This patch adds an repair mode for netlink sockets. sendmsg queues
messages into a receive queue if a socket is in the repair mode.
---
include/uapi/linux/netlink.h | 19 ++++++++++-------
net/netlink/af_netlink.c | 51 +++++++++++++++++++++++++++++++-------------
2 files changed, 47 insertions(+), 23 deletions(-)
diff --git a/include/uapi/linux/netlink.h b/include/uapi/linux/netlink.h
index 3e34b7d..56ddadf 100644
--- a/include/uapi/linux/netlink.h
+++ b/include/uapi/linux/netlink.h
@@ -101,14 +101,17 @@ struct nlmsgerr {
struct nlmsghdr msg;
};
-#define NETLINK_ADD_MEMBERSHIP 1
-#define NETLINK_DROP_MEMBERSHIP 2
-#define NETLINK_PKTINFO 3
-#define NETLINK_BROADCAST_ERROR 4
-#define NETLINK_NO_ENOBUFS 5
-#define NETLINK_RX_RING 6
-#define NETLINK_TX_RING 7
-#define NETLINK_LISTEN_ALL_NSID 8
+#define NETLINK_ADD_MEMBERSHIP 1
+#define NETLINK_DROP_MEMBERSHIP 2
+#define NETLINK_PKTINFO 3
+#define NETLINK_BROADCAST_ERROR 4
+#define NETLINK_NO_ENOBUFS 5
+#define NETLINK_RX_RING 6
+#define NETLINK_TX_RING 7
+#define NETLINK_LISTEN_ALL_NSID 8
+#define NETLINK_LIST_MEMBERSHIPS 9
+#define NETLINK_CAP_ACK 10
+#define NETLINK_REPAIR 11
struct nl_pktinfo {
__u32 group;
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 79526e5..113e2ae 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -83,6 +83,8 @@ struct listeners {
#define NETLINK_F_BROADCAST_SEND_ERROR 0x4
#define NETLINK_F_RECV_NO_ENOBUFS 0x8
#define NETLINK_F_LISTEN_ALL_NSID 0x10
+#define NETLINK_F_CAP_ACK 0x20
+#define NETLINK_F_REPAIR 0x40
static inline int netlink_is_kernel(struct sock *sk)
{
@@ -1744,6 +1746,7 @@ static int netlink_unicast_kernel(struct sock *sk, struct
sk_buff *skb,
int netlink_unicast(struct sock *ssk, struct sk_buff *skb,
u32 portid, int nonblock)
{
+ struct netlink_sock *nlk = nlk_sk(ssk);
struct sock *sk;
int err;
long timeo;
@@ -1752,19 +1755,24 @@ int netlink_unicast(struct sock *ssk, struct sk_buff
*skb,
timeo = sock_sndtimeo(ssk, nonblock);
retry:
- sk = netlink_getsockbyportid(ssk, portid);
- if (IS_ERR(sk)) {
- kfree_skb(skb);
- return PTR_ERR(sk);
- }
- if (netlink_is_kernel(sk))
- return netlink_unicast_kernel(sk, skb, ssk);
+ if (nlk->flags & NETLINK_F_REPAIR) {
+ sk = ssk;
+ sock_hold(sk);
+ } else {
+ sk = netlink_getsockbyportid(ssk, portid);
+ if (IS_ERR(sk)) {
+ kfree_skb(skb);
+ return PTR_ERR(sk);
+ }
+ if (netlink_is_kernel(sk))
+ return netlink_unicast_kernel(sk, skb, ssk);
- if (sk_filter(sk, skb)) {
- err = skb->len;
- kfree_skb(skb);
- sock_put(sk);
- return err;
+ if (sk_filter(sk, skb)) {
+ err = skb->len;
+ kfree_skb(skb);
+ sock_put(sk);
+ return err;
+ }
}
err = netlink_attachskb(sk, skb, &timeo, ssk);
@@ -2126,6 +2134,13 @@ static int netlink_setsockopt(struct socket *sock, int
level, int optname,
return -EFAULT;
switch (optname) {
+ case NETLINK_REPAIR:
+ if (val)
+ nlk->flags |= NETLINK_F_REPAIR;
+ else
+ nlk->flags &= ~NETLINK_F_REPAIR;
+ err = 0;
+ break;
case NETLINK_PKTINFO:
if (val)
nlk->flags |= NETLINK_F_RECV_PKTINFO;
@@ -2288,6 +2303,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct
socket *sock,
int err;
struct scm_cookie scm;
u32 netlink_skb_flags = 0;
+ bool repair = nlk->flags & NETLINK_F_REPAIR;
if (msg->msg_flags&MSG_OOB)
return -EOPNOTSUPP;
@@ -2307,7 +2323,8 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct
socket *sock,
dst_group = ffs(addr->nl_groups);
err = -EPERM;
if ((dst_group || dst_portid) &&
- !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND))
+ !netlink_allowed(sock, NL_CFG_F_NONROOT_SEND &&
+ !repair))
goto out;
netlink_skb_flags |= NETLINK_SKB_DST;
} else {
@@ -2336,7 +2353,11 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct
socket *sock,
if (skb == NULL)
goto out;
- NETLINK_CB(skb).portid = nlk->portid;
+ if (unlikely(repair))
+ NETLINK_CB(skb).portid = dst_portid;
+ else
+ NETLINK_CB(skb).portid = nlk->portid;
+
NETLINK_CB(skb).dst_group = dst_group;
NETLINK_CB(skb).creds = siocb->scm->creds;
NETLINK_CB(skb).flags = netlink_skb_flags;
@@ -2353,7 +2374,7 @@ static int netlink_sendmsg(struct kiocb *kiocb, struct
socket *sock,
goto out;
}
- if (dst_group) {
+ if (dst_group && !repair) {
atomic_inc(&skb->users);
netlink_broadcast(sk, skb, dst_portid, dst_group, GFP_KERNEL);
}
--
2.5.5
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