From f8d858e607b2a36808ac6d4218f5f5203d7a7d63 Mon Sep 17 00:00:00 2001 From: Nicolas Dichtel Date: Tue, 14 Sep 2021 16:46:33 +0200 Subject: [PATCH] xfrm: make user policy API complete >From a userland POV, this API was based on some magic values: - dirmask and action were bitfields but meaning of bits (XFRM_POL_DEFAULT_*) are not exported; - action is confusing, if a bit is set, does it mean drop or accept? Let's try to simplify this uapi by using explicit field and macros. Fixes: 2d151d39073a ("xfrm: Add possibility to set the default to block if we have no policy") Signed-off-by: Nicolas Dichtel Signed-off-by: Steffen Klassert --- include/uapi/linux/xfrm.h | 9 ++++++--- net/xfrm/xfrm_user.c | 36 +++++++++++++++++++----------------- 2 files changed, 25 insertions(+), 20 deletions(-) diff --git a/include/uapi/linux/xfrm.h b/include/uapi/linux/xfrm.h index 26f456b1..eda0426 100644 --- a/include/uapi/linux/xfrm.h +++ b/include/uapi/linux/xfrm.h @@ -514,9 +514,12 @@ struct xfrm_user_offload { #define XFRM_OFFLOAD_INBOUND 2 struct xfrm_userpolicy_default { -#define XFRM_USERPOLICY_DIRMASK_MAX (sizeof(__u8) * 8) - __u8 dirmask; - __u8 action; +#define XFRM_USERPOLICY_UNSPEC 0 +#define XFRM_USERPOLICY_BLOCK 1 +#define XFRM_USERPOLICY_ACCEPT 2 + __u8 in; + __u8 fwd; + __u8 out; }; #ifndef __KERNEL__ diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c index 4719a6d..90c8839 100644 --- a/net/xfrm/xfrm_user.c +++ b/net/xfrm/xfrm_user.c @@ -1966,16 +1966,21 @@ static int xfrm_set_default(struct sk_buff *skb, struct nlmsghdr *nlh, { struct net *net = sock_net(skb->sk); struct xfrm_userpolicy_default *up = nlmsg_data(nlh); - u8 dirmask; - u8 old_default = net->xfrm.policy_default; - if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX) - return -EINVAL; + if (up->in == XFRM_USERPOLICY_BLOCK) + net->xfrm.policy_default |= XFRM_POL_DEFAULT_IN; + else if (up->in == XFRM_USERPOLICY_ACCEPT) + net->xfrm.policy_default &= ~XFRM_POL_DEFAULT_IN; - dirmask = (1 << up->dirmask) & XFRM_POL_DEFAULT_MASK; + if (up->fwd == XFRM_USERPOLICY_BLOCK) + net->xfrm.policy_default |= XFRM_POL_DEFAULT_FWD; + else if (up->fwd == XFRM_USERPOLICY_ACCEPT) + net->xfrm.policy_default &= ~XFRM_POL_DEFAULT_FWD; - net->xfrm.policy_default = (old_default & (0xff ^ dirmask)) - | (up->action << up->dirmask); + if (up->out == XFRM_USERPOLICY_BLOCK) + net->xfrm.policy_default |= XFRM_POL_DEFAULT_OUT; + else if (up->out == XFRM_USERPOLICY_ACCEPT) + net->xfrm.policy_default &= ~XFRM_POL_DEFAULT_OUT; rt_genid_bump_all(net); @@ -1988,13 +1993,11 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh, struct sk_buff *r_skb; struct nlmsghdr *r_nlh; struct net *net = sock_net(skb->sk); - struct xfrm_userpolicy_default *r_up, *up; + struct xfrm_userpolicy_default *r_up; int len = NLMSG_ALIGN(sizeof(struct xfrm_userpolicy_default)); u32 portid = NETLINK_CB(skb).portid; u32 seq = nlh->nlmsg_seq; - up = nlmsg_data(nlh); - r_skb = nlmsg_new(len, GFP_ATOMIC); if (!r_skb) return -ENOMEM; @@ -2005,15 +2008,14 @@ static int xfrm_get_default(struct sk_buff *skb, struct nlmsghdr *nlh, return -EMSGSIZE; } - if (up->dirmask >= XFRM_USERPOLICY_DIRMASK_MAX) { - kfree_skb(r_skb); - return -EINVAL; - } - r_up = nlmsg_data(r_nlh); - r_up->action = ((net->xfrm.policy_default & (1 << up->dirmask)) >> up->dirmask); - r_up->dirmask = up->dirmask; + r_up->in = net->xfrm.policy_default & XFRM_POL_DEFAULT_IN ? + XFRM_USERPOLICY_BLOCK : XFRM_USERPOLICY_ACCEPT; + r_up->fwd = net->xfrm.policy_default & XFRM_POL_DEFAULT_FWD ? + XFRM_USERPOLICY_BLOCK : XFRM_USERPOLICY_ACCEPT; + r_up->out = net->xfrm.policy_default & XFRM_POL_DEFAULT_OUT ? + XFRM_USERPOLICY_BLOCK : XFRM_USERPOLICY_ACCEPT; nlmsg_end(r_skb, r_nlh); return nlmsg_unicast(net->xfrm.nlsk, r_skb, portid); -- 2.7.4