On Wed, May 17, 2023 at 7:08 PM Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>
> On Wed, 17 May 2023 18:18:14 -0700
> Beau Belgrave <beaub@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > We should tell folks to use a group and give access to the group like
> > Steven said earlier.
>
> Could we possibly add an "owner" attribute to the event. That is, the
> creator of the event is the only one that can write to that event. Or at
> least by the user that created it (not actually the process).
>
> So if the user "rostedt" creates an event, only "rostedt" can write to or
> delete the event.
That can work, but why name is global in the first place?
Just make everything per-fd.
> The delete IOCTL is different than reg/unreg. I don't see a problem with
> adding a CAP_SYSADMIN check on the delete IOCTL (and other delete paths)
> to prevent this. It shouldn't affect anything we are doing to add this
> and it makes it so non-admins cannot delete any events if they are given
> write access to the user_events_data file.
sysadmin for delete is a pointless.
user_events_ioctl_reg() has the same issue.
Two different processes using you fancy TRACELOGGING_DEFINE_PROVIDER()
macro and picking the same name will race.
TRACELOGGING_DEFINE_PROVIDER( // defines the MyProvider symbol
MyProvider, // Name of the provider symbol to define
"MyCompany_MyComponent_MyProvider", // Human-readable provider
name, no ' ' or ':' chars.
// {d5b90669-1aad-5db8-16c9-6286a7fcfe33} // Provider guid
(ignored on Linux)
(0xd5b90669,0x1aad,0x5db8,0x16,0xc9,0x62,0x86,0xa7,0xfc,0xfe,0x33));
I totally get it that Beau is copy pasting these ideas from windows,
but windows is likely similarly broken if it's registering names
globally.
FD should be the isolation boundary.
fd = open("/sys/kernel/tracing/user_event")
and make sure all events are bound to that file.
when file is closed the events _should be auto deleted_.
That's another issue I just spotted.
Looks like user_events_release() is leaking memory.
user_event_refs are just lost.
tbh the more I look into the code the more I want to suggest to mark it
depends on BROKEN
and go back to redesign.
