Messages in this thread |  | | Date | Tue, 08 Aug 2017 02:46:16 +0200 | From | Daniel Borkmann <> | Subject | Re: [PATCH v5 net-next 00/12] bpf: rewrite value tracking in verifier |
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On 08/07/2017 04:21 PM, Edward Cree wrote: > This series simplifies alignment tracking, generalises bounds tracking and > fixes some bounds-tracking bugs in the BPF verifier. Pointer arithmetic on > packet pointers, stack pointers, map value pointers and context pointers has > been unified, and bounds on these pointers are only checked when the pointer > is dereferenced. > Operations on pointers which destroy all relation to the original pointer > (such as multiplies and shifts) are disallowed if !env->allow_ptr_leaks, > otherwise they convert the pointer to an unknown scalar and feed it to the > normal scalar arithmetic handling. > Pointer types have been unified with the corresponding adjusted-pointer types > where those existed (e.g. PTR_TO_MAP_VALUE[_ADJ] or FRAME_PTR vs > PTR_TO_STACK); similarly, CONST_IMM and UNKNOWN_VALUE have been unified into > SCALAR_VALUE. > Pointer types (except CONST_PTR_TO_MAP, PTR_TO_MAP_VALUE_OR_NULL and > PTR_TO_PACKET_END, which do not allow arithmetic) have a 'fixed offset' and > a 'variable offset'; the former is used when e.g. adding an immediate or a > known-constant register, as long as it does not overflow. Otherwise the > latter is used, and any operation creating a new variable offset creates a > new 'id' (and, for PTR_TO_PACKET, clears the 'range'). > SCALAR_VALUEs use the 'variable offset' fields to track the range of possible > values; the 'fixed offset' should never be set on a scalar.
Been testing and reviewing the series over the last several days, looks reasonable to me as far as I can tell. Thanks for all the hard work on unifying this, Edward!
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
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