[PATCH 6.6 096/113] arm64: bpf: Only mitigate cBPF programs loaded by unprivileged users

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

6.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: James Morse <james.morse@arm.com>

commit f300769ead032513a68e4a02e806393402e626f8 upstream.

Support for eBPF programs loaded by unprivileged users is typically
disabled. This means only cBPF programs need to be mitigated for BHB.

In addition, only mitigate cBPF programs that were loaded by an
unprivileged user. Privileged users can also load the same program
via eBPF, making the mitigation pointless.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/arm64/net/bpf_jit_comp.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/arch/arm64/net/bpf_jit_comp.c
+++ b/arch/arm64/net/bpf_jit_comp.c
@@ -666,6 +666,9 @@ static void __maybe_unused build_bhb_mit
 	    arm64_get_spectre_v2_state() == SPECTRE_VULNERABLE)
 		return;
 
+	if (capable(CAP_SYS_ADMIN))
+		return;
+
 	if (supports_clearbhb(SCOPE_SYSTEM)) {
 		emit(aarch64_insn_gen_hint(AARCH64_INSN_HINT_CLEARBHB), ctx);
 		return;