af_alg_sendmsg(9)

📦 version 7.3.1, in nixpkgs unstable

💅 af_alg_sendmsg(9) — like, the whole kernel API manual vibe 🎀

okay so bestie, welcome to af_alg_sendmsg — this is a page straight out of the Kernel API Manual, and it's literally the implementation of the sendmsg system call handler. no cap. sit down, grab a strawberry drink 🍓, we're getting into it.

✨ SYNOPSIS ✨

int af_alg_sendmsg (struct socket *sock , struct msghdr *msg , size_t
size , unsigned int ivsize );

that's it. that's the whole signature. she's giving four-arguments-and-a-dream energy 💅

🌸 ARGUMENTS 🌸

  • sock — the socket of the connection to user space. that's your girl, the link between here and there 🫶
  • msg — the message coming in from user space. the actual tea being passed ☕
  • size — the size of that message from user space. gotta know how much tea, fr fr
  • ivsize — the size of the IV for the cipher operation, and it's there to verify that the user-space-provided IV has the right size. like a vibe check but for IVs 👑 if the size is wrong, that's a problem, iykyk

🦋 DESCRIPTION 🦋

so the sendmsg system call handler obtains the user data and stores it in ctx->tsgl_list. the way that it does this is — and this is the iconic part — it implies allocation of the required numbers of struct af_alg_tsgl. yes, allocation. on purpose. as a consequence. we love a data structure moment 💖

and in addition?? the ctx gets filled with the information sent via CMSG. both things. at once. main character energy honestly ✨

⭐ RETURN ⭐

  • the number of copied data upon success 🎉
  • < 0 upon error 💀

that's it, that's the return contract, no notes.

ngl bestie, if you get a negative number back, something went sideways — the manpage just says < 0 and leaves the drama to you 🙈

🌈 SEE ALSO 🌈

that's the whole friend group right there — go say hi to all of them, they're all in ./crypto, they're all iconic 🧚‍♀️

okay and that's the page!! mwah 💋 this little gem lives in ./crypto, it's the October 2026 edition of the Kernel API Manual, and it's signed off with the classic af_alg_sendmsg(9) energy. go read the source, bestie — periodt 👑🔥

📦 where this page comes from