bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.
mainline inclusion from mainline-v5.17-rc1 commit 216e3cd2 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4WRPV CVE: CVE-2022-0500 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=216e3cd2f28dbbf1fe86848e0e29e6693b9f0a20 -------------------------------- Some helper functions may modify its arguments, for example, bpf_d_path, bpf_get_stack etc. Previously, their argument types were marked as ARG_PTR_TO_MEM, which is compatible with read-only mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate, but technically incorrect, to modify a read-only memory by passing it into one of such helper functions. This patch tags the bpf_args compatible with immutable memory with MEM_RDONLY flag. The arguments that don't have this flag will be only compatible with mutable memory types, preventing the helper from modifying a read-only memory. The bpf_args that have MEM_RDONLY are compatible with both mutable memory and immutable memory. Signed-off-by: NHao Luo <haoluo@google.com> Signed-off-by: NAlexei Starovoitov <ast@kernel.org> Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com Conflicts: kernel/bpf/btf.c kernel/bpf/helpers.c kernel/bpf/syscall.c kernel/trace/bpf_trace.c net/core/filter.c Signed-off-by: NPu Lehui <pulehui@huawei.com> Reviewed-by: NKuohai Xu <xukuohai@huawei.com> Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
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