[XFRM] user: Move attribute copying code into copy_to_user_state_extra

Here's a good example of code duplication leading to code rot.  The
notification patch did its own netlink message creation for xfrm states.
It duplicated code that was already in dump_one_state.  Guess what, the
next time (and the time after) when someone updated dump_one_state the
notification path got zilch.

This patch moves that code from dump_one_state to copy_to_user_state_extra
and uses it in xfrm_notify_sa too.  Unfortunately whoever updates this
still needs to update xfrm_sa_len since the notification path wants to
know the exact size for allocation.

At least I've added a comment saying so and if someone still forgest, we'll
have a WARN_ON telling us so.

I also changed the security size calculation to use xfrm_user_sec_ctx since
that's what we actually put into the skb.  However it makes no practical
difference since it has the same size as xfrm_sec_ctx.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 47 insertions, 29 deletions

diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index 52c7fce54641..2cbbe5e93a7b 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -483,9 +483,9 @@ struct xfrm_dump_info {
 
 static int copy_sec_ctx(struct xfrm_sec_ctx *s, struct sk_buff *skb)
 {
-        int ctx_size = sizeof(struct xfrm_sec_ctx) + s->ctx_len;
         struct xfrm_user_sec_ctx *uctx;
         struct nlattr *attr;
+        int ctx_size = sizeof(*uctx) + s->ctx_len;
 
         attr = nla_reserve(skb, XFRMA_SEC_CTX, ctx_size);
         if (attr == NULL)
@@ -502,23 +502,11 @@ static int copy_sec_ctx(struct xfrm_sec_ctx *s, struct sk_buff *skb)
         return 0;
 }
 
-static int dump_one_state(struct xfrm_state *x, int count, void *ptr)
+/* Don't change this without updating xfrm_sa_len! */
+static int copy_to_user_state_extra(struct xfrm_state *x,
+                                    struct xfrm_usersa_info *p,
+                                    struct sk_buff *skb)
 {
-        struct xfrm_dump_info *sp = ptr;
-        struct sk_buff *in_skb = sp->in_skb;
-        struct sk_buff *skb = sp->out_skb;
-        struct xfrm_usersa_info *p;
-        struct nlmsghdr *nlh;
-
-        if (sp->this_idx < sp->start_idx)
-                goto out;
-
-        nlh = nlmsg_put(skb, NETLINK_CB(in_skb).pid, sp->nlmsg_seq,
-                        XFRM_MSG_NEWSA, sizeof(*p), sp->nlmsg_flags);
-        if (nlh == NULL)
-                return -EMSGSIZE;
-
-        p = nlmsg_data(nlh);
         copy_to_user_state(x, p);
 
         if (x->aalg)
@@ -540,6 +528,35 @@ static int dump_one_state(struct xfrm_state *x, int count, void *ptr)
         if (x->lastused)
                 NLA_PUT_U64(skb, XFRMA_LASTUSED, x->lastused);
 
+        return 0;
+
+nla_put_failure:
+        return -EMSGSIZE;
+}
+
+static int dump_one_state(struct xfrm_state *x, int count, void *ptr)
+{
+        struct xfrm_dump_info *sp = ptr;
+        struct sk_buff *in_skb = sp->in_skb;
+        struct sk_buff *skb = sp->out_skb;
+        struct xfrm_usersa_info *p;
+        struct nlmsghdr *nlh;
+        int err;
+
+        if (sp->this_idx < sp->start_idx)
+                goto out;
+
+        nlh = nlmsg_put(skb, NETLINK_CB(in_skb).pid, sp->nlmsg_seq,
+                        XFRM_MSG_NEWSA, sizeof(*p), sp->nlmsg_flags);
+        if (nlh == NULL)
+                return -EMSGSIZE;
+
+        p = nlmsg_data(nlh);
+
+        err = copy_to_user_state_extra(x, p, skb);
+        if (err)
+                goto nla_put_failure;
+
         nlmsg_end(skb, nlh);
 out:
         sp->this_idx++;
@@ -547,7 +564,7 @@ out:
 
 nla_put_failure:
         nlmsg_cancel(skb, nlh);
-        return -EMSGSIZE;
+        return err;
 }
 
 static int xfrm_dump_sa(struct sk_buff *skb, struct netlink_callback *cb)
@@ -1973,6 +1990,14 @@ static inline size_t xfrm_sa_len(struct xfrm_state *x)
                 l += nla_total_size(sizeof(*x->calg));
         if (x->encap)
                 l += nla_total_size(sizeof(*x->encap));
+        if (x->security)
+                l += nla_total_size(sizeof(struct xfrm_user_sec_ctx) +
+                                    x->security->ctx_len);
+        if (x->coaddr)
+                l += nla_total_size(sizeof(*x->coaddr));
+
+        /* Must count this as this may become non-zero behind our back. */
+        l += nla_total_size(sizeof(x->lastused));
 
         return l;
 }
@@ -2018,23 +2043,16 @@ static int xfrm_notify_sa(struct xfrm_state *x, struct km_event *c)
                 p = nla_data(attr);
         }
 
-        copy_to_user_state(x, p);
-
-        if (x->aalg)
-                NLA_PUT(skb, XFRMA_ALG_AUTH, alg_len(x->aalg), x->aalg);
-        if (x->ealg)
-                NLA_PUT(skb, XFRMA_ALG_CRYPT, alg_len(x->ealg), x->ealg);
-        if (x->calg)
-                NLA_PUT(skb, XFRMA_ALG_COMP, sizeof(*(x->calg)), x->calg);
-
-        if (x->encap)
-                NLA_PUT(skb, XFRMA_ENCAP, sizeof(*x->encap), x->encap);
+        if (copy_to_user_state_extra(x, p, skb))
+                goto nla_put_failure;
 
         nlmsg_end(skb, nlh);
 
         return nlmsg_multicast(xfrm_nl, skb, 0, XFRMNLGRP_SA, GFP_ATOMIC);
 
 nla_put_failure:
+        /* Somebody screwed up with xfrm_sa_len! */
+        WARN_ON(1);
         kfree_skb(skb);
         return -1;
 }