Re: does e2fsprogs needs to invoke file system related system calls?

[Valdis . Kletnieks]

On Thu, 05 May 2005 16:49:33 EDT, Xin Zhao said:
> does e2fsprogs needs to invoke file system related system calls?

Which calls do you mean?  I suspect that for the most part, it's
doing read/write/etc to the *underlying medium* - for instance, mkfs.ext3
can't use calls related to the *file system* because it's not mounted
yet (it doesn't even *exist* yet).

> The reason I want to ask this question is to know whether we can
> bypass the system call monitoring based access control with e2fsprogs.

It's been known since the Unix V7 days and even earlier that having read/write
access to the underlying /dev/hd-whatever partition was able to bypass
file permissions on the file system built on that partition.  Of course, write
access is at your own risk, as there's no easy/clean way to ensure that the
kernel doesn't have an in-core copy that doesn't match what you wrote (as
everybody who's run fsck on a live file system can testify ;)

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