linux.git/net/ipv4/ip_output.c, branch v6.9

ipv4: Fix uninit-value access in __ip_make_skb()

2024-05-02T08:16:35+00:00

KMSAN reported uninit-value access in __ip_make_skb() [1].  __ip_make_skb()
tests HDRINCL to know if the skb has icmphdr. However, HDRINCL can cause a
race condition. If calling setsockopt(2) with IP_HDRINCL changes HDRINCL
while __ip_make_skb() is running, the function will access icmphdr in the
skb even if it is not included. This causes the issue reported by KMSAN.

Check FLOWI_FLAG_KNOWN_NH on fl4->flowi4_flags instead of testing HDRINCL
on the socket.

Also, fl4->fl4_icmp_type and fl4->fl4_icmp_code are not initialized. These
are union in struct flowi4 and are implicitly initialized by
flowi4_init_output(), but we should not rely on specific union layout.

Initialize these explicitly in raw_sendmsg().

[1]
BUG: KMSAN: uninit-value in __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481
 __ip_make_skb+0x2b74/0x2d20 net/ipv4/ip_output.c:1481
 ip_finish_skb include/net/ip.h:243 [inline]
 ip_push_pending_frames+0x4c/0x5c0 net/ipv4/ip_output.c:1508
 raw_sendmsg+0x2381/0x2690 net/ipv4/raw.c:654
 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x274/0x3c0 net/socket.c:745
 __sys_sendto+0x62c/0x7b0 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x130/0x200 net/socket.c:2199
 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

Uninit was created at:
 slab_post_alloc_hook mm/slub.c:3804 [inline]
 slab_alloc_node mm/slub.c:3845 [inline]
 kmem_cache_alloc_node+0x5f6/0xc50 mm/slub.c:3888
 kmalloc_reserve+0x13c/0x4a0 net/core/skbuff.c:577
 __alloc_skb+0x35a/0x7c0 net/core/skbuff.c:668
 alloc_skb include/linux/skbuff.h:1318 [inline]
 __ip_append_data+0x49ab/0x68c0 net/ipv4/ip_output.c:1128
 ip_append_data+0x1e7/0x260 net/ipv4/ip_output.c:1365
 raw_sendmsg+0x22b1/0x2690 net/ipv4/raw.c:648
 inet_sendmsg+0x27b/0x2a0 net/ipv4/af_inet.c:851
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg+0x274/0x3c0 net/socket.c:745
 __sys_sendto+0x62c/0x7b0 net/socket.c:2191
 __do_sys_sendto net/socket.c:2203 [inline]
 __se_sys_sendto net/socket.c:2199 [inline]
 __x64_sys_sendto+0x130/0x200 net/socket.c:2199
 do_syscall_64+0xd8/0x1f0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x6d/0x75

CPU: 1 PID: 15709 Comm: syz-executor.7 Not tainted 6.8.0-11567-gb3603fcb79b1 #25
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.3-1.fc39 04/01/2014

Fixes: 99e5acae193e ("ipv4: Fix potential uninit variable access bug in __ip_make_skb()")
Reported-by: syzkaller 
Signed-off-by: Shigeru Yoshida 
Link: https://lore.kernel.org/r/20240430123945.2057348-1-syoshida@redhat.com
Signed-off-by: Paolo Abeni

Revert "net: Re-use and set mono_delivery_time bit for userspace tstamp packets"

2024-03-18T12:29:53+00:00

This reverts commit 885c36e59f46375c138de18ff1692f18eff67b7f.

The patch currently broke the bpf selftest test_tc_dtime because
uapi field __sk_buff->tstamp_type depends on skb->mono_delivery_time which
does not necessarily mean mono with the original fix as the bit was re-used
for userspace timestamp as well to avoid tstamp reset in the forwarding
path. To solve this we need to keep mono_delivery_time as is and
introduce another bit called user_delivery_time and fall back to the
initial proposal of setting the user_delivery_time bit based on
sk_clockid set from userspace.

Fixes: 885c36e59f46 ("net: Re-use and set mono_delivery_time bit for userspace tstamp packets")
Link: https://lore.kernel.org/netdev/bc037db4-58bb-4861-ac31-a361a93841d3@linux.dev/
Signed-off-by: Abhishek Chauhan 
Acked-by: Daniel Borkmann 
Acked-by: Martin KaFai Lau 
Signed-off-by: David S. Miller

net: Re-use and set mono_delivery_time bit for userspace tstamp packets

2024-03-05T12:41:16+00:00

Bridge driver today has no support to forward the userspace timestamp
packets and ends up resetting the timestamp. ETF qdisc checks the
packet coming from userspace and encounters to be 0 thereby dropping
time sensitive packets. These changes will allow userspace timestamps
packets to be forwarded from the bridge to NIC drivers.

Setting the same bit (mono_delivery_time) to avoid dropping of
userspace tstamp packets in the forwarding path.

Existing functionality of mono_delivery_time remains unaltered here,
instead just extended with userspace tstamp support for bridge
forwarding path.

Signed-off-by: Abhishek Chauhan 
Reviewed-by: Willem de Bruijn 
Link: https://lore.kernel.org/r/20240301201348.2815102-1-quic_abchauha@quicinc.com
Signed-off-by: Paolo Abeni

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2024-02-16T00:20:04+00:00

Cross-merge networking fixes after downstream PR.

No conflicts.

Adjacent changes:

net/core/dev.c
  9f30831390ed ("net: add rcu safety to rtnl_prop_list_size()")
  723de3ebef03 ("net: free altname using an RCU callback")

net/unix/garbage.c
  11498715f266 ("af_unix: Remove io_uring code for GC.")
  25236c91b5ab ("af_unix: Fix task hung while purging oob_skb in GC.")

drivers/net/ethernet/renesas/ravb_main.c
  ed4adc07207d ("net: ravb: Count packets instead of descriptors in GbEth RX path"
)
  c2da9408579d ("ravb: Add Rx checksum offload support for GbEth")

net/mptcp/protocol.c
  bdd70eb68913 ("mptcp: drop the push_pending field")
  28e5c1380506 ("mptcp: annotate lockless accesses around read-mostly fields")

Signed-off-by: Jakub Kicinski

net-timestamp: make sk_tskey more predictable in error path

2024-02-15T11:04:04+00:00

When SOF_TIMESTAMPING_OPT_ID is used to ambiguate timestamped datagrams,
the sk_tskey can become unpredictable in case of any error happened
during sendmsg(). Move increment later in the code and make decrement of
sk_tskey in error path. This solution is still racy in case of multiple
threads doing snedmsg() over the very same socket in parallel, but still
makes error path much more predictable.

Fixes: 09c2d251b707 ("net-timestamp: add key to disambiguate concurrent datagrams")
Reported-by: Andy Lutomirski 
Signed-off-by: Vadim Fedorenko 
Reviewed-by: Willem de Bruijn 
Link: https://lore.kernel.org/r/20240213110428.1681540-1-vadfed@meta.com
Signed-off-by: Paolo Abeni

ipv4: Set the routing scope properly in ip_route_output_ports().

2024-02-13T01:33:05+00:00

Set scope automatically in ip_route_output_ports() (using the socket
SOCK_LOCALROUTE flag). This way, callers don't have to overload the
tos with the RTO_ONLINK flag, like RT_CONN_FLAGS() does.

For callers that don't pass a struct sock, this doesn't change anything
as the scope is still set to RT_SCOPE_UNIVERSE when sk is NULL.

Callers that passed a struct sock and used RT_CONN_FLAGS(sk) or
RT_CONN_FLAGS_TOS(sk, tos) for the tos are modified to use
ip_sock_tos(sk) and RT_TOS(tos) respectively, as overloading tos with
the RTO_ONLINK flag now becomes unnecessary.

In drivers/net/amt.c, all ip_route_output_ports() calls use a 0 tos
parameter, ignoring the SOCK_LOCALROUTE flag of the socket. But the sk
parameter is a kernel socket, which doesn't have any configuration path
for setting SOCK_LOCALROUTE anyway. Therefore, ip_route_output_ports()
will continue to initialise scope with RT_SCOPE_UNIVERSE and amt.c
doesn't need to be modified.

Also, remove RT_CONN_FLAGS() and RT_CONN_FLAGS_TOS() from route.h as
these macros are now unused.

The objective is to eventually remove RTO_ONLINK entirely to allow
converting ->flowi4_tos to dscp_t. This will ensure proper isolation
between the DSCP and ECN bits, thus minimising the risk of introducing
bugs where TOS values interfere with ECN.

Signed-off-by: Guillaume Nault 
Reviewed-by: David Ahern 
Link: https://lore.kernel.org/r/dacfd2ab40685e20959ab7b53c427595ba229e7d.1707496938.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski

net: ipv4: fix a memleak in ip_setup_cork

2024-01-31T23:53:25+00:00

When inetdev_valid_mtu fails, cork->opt should be freed if it is
allocated in ip_setup_cork. Otherwise there could be a memleak.

Fixes: 501a90c94510 ("inet: protect against too small mtu values.")
Signed-off-by: Zhipeng Lu 
Reviewed-by: Eric Dumazet 
Link: https://lore.kernel.org/r/20240129091017.2938835-1-alexious@zju.edu.cn
Signed-off-by: Jakub Kicinski

net: fix IPSTATS_MIB_OUTPKGS increment in OutForwDatagrams.

2023-10-20T11:01:00+00:00

Reproduce environment:
network with 3 VM linuxs is connected as below:
VM1<---->VM2(latest kernel 6.5.0-rc7)<---->VM3
VM1: eth0 ip: 192.168.122.207 MTU 1500
VM2: eth0 ip: 192.168.122.208, eth1 ip: 192.168.123.224 MTU 1500
VM3: eth0 ip: 192.168.123.240 MTU 1500

Reproduce:
VM1 send 1400 bytes UDP data to VM3 using tools scapy with flags=0.
scapy command:
send(IP(dst="192.168.123.240",flags=0)/UDP()/str('0'*1400),count=1,
inter=1.000000)

Result:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates
Ip: 1 64 11 0 3 4 0 0 4 7 0 0 0 0 0 0 0 0 0
......
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates
Ip: 1 64 12 0 3 5 0 0 4 8 0 0 0 0 0 0 0 0 0
......
----------------------------------------------------------------------
"ForwDatagrams" increase from 4 to 5 and "OutRequests" also increase
from 7 to 8.

Issue description and patch:
IPSTATS_MIB_OUTPKTS("OutRequests") is counted with IPSTATS_MIB_OUTOCTETS
("OutOctets") in ip_finish_output2().
According to RFC 4293, it is "OutOctets" counted with "OutTransmits" but
not "OutRequests". "OutRequests" does not include any datagrams counted
in "ForwDatagrams".
ipSystemStatsOutOctets OBJECT-TYPE
    DESCRIPTION
           "The total number of octets in IP datagrams delivered to the
            lower layers for transmission.  Octets from datagrams
            counted in ipIfStatsOutTransmits MUST be counted here.
ipSystemStatsOutRequests OBJECT-TYPE
    DESCRIPTION
           "The total number of IP datagrams that local IP user-
            protocols (including ICMP) supplied to IP in requests for
            transmission.  Note that this counter does not include any
            datagrams counted in ipSystemStatsOutForwDatagrams.
So do patch to define IPSTATS_MIB_OUTPKTS to "OutTransmits" and add
IPSTATS_MIB_OUTREQUESTS for "OutRequests".
Add IPSTATS_MIB_OUTREQUESTS counter in __ip_local_out() for ipv4 and add
IPSTATS_MIB_OUT counter in ip6_finish_output2() for ipv6.

Test result with patch:
Before IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates OutTransmits
Ip: 1 64 9 0 5 1 0 0 3 3 0 0 0 0 0 0 0 0 0 4
......
root@qemux86-64:~# cat /proc/net/netstat
......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
  OutBcastPkts InOctets OutOctets InMcastOctets OutMcastOctets
  InBcastOctets OutBcastOctets InCsumErrors InNoECTPkts InECT1Pkts
  InECT0Pkts InCEPkts ReasmOverlaps
IpExt: 0 0 0 0 0 0 2976 1896 0 0 0 0 0 9 0 0 0 0
----------------------------------------------------------------------
After IP data is sent.
----------------------------------------------------------------------
root@qemux86-64:~# cat /proc/net/snmp
Ip: Forwarding DefaultTTL InReceives InHdrErrors InAddrErrors
  ForwDatagrams InUnknownProtos InDiscards InDelivers OutRequests
  OutDiscards OutNoRoutes ReasmTimeout ReasmReqds ReasmOKs ReasmFails
  FragOKs FragFails FragCreates OutTransmits
Ip: 1 64 10 0 5 2 0 0 3 3 0 0 0 0 0 0 0 0 0 5
......
root@qemux86-64:~# cat /proc/net/netstat
......
IpExt: InNoRoutes InTruncatedPkts InMcastPkts OutMcastPkts InBcastPkts
  OutBcastPkts InOctets OutOctets InMcastOctets OutMcastOctets
  InBcastOctets OutBcastOctets InCsumErrors InNoECTPkts InECT1Pkts
  InECT0Pkts InCEPkts ReasmOverlaps
IpExt: 0 0 0 0 0 0 4404 3324 0 0 0 0 0 10 0 0 0 0
----------------------------------------------------------------------
"ForwDatagrams" increase from 1 to 2 and "OutRequests" is keeping 3.
"OutTransmits" increase from 4 to 5 and "OutOctets" increase 1428.

Signed-off-by: Heng Guo 
Reviewed-by: Kun Song 
Reviewed-by: Filip Pudak 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller

inet: implement lockless IP_TOS

2023-10-01T18:39:18+00:00

Some reads of inet->tos are racy.

Add needed READ_ONCE() annotations and convert IP_TOS option lockless.

v2: missing changes in include/net/route.h (David Ahern)

Signed-off-by: Eric Dumazet 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller

inet: implement lockless IP_MTU_DISCOVER

2023-10-01T18:39:18+00:00

inet->pmtudisc can be read locklessly.

Implement proper lockless reads and writes to inet->pmtudisc

ip_sock_set_mtu_discover() can now be called from arbitrary
contexts.

Signed-off-by: Eric Dumazet 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller