Messages in this thread | | | From | Rusty Russell <> | Subject | Re: [PATCH 9/9] sysfs: disallow world-writable files. | Date | Thu, 30 Apr 2015 11:32:05 +0930 |
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Gobinda Maji <gobinda.cemk07@gmail.com> writes: > Hi Rusty,
Hi Gobinda,
> I have a small doubt about the permission restriction (User perms >= > group perms >= other perms) in VERIFY_OCTAL_PERMISSIONS(). Please Note > that permission field of User, Group or Other consists of three bits. > LSB is EXECUTE permission, MSB is READ permission and the middle bit > is WRITE permission. Say for example, permission value is "0431". Here > User has only READ permission whereas Group has both WRITE and EXECUTE > permission and Other has EXECUTE permission. I guess, it is not good > to give Group the WRITE permission whereas User itself has no WRITE > permission.
You're absolutely right, well spotted! The checks can be tightened. We don't really care about execute, but logically write is "more privileged" than read.
Best to separate the tests; OTHER_WRITABLE <= GROUP_WRITABLE <= OWNER_WRITABLE and OTHER_READABLE <= GROUP_READABLE <= OWNER_READABLE.
A patch would be welcome!
Thanks, Rusty.
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