nla_nest_end_safe(9)

📦 version 7.3.1, in nixpkgs unstable

💅 nla_nest_end_safe(9) — the Kernel API Manual, bestie edition ✨

okay so this is a page from the Kernel API Manual (section 9, the kernel-internals girlies) and it's about one very specific little function that closes out your netlink attribute nests. it's short, it's sweet, and it's lowkey a lifesaver. let's get into it 🎀

🌸 NAME

nla_nest_end_safe — validate and finalize nesting of attributes 🪺

like, you opened a nest, you stuffed attributes in it, and now you need to seal it up correctly and safely. this is that function. periodt.

✨ SYNOPSIS

int nla_nest_end_safe (struct sk_buff *skb , struct nlattr *start );

that's the whole vibe. two args, one int back. no drama 💅

🫶 ARGUMENTS

  • skb — the socket buffer where all your attributes are chillin'. literally the container of the container, iykyk 📦
  • start — the container attribute itself. the nesting mothership. the one whose header needs correcting 👑

🦋 DESCRIPTION

so here's the tea: this function corrects the container attribute header so that it includes all the appended attributes. 🧚

that's it. that's the whole job. you appended stuff inside your nest, and now somebody's gotta go back and fix up the header so it actually reflects everything that's in there. otherwise your header is lying about its own contents, and that's not main character energy. nla_nest_end_safe is the friend who double-checks the group chat screenshot before it gets sent. iconic behavior, honestly. 🔥

💖 RETURN

  • the total data length of the skb ✅ — slay, everything fit
  • or -EMSGSIZE 😭 — which happens if the nested attribute length exceeds U16_MAX
bestie please note: U16_MAX is a real ceiling and it is not a vibe to hit it. if your nest gets too chonky, you get -EMSGSIZE back and you don't get a cute success return. check that thing fr fr 💀

🌈 SEE ALSO

okay this section is long and honestly it ate. everything below lives in the kernel file ./include/net/netlink.h, plus these fine pages:

struct nla_policy(9), struct nl_info(9), enum netlink_validation(9), nlmsg_msg_size(9), nlmsg_total_size(9), nlmsg_padlen(9), nlmsg_data(9), nlmsg_len(9), nlmsg_payload(9), nlmsg_attrdata(9), nlmsg_attrlen(9), nlmsg_ok(9), nlmsg_next(9), nla_parse(9), nla_parse_deprecated(9), nla_parse_deprecated_strict(9), __nlmsg_parse(9), nlmsg_parse(9), nlmsg_parse_deprecated(9), nlmsg_parse_deprecated_strict(9), nlmsg_find_attr(9), nla_validate_deprecated(9), nla_validate(9), nlmsg_validate_deprecated(9), nlmsg_report(9), nlmsg_seq(9), nlmsg_for_each_attr(9), nlmsg_for_each_attr_type(9), nlmsg_put(9), nlmsg_append(9), nlmsg_put_answer(9), nlmsg_new(9), nlmsg_new_large(9), nlmsg_end(9), nlmsg_get_pos(9), nlmsg_trim(9), nlmsg_cancel(9), nlmsg_free(9), nlmsg_consume(9), nlmsg_multicast_filtered(9), nlmsg_multicast(9), nlmsg_unicast(9), nlmsg_for_each_msg(9), nl_dump_check_consistent(9)

nla_attr_size(9), nla_total_size(9), nla_padlen(9), nla_type(9), nla_data(9), nla_len(9), nla_ok(9), nla_next(9), nla_find_nested(9), nla_parse_nested(9), nla_parse_nested_deprecated(9), nla_put_u8(9), nla_put_u16(9), nla_put_be16(9), nla_put_net16(9), nla_put_le16(9), nla_put_u32(9), nla_put_uint(9), nla_put_be32(9), nla_put_net32(9), nla_put_le32(9), nla_put_u64_64bit(9), nla_put_be64(9), nla_put_net64(9), nla_put_le64(9), nla_put_s8(9), nla_put_s16(9), nla_put_s32(9), nla_put_s64(9), nla_put_sint(9), nla_put_string(9), nla_put_flag(9), nla_put_msecs(9), nla_put_in_addr(9), nla_put_in6_addr(9), nla_put_bitfield32(9)

nla_get_u32(9), nla_get_u32_default(9), nla_get_be32(9), nla_get_be32_default(9), nla_get_le32(9), nla_get_le32_default(9), nla_get_u16(9), nla_get_u16_default(9), nla_get_be16(9), nla_get_be16_default(9), nla_get_le16(9), nla_get_le16_default(9), nla_get_u8(9), nla_get_u8_default(9), nla_get_u64(9), nla_get_u64_default(9), nla_get_uint(9), nla_get_uint_default(9), nla_get_be64(9), nla_get_be64_default(9), nla_get_le64(9), nla_get_le64_default(9), nla_get_s32(9), nla_get_s32_default(9), nla_get_s16(9), nla_get_s16_default(9), nla_get_s8(9), nla_get_s8_default(9), nla_get_s64(9), nla_get_s64_default(9), nla_get_sint(9), nla_get_sint_default(9), nla_get_flag(9), nla_get_msecs(9), nla_get_msecs_default(9), nla_get_in_addr(9), nla_get_in_addr_default(9), nla_get_in6_addr(9), nla_get_bitfield32(9)

nla_memdup(9), nla_nest_start_noflag(9), nla_nest_start(9), nla_nest_end(9), nla_nest_cancel(9), nla_put_empty_nest(9), __nla_validate_nested(9), nla_need_padding_for_64bit(9), nla_align_64bit(9), nla_total_size_64bit(9), nla_for_each_attr(9), nla_for_each_attr_type(9), nla_for_each_nested(9), nla_for_each_nested_type(9), nla_is_last(9)

🫶 real talk: some of those are marked deprecated in their names (nla_parse_deprecated, nla_parse_deprecated_strict, nla_validate_deprecated, nlmsg_parse_deprecated, nlmsg_parse_deprecated_strict, nlmsg_validate_deprecated, nla_parse_nested_deprecated, nla_nest_start_noflag) — the names are telling on themselves, so read those pages before you commit, bestie. i'm just the messenger 💅

that's the whole page, and honestly? she's perfect. this came out of ./include/net and it was dated October 2026 — so like, mark your calendars, screenshot it, put it in the group chat, and go nest responsibly 🦋💖✨

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