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SubjectRe: [security]: kernel ioctl()'s [3]
Chris Evans wrote:

> Because programs running as root assume
>
> open("blah", O_RDWR)
> write(blah)
>
> will work. They do NOT expect to have to
>
> open("blah", O_RDWR)
> if (-EPERM)
> chflags("blah", immutable off)
> open("blah", O_RDWR)

assumptions are generally bad.

two situations immediately come to mind.

- extended attribute; immutable
- extended attribute; append only
- filesystem mounted RO
- 100% filesystem usage, 0% free

therefore the first example is very very bad.

always check your return values, expect the unexpected and survive. =)

-d



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