netdev - [PATCH bpf 1/3] bpf: Add BPF_PROG_TYPE_CGROUP_SKB attach type enforcement in BPF_LINK

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Date: Fri, 26 Apr 2024 16:16:18 -0700
From: Stanislav Fomichev <sdf@...gle.com>
To: bpf@...r.kernel.org, netdev@...r.kernel.org
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	martin.lau@...ux.dev, song@...nel.org, yhs@...com, john.fastabend@...il.com, 
	kpsingh@...nel.org, sdf@...gle.com, haoluo@...gle.com, jolsa@...nel.org, 
	syzbot+838346b979830606c854@...kaller.appspotmail.com
Subject: [PATCH bpf 1/3] 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.

Fixes: af6eea57437a ("bpf: Implement bpf_link-based cgroup BPF program attachment")
Link: https://lore.kernel.org/bpf/0000000000004792a90615a1dde0@google.com/
Reported-by: syzbot+838346b979830606c854@...kaller.appspotmail.com
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
---
 kernel/bpf/syscall.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c287925471f6..cb61d8880dbe 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3985,6 +3985,11 @@ static int bpf_prog_attach_check_attach_type(const struct bpf_prog *prog,
 			 * check permissions at attach time.
 			 */
 			return -EPERM;
+
+		ptype = attach_type_to_prog_type(attach_type);
+		if (prog->type != ptype)
+			return -EINVAL;
+
 		return prog->enforce_expected_attach_type &&
 			prog->expected_attach_type != attach_type ?
 			-EINVAL : 0;
-- 
2.44.0.769.g3c40516874-goog