net: xfrm: Amend XFRMA_SEC_CTX nla_policy structure

stable inclusion
from stable-v5.10.192
commit 0f89909c80a9d426f98d4ada1ac0811372ac509f
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I933RF

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0f89909c80a9d426f98d4ada1ac0811372ac509f



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[ Upstream commit d1e0e61d ]

According to all consumers code of attrs[XFRMA_SEC_CTX], like

* verify_sec_ctx_len(), convert to xfrm_user_sec_ctx*
* xfrm_state_construct(), call security_xfrm_state_alloc whose prototype
is int security_xfrm_state_alloc(.., struct xfrm_user_sec_ctx *sec_ctx);
* copy_from_user_sec_ctx(), convert to xfrm_user_sec_ctx *
...

It seems that the expected parsing result for XFRMA_SEC_CTX should be
structure xfrm_user_sec_ctx, and the current xfrm_sec_ctx is confusing
and misleading (Luckily, they happen to have same size 8 bytes).

This commit amend the policy structure to xfrm_user_sec_ctx to avoid
ambiguity.

Fixes: cf5cb79f ("[XFRM] netlink: Establish an attribute policy")
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>