[PATCH v2] exec: Set file unwritable before LSM check

On Fri, 9 Mar 2018, Kees Cook wrote:

The LSM check should happen after the file has been confirmed to be
unchanging. Without this, we could have a race between the Time of Check
(the call to security_kernel_read_file() which could read the file and
make access policy decisions) and the Time of Use (starting with
kernel_read_file()'s reading of the file contents). In theory, file
contents could change between the two.

Signed-off-by: Kees Cook <redacted>
---
v2: Clarify the ToC/ToU race (Linus)

Applied to
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security.git next-general
and next-testing


-- 
James Morris
[off-list ref]

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