ip6tunnel_xmit() erases the contents of the SKB control block. In order to
be able to set particular IP6CB flags on the SKB, add a corresponding
parameter, and propagate it to udp_tunnel6_xmit_skb() as well.
In one of the following patches, VXLAN driver will use this facility to
mark packets as subject to IPv6 multicast routing.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://patch.msgid.link/acb4f9f3e40c3a931236c3af08a720b017fbfbfb.1750113335.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
iptunnel_xmit() erases the contents of the SKB control block. In order to
be able to set particular IPCB flags on the SKB, add a corresponding
parameter, and propagate it to udp_tunnel_xmit_skb() as well.
In one of the following patches, VXLAN driver will use this facility to
mark packets as subject to IP multicast routing.
Signed-off-by: Petr Machata <petrm@nvidia.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Nikolay Aleksandrov <razor@blackwall.org>
Acked-by: Antonio Quartulli <antonio@openvpn.net>
Link: https://patch.msgid.link/89c9daf9f2dc088b6b92ccebcc929f51742de91f.1750113335.git.petrm@nvidia.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
gtp_net_exit_batch_rtnl() iterates the dying netns list
and performs the same operations for each.
Let's use ->exit_rtnl().
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Sabrina Dubroca <sd@queasysnail.net>
Link: https://patch.msgid.link/20250411205258.63164-12-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Add two helper functions - rtnl_newlink_link_net() and
rtnl_newlink_peer_net() for netns fallback logic. Peer netns falls back
to link netns, and link netns falls back to source netns.
Convert the use of params->net in netdevice drivers to one of the helper
functions for clarity.
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250219125039.18024-4-shaw.leon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
There are 4 net namespaces involved when creating links:
- source netns - where the netlink socket resides,
- target netns - where to put the device being created,
- link netns - netns associated with the device (backend),
- peer netns - netns of peer device.
Currently, two nets are passed to newlink() callback - "src_net"
parameter and "dev_net" (implicitly in net_device). They are set as
follows, depending on netlink attributes in the request.
+------------+-------------------+---------+---------+
| peer netns | IFLA_LINK_NETNSID | src_net | dev_net |
+------------+-------------------+---------+---------+
| | absent | source | target |
| absent +-------------------+---------+---------+
| | present | link | link |
+------------+-------------------+---------+---------+
| | absent | peer | target |
| present +-------------------+---------+---------+
| | present | peer | link |
+------------+-------------------+---------+---------+
When IFLA_LINK_NETNSID is present, the device is created in link netns
first and then moved to target netns. This has some side effects,
including extra ifindex allocation, ifname validation and link events.
These could be avoided if we create it in target netns from
the beginning.
On the other hand, the meaning of src_net parameter is ambiguous. It
varies depending on how parameters are passed. It is the effective
link (or peer netns) by design, but some drivers ignore it and use
dev_net instead.
To provide more netns context for drivers, this patch packs existing
newlink() parameters, along with the source netns, link netns and peer
netns, into a struct. The old "src_net" is renamed to "net" to avoid
confusion with real source netns, and will be deprecated later. The use
of src_net are converted to params->net trivially.
Signed-off-by: Xiao Liang <shaw.leon@gmail.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://patch.msgid.link/20250219125039.18024-3-shaw.leon@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Use inet_sk_dscp() to get the socket DSCP value as dscp_t, instead of
ip_sock_rt_tos() which returns a __u8. This will ease the conversion
of fl4->flowi4_tos to dscp_t, which now just becomes a matter of
dropping the inet_dscp_to_dsfield() call.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/06bdb310a075355ff059cd32da2efc29a63981c9.1737034675.git.gnault@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
gtp_newlink() links the gtp device to a list in dev_net(dev).
However, even after the gtp device is moved to another netns,
it stays on the list but should be invisible.
Let's use for_each_netdev_rcu() for netdev traversal in
gtp_genl_dump_pdp().
Note that gtp_dev_list is no longer used under RCU, so list
helpers are converted to the non-RCU variant.
Fixes: 459aa660eb ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Reported-by: Xiao Liang <shaw.leon@gmail.com>
Closes: https://lore.kernel.org/netdev/CABAhCOQdBL6h9M2C+kd+bGivRJ9Q72JUxW+-gur0nub_=PmFPA@mail.gmail.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Most of the original conversion is from the spatch below,
but I edited some and left out other instances that were
either buggy after conversion (where default values don't
fit into the type) or just looked strange.
@@
expression attr, def;
expression val;
identifier fn =~ "^nla_get_.*";
fresh identifier dfn = fn ## "_default";
@@
(
-if (attr)
- val = fn(attr);
-else
- val = def;
+val = dfn(attr, def);
|
-if (!attr)
- val = def;
-else
- val = fn(attr);
+val = dfn(attr, def);
|
-if (!attr)
- return def;
-return fn(attr);
+return dfn(attr, def);
|
-attr ? fn(attr) : def
+dfn(attr, def)
|
-!attr ? def : fn(attr)
+dfn(attr, def)
)
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://patch.msgid.link/20241108114145.0580b8684e7f.I740beeaa2f70ebfc19bfca1045a24d6151992790@changeid
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Existing user space applications maintained by the Osmocom project are
breaking since a recent fix that addresses incorrect error checking.
Restore operation for user space programs that specify -1 as file
descriptor to skip GTPv0 or GTPv1 only sockets.
Fixes: defd8b3c37 ("gtp: fix a potential NULL pointer dereference")
Reported-by: Pau Espin Pedrol <pespin@sysmocom.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Tested-by: Oliver Smith <osmith@sysmocom.de>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20241022144825.66740-1-pablo@netfilter.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
NETIF_F_LLTX can't be changed via Ethtool and is not a feature,
rather an attribute, very similar to IFF_NO_QUEUE (and hot).
Free one netdev_features_t bit and make it a "hot" private flag.
Signed-off-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
When sockfd_lookup() fails, gtp_encap_enable_socket() returns a
NULL pointer, but its callers only check for error pointers thus miss
the NULL pointer case.
Fix it by returning an error pointer with the error code carried from
sockfd_lookup().
(I found this bug during code inspection.)
Fixes: 1e3a3abd8b ("gtp: make GTP sockets in gtp_newlink optional")
Cc: Andreas Schultz <aschultz@tpip.net>
Cc: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://patch.msgid.link/20240825191638.146748-1-xiyou.wangcong@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This allows to define a GTP tunnel for dual stack MS/UE with both IPv4
and IPv6 addresses while using the same TEID via two PDP context
objects.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add new protocol field to PDP context that determines the transmit path
IP protocol to encapsulate the original packets, either IPv4 or IPv6.
Relax existing netlink attribute checks to allow to specify different
family in MS and peer attributes from the control plane.
Use build helpers to tx path to encapsulate IPv4-in-IPv6-GTP and
IPv6-in-IPv4-GTP according to the user-specified configuration.
From rx path, snoop for the inner protocol header since outer
skb->protocol might differ and use this to validate for valid PDP
context and to restore skb->protocol after decapsulation.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add routine to attach an IPv6 route for the encapsulated packet, deal
with Path MTU and push GTP header.
This helper function will be used to deal with IPv4-in-IPv6-GTP.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add routine to attach an IPv4 route for the encapsulated packet, deal
with Path MTU and push GTP header.
This helper function will be used to deal with IPv6-in-IPv4-GTP.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Based on the idea that ip_tunnel_get_dsfield() provides the tos field
regardless the IP version, use either iph->tos or ipv6_get_dsfield().
This comes in preparation to support for IPv4-in-IPv6-GTP and
IPv6-in-IPv4-GTP.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Move debugging to the routine to build GTP packets in preparation
for supporting IPv4-in-IPv6-GTP and IPv6-in-IPv4-GTP.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
According to TS 29.061, it is possible to see IPv6 link-local traffic in
the GTP tunnel, see 11.2.1.3.2 IPv6 Stateless Address Autoconfiguration
(IPv6 SLAAC).
Pass up these packets to the userspace daemon to handle them as control
GTP traffic.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Harald Welte reports that according to 3GPP TS 29.060:
PDN Connection: the association between a MS represented by one IPv4
address and/or one IPv6 prefix and a PDN represented by an APN.
this clearly states that IPv4 is a single address while IPv6 is a single prefix.
Then, 3GPP TS 29.061, Section 11.2.1.3:
For APNs that are configured for IPv6 address allocation, the GGSN/P-GW
shall only use the Prefix part of the IPv6 address for forwarding of mobile
terminated IP packets. The size of the prefix shall be according to the maximum
prefix length for a global IPv6 address as specified in the IPv6 Addressing
Architecture, see RFC 4291 [82].
RFC 4291 section 2.5.4 states
All Global Unicast addresses other than those that start with binary 000
have a 64-bit interface ID field (i.e., n + m = 64) ...
3GPP TS 29.61 Section 11.2.1.3.2a:
In the procedure in the cases of using GTP-based S5/S8, P-GW acts as an
access router, and allocates to a UE a globally unique /64 IPv6 prefix if the
PLMN allocates the prefix.
Therefore, compare IPv6 address /64 prefix only since MS/UE is not a single
address like in the IPv4 case.
Reject IPv6 address with EADDRNOTAVAIL if it lower 64 bits of the IPv6 address
from the control plane are set.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Add new iflink attributes to configure in-kernel UDP listener socket
address: IFLA_GTP_LOCAL and IFLA_GTP_LOCAL6. If none of these attributes
are specified, default is still to IPv4 INADDR_ANY for backward
compatibility.
Add new attributes to set up family and IPv6 address of GTP tunnels:
GTPA_FAMILY, GTPA_PEER_ADDR6 and GTPA_MS_ADDR6. If no GTPA_FAMILY is
specified, AF_INET is assumed for backward compatibility.
setsockopt IPV6_ADDRFORM allows to downgrade socket from IPv6 to IPv4
after socket is bound. Assumption is that socket listener that is
attached to the gtp device needs to be either IPv4 or IPv6. Therefore,
GTP socket listener does not allow for IPv4-mapped-IPv6 listener.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Currently GTP packets are dropped if the next extension field is set to
non-zero value, but this are valid GTP packets.
TS 29.281 provides a longer header format, which is defined as struct
gtp1_header_long. Such long header format is used if any of the S, PN, E
flags is set.
This long header is 4 bytes longer than struct gtp1_header, plus
variable length (optional) extension headers. The next extension header
field is zero is no extension header is provided.
The extension header is composed of a length field which includes total
number of 4 byte words including the extension header itself (1 byte),
payload (variable length) and next type (1 byte). The extension header
size and its payload is aligned to 4 bytes.
A GTP packet might come with a chain extensions headers, which makes it
slightly cumbersome to parse because the extension next header field
comes at the end of the extension header, and there is a need to check
if this field becomes zero to stop the extension header parser.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Update b20dc3c684 ("gtp: Allow to create GTP device without FDs") to
remove useless initialization to NULL, sockets are initialized to
non-NULL just a few lines of code after this.
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Since call_rcu, which is called in the hlist_for_each_entry_rcu traversal
of gtp_dellink, is not part of the RCU read critical section, it
is possible that the RCU grace period will pass during the traversal and
the key will be free.
To prevent this, it should be changed to hlist_for_each_entry_safe.
Fixes: 94dc550a50 ("gtp: fix an use-after-free in ipv4_pdp_find()")
Signed-off-by: Hyunwoo Kim <v4bel@theori.io>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Assign netdev to gtp->dev at setup time, so, we can get rid of
gtp_dev_init() completely.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://lore.kernel.org/r/20240305121524.2254533-3-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Commit 3e2f544dd8 ("net: get stats64 if device if driver is
configured") moved the callback to dev_get_tstats64() to net core, so,
unless the driver is doing some custom stats collection, it does not
need to set .ndo_get_stats64.
Since this driver is now relying in NETDEV_PCPU_STAT_TSTATS, then, it
doesn't need to set the dev_get_tstats64() generic .ndo_get_stats64
function pointer.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://lore.kernel.org/r/20240305121524.2254533-2-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
With commit 34d21de99c ("net: Move {l,t,d}stats allocation to core and
convert veth & vrf"), stats allocation could be done on net core
instead of in this driver.
With this new approach, the driver doesn't have to bother with error
handling (allocation failure checking, making sure free happens in the
right spot, etc). This is core responsibility now.
Remove the allocation in the gtp driver and leverage the network
core allocation instead.
Signed-off-by: Breno Leitao <leitao@debian.org>
Acked-by: Pablo Neira Ayuso <pablo@netfilter.org>
Link: https://lore.kernel.org/r/20240305121524.2254533-1-leitao@debian.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
exit_batch_rtnl() is called while RTNL is held,
and devices to be unregistered can be queued in the dev_kill_list.
This saves one rtnl_lock()/rtnl_unlock() pair per netns
and one unregister_netdevice_many() call per netns.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Antoine Tenart <atenart@kernel.org>
Link: https://lore.kernel.org/r/20240206144313.2050392-8-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Call skb_gso_validate_network_len() to check if packet is over PMTU.
Fixes: 459aa660eb ("gtp: add initial driver for datapath of GPRS Tunneling Protocol (GTP-U)")
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
There's no reason for setting the RTO_ONLINK flag in ->flowi4_tos as
RT_CONN_FLAGS() does. We can easily set ->flowi4_scope properly
instead. This makes the code more explicit and will allow to convert
->flowi4_tos to dscp_t in the future.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
We had historically not checked that genlmsghdr.reserved
is 0 on input which prevents us from using those precious
bytes in the future.
One use case would be to extend the cmd field, which is
currently just 8 bits wide and 256 is not a lot of commands
for some core families.
To make sure that new families do the right thing by default
put the onus of opting out of validation on existing families.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com> (NetLabel)
Signed-off-by: David S. Miller <davem@davemloft.net>
Fix the following warning as reported by smatch:
New smatch warnings:
drivers/net/gtp.c:1796 gtp_genl_send_echo_req() warn: inconsistent indenting
Fixes: d33bd757d3 ("gtp: Implement GTP echo request")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Adding GTP device through ip link creates the situation where
GTP instance is not able to send GTP echo requests.
Echo requests are used to check if GTP peer is still alive.
With this patch, gtp_genl_ops are extended by new cmd (GTP_CMD_ECHOREQ)
which allows to send echo request in the given version of GTP
protocol (v0 or v1), from the given ms address to he given
peer. TID is not inclued because in all path management
messages it should be equal to 0.
When GTP echo response is detected, multicast message is
send to everyone in the gtp_genl_family. Message contains
GTP version, ms address and peer address.
Suggested-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Adding GTP device through ip link creates the situation where
there is no userspace daemon which would handle GTP messages
(Echo Request for example). GTP-U instance which would not respond
to echo requests would violate GTP specification.
When GTP packet arrives with GTP_ECHO_REQ message type,
GTP_ECHO_RSP is send to the sender. GTP_ECHO_RSP message
should contain information element with GTPIE_RECOVERY tag and
restart counter value. For GTPv1 restart counter is not used
and should be equal to 0, for GTPv0 restart counter contains
information provided from userspace(IFLA_GTP_RESTART_COUNT).
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Suggested-by: Harald Welte <laforge@gnumonks.org>
Reviewed-by: Harald Welte <laforge@gnumonks.org>
Tested-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Currently, when the user wants to create GTP device, he has to
provide file handles to the sockets created in userspace (IFLA_GTP_FD0,
IFLA_GTP_FD1). This behaviour is not ideal, considering the option of
adding support for GTP device creation through ip link. Ip link
application is not a good place to create such sockets.
This patch allows to create GTP device without providing
IFLA_GTP_FD0 and IFLA_GTP_FD1 arguments. If the user sets
IFLA_GTP_CREATE_SOCKETS attribute, then GTP module takes care
of creating UDP sockets by itself. Sockets are created with the
commonly known UDP ports used for GTP protocol (GTP0_PORT and
GTP1U_PORT). In this case we don't have to provide encap_destroy
because no extra deinitialization is needed, everything is covered
by udp_tunnel_sock_release.
Note: GTP instance created with only this change applied, does
not handle GTP Echo Requests. This is implemented in the following
patch.
Signed-off-by: Wojciech Drewek <wojciech.drewek@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>
Dave suggested a while ago (eleven years by now) "Let's make netif_rx()
work in all contexts and get rid of netif_rx_ni()". Eric agreed and
pointed out that modern devices should use netif_receive_skb() to avoid
the overhead.
In the meantime someone added another variant, netif_rx_any_context(),
which behaves as suggested.
netif_rx() must be invoked with disabled bottom halves to ensure that
pending softirqs, which were raised within the function, are handled.
netif_rx_ni() can be invoked only from process context (bottom halves
must be enabled) because the function handles pending softirqs without
checking if bottom halves were disabled or not.
netif_rx_any_context() invokes on the former functions by checking
in_interrupts().
netif_rx() could be taught to handle both cases (disabled and enabled
bottom halves) by simply disabling bottom halves while invoking
netif_rx_internal(). The local_bh_enable() invocation will then invoke
pending softirqs only if the BH-disable counter drops to zero.
Eric is concerned about the overhead of BH-disable+enable especially in
regard to the loopback driver. As critical as this driver is, it will
receive a shortcut to avoid the additional overhead which is not needed.
Add a local_bh_disable() section in netif_rx() to ensure softirqs are
handled if needed.
Provide __netif_rx() which does not disable BH and has a lockdep assert
to ensure that interrupts are disabled. Use this shortcut in the
loopback driver and in drivers/net/*.c.
Make netif_rx_ni() and netif_rx_any_context() invoke netif_rx() so they
can be removed once they are no more users left.
Link: https://lkml.kernel.org/r/20100415.020246.218622820.davem@davemloft.net
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
skb_dst_update_pmtu_no_confirm() is a just wrapper function of
->update_pmtu(). So, it doesn't change logic
Signed-off-by: Gyeongun Kang <kyeongun15@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
For consistency with other L3 tunnel devices, reset the mac_header
pointer after decapsulation. This makes the mac_header 0 bytes long,
thus making it clear that this skb has no mac_header.
Compile tested only.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The icmp{,v6}_send functions make all sorts of use of skb->cb, casting
it with IPCB or IP6CB, assuming the skb to have come directly from the
inet layer. But when the packet comes from the ndo layer, especially
when forwarded, there's no telling what might be in skb->cb at that
point. As a result, the icmp sending code risks reading bogus memory
contents, which can result in nasty stack overflows such as this one
reported by a user:
panic+0x108/0x2ea
__stack_chk_fail+0x14/0x20
__icmp_send+0x5bd/0x5c0
icmp_ndo_send+0x148/0x160
In icmp_send, skb->cb is cast with IPCB and an ip_options struct is read
from it. The optlen parameter there is of particular note, as it can
induce writes beyond bounds. There are quite a few ways that can happen
in __ip_options_echo. For example:
// sptr/skb are attacker-controlled skb bytes
sptr = skb_network_header(skb);
// dptr/dopt points to stack memory allocated by __icmp_send
dptr = dopt->__data;
// sopt is the corrupt skb->cb in question
if (sopt->rr) {
optlen = sptr[sopt->rr+1]; // corrupt skb->cb + skb->data
soffset = sptr[sopt->rr+2]; // corrupt skb->cb + skb->data
// this now writes potentially attacker-controlled data, over
// flowing the stack:
memcpy(dptr, sptr+sopt->rr, optlen);
}
In the icmpv6_send case, the story is similar, but not as dire, as only
IP6CB(skb)->iif and IP6CB(skb)->dsthao are used. The dsthao case is
worse than the iif case, but it is passed to ipv6_find_tlv, which does
a bit of bounds checking on the value.
This is easy to simulate by doing a `memset(skb->cb, 0x41,
sizeof(skb->cb));` before calling icmp{,v6}_ndo_send, and it's only by
good fortune and the rarity of icmp sending from that context that we've
avoided reports like this until now. For example, in KASAN:
BUG: KASAN: stack-out-of-bounds in __ip_options_echo+0xa0e/0x12b0
Write of size 38 at addr ffff888006f1f80e by task ping/89
CPU: 2 PID: 89 Comm: ping Not tainted 5.10.0-rc7-debug+ #5
Call Trace:
dump_stack+0x9a/0xcc
print_address_description.constprop.0+0x1a/0x160
__kasan_report.cold+0x20/0x38
kasan_report+0x32/0x40
check_memory_region+0x145/0x1a0
memcpy+0x39/0x60
__ip_options_echo+0xa0e/0x12b0
__icmp_send+0x744/0x1700
Actually, out of the 4 drivers that do this, only gtp zeroed the cb for
the v4 case, while the rest did not. So this commit actually removes the
gtp-specific zeroing, while putting the code where it belongs in the
shared infrastructure of icmp{,v6}_ndo_send.
This commit fixes the issue by passing an empty IPCB or IP6CB along to
the functions that actually do the work. For the icmp_send, this was
already trivial, thanks to __icmp_send providing the plumbing function.
For icmpv6_send, this required a tiny bit of refactoring to make it
behave like the v4 case, after which it was straight forward.
Fixes: a2b78e9b2c ("sunvnet: generate ICMP PTMUD messages for smaller port MTUs")
Reported-by: SinYu <liuxyon@gmail.com>
Reviewed-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/netdev/CAF=yD-LOF116aHub6RMe8vB8ZpnrrnoTdqhobEx+bvoA8AsP0w@mail.gmail.com/T/
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Link: https://lore.kernel.org/r/20210223131858.72082-1-Jason@zx2c4.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
