Re: [PATCH v8 3/6] tracefs: Check file permission even if user has CAP_DAC_OVERRIDE

[Google]

On Wed, 11 Feb 2026 10:46:23 -0500
Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:

> On Tue, 10 Feb 2026 17:43:51 +0900
> "Masami Hiramatsu (Google)" <mhiramat@xxxxxxxxxx> wrote:
> 
> > From: Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>
> > 
> > Strictly checking the file read/write permission even if the owner has
> > CAP_DAC_OVERRIDE on tracefs as same as sysfs.
> > Tracefs is a pseudo filesystem, just like sysfs, so any file that the
> > system defines as unwritable should actually be unwritable by anyone.
> 
> This is getting too complex and still doesn't work. As I said in my
> other email, simply check for the trace_array being readonly on opens()
> and return -EACCES if it is and was opened for write or read-write.

yeah, I understand I confused "permission" and "possibility".

> 
> With this still not working this late in the game, it will need to wait
> until the next merge window. I'll take the first two patches of this
> series now though.

OK. I will send the next version without the first 2 patches.

Thank you,

> 
> -- Steve
> 


-- 
Masami Hiramatsu (Google) <mhiramat@xxxxxxxxxx>