Re: [PATCH v4 5/9] trace/bpf_trace: open access for CAP_SYS_PERFMON privileged process

Song Liu <[email protected]> Mon, 13 Jan 2020 20:47:04 +0000
Newsgroups gmane.linux.ports.arm.kernel,gmane.linux.oprofile,gmane.comp.freedesktop.xorg.drivers.intel,gmane.linux.ports.parisc,gmane.linux.kernel,gmane.linux.kernel.perf.user,gmane.linux.kernel.lsm,gmane.linux.ports.ppc64.devel
Message-ID <[email protected]>

> On Dec 18, 2019, at 1:28 AM, Alexey Budankov <[email protected]> wrote:
> 
> 
> Open access to bpf_trace monitoring for CAP_SYS_PERFMON privileged
> processes. For backward compatibility reasons access to bpf_trace
> monitoring remains open for CAP_SYS_ADMIN privileged processes but
> CAP_SYS_ADMIN usage for secure bpf_trace monitoring is discouraged
> with respect to CAP_SYS_PERFMON capability.
> 
> Signed-off-by: Alexey Budankov <[email protected]>

Acked-by: Song Liu <[email protected]>

> ---
> kernel/trace/bpf_trace.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
> index 44bd08f2443b..bafe21ac6d92 100644
> --- a/kernel/trace/bpf_trace.c
> +++ b/kernel/trace/bpf_trace.c
> @@ -1272,7 +1272,7 @@ int perf_event_query_prog_array(struct perf_event *event, void __user *info)
> 	u32 *ids, prog_cnt, ids_len;
> 	int ret;
> 
> -	if (!capable(CAP_SYS_ADMIN))
> +	if (!perfmon_capable())
> 		return -EPERM;
> 	if (event->attr.type != PERF_TYPE_TRACEPOINT)
> 		return -EINVAL;

I guess we need to fix this check for kprobe/uprobe created with 
perf_event_open()...

Thanks,
Song