bpf_crypto_decrypt(9)

💅 bpf_crypto_decrypt — Kernel API Manual, bestie edition 🎀

Okay so real talk, this one is <pink>bpf_crypto_decrypt(9) from the <purple>Kernel API Manual</purple>, and it's literally the glow-up-your-secret-bytes function. Sit down, hydrate, let's get into it. ✨

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🌸 NAME 🌸

bpf_crypto_decrypt — decrypt a buffer using the configured context plus the IV data you hand it. That's it, that's the whole vibe. 💖

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🦋 SYNOPSIS 🦋

__bpf_kfunc int bpf_crypto_decrypt (struct bpf_crypto_ctx *ctx , const
       struct bpf_dynptr *src , const struct bpf_dynptr *dst , const struct
       bpf_dynptr *siv__nullable );

Like, yes, the return type is __bpf_kfunc int, and yes, there are four args, and no, you cannot skip any of the first three. siv__nullable is the one with main character energy because it's allowed to be NULL. 👑

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💜 ARGUMENTS 💜

• ctx — the crypto context you're working with. It must be a trusted pointer. No sketchy pointers, we don't do that here. 🚫
• src — a bpf_dynptr pointing at the <hotpink>encrypted</hotpink> data (the locked little mystery box 📦). Must be a trusted pointer.
• dst — a bpf_dynptr to the buffer where the decrypted result gets stored. Must be a trusted pointer. This is where the reveal happens, bestie. ✨
• siv__nullable — a bpf_dynptr to the IV data and state data that the decryptor uses. May be NULL. Lowkey the only flexible one in the group chat. 🙈

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🔥 DESCRIPTION 🔥

So it <rainbow>decrypts the buffer you gave it, using the IV data and the crypto context. The catch? The crypto context <yellow>must be configured first — like, you can't just roll up with an unconfigured context and expect results, that's not how any of this works. Set it up, then decrypt. Periodt. 💅

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🫶 SEE ALSO 🫶

Kernel file ./kernel/bpf/crypto.c, and honestly the whole friend group:

• struct bpf_crypto_params(9)
• struct bpf_crypto_ctx(9)
• bpf_crypto_ctx_create(9)
• bpf_crypto_ctx_acquire(9)
• bpf_crypto_ctx_release(9)
• bpf_crypto_encrypt(9)

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ngl, go read the friends too — bpf_crypto_ctx_create(9) and bpf_crypto_ctx_acquire(9) are how you get a context worth using in the first place. 💖

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That's the whole page, bestie — no gatekeeping. Sourced from ./kernel/bpf, dated October 2026, and it lives at bpf_crypto_decrypt(9) in the Kernel API Manual. Now go decrypt something iconic. 🌈💫🎀