YiFei Zhu ab022c8eb4 bpf: Add cgroup helpers bpf_{get,set}_retval to get/set syscall return value ... The helpers continue to use int for retval because all the hooks are int-returning rather than long-returning. The return value of bpf_set_retval is int for future-proofing, in case in the future there may be errors trying to set the retval. After the previous patch, if a program rejects a syscall by returning 0, an -EPERM will be generated no matter if the retval is already set to -err. This patch change it being forced only if retval is not -err. This is because we want to support, for example, invoking bpf_set_retval(-EINVAL) and return 0, and have the syscall return value be -EINVAL not -EPERM. For BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY, the prior behavior is that, if the return value is NET_XMIT_DROP, the packet is silently dropped. We preserve this behavior for backward compatibility reasons, so even if an errno is set, the errno does not return to caller. However, setting a non-err to retval cannot propagate so this is not allowed and we return a -EFAULT in that case. Signed-off-by: YiFei Zhu <zhuyifei@google.com> Reviewed-by: Stanislav Fomichev <sdf@google.com> Link: https://lore.kernel.org/r/b4013fd5d16bed0b01977c1fafdeae12e1de61fb.1639619851.git.zhuyifei@google.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>		2022-01-21 16:54:32 -08:00
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asm	AF_XDP: add xsk.{c,h} to Makefile and fix build	2019-03-05 09:22:54 -08:00
linux	include: Include linux/stddef.h	2022-01-14 12:21:53 -08:00
uapi/linux	bpf: Add cgroup helpers bpf_{get,set}_retval to get/set syscall return value	2022-01-21 16:54:32 -08:00