From: Daniel Borkmann <daniel@iogearbox.net>
To: Alexei Starovoitov <ast@kernel.org>, luto@amacapital.net
Cc: davem@davemloft.net, peterz@infradead.org, rostedt@goodmis.org,
netdev@vger.kernel.org, bpf@vger.kernel.org, kernel-team@fb.com,
linux-api@vger.kernel.org
Subject: Re: [PATCH v2 bpf-next 1/3] capability: introduce CAP_BPF and CAP_TRACING
Date: Thu, 29 Aug 2019 17:47:25 +0200 [thread overview]
Message-ID: <536636ad-0baf-31e9-85fe-2591b65068df@iogearbox.net> (raw)
In-Reply-To: <20190829051253.1927291-1-ast@kernel.org>
On 8/29/19 7:12 AM, Alexei Starovoitov wrote:
[...]
>
> +/*
> + * CAP_BPF allows the following BPF operations:
> + * - Loading all types of BPF programs
> + * - Creating all types of BPF maps except:
> + * - stackmap that needs CAP_TRACING
> + * - devmap that needs CAP_NET_ADMIN
> + * - cpumap that needs CAP_SYS_ADMIN
> + * - Advanced verifier features
> + * - Indirect variable access
> + * - Bounded loops
> + * - BPF to BPF function calls
> + * - Scalar precision tracking
> + * - Larger complexity limits
> + * - Dead code elimination
> + * - And potentially other features
> + * - Use of pointer-to-integer conversions in BPF programs
> + * - Bypassing of speculation attack hardening measures
> + * - Loading BPF Type Format (BTF) data
> + * - Iterate system wide loaded programs, maps, BTF objects
> + * - Retrieve xlated and JITed code of BPF programs
> + * - Access maps and programs via id
> + * - Use bpf_spin_lock() helper
This is still very wide. Consider following example: app has CAP_BPF +
CAP_NET_ADMIN. Why can't we in this case *only* allow loading networking
related [plus generic] maps and programs? If it doesn't have CAP_TRACING,
what would be a reason to allow loading it? Same vice versa. There are
some misc program types like the infraread stuff, but they could continue
to live under [CAP_BPF +] CAP_SYS_ADMIN as fallback. I think categorizing
a specific list of prog and map types might be more clear than disallowing
some helpers like below (e.g. why choice of bpf_probe_read() but not
bpf_probe_write_user() etc).
> + * CAP_BPF and CAP_TRACING together allow the following:
> + * - bpf_probe_read to read arbitrary kernel memory
> + * - bpf_trace_printk to print data to ftrace ring buffer
> + * - Attach to raw_tracepoint
> + * - Query association between kprobe/tracepoint and bpf program
> + *
> + * CAP_BPF and CAP_NET_ADMIN together allow the following:
> + * - Attach to cgroup-bpf hooks and query
> + * - skb, xdp, flow_dissector test_run command
> + *
> + * CAP_NET_ADMIN allows:
> + * - Attach networking bpf programs to xdp, tc, lwt, flow dissector
> + */
> +#define CAP_BPF 38
> +
> +/*
> + * CAP_TRACING allows:
> + * - Full use of perf_event_open(), similarly to the effect of
> + * kernel.perf_event_paranoid == -1
> + * - Full use of tracefs
> + * - Creation of [ku][ret]probe
> + * - Accessing arbitrary kernel memory via kprobe + probe_kernel_read
> + * - Attach tracing bpf programs to perf events
> + * - Access to kallsyms
> + */
> +#define CAP_TRACING 39
>
> -#define CAP_LAST_CAP CAP_AUDIT_READ
> +#define CAP_LAST_CAP CAP_TRACING
>
> #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
>
> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
> index 201f7e588a29..0b364e245163 100644
> --- a/security/selinux/include/classmap.h
> +++ b/security/selinux/include/classmap.h
> @@ -26,9 +26,9 @@
> "audit_control", "setfcap"
>
> #define COMMON_CAP2_PERMS "mac_override", "mac_admin", "syslog", \
> - "wake_alarm", "block_suspend", "audit_read"
> + "wake_alarm", "block_suspend", "audit_read", "bpf", "tracing"
>
> -#if CAP_LAST_CAP > CAP_AUDIT_READ
> +#if CAP_LAST_CAP > CAP_TRACING
> #error New capability defined, please update COMMON_CAP2_PERMS.
> #endif
>
>
next prev parent reply other threads:[~2019-08-29 15:47 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-29 5:12 [PATCH v2 bpf-next 1/3] capability: introduce CAP_BPF and CAP_TRACING Alexei Starovoitov
2019-08-29 5:12 ` [PATCH v2 bpf-next 2/3] bpf: implement CAP_BPF Alexei Starovoitov
2019-08-29 6:04 ` Song Liu
2019-08-29 17:28 ` Alexei Starovoitov
2019-08-29 15:32 ` Daniel Borkmann
2019-08-29 17:30 ` Alexei Starovoitov
2019-08-30 15:19 ` Nicolas Dichtel
2019-09-04 1:39 ` Alexei Starovoitov
2019-09-04 15:16 ` Daniel Borkmann
2019-09-04 15:21 ` Alexei Starovoitov
2019-09-05 8:37 ` Daniel Borkmann
2019-09-05 22:00 ` Alexei Starovoitov
2019-08-29 5:12 ` [PATCH v2 bpf-next 3/3] perf: implement CAP_TRACING Alexei Starovoitov
2019-08-29 6:06 ` Song Liu
2019-08-29 6:00 ` [PATCH v2 bpf-next 1/3] capability: introduce CAP_BPF and CAP_TRACING Song Liu
2019-08-29 7:44 ` Toke Høiland-Jørgensen
2019-08-29 17:24 ` Alexei Starovoitov
2019-08-29 18:05 ` Toke Høiland-Jørgensen
2019-08-29 20:25 ` Jesper Dangaard Brouer
2019-08-29 21:10 ` Alexei Starovoitov
2019-08-29 13:36 ` Nicolas Dichtel
2019-08-29 17:25 ` Alexei Starovoitov
2019-08-29 15:47 ` Daniel Borkmann [this message]
2019-08-29 16:28 ` Andy Lutomirski
2019-08-30 4:16 ` Alexei Starovoitov
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