# \[RFC PATCH 3/3\] fs: detect that the i\_rwsem has already been taken exclusively

- From: Linus Torvalds \<torvalds@linux-foundation.org\>
- Date: 2017-09-29 03:26:15 
- List: linux-security-module
- Page: https://ratatoskr.run/linux-security-module/2017/09/125901
- Thread: https://ratatoskr.run/linux-security-module/2017/09/126554/t.md

```text
On Thu, Sep 28, 2017 at 6:53 PM, Mimi Zohar [ref] wrote:
>
> The locking issue isn't with validating the file hash, but with the
> setxattr, chmod, chown syscalls.  Each of these syscalls takes the
> i_rwsem exclusively before IMA (or EVM) is called.

Read my email again.

> In setxattr, chmod, chown syscalls, IMA (and EVM) are called after the
> i_rwsem is already taken.  So the locking would be:
>
> lock: i_rwsem
> lock: iint->mutex

No.

Two locks. One inner, one outer. Only the actual ones that calculates
the hash would take the outer one. Read my email.

           Linus
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```