diff mbox series

[1/4] xfrm/compat: Translate by copying XFRMA_UNSPEC attribute

Message ID 20201207093937.2874932-2-steffen.klassert@secunet.com (mailing list archive)
State Accepted
Delegated to: Netdev Maintainers
Headers show
Series [1/4] xfrm/compat: Translate by copying XFRMA_UNSPEC attribute | expand

Checks

Context Check Description
netdev/cover_letter success Pull request
netdev/fixes_present success Link
netdev/patch_count success Link
netdev/tree_selection success Guessed tree name to be net-next
netdev/subject_prefix warning Target tree name not specified in the subject
netdev/source_inline success Was 0 now: 0
netdev/verify_signedoff success Link
netdev/module_param success Was 0 now: 0
netdev/build_32bit success Errors and warnings before: 0 this patch: 0
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/verify_fixes success Link
netdev/checkpatch success total: 0 errors, 0 warnings, 0 checks, 7 lines checked
netdev/build_allmodconfig_warn success Errors and warnings before: 0 this patch: 0
netdev/header_inline success Link
netdev/stable success Stable not CCed

Commit Message

Steffen Klassert Dec. 7, 2020, 9:39 a.m. UTC 
From: Dmitry Safonov <dima@arista.com>

xfrm_xlate32() translates 64-bit message provided by kernel to be sent
for 32-bit listener (acknowledge or monitor). Translator code doesn't
expect XFRMA_UNSPEC attribute as it doesn't know its payload.
Kernel never attaches such attribute, but a user can.

I've searched if any opensource does it and the answer is no.
Nothing on github and google finds only tfcproject that has such code
commented-out.

What will happen if a user sends a netlink message with XFRMA_UNSPEC
attribute? Ipsec code ignores this attribute. But if there is a
monitor-process or 32-bit user requested ack - kernel will try to
translate such message and will hit WARN_ONCE() in xfrm_xlate64_attr().

Deal with XFRMA_UNSPEC by copying the attribute payload with
xfrm_nla_cpy(). In result, the default switch-case in xfrm_xlate64_attr()
becomes an unused code. Leave those 3 lines in case a new xfrm attribute
will be added.

Fixes: 5461fc0c8d9f ("xfrm/compat: Add 64=>32-bit messages translator")
Reported-by: syzbot+a7e701c8385bd8543074@syzkaller.appspotmail.com
Signed-off-by: Dmitry Safonov <dima@arista.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
 net/xfrm/xfrm_compat.c | 1 +
 1 file changed, 1 insertion(+)
diff mbox series

Patch

diff --git a/net/xfrm/xfrm_compat.c b/net/xfrm/xfrm_compat.c
index e28f0c9ecd6a..17edbf935e35 100644
--- a/net/xfrm/xfrm_compat.c
+++ b/net/xfrm/xfrm_compat.c
@@ -234,6 +234,7 @@  static int xfrm_xlate64_attr(struct sk_buff *dst, const struct nlattr *src)
 	case XFRMA_PAD:
 		/* Ignore */
 		return 0;
+	case XFRMA_UNSPEC:
 	case XFRMA_ALG_AUTH:
 	case XFRMA_ALG_CRYPT:
 	case XFRMA_ALG_COMP: