linux-kernel - Re: CVE-2024-38564: bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK

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Date: Thu, 27 Jun 2024 15:29:20 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Shung-Hsi Yu <shung-hsi.yu@...e.com>
Cc: cve@...nel.org, linux-kernel@...r.kernel.org, bpf@...r.kernel.org,
	Stanislav Fomichev <sdf@...gle.com>,
	Eduard Zingerman <eddyz87@...il.com>,
	Toke Høiland-Jørgensen <toke@...hat.com>,
	Alexei Starovoitov <ast@...nel.org>,
	Andrii Nakryiko <andrii@...nel.org>
Subject: Re: CVE-2024-38564: bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type
 enforcement in BPF_LINK_CREATE

On Wed, Jun 26, 2024 at 02:44:31PM +0800, Shung-Hsi Yu wrote:
> On Wed, Jun 19, 2024 at 03:36:13PM GMT, Greg Kroah-Hartman wrote:
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK_CREATE
> > 
> > bpf_prog_attach uses attach_type_to_prog_type to enforce proper
> > attach type for BPF_PROG_TYPE_CGROUP_SKB. link_create uses
> > bpf_prog_get and relies on bpf_prog_attach_check_attach_type
> > to properly verify prog_type <> attach_type association.
> > 
> > Add missing attach_type enforcement for the link_create case.
> > Otherwise, it's currently possible to attach cgroup_skb prog
> > types to other cgroup hooks.
> > 
> > The Linux kernel CVE team has assigned CVE-2024-38564 to this issue.
> > 
> > 
> > Affected and fixed versions
> > ===========================
> > 
> > 	Issue introduced in 5.7 with commit af6eea57437a and fixed in 6.6.33 with commit 6675c541f540
> > 	Issue introduced in 5.7 with commit af6eea57437a and fixed in 6.8.12 with commit 67929e973f5a
> > 	Issue introduced in 5.7 with commit af6eea57437a and fixed in 6.9.3 with commit b34bbc766510
> > 	Issue introduced in 5.7 with commit af6eea57437a and fixed in 6.10-rc1 with commit 543576ec15b1
> 
> I'd like to dispute the affected commit for this CVE.
> 
> The commit that introduced the issue should instead be commit
> 4a1e7c0c63e02 ("bpf: Support attaching freplace programs to multiple
> attach points") in 5.10.
> 
> When link_create() was added in commit af6eea57437a, it uses
> bpf_prog_get_type(attr->link_create.prog_fd, ptype) to resolve struct
> bpf_prog, which effectively does the requried
> 
> 	prog->type == attach_type_to_prog_type(attach_type)
> 
> check through bpf_prog_get_ok(), and thus would not allow
> BPF_PROG_TYPE_CGROUP_SKB to be attached to other cgroup hooks.
> 
> It is in commit 4a1e7c0c63e02 ("bpf: Support attaching freplace programs
> to multiple attach points") that had bpf_prog_get_type() replaced with
> bpf_prog_get() and lead to the removal of such check, making it possible
> to attach BPF_PROG_TYPE_CGROUP_SKB to other cgroup hooks.
> 
> [...]

Thanks for the information, we have now adjusted the vulnerable commit
and pushed out the new json information to cve.org

greg k-h