nft_data_init(9)

💅 nft_data_init — the kernel API manual, but make it make sense ✨

okay so bestie, welcome to the nft_data_init(9) page, straight out of the Kernel API Manual 🎀. This is the little kernel function that takes your raw netlink attributes and turns them into actual, usable nf_tables data. It's giving "backend bestie doing the heavy lifting" energy fr fr. Let's get into it 🫶

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✨ SYNOPSIS ✨

int nft_data_init (const struct nft_ctx *ctx , struct nft_data *data ,
struct nft_data_desc *desc , const struct nlattr *nla );

yeah that's the whole squad right there 😭 four args, one int return, no drama. Slay.

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🌸 ARGUMENTS 🌸

• ctx — the context of the expression that's using the data 👑 like, whose data is this anyway
• data — the destination struct nft_data 💖 this is where the parsed goodies land
• desc — the data description, aka the receipts 📝
• nla — the netlink attribute that's carrying the data 🦋

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💜 DESCRIPTION 💜

So what does it actually do? It parses the netlink data attributes and initializes a struct nft_data for you ✨. The type and length of the data get returned in the data description — so desc is literally telling you what you just got, iykyk 💅.

And here's the cute part 🎀: the caller can say "bestie, I only want data of type NFT_DATA_VALUE" by passing NULL for the ctx argument. That's it. That's the whole flex. No ctx, no other types, just pure NFT_DATA_VALUE energy ⭐.

ngl, passing NULL isn't a bug, it's a choice — you're lowkey gatekeeping which data types get through 🙈

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🌈 SEE ALSO 🌈

the whole friend group 💖 go check these out:

• Kernel file ./net/netfilter/nf_tables_api.c — the source file, main character of the directory fr
• nft_register_expr(9)
• nft_unregister_expr(9)
• nft_data_hold(9)
• nft_register_obj(9)
• nft_unregister_obj(9)
• nft_parse_u32_check(9)
• nft_dump_register(9)
• nft_data_release(9)

like, that's a lot of siblings but they all ate 🔥

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okay that's the whole page bestie, you're officially fluent in nft_data_init 💅✨. shoutout to ./net/netfilter for hosting this absolute icon, and to October 2026 for the timestamp 🎀 — no cap, we love a documented kernel API. bye bestie, go parse some attributes 🦋💖