bpf: improve read-only handling
Improve bpf_{prog,jit_binary}_{un,}lock_ro() by throwing a one-time warning in case of an error when the image couldn't be set read-only, and also mark struct bpf_prog as locked when bpf_prog_lock_ro() was called. Reason for the latter is that bpf_prog_unlock_ro() is called from various places including error paths, and we shouldn't mess with page attributes when really not needed. For bpf_jit_binary_unlock_ro() this is not needed as jited flag implicitly indicates this, thus for archs with ARCH_HAS_SET_MEMORY we're guaranteed to have a previously locked image. Overall, this should also help us to identify any further potential issues with set_memory_*() helpers. Signed-off-by: NDaniel Borkmann <daniel@iogearbox.net> Acked-by: NAlexei Starovoitov <ast@kernel.org> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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