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Yonghong Song authored
Commit 31fd8581 ("bpf: permits narrower load from bpf program context fields") permits narrower load for certain ctx fields. The commit however will already generate a masking even if the prog-specific ctx conversion produces the result with narrower size. For example, for __sk_buff->protocol, the ctx conversion loads the data into register with 2-byte load. A narrower 2-byte load should not generate masking. For __sk_buff->vlan_present, the conversion function set the result as either 0 or 1, essentially a byte. The narrower 2-byte or 1-byte load should not generate masking. To avoid unnecessary masking, prog-specific *_is_valid_access now passes converted_op_size back to verifier, which indicates the valid data width after perceived future conversion. Based on this information, verifier is able to avoid unnecessary marking. Since we want more information back from prog-specific *_is_valid_access checking, all of them are packed into one data structure for more clarity. Acked-by:
Daniel Borkmann <daniel@iogearbox.net> Signed-off-by:
Yonghong Song <yhs@fb.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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