linux.git/net/ipv4, branch v5.12.5

net: Only allow init netns to set default tcp cong to a restricted algo

2021-05-14T08:53:06+00:00

commit 8d432592f30fcc34ef5a10aac4887b4897884493 upstream.

tcp_set_default_congestion_control() is netns-safe in that it writes
to &net->ipv4.tcp_congestion_control, but it also sets
ca->flags |= TCP_CONG_NON_RESTRICTED which is not namespaced.
This has the unintended side-effect of changing the global
net.ipv4.tcp_allowed_congestion_control sysctl, despite the fact that it
is read-only: 97684f0970f6 ("net: Make tcp_allowed_congestion_control
readonly in non-init netns")

Resolve this netns "leak" by only allowing the init netns to set the
default algorithm to one that is restricted. This restriction could be
removed if tcp_allowed_congestion_control were namespace-ified in the
future.

This bug was uncovered with
https://github.com/JonathonReinhart/linux-netns-sysctl-verify

Fixes: 6670e1524477 ("tcp: Namespace-ify sysctl_tcp_default_congestion_control")
Signed-off-by: Jonathon Reinhart 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

udp: never accept GSO_FRAGLIST packets

2021-05-14T08:52:47+00:00

[ Upstream commit 78352f73dc5047f3f744764cc45912498c52f3c9 ]

Currently the UDP protocol delivers GSO_FRAGLIST packets to
the sockets without the expected segmentation.

This change addresses the issue introducing and maintaining
a couple of new fields to explicitly accept SKB_GSO_UDP_L4
or GSO_FRAGLIST packets. Additionally updates  udp_unexpected_gso()
accordingly.

UDP sockets enabling UDP_GRO stil keep accept_udp_fraglist
zeroed.

v1 -> v2:
 - use 2 bits instead of a whole GSO bitmask (Willem)

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Signed-off-by: Paolo Abeni 
Reviewed-by: Willem de Bruijn 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

udp: skip L4 aggregation for UDP tunnel packets

2021-05-14T08:52:47+00:00

[ Upstream commit 18f25dc399901426dff61e676ba603ff52c666f7 ]

If NETIF_F_GRO_FRAGLIST or NETIF_F_GRO_UDP_FWD are enabled, and there
are UDP tunnels available in the system, udp_gro_receive() could end-up
doing L4 aggregation (either SKB_GSO_UDP_L4 or SKB_GSO_FRAGLIST) at
the outer UDP tunnel level for packets effectively carrying and UDP
tunnel header.

That could cause inner protocol corruption. If e.g. the relevant
packets carry a vxlan header, different vxlan ids will be ignored/
aggregated to the same GSO packet. Inner headers will be ignored, too,
so that e.g. TCP over vxlan push packets will be held in the GRO
engine till the next flush, etc.

Just skip the SKB_GSO_UDP_L4 and SKB_GSO_FRAGLIST code path if the
current packet could land in a UDP tunnel, and let udp_gro_receive()
do GRO via udp_sk(sk)->gro_receive.

The check implemented in this patch is broader than what is strictly
needed, as the existing UDP tunnel could be e.g. configured on top of
a different device: we could end-up skipping GRO at-all for some packets.

Anyhow, that is a very thin corner case and covering it will add quite
a bit of complexity.

v1 -> v2:
 - hopefully clarify the commit message

Fixes: 9fd1ff5d2ac7 ("udp: Support UDP fraglist GRO/GSO.")
Fixes: 36707061d6ba ("udp: allow forwarding of plain (non-fraglisted) UDP GRO packets")
Reviewed-by: Willem de Bruijn 
Signed-off-by: Paolo Abeni 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

inet: use bigger hash table for IP ID generation

2021-05-14T08:52:46+00:00

[ Upstream commit aa6dd211e4b1dde9d5dc25d699d35f789ae7eeba ]

In commit 73f156a6e8c1 ("inetpeer: get rid of ip_id_count")
I used a very small hash table that could be abused
by patient attackers to reveal sensitive information.

Switch to a dynamic sizing, depending on RAM size.

Typical big hosts will now use 128x more storage (2 MB)
to get a similar increase in security and reduction
of hash collisions.

As a bonus, use of alloc_large_system_hash() spreads
allocated memory among all NUMA nodes.

Fixes: 73f156a6e8c1 ("inetpeer: get rid of ip_id_count")
Reported-by: Amit Klein 
Signed-off-by: Eric Dumazet 
Cc: Willy Tarreau 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

net: Make tcp_allowed_congestion_control readonly in non-init netns

2021-04-13T21:42:51+00:00

Currently, tcp_allowed_congestion_control is global and writable;
writing to it in any net namespace will leak into all other net
namespaces.

tcp_available_congestion_control and tcp_allowed_congestion_control are
the only sysctls in ipv4_net_table (the per-netns sysctl table) with a
NULL data pointer; their handlers (proc_tcp_available_congestion_control
and proc_allowed_congestion_control) have no other way of referencing a
struct net. Thus, they operate globally.

Because ipv4_net_table does not use designated initializers, there is no
easy way to fix up this one "bad" table entry. However, the data pointer
updating logic shouldn't be applied to NULL pointers anyway, so we
instead force these entries to be read-only.

These sysctls used to exist in ipv4_table (init-net only), but they were
moved to the per-net ipv4_net_table, presumably without realizing that
tcp_allowed_congestion_control was writable and thus introduced a leak.

Because the intent of that commit was only to know (i.e. read) "which
congestion algorithms are available or allowed", this read-only solution
should be sufficient.

The logic added in recent commit
31c4d2f160eb: ("net: Ensure net namespace isolation of sysctls")
does not and cannot check for NULL data pointers, because
other table entries (e.g. /proc/sys/net/netfilter/nf_log/) have
.data=NULL but use other methods (.extra2) to access the struct net.

Fixes: 9cb8e048e5d9 ("net/ipv4/sysctl: show tcp_{allowed, available}_congestion_control in non-initial netns")
Signed-off-by: Jonathon Reinhart 
Signed-off-by: David S. Miller

Merge git://git.kernel.org/pub/scm/linux/kernel/git/pablo/nf

2021-04-12T23:17:50+00:00

Pablo Neira Ayuso says:

====================
Netfilter fixes for net

The following patchset contains Netfilter fixes for net:

1) Fix NAT IPv6 offload in the flowtable.

2) icmpv6 is printed as unknown in /proc/net/nf_conntrack.

3) Use div64_u64() in nft_limit, from Eric Dumazet.

4) Use pre_exit to unregister ebtables and arptables hooks,
   from Florian Westphal.

5) Fix out-of-bound memset in x_tables compat match/target,
   also from Florian.

6) Clone set elements expression to ensure proper initialization.
====================

Signed-off-by: David S. Miller

netfilter: x_tables: fix compat match/target pad out-of-bound write

2021-04-12T22:18:57+00:00

xt_compat_match/target_from_user doesn't check that zeroing the area
to start of next rule won't write past end of allocated ruleset blob.

Remove this code and zero the entire blob beforehand.

Reported-by: syzbot+cfc0247ac173f597aaaa@syzkaller.appspotmail.com
Reported-by: Andy Nguyen 
Fixes: 9fa492cdc160c ("[NETFILTER]: x_tables: simplify compat API")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

netfilter: arp_tables: add pre_exit hook for table unregister

2021-04-10T19:18:24+00:00

Same problem that also existed in iptables/ip(6)tables, when
arptable_filter is removed there is no longer a wait period before the
table/ruleset is free'd.

Unregister the hook in pre_exit, then remove the table in the exit
function.
This used to work correctly because the old nf_hook_unregister API
did unconditional synchronize_net.

The per-net hook unregister function uses call_rcu instead.

Fixes: b9e69e127397 ("netfilter: xtables: don't hook tables by default")
Signed-off-by: Florian Westphal 
Signed-off-by: Pablo Neira Ayuso

ipv6: report errors for iftoken via netlink extack

2021-04-08T20:52:36+00:00

Setting iftoken can fail for several different reasons but there
and there was no report to user as to the cause. Add netlink
extended errors to the processing of the request.

This requires adding additional argument through rtnl_af_ops
set_link_af callback.

Reported-by: Hongren Zheng 
Signed-off-by: Stephen Hemminger 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller

net: udp: Add support for getsockopt(..., ..., UDP_GRO, ..., ...);

2021-04-01T22:50:50+00:00

Support for UDP_GRO was added in the past but the implementation for
getsockopt was missed which did lead to an error when we tried to
retrieve the setting for UDP_GRO. This patch adds the missing switch
case for UDP_GRO

Fixes: e20cf8d3f1f7 ("udp: implement GRO for plain UDP sockets.")
Signed-off-by: Norman Maurer 
Reviewed-by: David Ahern 
Signed-off-by: David S. Miller