bpf_dynptr_copy(9)

💖 NAME 💖

Okay so we're in the Kernel API Manual, section 9, and today's main character is bpf_dynptr_copy — it copies data from one dynptr to another. That's it. That's the whole vibe. A dynptr-to-dynptr copy, no cap 🫶

✨ SYNOPSIS ✨

__bpf_kfunc int bpf_dynptr_copy (const struct bpf_dynptr *dst_ptr , u64
dst_off , const struct bpf_dynptr *src_ptr , u64 src_off , u64 size );

🎀 ARGUMENTS 🎀

• dst_ptr — the destination dynptr, aka where the data is gonna land 💅
• dst_off — the offset into that destination dynptr 🎯
• src_ptr — the source dynptr, aka where the data is coming from ✨
• src_off — the offset into the source dynptr 🍓
• size — how much data we're copying from source to destination, in length terms 📏

🌸 DESCRIPTION 🌸

So what it does is literally just copy data from the source dynptr over to the destination dynptr. That's the whole job. And the tea on the return value: it hands back 0 on success, or a negative error otherwise 😭 so like, check your return values, bestie, fr fr.

🦋 SEE ALSO 🦋

Kernel file ./kernel/bpf/helpers.c, plus the whole squad: bpf_obj_new(9), bpf_percpu_obj_new(9), bpf_obj_drop(9), bpf_percpu_obj_drop(9), bpf_refcount_acquire(9), bpf_list_push_front(9), bpf_list_push_back(9), bpf_rbtree_add(9), bpf_task_acquire(9), bpf_task_release(9), bpf_cgroup_acquire(9), bpf_cgroup_release(9), bpf_cgroup_ancestor(9), bpf_cgroup_from_id(9), bpf_task_under_cgroup(9), bpf_task_get_cgroup1(9), bpf_task_from_pid(9), bpf_task_from_vpid(9), bpf_dynptr_slice(9), bpf_dynptr_slice_rdwr(9), bpf_dynptr_memset(9), bpf_iter_bits_new(9), bpf_iter_bits_next(9), bpf_iter_bits_destroy(9), bpf_copy_from_user_str(9), bpf_copy_from_user_task_str(9), bpf_strcmp(9), bpf_strcasecmp(9), bpf_strnchr(9), bpf_strchr(9), bpf_strchrnul(9), bpf_strrchr(9), bpf_strnlen(9), bpf_strlen(9), bpf_strspn(9), bpf_strcspn(9), bpf_strstr(9), bpf_strcasestr(9), bpf_strnstr(9), bpf_strncasestr(9), bpf_lookup_user_key(9), bpf_lookup_system_key(9), bpf_key_put(9), bpf_verify_pkcs7_signature(9), bpf_task_work_schedule_signal(9), bpf_task_work_schedule_resume(9), bpf_timer_cancel_async(9). Go read them, iykyk 👑

That's the whole page, bestie — it lives under ./kernel/bpf and it's dated October 2026 🌈 mwah, go copy some dynptr data responsibly 💜