bpf_crypto_ctx_create(9)

💅 bpf_crypto_ctx_create(9)

okay so this is a page from the Kernel API Manual — yes, the kernel has manpages too, we stay educated 💖 — and it's all about bpf_crypto_ctx_create, the little function that spawns a mutable BPF crypto context for you. mutable!! crypto!! bestie we are SO back 🔥

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✨ NAME ✨

bpf_crypto_ctx_create — creates a mutable BPF crypto context. that's it, that's the whole name, and honestly it ate 👑

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🎀 SYNOPSIS 🎀

__bpf_kfunc struct bpf_crypto_ctx * bpf_crypto_ctx_create (const struct
bpf_crypto_params *params , u32 params__sz , int *err );

it's giving "long signature, tiny name" energy. she's a __bpf_kfunc, she returns a struct bpf_crypto_ctx *, and she takes three things. let's get into it 🦋

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🌸 ARGUMENTS 🌸

• params — pointer to struct bpf_crypto_params, which holds literally all the details you need to initialise the crypto context. the whole blueprint. the vibe check for your cipher 💅
• params__sz — the size of struct bpf_crypto_params as used by the BPF program. (ngl the original page spells it "steuct" and "usef" — iconic typo moment, we keep it real 🫶, but it's struct and used, iykyk)
• err — an integer where the error code gets stored whenever NULL comes back. so like, if it flops, this is where the receipts live 😭

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🌈 DESCRIPTION 🌈

so what does she do? she allocates a crypto context that a BPF program can use, acquire, and release. main character energy honestly 💜

the context she returns has exactly two acceptable fates, no third option, periodt:

• it gets embedded in a map as a kptr, or
• it gets freed with bpf_crypto_ctx_release 💀

⭐ fr fr do not just leave it lying around — those are the options.

and because crypto API functions use GFP_KERNEL allocations, this function can only be used in sleepable BPF programs. no cap, that's a hard requirement, not a suggestion 🧚

bpf_crypto_ctx_create allocates memory for the crypto context, and it may return NULL if no memory is available. lowkey devastating but that's what err is for 🍓

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👑 SEE ALSO 👑

• Kernel file ./kernel/bpf/crypto.c
• struct bpf_crypto_params(9)
• struct bpf_crypto_ctx(9)
• bpf_crypto_ctx_acquire(9)
• bpf_crypto_ctx_release(9)
• bpf_crypto_decrypt(9)
• bpf_crypto_encrypt(9)

go read the whole friend group, they're all connected 💖

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and that's the page!! this one lives at ./kernel/bpf (the directory, not a person, sadly), it's dated October 2026 ⭐ — yes, the future, we're ahead of schedule — and it's page bpf_crypto_ctx_create(9) of the Kernel API Manual. slay, go create some contexts responsibly 💅✨🎀