Messages in this thread | | | From | Linus Torvalds <> | Date | Tue, 17 Nov 2020 10:23:58 -0800 | Subject | Re: [RESEND][PATCH] ima: Set and clear FMODE_CAN_READ in ima_calc_file_hash() |
| |
On Mon, Nov 16, 2020 at 10:35 AM Mimi Zohar <zohar@linux.ibm.com> wrote: > > We need to differentiate between signed files, which by definition are > immutable, and those that are mutable. Appending to a mutable file, > for example, would result in the file hash not being updated. > Subsequent reads would fail.
Why would that require any reading of the file at all AT WRITE TIME?
Don't do it. Really.
When opening the file write-only, you just invalidate the hash. It doesn't matter anyway - you're only writing.
Later on, when reading, only at that point does the hash matter, and then you can do the verification.
Although honestly, I don't even see the point. You know the hash won't match, if you wrote to the file.
Linus
| |