02 23:26 ` [PATCH 5/5] bpf: Check correct cred for CAP_SYSLOG in bpf_dump_raw_ok() Kees Cook
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