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bpf: Restrict bpf_sys_bpf to CAP_PERFMON

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The verifier cannot perform sufficient validation of any pointers passed
into bpf_attr and treats them as integers rather than pointers. The helper
will then read from arbitrary pointers passed into it. Restrict the helper
to CAP_PERFMON since the security model in BPF of arbitrary kernel read is
CAP_BPF + CAP_PERFMON.

Fixes: af2ac3e13e45 ("bpf: Prepare bpf syscall to be used from kernel and user space.")
Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220816205517.682470-1-zhuyifei@google.com
This commit is contained in:
YiFei Zhu 2022-08-16 20:55:16 +00:00 committed by Daniel Borkmann
parent 3024d95a4c
commit 14b20b784f
1 changed files with 1 additions and 1 deletions
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2
kernel/bpf/syscall.c
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@ -5197,7 +5197,7 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{ {
switch (func_id) { switch (func_id) {
case BPF_FUNC_sys_bpf: case BPF_FUNC_sys_bpf:
return &bpf_sys_bpf_proto; return !perfmon_capable() ? NULL : &bpf_sys_bpf_proto;
case BPF_FUNC_btf_find_by_name_kind: case BPF_FUNC_btf_find_by_name_kind:
return &bpf_btf_find_by_name_kind_proto; return &bpf_btf_find_by_name_kind_proto;
case BPF_FUNC_sys_close: case BPF_FUNC_sys_close: