From: John Fastabend <john.fastabend@gmail.com>
To: Andrii Nakryiko <andrii@kernel.org>,
bpf@vger.kernel.org, netdev@vger.kernel.org,
paul@paul-moore.com, brauner@kernel.org
Cc: linux-fsdevel@vger.kernel.org,
linux-security-module@vger.kernel.org, keescook@chromium.org,
kernel-team@meta.com, sargun@sargun.me
Subject: RE: [PATCH bpf-next 1/8] bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS
Date: Mon, 11 Dec 2023 13:33:34 -0800 [thread overview]
Message-ID: <6577802ea99b2_edaa208b7@john.notmuch> (raw)
In-Reply-To: <20231207185443.2297160-2-andrii@kernel.org>
Andrii Nakryiko wrote:
> It's quite confusing in practice when it's possible to successfully
> create a BPF token from BPF FS that didn't have any of delegate_xxx
> mount options set up. While it's not wrong, it's actually more
> meaningful to reject BPF_TOKEN_CREATE with specific error code (-ENOENT)
> to let user-space know that no token delegation is setup up.
>
> So, instead of creating empty BPF token that will be always ignored
> because it doesn't have any of the allow_xxx bits set, reject it with
> -ENOENT. If we ever need empty BPF token to be possible, we can support
> that with extra flag passed into BPF_TOKEN_CREATE.
>
> Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
> ---
> kernel/bpf/token.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/kernel/bpf/token.c b/kernel/bpf/token.c
> index 17212efcde60..a86fccd57e2d 100644
> --- a/kernel/bpf/token.c
> +++ b/kernel/bpf/token.c
> @@ -152,6 +152,15 @@ int bpf_token_create(union bpf_attr *attr)
> goto out_path;
> }
>
> + mnt_opts = path.dentry->d_sb->s_fs_info;
> + if (mnt_opts->delegate_cmds == 0 &&
> + mnt_opts->delegate_maps == 0 &&
> + mnt_opts->delegate_progs == 0 &&
> + mnt_opts->delegate_attachs == 0) {
> + err = -ENOENT; /* no BPF token delegation is set up */
> + goto out_path;
> + }
> +
> mode = S_IFREG | ((S_IRUSR | S_IWUSR) & ~current_umask());
> inode = bpf_get_inode(path.mnt->mnt_sb, NULL, mode);
> if (IS_ERR(inode)) {
> @@ -181,7 +190,6 @@ int bpf_token_create(union bpf_attr *attr)
> /* remember bpffs owning userns for future ns_capable() checks */
> token->userns = get_user_ns(userns);
>
> - mnt_opts = path.dentry->d_sb->s_fs_info;
> token->allowed_cmds = mnt_opts->delegate_cmds;
> token->allowed_maps = mnt_opts->delegate_maps;
> token->allowed_progs = mnt_opts->delegate_progs;
> --
> 2.34.1
>
>
Acked-by: John Fastabend <john.fastabend@gmail.com>
next prev parent reply other threads:[~2023-12-11 21:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-07 18:54 [PATCH bpf-next 0/8] BPF token support in libbpf's BPF object Andrii Nakryiko
2023-12-07 18:54 ` [PATCH bpf-next 1/8] bpf: fail BPF_TOKEN_CREATE if no delegation option was set on BPF FS Andrii Nakryiko
2023-12-08 21:49 ` Christian Brauner
2023-12-08 22:42 ` Andrii Nakryiko
2023-12-11 21:33 ` John Fastabend [this message]
2023-12-07 18:54 ` [PATCH bpf-next 2/8] libbpf: split feature detectors definitions from cached results Andrii Nakryiko
2023-12-11 21:38 ` John Fastabend
2023-12-07 18:54 ` [PATCH bpf-next 3/8] libbpf: further decouple feature checking logic from bpf_object Andrii Nakryiko
2023-12-10 15:31 ` Eduard Zingerman
2023-12-11 18:20 ` Andrii Nakryiko
2023-12-11 21:41 ` John Fastabend
2023-12-11 22:50 ` Andrii Nakryiko
2023-12-07 18:54 ` [PATCH bpf-next 4/8] libbpf: move feature detection code into its own file Andrii Nakryiko
2023-12-11 21:41 ` John Fastabend
2023-12-07 18:54 ` [PATCH bpf-next 5/8] libbpf: wire up token_fd into feature probing logic Andrii Nakryiko
2023-12-11 21:44 ` John Fastabend
2023-12-07 18:54 ` [PATCH bpf-next 6/8] libbpf: wire up BPF token support at BPF object level Andrii Nakryiko
2023-12-11 22:56 ` John Fastabend
2023-12-12 0:05 ` Andrii Nakryiko
2023-12-12 0:26 ` John Fastabend
2023-12-07 18:54 ` [PATCH bpf-next 7/8] selftests/bpf: add BPF object loading tests with explicit token passing Andrii Nakryiko
2023-12-11 22:59 ` John Fastabend
2023-12-07 18:54 ` [PATCH bpf-next 8/8] selftests/bpf: add tests for BPF object load with implicit token Andrii Nakryiko
2023-12-11 23:00 ` John Fastabend
2023-12-10 15:30 ` [PATCH bpf-next 0/8] BPF token support in libbpf's BPF object Eduard Zingerman
2023-12-11 18:21 ` Andrii Nakryiko
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