IMA + O_DIRECT (Re: [PATCH 0/1] fix IMA + Apparmor kernel panic)

From: J. R. Okajima
Date: Thu May 08 2014 - 23:20:31 EST



Dmitry Kasatkin:
> Following patch replaces IMA usage of kernel_read() with special
> version which skips security check that triggers kernel panic
> when Apparmor and IMA appraisal are enabled together.

I know this is related to exit(2), but this behaviour of IMA is related
to open(2) too.
When O_DIRECT is specified, some filesystems (for example, ext2) call
do_blockdev_direct_IO() which acquires i_mutex. But
IMA:process_measurement() already acquires i_mutex before kernel_read().
It causes a deadlock even if you replace kernel_read() by a simpler one.
How can we stop reading the file from IMA?


J. R. Okajima
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