From: Kees Cook <keescook@chromium.org>
To: Andrii Nakryiko <andrii@kernel.org>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
kpsingh@kernel.org, paul@paul-moore.com,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH bpf-next 6/8] bpf: drop unnecessary bpf_capable() check in BPF_MAP_FREEZE command
Date: Wed, 12 Apr 2023 11:24:37 -0700 [thread overview]
Message-ID: <6436f765.a70a0220.1091d.f714@mx.google.com> (raw)
In-Reply-To: <20230412043300.360803-7-andrii@kernel.org>
On Tue, Apr 11, 2023 at 09:32:58PM -0700, Andrii Nakryiko wrote:
> Seems like that extra bpf_capable() check in BPF_MAP_FREEZE handler was
> unintentionally left when we switched to a model that all BPF map
> operations should be allowed regardless of CAP_BPF (or any other
> capabilities), as long as process got BPF map FD somehow.
>
> This patch replaces bpf_capable() check in BPF_MAP_FREEZE handler with
> writeable access check, given conceptually freezing the map is modifying
> it: map becomes unmodifiable for subsequent updates.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Is this patch stand-alone? It seems like this could be taken separately,
or at least just be the first patch in the series?
> ---
> kernel/bpf/syscall.c | 9 +++++----
> 1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 7d1165814efc..42d8473237ab 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -2001,6 +2001,11 @@ static int map_freeze(const union bpf_attr *attr)
> return -ENOTSUPP;
> }
>
> + if (!(map_get_sys_perms(map, f) & FMODE_CAN_WRITE)) {
> + err = -EPERM;
> + goto err_put;
> + }
> +
> mutex_lock(&map->freeze_mutex);
> if (bpf_map_write_active(map)) {
> err = -EBUSY;
> @@ -2010,10 +2015,6 @@ static int map_freeze(const union bpf_attr *attr)
> err = -EBUSY;
> goto err_put;
> }
> - if (!bpf_capable()) {
> - err = -EPERM;
> - goto err_put;
> - }
>
> WRITE_ONCE(map->frozen, true);
> err_put:
> --
> 2.34.1
>
--
Kees Cook
next prev parent reply other threads:[~2023-04-12 18:24 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-12 4:32 [PATCH bpf-next 0/8] New BPF map and BTF security LSM hooks Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 1/8] bpf: move unprivileged checks into map_create() and bpf_prog_load() Andrii Nakryiko
2023-04-12 17:49 ` Kees Cook
2023-04-13 0:22 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 2/8] bpf: inline map creation logic in map_create() function Andrii Nakryiko
2023-04-12 17:53 ` Kees Cook
2023-04-13 0:22 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 3/8] bpf: centralize permissions checks for all BPF map types Andrii Nakryiko
2023-04-12 18:01 ` Kees Cook
2023-04-13 0:23 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 4/8] bpf, lsm: implement bpf_map_create_security LSM hook Andrii Nakryiko
2023-04-12 18:20 ` Kees Cook
2023-04-13 0:23 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 5/8] selftests/bpf: validate new " Andrii Nakryiko
2023-04-12 18:23 ` Kees Cook
2023-04-13 0:23 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 6/8] bpf: drop unnecessary bpf_capable() check in BPF_MAP_FREEZE command Andrii Nakryiko
2023-04-12 18:24 ` Kees Cook [this message]
2023-04-13 0:17 ` Andrii Nakryiko
2023-04-12 4:32 ` [PATCH bpf-next 7/8] bpf, lsm: implement bpf_btf_load_security LSM hook Andrii Nakryiko
2023-04-12 16:52 ` Paul Moore
2023-04-13 1:43 ` Andrii Nakryiko
2023-04-13 2:47 ` Paul Moore
2023-04-12 4:33 ` [PATCH bpf-next 8/8] selftests/bpf: enhance lsm_map_create test with BTF LSM control Andrii Nakryiko
2023-04-12 16:49 ` [PATCH bpf-next 0/8] New BPF map and BTF security LSM hooks Paul Moore
2023-04-12 17:47 ` Kees Cook
2023-04-12 18:06 ` Paul Moore
2023-04-12 18:28 ` Kees Cook
2023-04-12 19:06 ` Paul Moore
2023-04-13 1:43 ` Andrii Nakryiko
2023-04-13 2:56 ` Paul Moore
2023-04-13 5:16 ` Andrii Nakryiko
2023-04-13 15:11 ` Paul Moore
2023-04-17 23:29 ` Andrii Nakryiko
2023-04-18 0:47 ` Casey Schaufler
2023-04-21 0:00 ` Andrii Nakryiko
2023-04-18 14:21 ` Paul Moore
2023-04-21 0:00 ` Andrii Nakryiko
2023-04-21 18:57 ` Kees Cook
2023-04-13 16:54 ` Casey Schaufler
2023-04-17 23:31 ` Andrii Nakryiko
2023-04-13 19:03 ` Jonathan Corbet
2023-04-17 23:28 ` Andrii Nakryiko
2023-04-13 16:27 ` Casey Schaufler
2023-04-17 23:31 ` Andrii Nakryiko
2023-04-17 23:53 ` Casey Schaufler
2023-04-18 0:28 ` Andrii Nakryiko
2023-04-18 0:52 ` Casey Schaufler
2023-04-12 18:38 ` Casey Schaufler
2023-04-14 20:23 ` Dr. Greg
2023-04-17 23:31 ` Andrii Nakryiko
2023-04-19 10:53 ` Dr. Greg
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