kernel/linux.git/include/uapi/linux/ipv6.h, branch v6.19.11

ipv6: add `force_forwarding` sysctl to enable per-interface forwarding

2025-07-25T20:06:19+00:00

It is currently impossible to enable ipv6 forwarding on a per-interface basis like in ipv4. To enable forwarding on an ipv6 interface we need to enable it on all interfaces and disable it on the other interfaces using a netfilter rule. This is especially cumbersome if you have lots of interfaces and only want to enable forwarding on a few. According to the sysctl docs [0] the `net.ipv6.conf.all.forwarding` enables forwarding for all interfaces, while the interface-specific `net.ipv6.conf..forwarding` configures the interface Host/Router configuration. Introduce a new sysctl flag `force_forwarding`, which can be set on every interface. The ip6_forwarding function will then check if the global forwarding flag OR the force_forwarding flag is active and forward the packet. To preserve backwards-compatibility reset the flag (on all interfaces) to 0 if the net.ipv6.conf.all.forwarding flag is set to 0. Add a short selftest that checks if a packet gets forwarded with and without `force_forwarding`. [0]: https://www.kernel.org/doc/Documentation/networking/ip-sysctl.txt Acked-by: Nicolas Dichtel Signed-off-by: Gabriel Goller Link: https://patch.msgid.link/20250722081847.132632-1-g.goller@proxmox.com Signed-off-by: Jakub Kicinski

net: change accept_ra_min_rtr_lft to affect all RA lifetimes

2023-07-28T20:30:51+00:00

accept_ra_min_rtr_lft only considered the lifetime of the default route and discarded entire RAs accordingly. This change renames accept_ra_min_rtr_lft to accept_ra_min_lft, and applies the value to individual RA sections; in particular, router lifetime, PIO preferred lifetime, and RIO lifetime. If any of those lifetimes are lower than the configured value, the specific RA section is ignored. In order for the sysctl to be useful to Android, it should really apply to all lifetimes in the RA, since that is what determines the minimum frequency at which RAs must be processed by the kernel. Android uses hardware offloads to drop RAs for a fraction of the minimum of all lifetimes present in the RA (some networks have very frequent RAs (5s) with high lifetimes (2h)). Despite this, we have encountered networks that set the router lifetime to 30s which results in very frequent CPU wakeups. Instead of disabling IPv6 (and dropping IPv6 ethertype in the WiFi firmware) entirely on such networks, it seems better to ignore the misconfigured routers while still processing RAs from other IPv6 routers on the same network (i.e. to support IoT applications). The previous implementation dropped the entire RA based on router lifetime. This turned out to be hard to expand to the other lifetimes present in the RA in a consistent manner; dropping the entire RA based on RIO/PIO lifetimes would essentially require parsing the whole thing twice. Fixes: 1671bcfd76fd ("net: add sysctl accept_ra_min_rtr_lft") Cc: Lorenzo Colitti Signed-off-by: Patrick Rohr Reviewed-by: Maciej Żenczykowski Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20230726230701.919212-1-prohr@google.com Signed-off-by: Jakub Kicinski

net: add sysctl accept_ra_min_rtr_lft

2023-07-23T10:51:24+00:00

This change adds a new sysctl accept_ra_min_rtr_lft to specify the minimum acceptable router lifetime in an RA. If the received RA router lifetime is less than the configured value (and not 0), the RA is ignored. This is useful for mobile devices, whose battery life can be impacted by networks that configure RAs with a short lifetime. On such networks, the device should never gain IPv6 provisioning and should attempt to drop RAs via hardware offload, if available. Signed-off-by: Patrick Rohr Cc: Maciej Żenczykowski Cc: Lorenzo Colitti Signed-off-by: David S. Miller

uapi: net: ipv6: Replace fake flex-array with flex-array member

2023-03-30T20:06:56+00:00

Zero-length arrays as fake flexible arrays are deprecated and we are moving towards adopting C99 flexible-array members instead. Address the following warning found with GCC-13 and -fstrict-flex-arrays=3 enabled: net/ipv6/exthdrs.c: In function ‘fl6_update_dst’: net/ipv6/exthdrs.c:1393:28: warning: array subscript 0 is outside array bounds of ‘struct in6_addr[0]’ [-Warray-bounds=] 1393 | fl6->daddr = *((struct rt0_hdr *)opt->srcrt)->addr; | ~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In file included from ./include/linux/ipv6.h:5, from ./include/linux/icmpv6.h:6, from net/ipv6/exthdrs.c:27: ./include/uapi/linux/ipv6.h:84:33: note: while referencing ‘addr’ 84 | struct in6_addr addr[0]; | ^~~~ net/ipv6/exthdrs.c: In function ‘ipv6_push_rthdr0.isra’: net/ipv6/exthdrs.c:1125:19: warning: array subscript is outside array bounds of ‘struct in6_addr[0]’ [-Warray-bounds=] 1125 | phdr->addr[hops - 1] = **addr_p; | ~~~~~~~~~~^~~~~~~~~~ ./include/uapi/linux/ipv6.h:84:33: note: while referencing ‘addr’ 84 | struct in6_addr addr[0]; | ^~~~ This helps with the ongoing efforts to tighten the FORTIFY_SOURCE routines on memcpy() and help us make progress towards globally enabling -fstrict-flex-arrays=3 [1]. Link: https://github.com/KSPP/linux/issues/21 Link: https://github.com/KSPP/linux/issues/276 Link: https://gcc.gnu.org/pipermail/gcc-patches/2022-October/602902.html [1] Signed-off-by: Gustavo A. R. Silva

uapi: add missing ip/ipv6 header dependencies for linux/stddef.h

2023-02-06T09:01:00+00:00

Since commit 58e0be1ef6118 ("net: use struct_group to copy ip/ipv6 header addresses"), ip and ipv6 headers started to use the __struct_group definition, which is defined at include/uapi/linux/stddef.h. However, linux/stddef.h isn't explicitly included in include/uapi/linux/{ip,ipv6}.h, which breaks build of xskxceiver bpf selftest if you install the uapi headers in the system: $ make V=1 xskxceiver -C tools/testing/selftests/bpf ... make: Entering directory '(...)/tools/testing/selftests/bpf' gcc -g -O0 -rdynamic -Wall -Werror (...) In file included from xskxceiver.c:79: /usr/include/linux/ip.h:103:9: error: expected specifier-qualifier-list before ‘__struct_group’ 103 | __struct_group(/* no tag */, addrs, /* no attrs */, | ^~~~~~~~~~~~~~ ... Include the missing dependency in ip.h and do the same for the ipv6.h header. Fixes: 58e0be1ef611 ("net: use struct_group to copy ip/ipv6 header addresses") Signed-off-by: Herton R. Krzesinski Reviewed-by: Carlos O'Donell Tested-by: Carlos O'Donell Signed-off-by: David S. Miller

net: use struct_group to copy ip/ipv6 header addresses

2022-11-17T09:42:45+00:00

kernel test robot reported warnings when build bonding module with make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash drivers/net/bonding/: from ../drivers/net/bonding/bond_main.c:35: In function ‘fortify_memcpy_chk’, inlined from ‘iph_to_flow_copy_v4addrs’ at ../include/net/ip.h:566:2, inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3984:3: ../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning] 413 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ In function ‘fortify_memcpy_chk’, inlined from ‘iph_to_flow_copy_v6addrs’ at ../include/net/ipv6.h:900:2, inlined from ‘bond_flow_ip’ at ../drivers/net/bonding/bond_main.c:3994:3: ../include/linux/fortify-string.h:413:25: warning: call to ‘__read_overflow2_field’ declared with attribute warning: detected read beyond size of f ield (2nd parameter); maybe use struct_group()? [-Wattribute-warning] 413 | __read_overflow2_field(q_size_field, size); | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ This is because we try to copy the whole ip/ip6 address to the flow_key, while we only point the to ip/ip6 saddr. Note that since these are UAPI headers, __struct_group() is used to avoid the compiler warnings. Reported-by: kernel test robot Fixes: c3f8324188fa ("net: Add full IPv6 addresses to flow_keys") Signed-off-by: Hangbin Liu Link: https://lore.kernel.org/r/20221115142400.1204786-1-liuhangbin@gmail.com Signed-off-by: Paolo Abeni

net/ipv6: Expand and rename accept_unsolicited_na to accept_untracked_na

2022-05-31T09:36:57+00:00

RFC 9131 changes default behaviour of handling RX of NA messages when the corresponding entry is absent in the neighbour cache. The current implementation is limited to accept just unsolicited NAs. However, the RFC is more generic where it also accepts solicited NAs. Both types should result in adding a STALE entry for this case. Expand accept_untracked_na behaviour to also accept solicited NAs to be compliant with the RFC and rename the sysctl knob to accept_untracked_na. Fixes: f9a2fb73318e ("net/ipv6: Introduce accept_unsolicited_na knob to implement router-side changes for RFC9131") Signed-off-by: Arun Ajith S Reviewed-by: David Ahern Link: https://lore.kernel.org/r/20220530101414.65439-1-aajith@arista.com Signed-off-by: Paolo Abeni

net/ipv6: Introduce accept_unsolicited_na knob to implement router-side changes for RFC9131

2022-04-17T12:23:49+00:00

Add a new neighbour cache entry in STALE state for routers on receiving an unsolicited (gratuitous) neighbour advertisement with target link-layer-address option specified. This is similar to the arp_accept configuration for IPv4. A new sysctl endpoint is created to turn on this behaviour: /proc/sys/net/ipv6/conf/interface/accept_unsolicited_na. Signed-off-by: Arun Ajith S Reviewed-by: David Ahern Signed-off-by: David S. Miller

net: ndisc: introduce ndisc_evict_nocarrier sysctl parameter

2021-11-02T02:57:14+00:00

In most situations the neighbor discovery cache should be cleared on a NOCARRIER event which is currently done unconditionally. But for wireless roams the neighbor discovery cache can and should remain intact since the underlying network has not changed. This patch introduces a sysctl option ndisc_evict_nocarrier which can be disabled by a wireless supplicant during a roam. This allows packets to be sent after a roam immediately without having to wait for neighbor discovery. A user reported roughly a 1 second delay after a roam before packets could be sent out (note, on IPv4). This delay was due to the ARP cache being cleared. During testing of this same scenario using IPv6 no delay was noticed, but regardless there is no reason to clear the ndisc cache for wireless roams. Signed-off-by: James Prestwood Reviewed-by: David Ahern Signed-off-by: Jakub Kicinski

ipv6: ioam: Data plane support for Pre-allocated Trace

2021-07-21T15:14:33+00:00

Implement support for processing the IOAM Pre-allocated Trace with IPv6, see [1] and [2]. Introduce a new IPv6 Hop-by-Hop TLV option, see IANA [3]. A new per-interface sysctl is introduced. The value is a boolean to accept (=1) or ignore (=0, by default) IPv6 IOAM options on ingress for an interface: - net.ipv6.conf.XXX.ioam6_enabled Two other sysctls are introduced to define IOAM IDs, represented by an integer. They are respectively per-namespace and per-interface: - net.ipv6.ioam6_id - net.ipv6.conf.XXX.ioam6_id The value of the first one represents the IOAM ID of the node itself (u32; max and default value = U32_MAX>>8, due to hop limit concatenation) while the other represents the IOAM ID of an interface (u16; max and default value = U16_MAX). Each "ioam6_id" sysctl has a "_wide" equivalent: - net.ipv6.ioam6_id_wide - net.ipv6.conf.XXX.ioam6_id_wide The value of the first one represents the wide IOAM ID of the node itself (u64; max and default value = U64_MAX>>8, due to hop limit concatenation) while the other represents the wide IOAM ID of an interface (u32; max and default value = U32_MAX). The use of short and wide equivalents is not exclusive, a deployment could choose to leverage both. For example, net.ipv6.conf.XXX.ioam6_id (short format) could be an identifier for a physical interface, whereas net.ipv6.conf.XXX.ioam6_id_wide (wide format) could be an identifier for a logical sub-interface. Documentation about new sysctls is provided at the end of this patchset. Two relativistic hash tables are used: one for IOAM namespaces, the other for IOAM schemas. A namespace can only have a single active schema and a schema can only be attached to a single namespace (1:1 relationship). [1] https://tools.ietf.org/html/draft-ietf-ippm-ioam-ipv6-options [2] https://tools.ietf.org/html/draft-ietf-ippm-ioam-data [3] https://www.iana.org/assignments/ipv6-parameters/ipv6-parameters.xhtml#ipv6-parameters-2 Signed-off-by: Justin Iurman Signed-off-by: David S. Miller