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Re: [PATCH] IPv6: Don't assign a same IPv6 address on a same interface

To: davem@xxxxxxxxxx, kuznet@xxxxxxxxxxxxx
Subject: Re: [PATCH] IPv6: Don't assign a same IPv6 address on a same interface
From: YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@xxxxxxxxxxxxxx>
Date: Mon, 31 Mar 2003 10:34:51 +0900 (JST)
Cc: netdev@xxxxxxxxxxx, linux-kernel@xxxxxxxxxxxxxxx, usagi@xxxxxxxxxxxxxx, pioppo@xxxxxxxxxxxxxxxx
In-reply-to: <20030331.033524.114862210.yoshfuji@xxxxxxxxxxxxxx>
Organization: USAGI Project
References: <20030330.235809.70243437.yoshfuji@xxxxxxxxxxxxxx> <20030330163656.GA18645@xxxxxxxxxxxxxxxx> <20030331.033524.114862210.yoshfuji@xxxxxxxxxxxxxx>
Sender: netdev-bounce@xxxxxxxxxxx
In article <20030331.033524.114862210.yoshfuji@xxxxxxxxxxxxxx> (at Mon, 31 Mar 
2003 03:35:24 +0900 (JST)), YOSHIFUJI Hideaki / 吉藤英明 <yoshfuji@xxxxxxxxxxxxxx> 
says:

> In article <20030330163656.GA18645@xxxxxxxxxxxxxxxx> (at Sun, 30 Mar 2003 
> 18:36:56 +0200), Simone Piunno <pioppo@xxxxxxxxxxxxxxxx> says:
> 
> >  - locking inside ipv6_add_addr() is simpler and more linear but
> >    semantically wrong because you're unable to tell the user why his 
> >    "ip addr add" failed.  E.g. you answer ENOBUFS instead of EEXIST.
> 
> We don't want to create duplicate address in any case.
> ipv6_add_addr() IS right place.
> And, we can return error code by using IS_ERR() etc.
> I'll fix this.

Here's the revised patch.
Thank you.

Index: net/ipv6/addrconf.c
===================================================================
RCS file: /cvsroot/usagi/usagi-backport/linux25/net/ipv6/addrconf.c,v
retrieving revision 1.1.1.9
retrieving revision 1.1.1.9.2.6
diff -u -r1.1.1.9 -r1.1.1.9.2.6
--- net/ipv6/addrconf.c 25 Mar 2003 04:33:45 -0000      1.1.1.9
+++ net/ipv6/addrconf.c 30 Mar 2003 18:51:29 -0000      1.1.1.9.2.6
@@ -30,6 +30,8 @@
  *                                             address validation timer.
  *     YOSHIFUJI Hideaki @USAGI        :       Privacy Extensions (RFC3041)
  *                                             support.
+ *     Yuji SEKIYA @USAGI              :       Don't assign a same IPv6
+ *                                             address on a same interface.
  */
 
 #include <linux/config.h>
@@ -126,6 +128,8 @@
 static void addrconf_rs_timer(unsigned long data);
 static void ipv6_ifa_notify(int event, struct inet6_ifaddr *ifa);
 
+static int ipv6_chk_same_addr(const struct in6_addr *addr, struct net_device 
*dev);
+
 static struct notifier_block *inet6addr_chain;
 
 struct ipv6_devconf ipv6_devconf =
@@ -492,12 +496,23 @@
 {
        struct inet6_ifaddr *ifa;
        int hash;
+       static spinlock_t lock = SPIN_LOCK_UNLOCKED;
+
+       spin_lock_bh(&lock);
+
+       /* Ignore adding duplicate addresses on an interface */
+       if (ipv6_chk_same_addr(addr, idev->dev)) {
+               spin_unlock_bh(&lock);
+               ADBG(("ipv6_add_addr: already assigned\n"));
+               return ERR_PTR(-EEXIST);
+       }
 
        ifa = kmalloc(sizeof(struct inet6_ifaddr), GFP_ATOMIC);
 
        if (ifa == NULL) {
+               spin_unlock_bh(&lock);
                ADBG(("ipv6_add_addr: malloc failed\n"));
-               return NULL;
+               return ERR_PTR(-ENOBUFS);
        }
 
        memset(ifa, 0, sizeof(struct inet6_ifaddr));
@@ -513,8 +528,9 @@
        read_lock(&addrconf_lock);
        if (idev->dead) {
                read_unlock(&addrconf_lock);
+               spin_unlock_bh(&lock);
                kfree(ifa);
-               return NULL;
+               return ERR_PTR(-ENODEV);        /*XXX*/
        }
 
        inet6_ifa_count++;
@@ -551,6 +567,7 @@
        in6_ifa_hold(ifa);
        write_unlock_bh(&idev->lock);
        read_unlock(&addrconf_lock);
+       spin_unlock_bh(&lock);
 
        notifier_call_chain(&inet6addr_chain,NETDEV_UP,ifa);
 
@@ -697,7 +714,7 @@
        ift = ipv6_count_addresses(idev) < IPV6_MAX_ADDRESSES ?
                ipv6_add_addr(idev, &addr, tmp_plen,
                              ipv6_addr_type(&addr)&IPV6_ADDR_SCOPE_MASK, 
IFA_F_TEMPORARY) : 0;
-       if (!ift) {
+       if (IS_ERR(ift)) {
                in6_dev_put(idev);
                in6_ifa_put(ifp);
                printk(KERN_INFO
@@ -928,6 +945,23 @@
        return ifp != NULL;
 }
 
+static
+int ipv6_chk_same_addr(const struct in6_addr *addr, struct net_device *dev)
+{
+       struct inet6_ifaddr * ifp;
+       u8 hash = ipv6_addr_hash(addr);
+
+       read_lock_bh(&addrconf_hash_lock);
+       for(ifp = inet6_addr_lst[hash]; ifp; ifp=ifp->lst_next) {
+               if (ipv6_addr_cmp(&ifp->addr, addr) == 0) {
+                       if (dev == NULL || ifp->idev->dev == dev)
+                               break;
+               }
+       }
+       read_unlock_bh(&addrconf_hash_lock);
+       return ifp != NULL;
+}
+
 struct inet6_ifaddr * ipv6_get_ifaddr(struct in6_addr *addr, struct net_device 
*dev)
 {
        struct inet6_ifaddr * ifp;
@@ -1344,7 +1378,7 @@
                                ifp = ipv6_add_addr(in6_dev, &addr, 
pinfo->prefix_len,
                                                    
addr_type&IPV6_ADDR_SCOPE_MASK, 0);
 
-                       if (ifp == NULL) {
+                       if (IS_ERR(ifp)) {
                                in6_dev_put(in6_dev);
                                return;
                        }
@@ -1499,13 +1533,14 @@
 
        scope = ipv6_addr_scope(pfx);
 
-       if ((ifp = ipv6_add_addr(idev, pfx, plen, scope, IFA_F_PERMANENT)) != 
NULL) {
+       ifp = ipv6_add_addr(idev, pfx, plen, scope, IFA_F_PERMANENT);
+       if (!IS_ERR(ifp)) {
                addrconf_dad_start(ifp);
                in6_ifa_put(ifp);
                return 0;
        }
 
-       return -ENOBUFS;
+       return PTR_ERR(ifp);
 }
 
 static int inet6_addr_del(int ifindex, struct in6_addr *pfx, int plen)
@@ -1597,7 +1632,7 @@
 
        if (addr.s6_addr32[3]) {
                ifp = ipv6_add_addr(idev, &addr, 128, scope, IFA_F_PERMANENT);
-               if (ifp) {
+               if (!IS_ERR(ifp)) {
                        spin_lock_bh(&ifp->lock);
                        ifp->flags &= ~IFA_F_TENTATIVE;
                        spin_unlock_bh(&ifp->lock);
@@ -1633,7 +1668,7 @@
 
                                ifp = ipv6_add_addr(idev, &addr, plen, flag,
                                                    IFA_F_PERMANENT);
-                               if (ifp) {
+                               if (!IS_ERR(ifp)) {
                                        spin_lock_bh(&ifp->lock);
                                        ifp->flags &= ~IFA_F_TENTATIVE;
                                        spin_unlock_bh(&ifp->lock);
@@ -1660,7 +1695,7 @@
        }
 
        ifp = ipv6_add_addr(idev, &in6addr_loopback, 128, IFA_HOST, 
IFA_F_PERMANENT);
-       if (ifp) {
+       if (!IS_ERR(ifp)) {
                spin_lock_bh(&ifp->lock);
                ifp->flags &= ~IFA_F_TENTATIVE;
                spin_unlock_bh(&ifp->lock);
@@ -1674,7 +1709,7 @@
        struct inet6_ifaddr * ifp;
 
        ifp = ipv6_add_addr(idev, addr, 64, IFA_LINK, IFA_F_PERMANENT);
-       if (ifp) {
+       if (!IS_ERR(ifp)) {
                addrconf_dad_start(ifp);
                in6_ifa_put(ifp);
        }

-- 
Hideaki YOSHIFUJI @ USAGI Project <yoshfuji@xxxxxxxxxxxxxx>
GPG FP: 9022 65EB 1ECF 3AD1 0BDF  80D8 4807 F894 E062 0EEA

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