linux-kernel - [PATCH bpf-next 1/6] ip: frags: Return actual error codes from ip_check

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Message-Id: <cc96452ecae8a1934b0f96a73272e18c78ae5f90.1671049840.git.dxu@dxuuu.xyz>
Date:   Wed, 14 Dec 2022 16:25:28 -0700
From:   Daniel Xu <dxu@...uu.xyz>
To:     "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>,
        David Ahern <dsahern@...nel.org>
Cc:     ppenkov@...atrix.com, dbird@...atrix.com, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, bpf@...r.kernel.org
Subject: [PATCH bpf-next 1/6] ip: frags: Return actual error codes from ip_check_defrag()

Once we wrap ip_check_defrag() in a kfunc, it may be useful for progs to
know the exact error condition ip_check_defrag() encountered.

Signed-off-by: Daniel Xu <dxu@...uu.xyz>
---
 drivers/net/macvlan.c  |  2 +-
 net/ipv4/ip_fragment.c | 11 ++++++-----
 net/packet/af_packet.c |  2 +-
 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 99a971929c8e..b8310e13d7e1 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -456,7 +456,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
 		unsigned int hash;
 
 		skb = ip_check_defrag(dev_net(skb->dev), skb, IP_DEFRAG_MACVLAN);
-		if (!skb)
+		if (IS_ERR(skb))
 			return RX_HANDLER_CONSUMED;
 		*pskb = skb;
 		eth = eth_hdr(skb);
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index 69c00ffdcf3e..7406c6b6376d 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -514,6 +514,7 @@ struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
 	struct iphdr iph;
 	int netoff;
 	u32 len;
+	int err;
 
 	if (skb->protocol != htons(ETH_P_IP))
 		return skb;
@@ -535,15 +536,15 @@ struct sk_buff *ip_check_defrag(struct net *net, struct sk_buff *skb, u32 user)
 		if (skb) {
 			if (!pskb_may_pull(skb, netoff + iph.ihl * 4)) {
 				kfree_skb(skb);
-				return NULL;
+				return ERR_PTR(-ENOMEM);
 			}
-			if (pskb_trim_rcsum(skb, netoff + len)) {
+			if ((err = pskb_trim_rcsum(skb, netoff + len))) {
 				kfree_skb(skb);
-				return NULL;
+				return ERR_PTR(err);
 			}
 			memset(IPCB(skb), 0, sizeof(struct inet_skb_parm));
-			if (ip_defrag(net, skb, user))
-				return NULL;
+			if ((err = ip_defrag(net, skb, user)))
+				return ERR_PTR(err);
 			skb_clear_hash(skb);
 		}
 	}
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 41c4ccc3a5d6..cf706f98448e 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1472,7 +1472,7 @@ static int packet_rcv_fanout(struct sk_buff *skb, struct net_device *dev,
 
 	if (fanout_has_flag(f, PACKET_FANOUT_FLAG_DEFRAG)) {
 		skb = ip_check_defrag(net, skb, IP_DEFRAG_AF_PACKET);
-		if (!skb)
+		if (IS_ERR(skb))
 			return 0;
 	}
 	switch (f->type) {
-- 
2.39.0