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git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpfDavid S. Miller authored
Daniel Borkmann says: ==================== pull-request: bpf 2017-11-23 The following pull-request contains BPF updates for your *net* tree. The main changes are: 1) Several BPF offloading fixes, from Jakub. Among others: - Limit offload to cls_bpf and XDP program types only. - Move device validation into the driver and don't make any assumptions about the device in the classifier due to shared blocks semantics. - Don't pass offloaded XDP program into the driver when it should be run in native XDP instead. Offloaded ones are not JITed for the host in such cases. - Don't destroy device offload state when moved to another namespace. - Revert dumping offload info into user space for now, since ifindex alone is not sufficient. This will be redone properly for bpf-next tree. 2) Fix test_verifier to avoid using bpf_probe_write_user() helper in test cases, since it's dumping a warning into kernel log which may confuse users when only running tests. Switch to use bpf_trace_printk() instead, from Yonghong. 3) Several fixes for correcting ARG_CONST_SIZE_OR_ZERO semantics before it becomes uabi, from Gianluca. More specifically: - Add a type ARG_PTR_TO_MEM_OR_NULL that is used only by bpf_csum_diff(), where the argument is either a valid pointer or NULL. The subsequent ARG_CONST_SIZE_OR_ZERO then enforces a valid pointer in case of non-0 size or a valid pointer or NULL in case of size 0. Given that, the semantics for ARG_PTR_TO_MEM in combination with ARG_CONST_SIZE_OR_ZERO are now such that in case of size 0, the pointer must always be valid and cannot be NULL. This fix in semantics allows for bpf_probe_read() to drop the recently added size == 0 check in the helper that would become part of uabi otherwise once released. At the same time we can then fix bpf_probe_read_str() and bpf_perf_event_output() to use ARG_CONST_SIZE_OR_ZERO instead of ARG_CONST_SIZE in order to fix recently reported issues by Arnaldo et al, where LLVM optimizes two boundary checks into a single one for unknown variables where the verifier looses track of the variable bounds and thus rejects valid programs otherwise. 4) A fix for the verifier for the case when it detects comparison of two constants where the branch is guaranteed to not be taken at runtime. Verifier will rightfully prune the exploration of such paths, but we still pass the program to JITs, where they would complain about using reserved fields, etc. Track such dead instructions and sanitize them with mov r0,r0. Rejection is not possible since LLVM may generate them for valid C code and doesn't do as much data flow analysis as verifier. For bpf-next we might implement removal of such dead code and adjust branches instead. Fix from Alexei. ==================== Signed-off-by:
David S. Miller <davem@davemloft.net>
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