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ARM: include unprivileged BPF status in Spectre V2 reporting

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The mitigations for Spectre-BHB are only applied when an exception
is taken, but when unprivileged BPF is enabled, userspace can
load BPF programs that can be used to exploit the problem.

When unprivileged BPF is enabled, report the vulnerable status via
the spectre_v2 sysfs file.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Russell King (Oracle) 2022-03-07 19:28:32 +00:00
parent b9baf5c8c5
commit 25875aa71d
1 changed files with 13 additions and 0 deletions
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13
arch/arm/kernel/spectre.c
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@ -1,9 +1,19 @@
// SPDX-License-Identifier: GPL-2.0-only
#include <linux/bpf.h>
#include <linux/cpu.h>
#include <linux/device.h>
#include <asm/spectre.h>
static bool _unprivileged_ebpf_enabled(void)
{
#ifdef CONFIG_BPF_SYSCALL
return !sysctl_unprivileged_bpf_disabled;
#else
return false
#endif
}
ssize_t cpu_show_spectre_v1(struct device *dev, struct device_attribute *attr,
char *buf)
{
@ -31,6 +41,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr,
if (spectre_v2_state != SPECTRE_MITIGATED)
return sprintf(buf, "%s\n", "Vulnerable");
if (_unprivileged_ebpf_enabled())
return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n");
switch (spectre_v2_methods) {
case SPECTRE_V2_METHOD_BPIALL:
method = "Branch predictor hardening";