6.17-stable review patch. If anyone has any objections, please let me know.
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From: Ondrej Mosnacek omosnace@redhat.com
[ Upstream commit 881a9c9cb7856b24e390fad9f59acfd73b98b3b2 ]
The failure of this check only results in a security mitigation being applied, slightly affecting performance of the compiled BPF program. It doesn't result in a failed syscall, an thus auditing a failed LSM permission check for it is unwanted. For example with SELinux, it causes a denial to be reported for confined processes running as root, which tends to be flagged as a problem to be fixed in the policy. Yet dontauditing or allowing CAP_SYS_ADMIN to the domain may not be desirable, as it would allow/silence also other checks - either going against the principle of least privilege or making debugging potentially harder.
Fix it by changing it from capable() to ns_capable_noaudit(), which instructs the LSMs to not audit the resulting denials.
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2369326 Fixes: d4e89d212d40 ("x86/bpf: Call branch history clearing sequence on exit") Signed-off-by: Ondrej Mosnacek omosnace@redhat.com Reviewed-by: Paul Moore paul@paul-moore.com Link: https://lore.kernel.org/r/20251021122758.2659513-1-omosnace@redhat.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- arch/x86/net/bpf_jit_comp.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index 7e3fca1646203..574586a6d97f8 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -2592,7 +2592,7 @@ st: if (is_imm8(insn->off)) /* Update cleanup_addr */ ctx->cleanup_addr = proglen; if (bpf_prog_was_classic(bpf_prog) && - !capable(CAP_SYS_ADMIN)) { + !ns_capable_noaudit(&init_user_ns, CAP_SYS_ADMIN)) { u8 *ip = image + addrs[i - 1];
if (emit_spectre_bhb_barrier(&prog, ip, bpf_prog))