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

[J. R. Okajima]

Mimi Zohar:
> Another approach was posted here
> http://marc.info/?l=linux-security-module&m=138919062430367&w=2 which
> also was not upstreamed.

It might be better a little than previous one which handles the flag
temporarily. But, in order to make the code cleaner particulary for
do_blockdev_direct_IO(), I'd suggest
- make two new static inline functions like
  r = ima_aware_file_inode_mutex_lock(file) and ..._unlock(r, file).
- these new functions are complied when CONFIG_IMA is enabled, otherwise
  they are plain mutex_lock/unlock().
- then do_blockdev_direct_IO() can call them blindly.
- of course, O_DIRECT_HAVELOCK should be complied only when CONFIG_IMA
  is enabled too.

I can guess that several people thinks that is still "ugly locking", but
the deadlock is much ugly in real world. And we need some workaround for
it.


J. R. Okajima
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