From: YiFei Zhu zhuyifei@google.com
[ Upstream commit 14b20b784f59bdd95f6f1cfb112c9818bcec4d84 ]
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 Signed-off-by: Sasha Levin sashal@kernel.org --- kernel/bpf/syscall.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 82e83cfb4114a..dd0fc2a86ce17 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5153,7 +5153,7 @@ syscall_prog_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) { switch (func_id) { 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: return &bpf_btf_find_by_name_kind_proto; case BPF_FUNC_sys_close: