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Message-Id: <20191009160907.10981-1-christian.brauner@ubuntu.com>
Date: Wed, 9 Oct 2019 18:09:04 +0200
From: Christian Brauner <christian.brauner@...ntu.com>
To: Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>, bpf@...r.kernel.org
Cc: Martin KaFai Lau <kafai@...com>, Song Liu <songliubraving@...com>,
Yonghong Song <yhs@...com>, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org,
Christian Brauner <christian.brauner@...ntu.com>
Subject: [PATCH 0/3] bpf: switch to new usercopy helpers
Hey everyone,
In v5.4-rc2 we added two new helpers check_zeroed_user() and
copy_struct_from_user() including selftests (cf. [1]). It is a generic
interface designed to copy a struct from userspace. The helpers will be
especially useful for structs versioned by size of which we have quite a
few.
The most obvious benefit is that this helper lets us get rid of
duplicate code. We've already switched over sched_setattr(), perf_event_open(),
and clone3(). More importantly it will also help to ensure that users
implementing versioning-by-size end up with the same core semantics.
This point is especially crucial since we have at least one case where
versioning-by-size is used but with slighly different semantics:
sched_setattr(), perf_event_open(), and clone3() all do do similar
checks to copy_struct_from_user() while rt_sigprocmask(2) always rejects
differently-sized struct arguments.
This little series switches over bpf codepaths that have hand-rolled
implementations of these helpers.
Thanks!
Christian
/* Reference */
[1]: f5a1a536fa14 ("lib: introduce copy_struct_from_user() helper")
Christian Brauner (3):
bpf: use check_zeroed_user() in bpf_check_uarg_tail_zero()
bpf: use copy_struct_from_user() in bpf_prog_get_info_by_fd()
bpf: use copy_struct_from_user() in bpf() syscall
kernel/bpf/syscall.c | 38 ++++++++++++--------------------------
1 file changed, 12 insertions(+), 26 deletions(-)
--
2.23.0
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