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Merge branch 'net-first-round-to-use-dev_net_rcu'

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Eric Dumazet says:

====================
net: first round to use dev_net_rcu()

dev_net(dev) should either be protected by RTNL or RCU.

There is no LOCKDEP support yet for this helper.

Adding it would trigger too many splats.

Instead, add dev_net_rcu() for rcu_read_lock() contexts
and start to use it to fix bugs and clearly document the
safety requirements.

v4: https://lore.kernel.org/CANn89i+AozhFhZNK0Y4e_EqXV1=yKjGuvf43Wa6JJKWMOixWQQ@mail.gmail.com
v3: https://lore.kernel.org/20250203153633.46ce0337@kernel.org/
====================

Link: https://patch.msgid.link/20250205155120.1676781-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2025-02-06 16:14:34 -08:00
commit 3da81cb9a4
11 changed files with 113 additions and 65 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

6
include/linux/netdevice.h
View file

@ -2663,6 +2663,12 @@ struct net *dev_net(const struct net_device *dev)
return read_pnet(&dev->nd_net);
}
static inline
struct net *dev_net_rcu(const struct net_device *dev)
{
return read_pnet_rcu(&dev->nd_net);
}
static inline
void dev_net_set(struct net_device *dev, struct net *net)
{

13
include/net/ip.h
View file

@ -471,9 +471,12 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
bool forwarding)
{
const struct rtable *rt = dst_rtable(dst);
struct net *net = dev_net(dst->dev);
unsigned int mtu;
unsigned int mtu, res;
struct net *net;
rcu_read_lock();
net = dev_net_rcu(dst->dev);
if (READ_ONCE(net->ipv4.sysctl_ip_fwd_use_pmtu) ||
ip_mtu_locked(dst) ||
!forwarding) {
@ -497,7 +500,11 @@ static inline unsigned int ip_dst_mtu_maybe_forward(const struct dst_entry *dst,
out:
mtu = min_t(unsigned int, mtu, IP_MAX_MTU);
return mtu - lwtunnel_headroom(dst->lwtstate, mtu);
res = mtu - lwtunnel_headroom(dst->lwtstate, mtu);
rcu_read_unlock();
return res;
}
static inline unsigned int ip_skb_dst_mtu(struct sock *sk,

2
include/net/net_namespace.h
View file

@ -398,7 +398,7 @@ static inline struct net *read_pnet(const possible_net_t *pnet)
#endif
}
static inline struct net *read_pnet_rcu(possible_net_t *pnet)
static inline struct net *read_pnet_rcu(const possible_net_t *pnet)
{
#ifdef CONFIG_NET_NS
return rcu_dereference(pnet->net);

9
include/net/route.h
View file

@ -382,10 +382,15 @@ static inline int inet_iif(const struct sk_buff *skb)
static inline int ip4_dst_hoplimit(const struct dst_entry *dst)
{
int hoplimit = dst_metric_raw(dst, RTAX_HOPLIMIT);
struct net *net = dev_net(dst->dev);
if (hoplimit == 0)
if (hoplimit == 0) {
const struct net *net;
rcu_read_lock();
net = dev_net_rcu(dst->dev);
hoplimit = READ_ONCE(net->ipv4.sysctl_ip_default_ttl);
rcu_read_unlock();
}
return hoplimit;
}

21
net/core/flow_dissector.c
View file

@ -1108,10 +1108,12 @@ bool __skb_flow_dissect(const struct net *net,
FLOW_DISSECTOR_KEY_BASIC,
target_container);
rcu_read_lock();
if (skb) {
if (!net) {
if (skb->dev)
net = dev_net(skb->dev);
net = dev_net_rcu(skb->dev);
else if (skb->sk)
net = sock_net(skb->sk);
}
@ -1122,7 +1124,6 @@ bool __skb_flow_dissect(const struct net *net,
enum netns_bpf_attach_type type = NETNS_BPF_FLOW_DISSECTOR;
struct bpf_prog_array *run_array;
rcu_read_lock();
run_array = rcu_dereference(init_net.bpf.run_array[type]);
if (!run_array)
run_array = rcu_dereference(net->bpf.run_array[type]);
@ -1150,17 +1151,17 @@ bool __skb_flow_dissect(const struct net *net,
prog = READ_ONCE(run_array->items[0].prog);
result = bpf_flow_dissect(prog, &ctx, n_proto, nhoff,
hlen, flags);
if (result == BPF_FLOW_DISSECTOR_CONTINUE)
goto dissect_continue;
__skb_flow_bpf_to_target(&flow_keys, flow_dissector,
target_container);
rcu_read_unlock();
return result == BPF_OK;
if (result != BPF_FLOW_DISSECTOR_CONTINUE) {
__skb_flow_bpf_to_target(&flow_keys, flow_dissector,
target_container);
rcu_read_unlock();
return result == BPF_OK;
}
}
dissect_continue:
rcu_read_unlock();
}
rcu_read_unlock();
if (dissector_uses_key(flow_dissector,
FLOW_DISSECTOR_KEY_ETH_ADDRS)) {
struct ethhdr *eth = eth_hdr(skb);

3
net/ipv4/devinet.c
View file

@ -1371,10 +1371,11 @@ __be32 inet_select_addr(const struct net_device *dev, __be32 dst, int scope)
__be32 addr = 0;
unsigned char localnet_scope = RT_SCOPE_HOST;
struct in_device *in_dev;
struct net *net = dev_net(dev);
struct net *net;
int master_idx;
rcu_read_lock();
net = dev_net_rcu(dev);
in_dev = __in_dev_get_rcu(dev);
if (!in_dev)
goto no_in_dev;

31
net/ipv4/icmp.c
View file

@ -399,10 +399,10 @@ static void icmp_push_reply(struct sock *sk,
static void icmp_reply(struct icmp_bxm *icmp_param, struct sk_buff *skb)
{
struct ipcm_cookie ipc;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
struct net *net = dev_net_rcu(rt->dst.dev);
bool apply_ratelimit = false;
struct ipcm_cookie ipc;
struct flowi4 fl4;
struct sock *sk;
struct inet_sock *inet;
@ -608,12 +608,14 @@ void __icmp_send(struct sk_buff *skb_in, int type, int code, __be32 info,
struct sock *sk;
if (!rt)
goto out;
return;
rcu_read_lock();
if (rt->dst.dev)
net = dev_net(rt->dst.dev);
net = dev_net_rcu(rt->dst.dev);
else if (skb_in->dev)
net = dev_net(skb_in->dev);
net = dev_net_rcu(skb_in->dev);
else
goto out;
@ -785,7 +787,8 @@ out_unlock:
icmp_xmit_unlock(sk);
out_bh_enable:
local_bh_enable();
out:;
out:
rcu_read_unlock();
}
EXPORT_SYMBOL(__icmp_send);
@ -834,7 +837,7 @@ static void icmp_socket_deliver(struct sk_buff *skb, u32 info)
* avoid additional coding at protocol handlers.
*/
if (!pskb_may_pull(skb, iph->ihl * 4 + 8)) {
__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
return;
}
@ -868,7 +871,7 @@ static enum skb_drop_reason icmp_unreach(struct sk_buff *skb)
struct net *net;
u32 info = 0;
net = dev_net(skb_dst(skb)->dev);
net = dev_net_rcu(skb_dst(skb)->dev);
/*
* Incomplete header ?
@ -979,7 +982,7 @@ out_err:
static enum skb_drop_reason icmp_redirect(struct sk_buff *skb)
{
if (skb->len < sizeof(struct iphdr)) {
__ICMP_INC_STATS(dev_net(skb->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb->dev), ICMP_MIB_INERRORS);
return SKB_DROP_REASON_PKT_TOO_SMALL;
}
@ -1011,7 +1014,7 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
struct icmp_bxm icmp_param;
struct net *net;
net = dev_net(skb_dst(skb)->dev);
net = dev_net_rcu(skb_dst(skb)->dev);
/* should there be an ICMP stat for ignored echos? */
if (READ_ONCE(net->ipv4.sysctl_icmp_echo_ignore_all))
return SKB_NOT_DROPPED_YET;
@ -1040,9 +1043,9 @@ static enum skb_drop_reason icmp_echo(struct sk_buff *skb)
bool icmp_build_probe(struct sk_buff *skb, struct icmphdr *icmphdr)
{
struct net *net = dev_net_rcu(skb->dev);
struct icmp_ext_hdr *ext_hdr, _ext_hdr;
struct icmp_ext_echo_iio *iio, _iio;
struct net *net = dev_net(skb->dev);
struct inet6_dev *in6_dev;
struct in_device *in_dev;
struct net_device *dev;
@ -1181,7 +1184,7 @@ static enum skb_drop_reason icmp_timestamp(struct sk_buff *skb)
return SKB_NOT_DROPPED_YET;
out_err:
__ICMP_INC_STATS(dev_net(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
__ICMP_INC_STATS(dev_net_rcu(skb_dst(skb)->dev), ICMP_MIB_INERRORS);
return SKB_DROP_REASON_PKT_TOO_SMALL;
}
@ -1198,7 +1201,7 @@ int icmp_rcv(struct sk_buff *skb)
{
enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct rtable *rt = skb_rtable(skb);
struct net *net = dev_net(rt->dst.dev);
struct net *net = dev_net_rcu(rt->dst.dev);
struct icmphdr *icmph;
if (!xfrm4_policy_check(NULL, XFRM_POLICY_IN, skb)) {
@ -1371,9 +1374,9 @@ int icmp_err(struct sk_buff *skb, u32 info)
struct iphdr *iph = (struct iphdr *)skb->data;
int offset = iph->ihl<<2;
struct icmphdr *icmph = (struct icmphdr *)(skb->data + offset);
struct net *net = dev_net_rcu(skb->dev);
int type = icmp_hdr(skb)->type;
int code = icmp_hdr(skb)->code;
struct net *net = dev_net(skb->dev);
/*
* Use ping_err to handle all icmp errors except those

30
net/ipv4/route.c
View file

@ -390,7 +390,13 @@ static inline int ip_rt_proc_init(void)
static inline bool rt_is_expired(const struct rtable *rth)
{
return rth->rt_genid != rt_genid_ipv4(dev_net(rth->dst.dev));
bool res;
rcu_read_lock();
res = rth->rt_genid != rt_genid_ipv4(dev_net_rcu(rth->dst.dev));
rcu_read_unlock();
return res;
}
void rt_cache_flush(struct net *net)
@ -1002,9 +1008,9 @@ out: kfree_skb_reason(skb, reason);
static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
{
struct dst_entry *dst = &rt->dst;
struct net *net = dev_net(dst->dev);
struct fib_result res;
bool lock = false;
struct net *net;
u32 old_mtu;
if (ip_mtu_locked(dst))
@ -1014,6 +1020,8 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
if (old_mtu < mtu)
return;
rcu_read_lock();
net = dev_net_rcu(dst->dev);
if (mtu < net->ipv4.ip_rt_min_pmtu) {
lock = true;
mtu = min(old_mtu, net->ipv4.ip_rt_min_pmtu);
@ -1021,9 +1029,8 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
if (rt->rt_pmtu == mtu && !lock &&
time_before(jiffies, dst->expires - net->ipv4.ip_rt_mtu_expires / 2))
return;
goto out;
rcu_read_lock();
if (fib_lookup(net, fl4, &res, 0) == 0) {
struct fib_nh_common *nhc;
@ -1037,14 +1044,14 @@ static void __ip_rt_update_pmtu(struct rtable *rt, struct flowi4 *fl4, u32 mtu)
update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
jiffies + net->ipv4.ip_rt_mtu_expires);
}
rcu_read_unlock();
return;
goto out;
}
#endif /* CONFIG_IP_ROUTE_MULTIPATH */
nhc = FIB_RES_NHC(res);
update_or_create_fnhe(nhc, fl4->daddr, 0, mtu, lock,
jiffies + net->ipv4.ip_rt_mtu_expires);
}
out:
rcu_read_unlock();
}
@ -1307,10 +1314,15 @@ static void set_class_tag(struct rtable *rt, u32 tag)
static unsigned int ipv4_default_advmss(const struct dst_entry *dst)
{
struct net *net = dev_net(dst->dev);
unsigned int header_size = sizeof(struct tcphdr) + sizeof(struct iphdr);
unsigned int advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
net->ipv4.ip_rt_min_advmss);
unsigned int advmss;
struct net *net;
rcu_read_lock();
net = dev_net_rcu(dst->dev);
advmss = max_t(unsigned int, ipv4_mtu(dst) - header_size,
net->ipv4.ip_rt_min_advmss);
rcu_read_unlock();
return min(advmss, IPV4_MAX_PMTU - header_size);
}

42
net/ipv6/icmp.c
View file

@ -76,7 +76,7 @@ static int icmpv6_err(struct sk_buff *skb, struct inet6_skb_parm *opt,
{
/* icmpv6_notify checks 8 bytes can be pulled, icmp6hdr is 8 bytes */
struct icmp6hdr *icmp6 = (struct icmp6hdr *) (skb->data + offset);
struct net *net = dev_net(skb->dev);
struct net *net = dev_net_rcu(skb->dev);
if (type == ICMPV6_PKT_TOOBIG)
ip6_update_pmtu(skb, net, info, skb->dev->ifindex, 0, sock_net_uid(net, NULL));
@ -473,7 +473,10 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
if (!skb->dev)
return;
net = dev_net(skb->dev);
rcu_read_lock();
net = dev_net_rcu(skb->dev);
mark = IP6_REPLY_MARK(net, skb->mark);
/*
* Make sure we respect the rules
@ -496,7 +499,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
!(type == ICMPV6_PARAMPROB &&
code == ICMPV6_UNK_OPTION &&
(opt_unrec(skb, info))))
return;
goto out;
saddr = NULL;
}
@ -526,7 +529,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
if ((addr_type == IPV6_ADDR_ANY) || (addr_type & IPV6_ADDR_MULTICAST)) {
net_dbg_ratelimited("icmp6_send: addr_any/mcast source [%pI6c > %pI6c]\n",
&hdr->saddr, &hdr->daddr);
return;
goto out;
}
/*
@ -535,7 +538,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
if (is_ineligible(skb)) {
net_dbg_ratelimited("icmp6_send: no reply to icmp error [%pI6c > %pI6c]\n",
&hdr->saddr, &hdr->daddr);
return;
goto out;
}
/* Needed by both icmpv6_global_allow and icmpv6_xmit_lock */
@ -582,7 +585,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
np = inet6_sk(sk);
if (!icmpv6_xrlim_allow(sk, type, &fl6, apply_ratelimit))
goto out;
goto out_unlock;
tmp_hdr.icmp6_type = type;
tmp_hdr.icmp6_code = code;
@ -600,7 +603,7 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
dst = icmpv6_route_lookup(net, skb, sk, &fl6);
if (IS_ERR(dst))
goto out;
goto out_unlock;
ipc6.hlimit = ip6_sk_dst_hoplimit(np, &fl6, dst);
@ -616,7 +619,6 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
goto out_dst_release;
}
rcu_read_lock();
idev = __in6_dev_get(skb->dev);
if (ip6_append_data(sk, icmpv6_getfrag, &msg,
@ -630,13 +632,15 @@ void icmp6_send(struct sk_buff *skb, u8 type, u8 code, __u32 info,
icmpv6_push_pending_frames(sk, &fl6, &tmp_hdr,
len + sizeof(struct icmp6hdr));
}
rcu_read_unlock();
out_dst_release:
dst_release(dst);
out:
out_unlock:
icmpv6_xmit_unlock(sk);
out_bh_enable:
local_bh_enable();
out:
rcu_read_unlock();
}
EXPORT_SYMBOL(icmp6_send);
@ -679,8 +683,8 @@ int ip6_err_gen_icmpv6_unreach(struct sk_buff *skb, int nhs, int type,
skb_pull(skb2, nhs);
skb_reset_network_header(skb2);
rt = rt6_lookup(dev_net(skb->dev), &ipv6_hdr(skb2)->saddr, NULL, 0,
skb, 0);
rt = rt6_lookup(dev_net_rcu(skb->dev), &ipv6_hdr(skb2)->saddr,
NULL, 0, skb, 0);
if (rt && rt->dst.dev)
skb2->dev = rt->dst.dev;
@ -717,7 +721,7 @@ EXPORT_SYMBOL(ip6_err_gen_icmpv6_unreach);
static enum skb_drop_reason icmpv6_echo_reply(struct sk_buff *skb)
{
struct net *net = dev_net(skb->dev);
struct net *net = dev_net_rcu(skb->dev);
struct sock *sk;
struct inet6_dev *idev;
struct ipv6_pinfo *np;
@ -832,7 +836,7 @@ enum skb_drop_reason icmpv6_notify(struct sk_buff *skb, u8 type,
u8 code, __be32 info)
{
struct inet6_skb_parm *opt = IP6CB(skb);
struct net *net = dev_net(skb->dev);
struct net *net = dev_net_rcu(skb->dev);
const struct inet6_protocol *ipprot;
enum skb_drop_reason reason;
int inner_offset;
@ -889,7 +893,7 @@ out:
static int icmpv6_rcv(struct sk_buff *skb)
{
enum skb_drop_reason reason = SKB_DROP_REASON_NOT_SPECIFIED;
struct net *net = dev_net(skb->dev);
struct net *net = dev_net_rcu(skb->dev);
struct net_device *dev = icmp6_dev(skb);
struct inet6_dev *idev = __in6_dev_get(dev);
const struct in6_addr *saddr, *daddr;
@ -921,7 +925,7 @@ static int icmpv6_rcv(struct sk_buff *skb)
skb_set_network_header(skb, nh);
}
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INMSGS);
__ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_INMSGS);
saddr = &ipv6_hdr(skb)->saddr;
daddr = &ipv6_hdr(skb)->daddr;
@ -939,7 +943,7 @@ static int icmpv6_rcv(struct sk_buff *skb)
type = hdr->icmp6_type;
ICMP6MSGIN_INC_STATS(dev_net(dev), idev, type);
ICMP6MSGIN_INC_STATS(dev_net_rcu(dev), idev, type);
switch (type) {
case ICMPV6_ECHO_REQUEST:
@ -1034,9 +1038,9 @@ static int icmpv6_rcv(struct sk_buff *skb)
csum_error:
reason = SKB_DROP_REASON_ICMP_CSUM;
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_CSUMERRORS);
__ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_CSUMERRORS);
discard_it:
__ICMP6_INC_STATS(dev_net(dev), idev, ICMP6_MIB_INERRORS);
__ICMP6_INC_STATS(dev_net_rcu(dev), idev, ICMP6_MIB_INERRORS);
drop_no_count:
kfree_skb_reason(skb, reason);
return 0;

14
net/ipv6/ip6_input.c
View file

@ -477,9 +477,7 @@ discard:
static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
skb_clear_delivery_time(skb);
rcu_read_lock();
ip6_protocol_deliver_rcu(net, skb, 0, false);
rcu_read_unlock();
return 0;
}
@ -487,9 +485,15 @@ static int ip6_input_finish(struct net *net, struct sock *sk, struct sk_buff *sk
int ip6_input(struct sk_buff *skb)
{
return NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
dev_net(skb->dev), NULL, skb, skb->dev, NULL,
ip6_input_finish);
int res;
rcu_read_lock();
res = NF_HOOK(NFPROTO_IPV6, NF_INET_LOCAL_IN,
dev_net_rcu(skb->dev), NULL, skb, skb->dev, NULL,
ip6_input_finish);
rcu_read_unlock();
return res;
}
EXPORT_SYMBOL_GPL(ip6_input);

7
net/ipv6/route.c
View file

@ -3196,13 +3196,18 @@ static unsigned int ip6_default_advmss(const struct dst_entry *dst)
{
struct net_device *dev = dst->dev;
unsigned int mtu = dst_mtu(dst);
struct net *net = dev_net(dev);
struct net *net;
mtu -= sizeof(struct ipv6hdr) + sizeof(struct tcphdr);
rcu_read_lock();
net = dev_net_rcu(dev);
if (mtu < net->ipv6.sysctl.ip6_rt_min_advmss)
mtu = net->ipv6.sysctl.ip6_rt_min_advmss;
rcu_read_unlock();
/*
* Maximal non-jumbo IPv6 payload is IPV6_MAXPLEN and
* corresponding MSS is IPV6_MAXPLEN - tcp_header_size.