Messages in this thread | | | Subject | Re: [PATCH v1] perf_event_open.2: update the man page with CAP_PERFMON related information | From | "Michael Kerrisk (man-pages)" <> | Date | Sun, 23 Aug 2020 19:28:31 +0200 |
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Hello Alexey,
Could you look at the question below and update the patch.
On 2/17/20 9:18 AM, Alexey Budankov wrote: > > Extend perf_event_open 2 man page with the information about > CAP_PERFMON capability designed to secure performance monitoring > and observability operation in a system according to the principle > of least privilege [1] (POSIX IEEE 1003.1e, 2.2.2.39). > > [1] https://sites.google.com/site/fullycapable/, posix_1003.1e-990310.pdf > > Signed-off-by: Alexey Budankov <alexey.budankov@linux.intel.com> > --- > man2/perf_event_open.2 | 27 +++++++++++++++++++++++++++ > 1 file changed, 27 insertions(+) > > diff --git a/man2/perf_event_open.2 b/man2/perf_event_open.2 > index 89d267c02..e9aab2ca1 100644 > --- a/man2/perf_event_open.2 > +++ b/man2/perf_event_open.2 > @@ -98,6 +98,8 @@ when running on the specified CPU. > .BR "pid == \-1" " and " "cpu >= 0" > This measures all processes/threads on the specified CPU. > This requires > +.B CAP_PERFMON > +or > .B CAP_SYS_ADMIN > capability or a > .I /proc/sys/kernel/perf_event_paranoid > @@ -2920,6 +2922,8 @@ to hold the result. > This allows attaching a Berkeley Packet Filter (BPF) > program to an existing kprobe tracepoint event. > You need > +.B CAP_PERFMON > +or > .B CAP_SYS_ADMIN > privileges to use this ioctl. > .IP > @@ -2962,6 +2966,8 @@ have multiple events attached to a tracepoint. > Querying this value on one tracepoint event returns the id > of all BPF programs in all events attached to the tracepoint. > You need > +.B CAP_PERFMON > +or > .B CAP_SYS_ADMIN > privileges to use this ioctl. > .IP > @@ -3170,6 +3176,8 @@ it was expecting. > .TP > .B EACCES > Returned when the requested event requires > +.B CAP_PERFMON > +or > .B CAP_SYS_ADMIN > permissions (or a more permissive perf_event paranoid setting). > Some common cases where an unprivileged process > @@ -3291,6 +3299,8 @@ setting is specified. > It can also happen, as with > .BR EACCES , > when the requested event requires > +.B CAP_PERFMON > +or > .B CAP_SYS_ADMIN > permissions (or a more permissive perf_event paranoid setting). > This includes setting a breakpoint on a kernel address, > @@ -3321,6 +3331,23 @@ The official way of knowing if > support is enabled is checking > for the existence of the file > .IR /proc/sys/kernel/perf_event_paranoid . > +.PP > +.B CAP_PERFMON > +capability (since Linux X.Y) provides secure approach to
What's the version?
> +performance monitoring and observability operations in a system > +according to the principal of least privilege (POSIX IEEE 1003.1e). > +Accessing system performance monitoring and observability operations > +using > +.B CAP_PERFMON > +capability singly, without the rest of > +.B CAP_SYS_ADMIN > +credentials, excludes chances to misuse the credentials and makes
I think that wording like "using CAP_PERFMON rather than the much more powerful CAP_SYS_ADMIN..."
> +the operations more secure. > +.B CAP_SYS_ADMIN > +usage for secure system performance monitoring and observability > +is discouraged with respect to > +.B CAP_PERFMON > +capability. > .SH BUGS > The > .B F_SETOWN_EX
Thanks,
Michael
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