[RFC PATCH v2 0/3] Allow sk_lookup UDP return traffic to egress when setting src port/address.
Currently, sk_lookup allows an ebpf program to run on the ingress socket lookup path, and accept traffic not only on a range of addresses, but also on a range of ports. At Cloudflare we use sk_lookup for two main cases: 1. Sharing a single port between multiple services - i.e. two services (or more) use disjoint IP ranges but share the same port; 2. Receiving traffic on all ports - i.e. a service which accepts traffic on specific IP ranges but any port [1].
However, one main challenge we face while using sk_lookup for these use cases is how to source return UDP traffic: - On point 1. above, sometimes this range of addresses are not local (i.e. there's no local routes for these in the server), which means we need IP_TRANSPARENT set to be able to egress traffic from addresses we've received traffic on (or simply IP_FREEBIND in the case of IPv6); - And on point 2. above, allowing traffic to a range of ports means a service could get traffic on multiple ports, but currently there's no way to set the source UDP port egress traffic should be sourced from - it's possible to receive the original destination port using the IP_ORIGDSTADDR ancilliary message in recvmsg, but not set it in sendmsg.
Both of these limitations can be worked around, but in a sub-optimal way. Using IP_TRANSPARENT, for instance, requires special privileges. And while one could use UDP connected sockets to send return traffic, creating a connected socket for each different address a UDP traffic is received on does have performance implications.
Given sk_lookup allows services to accept traffic on a range of addresses or ports, it seems sensible to also allow return traffic to proceed through as well, without needing extra configurations / set ups.
This patch sets out to fix both of this issues by: 1. Allowing users to set the src address/port egress traffic should be sent from, when calling sendmsg(); 2. Validating that this egress traffic comes from a socket that matches an ingress socket in sk_lookup. - If it does, traffic is allowed to proceed; - Otherwise it falls back to the regular egress path.
The downsides to this is that this runs on the egress hot path, although this work tries to minimise its impact by only performing the reverse socket lookup when necessary (i.e. only when the src address/port are modified). Further performance measurements are to be taken, but we're reaching out early for feedback to see what the technical concerns are and if we can address them.
[1] https://blog.cloudflare.com/how-we-built-spectrum/
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com --- Changes in v2: - Amended commit messages and cover letter to make the intent and implementation clearer (Willem de Bruijn); - Fixed socket comparison by not using socket cookies and comparing them directly (Eric Dumazet); - Fixed misspellings and checkpatch.pl warnings on line lengths (Simon Horman); - Fixed usage of start_server_addr() and gcc compilation (Philo Lu); - Link to v1: https://lore.kernel.org/r/20240913-reverse-sk-lookup-v1-0-e721ea003d4c@cloud...
--- Tiago Lam (3): ipv4: Support setting src port in sendmsg(). ipv6: Support setting src port in sendmsg(). bpf: Add sk_lookup test to use ORIGDSTADDR cmsg.
include/net/ip.h | 1 + net/ipv4/ip_sockglue.c | 11 +++ net/ipv4/udp.c | 35 +++++++++- net/ipv6/datagram.c | 79 ++++++++++++++++++++++ net/ipv6/udp.c | 8 ++- tools/testing/selftests/bpf/prog_tests/sk_lookup.c | 67 ++++++++++++------ 6 files changed, 176 insertions(+), 25 deletions(-) --- base-commit: 6562a89739bbefddb5495c09aaab67c1c3756f36 change-id: 20240909-reverse-sk-lookup-f7bf36292bc4
Best regards,
sendmsg() doesn't currently allow users to set the src port from which egress traffic should be sent from. This is possible if a user wants to configure the src address from which egress traffic should be sent from - with the IP_PKTINFO ancillary message, a user is currently able to specify a source address to egress from when calling sendmsg(). However, this still requires the user to set the IP_TRANSPARENT flag using setsockopt(), which happens to require special privileges in the case of IPv4.
To support users setting the src port for egress traffic when using sendmsg(), this patch extends the ancillary messages supported by sendmsg() to support the IP_ORIGDSTADDR ancillary message, reusing the same cmsg and struct used in recvmsg() - which already supports specifying a port.
Additionally, to avoid having to have special configurations, such as IP_TRANSPARENT, this patch allows egress traffic that's been configured using (the newly added) IP_ORIGDSTADDR to proceed if there's an ingress socket lookup (sk_lookup) that matches that traffic - by performing a reserve sk_lookup. Thus, if the sk_lookup reverse call returns a socket that matches the egress socket, we also let the egress traffic through - following the principle of, allowing return traffic to proceed if ingress traffic is allowed in. In case no match is found in the reverse sk_lookup, traffic falls back to the regular egress path.
This reverse lookup is only performed in case an sk_lookup ebpf program is attached and the source address and/or port for the return traffic have been modified using the (newly added) IP_ORIGDSTADDR in sendmsg.
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com --- include/net/ip.h | 1 + net/ipv4/ip_sockglue.c | 11 +++++++++++ net/ipv4/udp.c | 35 ++++++++++++++++++++++++++++++++++- 3 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/include/net/ip.h b/include/net/ip.h index c5606cadb1a5..e5753abd7247 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -75,6 +75,7 @@ static inline unsigned int ip_hdrlen(const struct sk_buff *skb) struct ipcm_cookie { struct sockcm_cookie sockc; __be32 addr; + __be16 port; int oif; struct ip_options_rcu *opt; __u8 protocol; diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index cf377377b52d..6e55bd25b5f7 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -297,6 +297,17 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, ipc->addr = info->ipi_spec_dst.s_addr; break; } + case IP_ORIGDSTADDR: + { + struct sockaddr_in *dst_addr; + + if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct sockaddr_in))) + return -EINVAL; + dst_addr = (struct sockaddr_in *)CMSG_DATA(cmsg); + ipc->port = dst_addr->sin_port; + ipc->addr = dst_addr->sin_addr.s_addr; + break; + } case IP_TTL: if (cmsg->cmsg_len != CMSG_LEN(sizeof(int))) return -EINVAL; diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 49c622e743e8..208cee40c0ec 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1060,6 +1060,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name); struct flowi4 fl4_stack; struct flowi4 *fl4; + __u8 flow_flags = inet_sk_flowi_flags(sk); int ulen = len; struct ipcm_cookie ipc; struct rtable *rt = NULL; @@ -1179,6 +1180,39 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) } }
+ /* If we're egressing with a different source address and/or port, we + * perform a reverse socket lookup. The rationale behind this is that + * we can allow return UDP traffic that has ingressed through sk_lookup + * to also egress correctly. In case this the reverse lookup fails. + * + * The lookup is performed if either source address and/or port + * changed, and neither is "0". + */ + if (static_branch_unlikely(&bpf_sk_lookup_enabled) && + !connected && + (ipc.port && ipc.addr) && + (inet->inet_saddr != ipc.addr || inet->inet_sport != ipc.port)) { + struct sock *sk_egress; + + bpf_sk_lookup_run_v4(sock_net(sk), IPPROTO_UDP, + daddr, dport, ipc.addr, ntohs(ipc.port), + 1, &sk_egress); + if (IS_ERR_OR_NULL(sk_egress) || sk_egress != sk) { + net_info_ratelimited("No reverse socket lookup match for local addr %pI4:%d remote addr %pI4:%d\n", + &ipc.addr, ntohs(ipc.port), &daddr, + ntohs(dport)); + } else { + /* Override the source port to use with the one we got + * in cmsg, and tell routing to let us use a non-local + * address. Otherwise route lookups will fail with + * non-local source address when IP_TRANSPARENT isn't + * set. + */ + inet->inet_sport = ipc.port; + flow_flags |= FLOWI_FLAG_ANYSRC; + } + } + saddr = ipc.addr; ipc.addr = faddr = daddr;
@@ -1223,7 +1257,6 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
if (!rt) { struct net *net = sock_net(sk); - __u8 flow_flags = inet_sk_flowi_flags(sk);
fl4 = &fl4_stack;
Tiago Lam wrote:
sendmsg() doesn't currently allow users to set the src port from which egress traffic should be sent from. This is possible if a user wants to configure the src address from which egress traffic should be sent from
- with the IP_PKTINFO ancillary message, a user is currently able to specify a source address to egress from when calling sendmsg().
However, this still requires the user to set the IP_TRANSPARENT flag using setsockopt(), which happens to require special privileges in the case of IPv4.
To support users setting the src port for egress traffic when using sendmsg(), this patch extends the ancillary messages supported by sendmsg() to support the IP_ORIGDSTADDR ancillary message, reusing the same cmsg and struct used in recvmsg() - which already supports specifying a port.
Additionally, to avoid having to have special configurations, such as IP_TRANSPARENT, this patch allows egress traffic that's been configured using (the newly added) IP_ORIGDSTADDR to proceed if there's an ingress socket lookup (sk_lookup) that matches that traffic - by performing a reserve sk_lookup. Thus, if the sk_lookup reverse call returns a socket that matches the egress socket, we also let the egress traffic through - following the principle of, allowing return traffic to proceed if ingress traffic is allowed in. In case no match is found in the reverse sk_lookup, traffic falls back to the regular egress path.
This reverse lookup is only performed in case an sk_lookup ebpf program is attached and the source address and/or port for the return traffic have been modified using the (newly added) IP_ORIGDSTADDR in sendmsg.
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com
include/net/ip.h | 1 + net/ipv4/ip_sockglue.c | 11 +++++++++++ net/ipv4/udp.c | 35 ++++++++++++++++++++++++++++++++++- 3 files changed, 46 insertions(+), 1 deletion(-)
diff --git a/include/net/ip.h b/include/net/ip.h index c5606cadb1a5..e5753abd7247 100644 --- a/include/net/ip.h +++ b/include/net/ip.h @@ -75,6 +75,7 @@ static inline unsigned int ip_hdrlen(const struct sk_buff *skb) struct ipcm_cookie { struct sockcm_cookie sockc; __be32 addr;
- __be16 port; int oif; struct ip_options_rcu *opt; __u8 protocol;
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c index cf377377b52d..6e55bd25b5f7 100644 --- a/net/ipv4/ip_sockglue.c +++ b/net/ipv4/ip_sockglue.c @@ -297,6 +297,17 @@ int ip_cmsg_send(struct sock *sk, struct msghdr *msg, struct ipcm_cookie *ipc, ipc->addr = info->ipi_spec_dst.s_addr; break; }
case IP_ORIGDSTADDR:
Should this just be IP_SRCADDR?
{struct sockaddr_in *dst_addr;if (cmsg->cmsg_len != CMSG_LEN(sizeof(struct sockaddr_in)))return -EINVAL;dst_addr = (struct sockaddr_in *)CMSG_DATA(cmsg);ipc->port = dst_addr->sin_port;ipc->addr = dst_addr->sin_addr.s_addr;break;}diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c index 49c622e743e8..208cee40c0ec 100644 --- a/net/ipv4/udp.c +++ b/net/ipv4/udp.c @@ -1060,6 +1060,7 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) DECLARE_SOCKADDR(struct sockaddr_in *, usin, msg->msg_name); struct flowi4 fl4_stack; struct flowi4 *fl4;
- __u8 flow_flags = inet_sk_flowi_flags(sk); int ulen = len; struct ipcm_cookie ipc; struct rtable *rt = NULL;
@@ -1179,6 +1180,39 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) } }
- /* If we're egressing with a different source address and/or port, we
* perform a reverse socket lookup. The rationale behind this is that* we can allow return UDP traffic that has ingressed through sk_lookup* to also egress correctly. In case this the reverse lookup fails.** The lookup is performed if either source address and/or port* changed, and neither is "0".*/- if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
!connected &&(ipc.port && ipc.addr) &&(inet->inet_saddr != ipc.addr || inet->inet_sport != ipc.port)) {struct sock *sk_egress;bpf_sk_lookup_run_v4(sock_net(sk), IPPROTO_UDP,daddr, dport, ipc.addr, ntohs(ipc.port),1, &sk_egress);
Does this need to use a bpf helper rather than a normal route lookup function?
I don't know this func, but the sk is returned without a reference taken?
if (IS_ERR_OR_NULL(sk_egress) || sk_egress != sk) {net_info_ratelimited("No reverse socket lookup match for local addr %pI4:%d remote addr %pI4:%d\n",&ipc.addr, ntohs(ipc.port), &daddr,ntohs(dport));
No need for logging to the kernel log when syscalls can just return an error.
} else {/* Override the source port to use with the one we got* in cmsg, and tell routing to let us use a non-local* address. Otherwise route lookups will fail with* non-local source address when IP_TRANSPARENT isn't* set.*/inet->inet_sport = ipc.port;flow_flags |= FLOWI_FLAG_ANYSRC;}- }
- saddr = ipc.addr; ipc.addr = faddr = daddr;
@@ -1223,7 +1257,6 @@ int udp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) if (!rt) { struct net *net = sock_net(sk);
__u8 flow_flags = inet_sk_flowi_flags(sk);fl4 = &fl4_stack;
-- 2.34.1
Le ven. 20 sept. 2024 à 19:03, Tiago Lam tiagolam@cloudflare.com a écrit :
sendmsg() doesn't currently allow users to set the src port from which egress traffic should be sent from. This is possible if a user wants to configure the src address from which egress traffic should be sent from
- with the IP_PKTINFO ancillary message, a user is currently able to specify a source address to egress from when calling sendmsg().
However, this still requires the user to set the IP_TRANSPARENT flag using setsockopt(), which happens to require special privileges in the case of IPv4.
To support users setting the src port for egress traffic when using sendmsg(), this patch extends the ancillary messages supported by sendmsg() to support the IP_ORIGDSTADDR ancillary message, reusing the same cmsg and struct used in recvmsg() - which already supports specifying a port.
Additionally, to avoid having to have special configurations, such as IP_TRANSPARENT, this patch allows egress traffic that's been configured using (the newly added) IP_ORIGDSTADDR to proceed if there's an ingress socket lookup (sk_lookup) that matches that traffic - by performing a reserve sk_lookup. Thus, if the sk_lookup reverse call returns a socket that matches the egress socket, we also let the egress traffic through - following the principle of, allowing return traffic to proceed if ingress traffic is allowed in. In case no match is found in the reverse sk_lookup, traffic falls back to the regular egress path.
This reverse lookup is only performed in case an sk_lookup ebpf program is attached and the source address and/or port for the return traffic have been modified using the (newly added) IP_ORIGDSTADDR in sendmsg.
Is it compatible with SO_REUSEPORT ?
Most heavy duty UDP servers use SO_REUSEPORT to spread incoming packets to multiple sockets.
How is the reverse lookup going to choose the 'right' socket ?
This follows the same rationale provided for the ipv4 counterpart, where the sendmsg() path is also extended here to support the IPV6_ORIGDSTADDR ancillary message to be able to specify a source address/port. This allows users to configure the source address and/or port egress traffic should be sent from.
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com --- net/ipv6/datagram.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++ net/ipv6/udp.c | 8 ++++-- 2 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index fff78496803d..369c64a478ec 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -756,6 +756,29 @@ void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg, } EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);
+static inline bool reverse_sk_lookup(struct flowi6 *fl6, struct sock *sk, + struct in6_addr *saddr, __be16 sport) +{ + if (static_branch_unlikely(&bpf_sk_lookup_enabled) && + (saddr && sport) && + (ipv6_addr_cmp(&sk->sk_v6_rcv_saddr, saddr) || + inet_sk(sk)->inet_sport != sport)) { + struct sock *sk_egress; + + bpf_sk_lookup_run_v6(sock_net(sk), IPPROTO_UDP, &fl6->daddr, + fl6->fl6_dport, saddr, ntohs(sport), 0, + &sk_egress); + if (!IS_ERR_OR_NULL(sk_egress) && sk_egress == sk) + return true; + + net_info_ratelimited("No reverse socket lookup match for local addr %pI6:%d remote addr %pI6:%d\n", + &saddr, ntohs(sport), &fl6->daddr, + ntohs(fl6->fl6_dport)); + } + + return false; +} + int ip6_datagram_send_ctl(struct net *net, struct sock *sk, struct msghdr *msg, struct flowi6 *fl6, struct ipcm6_cookie *ipc6) @@ -844,7 +867,63 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
break; } + case IPV6_ORIGDSTADDR: + { + struct sockaddr_in6 *sockaddr_in; + struct net_device *dev = NULL; + + if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct sockaddr_in6))) { + err = -EINVAL; + goto exit_f; + } + + sockaddr_in = (struct sockaddr_in6 *)CMSG_DATA(cmsg); + + addr_type = __ipv6_addr_type(&sockaddr_in->sin6_addr); + + if (addr_type & IPV6_ADDR_LINKLOCAL) + return -EINVAL; + + /* If we're egressing with a different source address + * and/or port, we perform a reverse socket lookup. The + * rationale behind this is that we can allow return + * UDP traffic that has ingressed through sk_lookup to + * also egress correctly. In case the reverse lookup + * fails, we continue with the normal path. + * + * The lookup is performed if either source address + * and/or port changed, and neither is "0". + */ + if (reverse_sk_lookup(fl6, sk, &sockaddr_in->sin6_addr, + sockaddr_in->sin6_port)) { + /* Override the source port and address to use + * with the one we got in cmsg and bail early. + */ + fl6->saddr = sockaddr_in->sin6_addr; + fl6->fl6_sport = sockaddr_in->sin6_port; + break; + }
+ if (addr_type != IPV6_ADDR_ANY) { + int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL; + + if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) && + !ipv6_chk_addr_and_flags(net, + &sockaddr_in->sin6_addr, + dev, !strict, 0, + IFA_F_TENTATIVE) && + !ipv6_chk_acast_addr_src(net, dev, + &sockaddr_in->sin6_addr)) + err = -EINVAL; + else + fl6->saddr = sockaddr_in->sin6_addr; + } + + if (err) + goto exit_f; + + break; + } case IPV6_FLOWINFO: if (cmsg->cmsg_len < CMSG_LEN(4)) { err = -EINVAL; diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 6602a2e9cdb5..6121cbb71ad3 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1476,6 +1476,12 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_uid = sk->sk_uid;
+ /* We use fl6's daddr and fl6_sport in the reverse sk_lookup done + * within ip6_datagram_send_ctl() now. + */ + fl6->daddr = *daddr; + fl6->fl6_sport = inet->inet_sport; + if (msg->msg_controllen) { opt = &opt_space; memset(opt, 0, sizeof(struct ipv6_txoptions)); @@ -1511,10 +1517,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_proto = sk->sk_protocol; fl6->flowi6_mark = ipc6.sockc.mark; - fl6->daddr = *daddr; if (ipv6_addr_any(&fl6->saddr) && !ipv6_addr_any(&np->saddr)) fl6->saddr = np->saddr; - fl6->fl6_sport = inet->inet_sport;
if (cgroup_bpf_enabled(CGROUP_UDP6_SENDMSG) && !connected) { err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
Tiago Lam wrote:
This follows the same rationale provided for the ipv4 counterpart, where the sendmsg() path is also extended here to support the IPV6_ORIGDSTADDR ancillary message to be able to specify a source address/port. This allows users to configure the source address and/or port egress traffic should be sent from.
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com
net/ipv6/datagram.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++ net/ipv6/udp.c | 8 ++++-- 2 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index fff78496803d..369c64a478ec 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -756,6 +756,29 @@ void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg, } EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl); +static inline bool reverse_sk_lookup(struct flowi6 *fl6, struct sock *sk,
struct in6_addr *saddr, __be16 sport)+{
- if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
(saddr && sport) &&(ipv6_addr_cmp(&sk->sk_v6_rcv_saddr, saddr) ||inet_sk(sk)->inet_sport != sport)) {struct sock *sk_egress;bpf_sk_lookup_run_v6(sock_net(sk), IPPROTO_UDP, &fl6->daddr,fl6->fl6_dport, saddr, ntohs(sport), 0,&sk_egress);if (!IS_ERR_OR_NULL(sk_egress) && sk_egress == sk)return true;net_info_ratelimited("No reverse socket lookup match for local addr %pI6:%d remote addr %pI6:%d\n",&saddr, ntohs(sport), &fl6->daddr,ntohs(fl6->fl6_dport));- }
- return false;
+}
int ip6_datagram_send_ctl(struct net *net, struct sock *sk, struct msghdr *msg, struct flowi6 *fl6, struct ipcm6_cookie *ipc6) @@ -844,7 +867,63 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk, break; }
case IPV6_ORIGDSTADDR:{struct sockaddr_in6 *sockaddr_in;struct net_device *dev = NULL;if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct sockaddr_in6))) {err = -EINVAL;goto exit_f;}sockaddr_in = (struct sockaddr_in6 *)CMSG_DATA(cmsg);addr_type = __ipv6_addr_type(&sockaddr_in->sin6_addr);if (addr_type & IPV6_ADDR_LINKLOCAL)return -EINVAL;/* If we're egressing with a different source address* and/or port, we perform a reverse socket lookup. The* rationale behind this is that we can allow return* UDP traffic that has ingressed through sk_lookup to* also egress correctly. In case the reverse lookup* fails, we continue with the normal path.** The lookup is performed if either source address* and/or port changed, and neither is "0".*/if (reverse_sk_lookup(fl6, sk, &sockaddr_in->sin6_addr,sockaddr_in->sin6_port)) {/* Override the source port and address to use* with the one we got in cmsg and bail early.*/fl6->saddr = sockaddr_in->sin6_addr;fl6->fl6_sport = sockaddr_in->sin6_port;break;}
if (addr_type != IPV6_ADDR_ANY) {int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) &&!ipv6_chk_addr_and_flags(net,&sockaddr_in->sin6_addr,dev, !strict, 0,IFA_F_TENTATIVE) &&!ipv6_chk_acast_addr_src(net, dev,&sockaddr_in->sin6_addr))err = -EINVAL;elsefl6->saddr = sockaddr_in->sin6_addr;}if (err)goto exit_f;break;}
How come IPv6 runs the check in the cmsg handler, but ipv4 in sendmsg directly? Can the two be symmetric?
case IPV6_FLOWINFO: if (cmsg->cmsg_len < CMSG_LEN(4)) { err = -EINVAL;diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 6602a2e9cdb5..6121cbb71ad3 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1476,6 +1476,12 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) fl6->flowi6_uid = sk->sk_uid;
- /* We use fl6's daddr and fl6_sport in the reverse sk_lookup done
* within ip6_datagram_send_ctl() now.*/- fl6->daddr = *daddr;
- fl6->fl6_sport = inet->inet_sport;
- if (msg->msg_controllen) { opt = &opt_space; memset(opt, 0, sizeof(struct ipv6_txoptions));
@@ -1511,10 +1517,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len) fl6->flowi6_proto = sk->sk_protocol; fl6->flowi6_mark = ipc6.sockc.mark;
- fl6->daddr = *daddr; if (ipv6_addr_any(&fl6->saddr) && !ipv6_addr_any(&np->saddr)) fl6->saddr = np->saddr;
- fl6->fl6_sport = inet->inet_sport;
if (cgroup_bpf_enabled(CGROUP_UDP6_SENDMSG) && !connected) { err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
-- 2.34.1
From: Tiago Lam tiagolam@cloudflare.com
Sent: 20 September 2024 18:02
This follows the same rationale provided for the ipv4 counterpart, where the sendmsg() path is also extended here to support the IPV6_ORIGDSTADDR ancillary message to be able to specify a source address/port. This allows users to configure the source address and/or port egress traffic should be sent from.
I'd missed that being added - could save us the horrid problem of getting the UDP checksum correct when sending UDP over a raw socket. (That isn't a problem for IPv6.)
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Is that really useful/necessary? The check (but not the commit message) implies that some 'bpf thingy' also needs to be enabled. Any check would need to include the test that the program sending the packet has the ability to send a packet through the ingress socket. Additionally a check for the sending process having (IIRC) CAP_NET_ADMIN (which would let the process send the message by other means) would save the slow path.
The code we have sends a lot of UDP RTP (typically 160 bytes of audio every 20ms). There is actually no reason for there to be a valid matching ingress path. (That code would benefit from being able to bind a lot of ports to the same UDP socket.)
David
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com
net/ipv6/datagram.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++ net/ipv6/udp.c | 8 ++++-- 2 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index fff78496803d..369c64a478ec 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -756,6 +756,29 @@ void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg, } EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);
+static inline bool reverse_sk_lookup(struct flowi6 *fl6, struct sock *sk,
struct in6_addr *saddr, __be16 sport)+{
- if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
(saddr && sport) &&(ipv6_addr_cmp(&sk->sk_v6_rcv_saddr, saddr) ||inet_sk(sk)->inet_sport != sport)) {struct sock *sk_egress;bpf_sk_lookup_run_v6(sock_net(sk), IPPROTO_UDP, &fl6->daddr,fl6->fl6_dport, saddr, ntohs(sport), 0,&sk_egress);if (!IS_ERR_OR_NULL(sk_egress) && sk_egress == sk)return true;net_info_ratelimited("No reverse socket lookup match for local addr %pI6:%d remote addr%pI6:%d\n",
&saddr, ntohs(sport), &fl6->daddr,ntohs(fl6->fl6_dport));- }
- return false;
+}
int ip6_datagram_send_ctl(struct net *net, struct sock *sk, struct msghdr *msg, struct flowi6 *fl6, struct ipcm6_cookie *ipc6) @@ -844,7 +867,63 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
break; }
case IPV6_ORIGDSTADDR:{struct sockaddr_in6 *sockaddr_in;struct net_device *dev = NULL;if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct sockaddr_in6))) {err = -EINVAL;goto exit_f;}sockaddr_in = (struct sockaddr_in6 *)CMSG_DATA(cmsg);addr_type = __ipv6_addr_type(&sockaddr_in->sin6_addr);if (addr_type & IPV6_ADDR_LINKLOCAL)return -EINVAL;/* If we're egressing with a different source address* and/or port, we perform a reverse socket lookup. The* rationale behind this is that we can allow return* UDP traffic that has ingressed through sk_lookup to* also egress correctly. In case the reverse lookup* fails, we continue with the normal path.** The lookup is performed if either source address* and/or port changed, and neither is "0".*/if (reverse_sk_lookup(fl6, sk, &sockaddr_in->sin6_addr,sockaddr_in->sin6_port)) {/* Override the source port and address to use* with the one we got in cmsg and bail early.*/fl6->saddr = sockaddr_in->sin6_addr;fl6->fl6_sport = sockaddr_in->sin6_port;break;}if (addr_type != IPV6_ADDR_ANY) {int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) &&!ipv6_chk_addr_and_flags(net,&sockaddr_in->sin6_addr,dev, !strict, 0,IFA_F_TENTATIVE) &&!ipv6_chk_acast_addr_src(net, dev,&sockaddr_in->sin6_addr))err = -EINVAL;elsefl6->saddr = sockaddr_in->sin6_addr;}if (err)goto exit_f;break;}case IPV6_FLOWINFO: if (cmsg->cmsg_len < CMSG_LEN(4)) { err = -EINVAL;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 6602a2e9cdb5..6121cbb71ad3 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1476,6 +1476,12 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_uid = sk->sk_uid;
- /* We use fl6's daddr and fl6_sport in the reverse sk_lookup done
* within ip6_datagram_send_ctl() now.*/- fl6->daddr = *daddr;
- fl6->fl6_sport = inet->inet_sport;
- if (msg->msg_controllen) { opt = &opt_space; memset(opt, 0, sizeof(struct ipv6_txoptions));
@@ -1511,10 +1517,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_proto = sk->sk_protocol; fl6->flowi6_mark = ipc6.sockc.mark;
fl6->daddr = *daddr; if (ipv6_addr_any(&fl6->saddr) && !ipv6_addr_any(&np->saddr)) fl6->saddr = np->saddr;
fl6->fl6_sport = inet->inet_sport;
if (cgroup_bpf_enabled(CGROUP_UDP6_SENDMSG) && !connected) { err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
-- 2.34.1
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Mon, Sep 23, 2024 at 01:08 PM GMT, David Laight wrote:
From: Tiago Lam tiagolam@cloudflare.com
[...]
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Is that really useful/necessary?
We've been asking ourselves the same question during Plumbers with Martin.
Unprivileges processes can already source UDP traffic from (almost) any IP & port by binding a socket to the desired source port and passing IP_PKTINFO. So perhaps having a reverse socket lookup is an overkill.
We should probably respect net.ipv4.ip_local_reserved_ports and net.ipv4.ip_unprivileged_port_start system settings, though, or check for relevant caps.
Open question if it is acceptable to disregard exclusive UDP port ownership by sockets binding to a wildcard address without SO_REUSEADDR?
[...]
The check (but not the commit message) implies that some 'bpf thingy' also needs to be enabled. Any check would need to include the test that the program sending the packet has the ability to send a packet through the ingress socket. Additionally a check for the sending process having (IIRC) CAP_NET_ADMIN (which would let the process send the message by other means) would save the slow path.
The code we have sends a lot of UDP RTP (typically 160 bytes of audio every 20ms). There is actually no reason for there to be a valid matching ingress path. (That code would benefit from being able to bind a lot of ports to the same UDP socket.)
David
Suggested-by: Jakub Sitnicki jakub@cloudflare.com Signed-off-by: Tiago Lam tiagolam@cloudflare.com
net/ipv6/datagram.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++++++++ net/ipv6/udp.c | 8 ++++-- 2 files changed, 85 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/datagram.c b/net/ipv6/datagram.c index fff78496803d..369c64a478ec 100644 --- a/net/ipv6/datagram.c +++ b/net/ipv6/datagram.c @@ -756,6 +756,29 @@ void ip6_datagram_recv_ctl(struct sock *sk, struct msghdr *msg, } EXPORT_SYMBOL_GPL(ip6_datagram_recv_ctl);
+static inline bool reverse_sk_lookup(struct flowi6 *fl6, struct sock *sk,
struct in6_addr *saddr, __be16 sport)+{
- if (static_branch_unlikely(&bpf_sk_lookup_enabled) &&
(saddr && sport) &&(ipv6_addr_cmp(&sk->sk_v6_rcv_saddr, saddr) ||inet_sk(sk)->inet_sport != sport)) {struct sock *sk_egress;bpf_sk_lookup_run_v6(sock_net(sk), IPPROTO_UDP, &fl6->daddr,fl6->fl6_dport, saddr, ntohs(sport), 0,&sk_egress);if (!IS_ERR_OR_NULL(sk_egress) && sk_egress == sk)return true;net_info_ratelimited("No reverse socket lookup match for local addr %pI6:%d remote addr%pI6:%d\n",
&saddr, ntohs(sport), &fl6->daddr,ntohs(fl6->fl6_dport));- }
- return false;
+}
int ip6_datagram_send_ctl(struct net *net, struct sock *sk, struct msghdr *msg, struct flowi6 *fl6, struct ipcm6_cookie *ipc6) @@ -844,7 +867,63 @@ int ip6_datagram_send_ctl(struct net *net, struct sock *sk,
break; }
case IPV6_ORIGDSTADDR:{struct sockaddr_in6 *sockaddr_in;struct net_device *dev = NULL;if (cmsg->cmsg_len < CMSG_LEN(sizeof(struct sockaddr_in6))) {err = -EINVAL;goto exit_f;}sockaddr_in = (struct sockaddr_in6 *)CMSG_DATA(cmsg);addr_type = __ipv6_addr_type(&sockaddr_in->sin6_addr);if (addr_type & IPV6_ADDR_LINKLOCAL)return -EINVAL;/* If we're egressing with a different source address* and/or port, we perform a reverse socket lookup. The* rationale behind this is that we can allow return* UDP traffic that has ingressed through sk_lookup to* also egress correctly. In case the reverse lookup* fails, we continue with the normal path.** The lookup is performed if either source address* and/or port changed, and neither is "0".*/if (reverse_sk_lookup(fl6, sk, &sockaddr_in->sin6_addr,sockaddr_in->sin6_port)) {/* Override the source port and address to use* with the one we got in cmsg and bail early.*/fl6->saddr = sockaddr_in->sin6_addr;fl6->fl6_sport = sockaddr_in->sin6_port;break;}if (addr_type != IPV6_ADDR_ANY) {int strict = __ipv6_addr_src_scope(addr_type) <= IPV6_ADDR_SCOPE_LINKLOCAL;if (!ipv6_can_nonlocal_bind(net, inet_sk(sk)) &&!ipv6_chk_addr_and_flags(net,&sockaddr_in->sin6_addr,dev, !strict, 0,IFA_F_TENTATIVE) &&!ipv6_chk_acast_addr_src(net, dev,&sockaddr_in->sin6_addr))err = -EINVAL;elsefl6->saddr = sockaddr_in->sin6_addr;}if (err)goto exit_f;break;}case IPV6_FLOWINFO: if (cmsg->cmsg_len < CMSG_LEN(4)) { err = -EINVAL;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c index 6602a2e9cdb5..6121cbb71ad3 100644 --- a/net/ipv6/udp.c +++ b/net/ipv6/udp.c @@ -1476,6 +1476,12 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_uid = sk->sk_uid;
- /* We use fl6's daddr and fl6_sport in the reverse sk_lookup done
* within ip6_datagram_send_ctl() now.*/- fl6->daddr = *daddr;
- fl6->fl6_sport = inet->inet_sport;
- if (msg->msg_controllen) { opt = &opt_space; memset(opt, 0, sizeof(struct ipv6_txoptions));
@@ -1511,10 +1517,8 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
fl6->flowi6_proto = sk->sk_protocol; fl6->flowi6_mark = ipc6.sockc.mark;
fl6->daddr = *daddr; if (ipv6_addr_any(&fl6->saddr) && !ipv6_addr_any(&np->saddr)) fl6->saddr = np->saddr;
fl6->fl6_sport = inet->inet_sport;
if (cgroup_bpf_enabled(CGROUP_UDP6_SENDMSG) && !connected) { err = BPF_CGROUP_RUN_PROG_UDP6_SENDMSG_LOCK(sk,
-- 2.34.1
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
From: Jakub Sitnicki
Sent: 23 September 2024 15:56
On Mon, Sep 23, 2024 at 01:08 PM GMT, David Laight wrote:
From: Tiago Lam tiagolam@cloudflare.com
[...]
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Is that really useful/necessary?
We've been asking ourselves the same question during Plumbers with Martin.
Unprivileges processes can already source UDP traffic from (almost) any IP & port by binding a socket to the desired source port and passing IP_PKTINFO. So perhaps having a reverse socket lookup is an overkill.
Traditionally you'd need to bind to the source port on any local IP (or the wildcard IP) that didn't have another socket bound to that port. Modern Linux might have more restrictions and SO_REUSADDR muddies things.
And I don't think you can do a connect() on an unbound UDP socket to set the source port at the same time as the destination IP+port. (That would actually be useful.)
OTOH if you just want to send a UDP message you can just use another system on the same network. You might need to spoof the source mac - but that isn't hard (although it might confuse any ethernet switches).
We should probably respect net.ipv4.ip_local_reserved_ports and net.ipv4.ip_unprivileged_port_start system settings, though, or check for relevant caps.
True.
Open question if it is acceptable to disregard exclusive UDP port ownership by sockets binding to a wildcard address without SO_REUSEADDR?
We've often suffered from the opposite - a program binds to the wildcard IP and everything works until something else binds to the same port and a specific local IP. I'm sure this is grief some on both TCP and UDP - especially since you often need to set SO_REUSADDR to stop other things breaking.
David
- Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
On Mon, Sep 23, 2024 at 03:45 PM GMT, David Laight wrote:
From: Jakub Sitnicki
Sent: 23 September 2024 15:56
On Mon, Sep 23, 2024 at 01:08 PM GMT, David Laight wrote:
From: Tiago Lam tiagolam@cloudflare.com
[...]
To limit its usage, a reverse socket lookup is performed to check if the configured egress source address and/or port have any ingress sk_lookup match. If it does, traffic is allowed to proceed, otherwise it falls back to the regular egress path.
Is that really useful/necessary?
We've been asking ourselves the same question during Plumbers with Martin.
Unprivileges processes can already source UDP traffic from (almost) any IP & port by binding a socket to the desired source port and passing IP_PKTINFO. So perhaps having a reverse socket lookup is an overkill.
Traditionally you'd need to bind to the source port on any local IP (or the wildcard IP) that didn't have another socket bound to that port.
Right. Linux IP_PKTINFO extension relaxes this requirement. You can bind to some local IP (whichever is free, plently to choose from in 127/8 local subnet), and specify the source address to use OOB at sendmsg() time (as long as the address is local to the host, otherwise you need additional capabilities).
Modern Linux might have more restrictions and SO_REUSADDR muddies things.
And I don't think you can do a connect() on an unbound UDP socket to set the source port at the same time as the destination IP+port. (That would actually be useful.)
You can. It's somewhat recent (v6.3+) [1]:
https://manpages.debian.org/unstable/manpages/ip.7.en.html#IP_LOCAL_PORT_RAN...
It's not on par with TCP when it comes to local port sharing because we hash UDP sockets only by 2-tuple. Though, some effort to improve that is taking place I see.
The recipe is:
1. delay the auto-bind until connect() time with IP_BIND_ADDRESS_NO_PORT socket option, and 2. tell the udp stack to consider only a single local port during the free port search with IP_LOCAL_PORT_RANGE option.
That amounts to something like (in pseudocode):
s = socket(AF_INET, SOCK_DGRAM) s.setsockopt(SOL_IP, IP_BIND_ADDRESS_NO_PORT, 1) s.setsockopt(SOL_IP, IP_LOCAL_PORT_RANGE, 44_444 << 16 | 44_444) s.bind(("192.0.2.42", 0)) s.connect(("1.1.1.1", 53))
You can combine it with SO_REUSEADDR to share the local address between sockets, but you have to ensure manually that you don't run into conflicts between sockets (two sockets using the same 4-tuple). That's something we're hoping to improve in the future.
OTOH if you just want to send a UDP message you can just use another system on the same network. You might need to spoof the source mac - but that isn't hard (although it might confuse any ethernet switches).
We should probably respect net.ipv4.ip_local_reserved_ports and net.ipv4.ip_unprivileged_port_start system settings, though, or check for relevant caps.
True.
Open question if it is acceptable to disregard exclusive UDP port ownership by sockets binding to a wildcard address without SO_REUSEADDR?
We've often suffered from the opposite - a program binds to the wildcard IP and everything works until something else binds to the same port and a specific local IP.
Let me see if I understand - what would happen today for UDP is:
app #1 - bind(("0.0.0.0", 53)) -> OK app #2 - bind(("192.0.2.1", 53)) -> EADDRINUSE
... unless both are setting SO_REUSEADDR (or SO_REUSEPORT and run under same UID).
That is why if we allow selecting the source port at sendmsg() time, we would be relaxing the existing UDP port ownership guarantees for wildcard binds.
Perhaps this merits a sysctl, so the admin can decide if it is an acceptable trade-off in their environment.
I'm sure this is grief some on both TCP and UDP - especially since you often need to set SO_REUSADDR to stop other things breaking.
David
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)
This patch reuses the framework already in place for sk_lookup, allowing it now to send a reply from the server fd directly, instead of having to create a socket bound to the original destination address and reply from there. It does this by passing the source address and port from where to reply from in a IP_ORIGDSTADDR ancillary message passed in sendmsg.
Signed-off-by: Tiago Lam tiagolam@cloudflare.com --- tools/testing/selftests/bpf/prog_tests/sk_lookup.c | 67 +++++++++++++++------- 1 file changed, 45 insertions(+), 22 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c index ae87c00867ba..df780624c16c 100644 --- a/tools/testing/selftests/bpf/prog_tests/sk_lookup.c +++ b/tools/testing/selftests/bpf/prog_tests/sk_lookup.c @@ -75,6 +75,7 @@ struct test { struct inet_addr listen_at; enum server accept_on; bool reuseport_has_conns; /* Add a connected socket to reuseport group */ + bool dont_bind_reply; /* Don't bind, send direct from server fd. */ };
struct cb_opts { @@ -363,7 +364,7 @@ static void v4_to_v6(struct sockaddr_storage *ss) memset(&v6->sin6_addr.s6_addr[0], 0, 10); }
-static int udp_recv_send(int server_fd) +static int udp_recv_send(int server_fd, bool dont_bind_reply) { char cmsg_buf[CMSG_SPACE(sizeof(struct sockaddr_storage))]; struct sockaddr_storage _src_addr = { 0 }; @@ -373,7 +374,7 @@ static int udp_recv_send(int server_fd) struct iovec iov = { 0 }; struct cmsghdr *cm; char buf[1]; - int ret, fd; + int fd; ssize_t n;
iov.iov_base = buf; @@ -415,26 +416,37 @@ static int udp_recv_send(int server_fd) v4_to_v6(dst_addr); }
- /* Reply from original destination address. */ - fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), NULL); - if (!ASSERT_OK_FD(fd, "start_server_addr")) { - log_err("failed to create tx socket"); - return -1; - } + if (dont_bind_reply) { + /* Reply directly from server fd, specifying the source address + * and/or port in struct msghdr. + */ + n = sendmsg(server_fd, &msg, 0); + if (CHECK(n <= 0, "sendmsg", "failed\n")) { + log_err("failed to send echo reply"); + return -1; + } + } else { + /* Reply from original destination address. */ + fd = start_server_addr(SOCK_DGRAM, dst_addr, sizeof(*dst_addr), + NULL); + if (!ASSERT_OK_FD(fd, "start_server_addr")) { + log_err("failed to create tx socket"); + return -1; + }
- msg.msg_control = NULL; - msg.msg_controllen = 0; - n = sendmsg(fd, &msg, 0); - if (CHECK(n <= 0, "sendmsg", "failed\n")) { - log_err("failed to send echo reply"); - ret = -1; - goto out; + msg.msg_control = NULL; + msg.msg_controllen = 0; + n = sendmsg(fd, &msg, 0); + if (CHECK(n <= 0, "sendmsg", "failed\n")) { + log_err("failed to send echo reply"); + close(fd); + return -1; + } + + close(fd); }
- ret = 0; -out: - close(fd); - return ret; + return 0; }
static int tcp_echo_test(int client_fd, int server_fd) @@ -454,14 +466,14 @@ static int tcp_echo_test(int client_fd, int server_fd) return 0; }
-static int udp_echo_test(int client_fd, int server_fd) +static int udp_echo_test(int client_fd, int server_fd, bool dont_bind_reply) { int err;
err = send_byte(client_fd); if (err) return -1; - err = udp_recv_send(server_fd); + err = udp_recv_send(server_fd, dont_bind_reply); if (err) return -1; err = recv_byte(client_fd); @@ -653,7 +665,8 @@ static void run_lookup_prog(const struct test *t) if (t->sotype == SOCK_STREAM) tcp_echo_test(client_fd, server_fds[t->accept_on]); else - udp_echo_test(client_fd, server_fds[t->accept_on]); + udp_echo_test(client_fd, server_fds[t->accept_on], + t->dont_bind_reply);
close(client_fd); close: @@ -775,6 +788,16 @@ static void test_redirect_lookup(struct test_sk_lookup *skel) .listen_at = { INT_IP4, INT_PORT }, .accept_on = SERVER_B, }, + { + .desc = "UDP IPv4 redir different ports", + .lookup_prog = skel->progs.select_sock_a_no_reuseport, + .sock_map = skel->maps.redir_map, + .sotype = SOCK_DGRAM, + .connect_to = { EXT_IP4, EXT_PORT }, + .listen_at = { INT_IP4, INT_PORT }, + .accept_on = SERVER_A, + .dont_bind_reply = true, + }, { .desc = "UDP IPv4 redir and reuseport with conns", .lookup_prog = skel->progs.select_sock_a,
Just an FYI to the reviewers -
Tiago is out this week, so his reponses will be delayed.
linux-kselftest-mirror@lists.linaro.org
-
David Laight -
ericnetdev dumazet -
Jakub Sitnicki -
Tiago Lam -
Willem de Bruijn