kernel/linux.git/include/net/netlink.h, branch v6.6.132

netlink: add variable-length / auto integers

2025-09-09T16:56:22+00:00

[ Upstream commit 374d345d9b5e13380c66d7042f9533a6ac6d1195 ] We currently push everyone to use padding to align 64b values in netlink. Un-padded nla_put_u64() doesn't even exist any more. The story behind this possibly start with this thread: https://lore.kernel.org/netdev/20121204.130914.1457976839967676240.davem@davemloft.net/ where DaveM was concerned about the alignment of a structure containing 64b stats. If user space tries to access such struct directly: struct some_stats *stats = nla_data(attr); printf("A: %llu", stats->a); lack of alignment may become problematic for some architectures. These days we most often put every single member in a separate attribute, meaning that the code above would use a helper like nla_get_u64(), which can deal with alignment internally. Even for arches which don't have good unaligned access - access aligned to 4B should be pretty efficient. Kernel and well known libraries deal with unaligned input already. Padded 64b is quite space-inefficient (64b + pad means at worst 16B per attr vs 32b which takes 8B). It is also more typing: if (nla_put_u64_pad(rsp, NETDEV_A_SOMETHING_SOMETHING, value, NETDEV_A_SOMETHING_PAD)) Create a new attribute type which will use 32 bits at netlink level if value is small enough (probably most of the time?), and (4B-aligned) 64 bits otherwise. Kernel API is just: if (nla_put_uint(rsp, NETDEV_A_SOMETHING_SOMETHING, value)) Calling this new type "just" sint / uint with no specific size will hopefully also make people more comfortable with using it. Currently telling people "don't use u8, you may need the bits, and netlink will round up to 4B, anyway" is the #1 comment we give to newcomers. In terms of netlink layout it looks like this: 0 4 8 12 16 32b: [nlattr][ u32 ] 64b: [ pad ][nlattr][ u64 ] uint(32) [nlattr][ u32 ] uint(64) [nlattr][ u64 ] Signed-off-by: Jakub Kicinski Acked-by: Nicolas Dichtel Signed-off-by: David S. Miller Stable-dep-of: 030e1c456666 ("macsec: read MACSEC_SA_ATTR_PN with nla_get_uint") Signed-off-by: Sasha Levin

netlink: allow be16 and be32 types in all uint policy checks

2023-07-27T11:45:51+00:00

__NLA_IS_BEINT_TYPE(tp) isn't useful. NLA_BE16/32 are identical to NLA_U16/32, the only difference is that it tells the netlink validation functions that byteorder conversion might be needed before comparing the value to the policy min/max ones. After this change all policy macros that can be used with UINT types, such as NLA_POLICY_MASK() can also be used with NLA_BE16/32. This will be used to validate nf_tables flag attributes which are in bigendian byte order. Signed-off-by: Florian Westphal

net: netlink: recommend policy range validation

2023-01-28T08:33:51+00:00

For large ranges (outside of s16) the documentation currently recommends open-coding the validation, but it's better to use the NLA_POLICY_FULL_RANGE() or NLA_POLICY_FULL_RANGE_SIGNED() policy validation instead; recommend that. Signed-off-by: Johannes Berg Reviewed-by: Ido Schimmel Link: https://lore.kernel.org/r/20230127084506.09f280619d64.I5dece85f06efa8ab0f474ca77df9e26d3553d4ab@changeid Signed-off-by: Jakub Kicinski

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

2022-11-03T20:21:54+00:00

No conflicts. Signed-off-by: Jakub Kicinski

netlink: introduce bigendian integer types

2022-11-02T04:29:06+00:00

Jakub reported that the addition of the "network_byte_order" member in struct nla_policy increases size of 32bit platforms. Instead of scraping the bit from elsewhere Johannes suggested to add explicit NLA_BE types instead, so do this here. NLA_POLICY_MAX_BE() macro is removed again, there is no need for it: NLA_POLICY_MAX(NLA_BE.., ..) will do the right thing. NLA_BE64 can be added later. Fixes: 08724ef69907 ("netlink: introduce NLA_POLICY_MAX_BE") Reported-by: Jakub Kicinski Suggested-by: Johannes Berg Signed-off-by: Florian Westphal Link: https://lore.kernel.org/r/20221031123407.9158-1-fw@strlen.de Signed-off-by: Jakub Kicinski

rtnetlink: pass netlink message header and portid to rtnl_configure_link()

2022-11-01T01:10:21+00:00

This patch pass netlink message header and portid to rtnl_configure_link() All the functions in this call chain need to add the parameters so we can use them in the last call rtnl_notify(), and notify the userspace about the new link info if NLM_F_ECHO flag is set. - rtnl_configure_link() - __dev_notify_flags() - rtmsg_ifinfo() - rtmsg_ifinfo_event() - rtmsg_ifinfo_build_skb() - rtmsg_ifinfo_send() - rtnl_notify() Also move __dev_notify_flags() declaration to net/core/dev.h, as Jakub suggested. Signed-off-by: Hangbin Liu Reviewed-by: Guillaume Nault Signed-off-by: Jakub Kicinski

netlink: split up copies in the ack construction

2022-10-31T09:13:10+00:00

Clean up the use of unsafe_memcpy() by adding a flexible array at the end of netlink message header and splitting up the header and data copies. Reviewed-by: Kees Cook Signed-off-by: Jakub Kicinski Signed-off-by: David S. Miller

netlink: hide validation union fields from kdoc

2022-10-29T03:19:15+00:00

Mark the validation fields as private, users shouldn't set them directly and they are too complicated to explain in a more succinct way (there's already a long explanation in the comment above). The strict_start_type field is set directly and has a dedicated comment so move that above the "private" section. Link: https://lore.kernel.org/r/20221027212107.2639255-1-kuba@kernel.org Signed-off-by: Jakub Kicinski

netlink: introduce NLA_POLICY_MAX_BE

2022-09-07T11:33:43+00:00

netlink allows to specify allowed ranges for integer types. Unfortunately, nfnetlink passes integers in big endian, so the existing NLA_POLICY_MAX() cannot be used. At the moment, nfnetlink users, such as nf_tables, need to resort to programmatic checking via helpers such as nft_parse_u32_check(). This is both cumbersome and error prone. This adds NLA_POLICY_MAX_BE which adds range check support for BE16, BE32 and BE64 integers. Signed-off-by: Florian Westphal Signed-off-by: David S. Miller

netlink: fix some kernel-doc comments

2022-08-25T01:46:16+00:00

Modify the comment of input parameter of nlmsg_ and nla_ function. Signed-off-by: Zhengchao Shao Link: https://lore.kernel.org/r/20220824013621.365103-1-shaozhengchao@huawei.com Signed-off-by: Jakub Kicinski