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bpf, net: Introduce skb_pointer_if_linear().
Network drivers always call skb_header_pointer() with non-null buffer. Remove !buffer check to prevent accidental misuse of skb_header_pointer(). Introduce skb_pointer_if_linear() instead. Reported-by: Jakub Kicinski <kuba@kernel.org> Acked-by: Jakub Kicinski <kuba@kernel.org> Link: https://lore.kernel.org/r/20230718234021.43640-1-alexei.starovoitov@gmail.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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41ee0145a4
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2 changed files with 13 additions and 2 deletions
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@ -4023,7 +4023,7 @@ __skb_header_pointer(const struct sk_buff *skb, int offset, int len,
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if (likely(hlen - offset >= len))
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return (void *)data + offset;
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if (!skb || !buffer || unlikely(skb_copy_bits(skb, offset, buffer, len) < 0))
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if (!skb || unlikely(skb_copy_bits(skb, offset, buffer, len) < 0))
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return NULL;
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return buffer;
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@ -4036,6 +4036,14 @@ skb_header_pointer(const struct sk_buff *skb, int offset, int len, void *buffer)
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skb_headlen(skb), buffer);
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}
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static inline void * __must_check
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skb_pointer_if_linear(const struct sk_buff *skb, int offset, int len)
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{
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if (likely(skb_headlen(skb) - offset >= len))
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return skb->data + offset;
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return NULL;
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}
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/**
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* skb_needs_linearize - check if we need to linearize a given skb
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* depending on the given device features.
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@ -2263,7 +2263,10 @@ __bpf_kfunc void *bpf_dynptr_slice(const struct bpf_dynptr_kern *ptr, u32 offset
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case BPF_DYNPTR_TYPE_RINGBUF:
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return ptr->data + ptr->offset + offset;
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case BPF_DYNPTR_TYPE_SKB:
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return skb_header_pointer(ptr->data, ptr->offset + offset, len, buffer__opt);
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if (buffer__opt)
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return skb_header_pointer(ptr->data, ptr->offset + offset, len, buffer__opt);
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else
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return skb_pointer_if_linear(ptr->data, ptr->offset + offset, len);
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case BPF_DYNPTR_TYPE_XDP:
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{
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void *xdp_ptr = bpf_xdp_pointer(ptr->data, ptr->offset + offset, len);
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