Backporting stacked security patch
Hi All, I week ago I asked the list about kernel 4.2 stacked security patch location , but Greg strongly advised me against, without going into details. I highly appreciate Greg advice, and I know he is a very busy person. Unfortunately I do not have a choice to upgrade kernel, and I am asking again : - what are major challenges of a such backport ? Does kernel security changed so much between 3.18 and 4.2 ? The link is https://kernelnewbies.org/Linux_4.2#Stacking_of_security_modules Regards, Lev
On Tue, Oct 30, 2018 at 02:43:12PM +0300, Lev Olshvang wrote:
Hi All,
I week ago I asked the list about kernel 4.2 stacked security patch location , but Greg strongly advised me against, without going into details. I highly appreciate Greg advice, and I know he is a very busy person. Unfortunately I do not have a choice to upgrade kernel, and I am asking again : - what are major challenges of a such backport ? Does kernel security changed so much between 3.18 and 4.2 ?
$ git log --no-merges v3.18..v4.2 | grep "^commit " | wc -l 48573 That's over 48 thousand changes between those kernels. That's a non-trivial thing to review and backport only parts of it. And if you were to backport only parts of it, then you would be dealing with a kernel that only you can support, not the company/vendor that is forcing you to stick with 3.18. Why not ask them to do this work for you as they are the ones you are paying for this type of work already? Also, why 3.18? That's a very old and obsolete kernel already, never use that for any new type of device, you are guaranteed to have problems with it as I'll probably stop doing security updates for it any week now... good luck! greg k-h
Hi Greg, Thanks for a reply. While diff between two kernels is indeed tremendous, the commits which were done in security subsystem do not look too bid,. There are 7 commits, and 2 of them is about comments and one about file deletion. I see that in 4.1 Smack was changed (couple of commits) and about 12 commits in SeLinux and Smack that we were changed in 4.0, and in 3.19 only IMA was changed. So the job is to apply very limited number of commits, and commits of 4.1 or 4.0 are not important for me because I am interested only in Apparmor stacking Perhaps I am overlooking some basic issue ? As I stated, I have no option to come to customer and ask to upgrade his kernel, but I will try to put his attention to mentioned by you cease of security updates. Best Regards Lev 30.10.2018, 17:32, "Greg KH" <greg@kroah.com>:
On Tue, Oct 30, 2018 at 02:43:12PM +0300, Lev Olshvang wrote:
Hi All,
I week ago I asked the list about kernel 4.2 stacked security patch location , but Greg strongly advised me against, without going into details. I highly appreciate Greg advice, and I know he is a very busy person. Unfortunately I do not have a choice to upgrade kernel, and I am asking again : - what are major challenges of a such backport ? Does kernel security changed so much between 3.18 and 4.2 ?
$ git log --no-merges v3.18..v4.2 | grep "^commit " | wc -l 48573
That's over 48 thousand changes between those kernels. That's a non-trivial thing to review and backport only parts of it.
And if you were to backport only parts of it, then you would be dealing with a kernel that only you can support, not the company/vendor that is forcing you to stick with 3.18. Why not ask them to do this work for you as they are the ones you are paying for this type of work already?
Also, why 3.18? That's a very old and obsolete kernel already, never use that for any new type of device, you are guaranteed to have problems with it as I'll probably stop doing security updates for it any week now...
good luck!
greg k-h
On Tue, 30 Oct 2018 21:19:08 +0300, Lev Olshvang said:
As I stated, I have no option to come to customer and ask to upgrade his kernel, but I will try to put his attention to mentioned by you cease of security updates.
If you can't get him to upgrade the installed kernel, it's not worth your effort to backport patches. And just updating the patches to the 4.2 level doesn't do your customer any favors, as there's been a lot of security patches between 4.2 and 4.19. And many of the important ones do *NOT* apply to the security/ branch of the tree - it's stuff like the Spectre fixes that show up elsewhere in the tree, networking fixes that resolve "packet of death" issues, and so on.
On Tue, Oct 30, 2018 at 09:19:08PM +0300, Lev Olshvang wrote:
Hi Greg,
Thanks for a reply.
While diff between two kernels is indeed tremendous, the commits which were done in security subsystem do not look too bid,. There are 7 commits, and 2 of them is about comments and one about file deletion.
Try them and see! :)
I see that in 4.1 Smack was changed (couple of commits) and about 12 commits in SeLinux and Smack that we were changed in 4.0, and in 3.19 only IMA was changed.
So the job is to apply very limited number of commits, and commits of 4.1 or 4.0 are not important for me because I am interested only in Apparmor stacking
Perhaps I am overlooking some basic issue ?
Why are you "allowed" to change a core part of how the kernel works, but not able to update to a newer kernel version? What keeps people from being even more worried about that? The fact that a number does not change? Realize that what you are attempting to do is create a kernel that no one else has ever tested or run before, so it is only up to you to get everything correct. And it is up to you to support that beast on your own, good luck! :) greg k-h
participants (3)
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Greg KH -
Lev Olshvang -
valdis.kletnieks＠vt.edu