skb_partial_csum_set(9)

💖 NAME 💖

okay bestie, welcome to the skb_partial_csum_set(9) page from the Kernel API Manual ✨ — this one is all about setting up and verifying partial csum values for a packet. periodt 💅

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✨ SYNOPSIS ✨

bool skb_partial_csum_set (struct sk_buff *skb , u16 start , u16 off );

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🫶 ARGUMENTS 🫶

• skb — the skb to set 🫶
• start — the number of bytes after skb->data to start checksumming ✨
• off — the offset from start to place the checksum 💖

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🧚 DESCRIPTION 🧚

okay so listen: for untrusted partially-checksummed packets, we need to make sure the values for skb->csum_start and skb->csum_offset are valid so we don’t oops 😭. like, that’s the whole vibe check.

This function checks and sets those values and skb->ip_summed 💅. If this returns false, you should drop the packet. no cap.

🚨 bestie warning: if this returns false you should drop the packet. do not keep it around like a bad situationship 🙈

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🌈 SEE ALSO 🌈

Kernel file: ./net/core/skbuff.c — yes, that’s the spot 💅. And here’s the whole extended fam, in the same order, no cap:

• drop_reasons_register_subsys(9), drop_reasons_unregister_subsys(9), skb_panic(9), napi_skb_cache_get_bulk(9)
• __build_skb(9), build_skb_around(9), __napi_build_skb(9), napi_build_skb(9)
• __alloc_skb(9), __netdev_alloc_skb(9), napi_alloc_skb(9), skb_pp_cow_data(9), skb_pp_frag_ref(9)
• __kfree_skb(9), sk_skb_reason_drop(9), skb_tx_error(9), consume_skb(9), __consume_stateless_skb(9), napi_consume_skb(9)
• alloc_skb_for_msg(9), skb_morph(9), skb_copy_ubufs(9), skb_clone(9), skb_copy(9), __pskb_copy_fclone(9)
• pskb_expand_head(9), skb_expand_head(9), skb_copy_expand(9), __skb_pad(9), pskb_put(9), skb_put(9), skb_push(9), skb_pull(9)
• skb_pull_data(9), skb_trim(9), __pskb_pull_tail(9), skb_copy_bits(9), skb_store_bits(9), skb_zerocopy(9)
• skb_dequeue(9), skb_dequeue_tail(9), skb_queue_purge_reason(9), skb_rbtree_purge(9), skb_queue_head(9), skb_queue_tail(9)
• skb_unlink(9), skb_append(9), skb_split(9), skb_shift(9), skb_prepare_seq_read(9), skb_seq_read(9)
• skb_abort_seq_read(9), skb_copy_seq_read(9), skb_find_text(9), skb_pull_rcsum(9), skb_segment(9), skb_to_sgvec(9)
• skb_cow_data(9), skb_clone_sk(9), skb_checksum_setup(9), skb_checksum_maybe_trim(9), skb_checksum_trimmed(9)
• skb_try_coalesce(9), skb_scrub_packet(9), skb_eth_pop(9), skb_eth_push(9), skb_mpls_push(9), skb_mpls_pop(9)
• skb_mpls_update_lse(9), skb_mpls_dec_ttl(9), alloc_skb_with_frags(9), skb_condense(9)
• __skb_ext_alloc(9), __skb_ext_set(9), skb_ext_add(9), skb_attempt_defer_free(9), skb_splice_from_iter(9)

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okay that’s the whole page 💖 — source/version: ./net/core, date: October 2026, and the main character is skb_partial_csum_set(9). byeeee 🎀✨