lkml.org 
[lkml]   [2019]   [Jan]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    Date
    SubjectRe: [PATCH AUTOSEL 4.20 016/117] fanotify: return only user requested event types in event mask
    On Tue, Jan 8, 2019 at 10:11 PM Sasha Levin <sashal@kernel.org> wrote:
    >
    > From: Matthew Bobrowski <mbobrowski@mbobrowski.org>
    >
    > [ Upstream commit 2d10b23082a7eb8be508b3789f2e7250a88a5ddb ]
    >
    > Modify fanotify_should_send_event() so that it now returns a mask for
    > an event that contains ONLY flags for the event types that have been
    > specifically requested by the user. Flags that may have been included
    > within the event mask, but have not been explicitly requested by the
    > user will not be present in the returned value.
    >
    > As an example, given the situation where a user requests events of type
    > FAN_OPEN. Traditionally, the event mask returned within an event that
    > occurred on a filesystem object that has been marked for monitoring and is
    > opened, will only ever have the FAN_OPEN bit set. With the introduction of
    > the new flags like FAN_OPEN_EXEC, and perhaps any other future event
    > flags, there is a possibility of the returned event mask containing more
    > than a single bit set, despite having only requested the single event type.
    > Prior to these modifications performed to fanotify_should_send_event(), a
    > user would have received a bundled event mask containing flags FAN_OPEN
    > and FAN_OPEN_EXEC in the instance that a file was opened for execution via
    > execve(), for example. This means that a user would receive event types
    > in the returned event mask that have not been requested. This runs the
    > possibility of breaking existing systems and causing other unforeseen
    > issues.
    >
    > To mitigate this possibility, fanotify_should_send_event() has been
    > modified to return the event mask containing ONLY event types explicitly
    > requested by the user. This means that we will NOT report events that the
    > user did no set a mask for, and we will NOT report events that the user
    > has set an ignore mask for.
    >
    > The function name fanotify_should_send_event() has also been updated so
    > that it's more relevant to what it has been designed to do.
    >
    > Signed-off-by: Matthew Bobrowski <mbobrowski@mbobrowski.org>
    > Reviewed-by: Amir Goldstein <amir73il@gmail.com>
    > Signed-off-by: Jan Kara <jack@suse.cz>
    > Signed-off-by: Sasha Levin <sashal@kernel.org>
    > ---

    Sasha,

    I have no objection to applying this patch to 4.20, but FYI, it does
    not fix anything.
    Before introducing FAN_OPEN_EXEC in 5.0-rc1, this patch has no visible effect.

    I don't mind if you apply it. It will make stable code closer to
    mainline, which is
    always a good thing IMO. And FWIW, I think that patch is quite trivial
    and low risk.

    Thanks,
    Amir.

    \
     
     \ /
      Last update: 2019-01-09 07:51    [W:4.052 / U:0.776 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site