Re: [PATCH 5.4 85/96] selinux: revert "stop passing MAY_NOT_BLOCK to the AVC upon follow_link"

[Stephen Smalley]

On 2/13/20 10:21 AM, Greg Kroah-Hartman wrote:
> From: Stephen Smalley <sds@xxxxxxxxxxxxx>
>
> commit 1a37079c236d55fb31ebbf4b59945dab8ec8764c upstream.
>
> This reverts commit e46e01eebbbc ("selinux: stop passing MAY_NOT_BLOCK
> to the AVC upon follow_link"). The correct fix is to instead fall
> back to ref-walk if audit is required irrespective of the specific
> audit data type.  This is done in the next commit.
>
> Fixes: e46e01eebbbc ("selinux: stop passing MAY_NOT_BLOCK to the AVC upon follow_link")
> Reported-by: Will Deacon <will@xxxxxxxxxx>
> Signed-off-by: Stephen Smalley <sds@xxxxxxxxxxxxx>
> Signed-off-by: Paul Moore <paul@xxxxxxxxxxxxxx>
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

This patch should be accompanied by commit 
0188d5c025ca8fe756ba3193bd7d150139af5a88 ("selinux: fall back to 
ref-walk if audit is required").  The former is reverting an incorrect 
fix for bda0be7ad994 ("security: make inode_follow_link RCU-walk 
aware"), the latter is providing the correct fix for it.

> ---
>   security/selinux/avc.c         |   24 ++++++++++++++++++++++--
>   security/selinux/hooks.c       |    5 +++--
>   security/selinux/include/avc.h |    5 +++++
>   3 files changed, 30 insertions(+), 4 deletions(-)

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