[XFRM]: Export SAD info.

On a system with a lot of SAs, counting SAD entries chews useful
CPU time since you need to dump the whole SAD to user space;
i.e something like ip xfrm state ls | grep -i src | wc -l
I have seen taking literally minutes on a 40K SAs when the system
is swapping.
With this patch, some of the SAD info (that was already being tracked)
is exposed to user space. i.e you do:
ip xfrm state count
And you get the count; you can also pass -s to the command line and
get the hash info.

Signed-off-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 56 insertions, 0 deletions

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index f91521d5f2ab..cb4cc1bde5d1 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -672,6 +672,61 @@ static struct sk_buff *xfrm_state_netlink(struct sk_buff *in_skb,
         return skb;
 }
 
+static int build_sadinfo(struct sk_buff *skb, u32 pid, u32 seq, u32 flags)
+{
+        struct xfrm_sadinfo si;
+        struct nlmsghdr *nlh;
+        u32 *f;
+
+        nlh = nlmsg_put(skb, pid, seq, XFRM_MSG_NEWSADINFO, sizeof(u32), 0);
+        if (nlh == NULL) /* shouldnt really happen ... */
+                return -EMSGSIZE;
+
+        f = nlmsg_data(nlh);
+        *f = flags;
+        xfrm_sad_getinfo(&si);
+
+        if (flags & XFRM_SAD_HMASK)
+                NLA_PUT_U32(skb, XFRMA_SADHMASK, si.sadhcnt);
+        if (flags & XFRM_SAD_HMAX)
+                NLA_PUT_U32(skb, XFRMA_SADHMAX, si.sadhmcnt);
+        if (flags & XFRM_SAD_CNT)
+                NLA_PUT_U32(skb, XFRMA_SADCNT, si.sadcnt);
+
+        return nlmsg_end(skb, nlh);
+
+nla_put_failure:
+        nlmsg_cancel(skb, nlh);
+        return -EMSGSIZE;
+}
+
+static int xfrm_get_sadinfo(struct sk_buff *skb, struct nlmsghdr *nlh,
+                struct rtattr **xfrma)
+{
+        struct sk_buff *r_skb;
+        u32 *flags = NLMSG_DATA(nlh);
+        u32 spid = NETLINK_CB(skb).pid;
+        u32 seq = nlh->nlmsg_seq;
+        int len = NLMSG_LENGTH(sizeof(u32));
+
+        if (*flags & XFRM_SAD_HMASK)
+                len += RTA_SPACE(sizeof(u32));
+        if (*flags & XFRM_SAD_HMAX)
+                len += RTA_SPACE(sizeof(u32));
+        if (*flags & XFRM_SAD_CNT)
+                len += RTA_SPACE(sizeof(u32));
+
+        r_skb = alloc_skb(len, GFP_ATOMIC);
+
+        if (r_skb == NULL)
+                return -ENOMEM;
+
+        if (build_sadinfo(r_skb, spid, seq, *flags) < 0)
+                BUG();
+
+        return nlmsg_unicast(xfrm_nl, r_skb, spid);
+}
+
 static int xfrm_get_sa(struct sk_buff *skb, struct nlmsghdr *nlh,
                 struct rtattr **xfrma)
 {
@@ -1850,6 +1905,7 @@ static struct xfrm_link {
         [XFRM_MSG_NEWAE       - XFRM_MSG_BASE] = { .doit = xfrm_new_ae  },
         [XFRM_MSG_GETAE       - XFRM_MSG_BASE] = { .doit = xfrm_get_ae  },
         [XFRM_MSG_MIGRATE     - XFRM_MSG_BASE] = { .doit = xfrm_do_migrate    },
+        [XFRM_MSG_GETSADINFO  - XFRM_MSG_BASE] = { .doit = xfrm_get_sadinfo    },
 };
 
 static int xfrm_user_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)