Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 17 Nov 2020 15:36:30 -0800 | Subject | Re: [RESEND][PATCH] ima: Set and clear FMODE_CAN_READ in ima_calc_file_hash() |
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On Tue, Nov 17, 2020 at 3:29 PM Linus Torvalds <torvalds@linux-foundation.org> wrote: > > On Tue, Nov 17, 2020 at 3:24 PM Mimi Zohar <zohar@linux.ibm.com> wrote: > > > > I really wish it wasn't needed. > > Seriously, I get the feeling that IMA is completely mis-designed, and > is doing actively bad things. > > Who uses this "feature", and who cares? Because I would suggest you > just change the policy and be done with it.
Another alternative is to change the policy and say "any write-only open gets turned into a read-write open".
But it needs to be done at *OPEN* time, not randomly afterwards by just lying to the 'struct file'.
Why? Because the open has told the filesystem that it's only for writing, and a filesystem could validly do things that make reading invalid. The simplest example of this is a network filesystem, where the server might simply not *allow* reads, because the open was for writing only.
See? IMA really does something fundamentally quite wrong when it tries to read from a non-readable file. It might "work" by accident, but I really do think that commit a1f9b1c0439db didn't "break" IMA - it showed that IMA was doing something fundamentally wrong.
Linus
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