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From foo@baz Tue Mar 8 08:47:19 PM CET 2022 |
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From: James Morse <james.morse@arm.com> |
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Date: Thu, 3 Mar 2022 16:53:56 +0000 |
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Subject: arm64: proton-pack: Include unprivileged eBPF status in Spectre v2 mitigation reporting |
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|
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From: James Morse <james.morse@arm.com> |
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|
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commit 58c9a5060cb7cd529d49c93954cdafe81c1d642a upstream. |
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|
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The mitigations for Spectre-BHB are only applied when an exception is |
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taken from user-space. The mitigation status is reported via the spectre_v2 |
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sysfs vulnerabilities file. |
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|
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When unprivileged eBPF is enabled the mitigation in the exception vectors |
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can be avoided by an eBPF program. |
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|
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When unprivileged eBPF is enabled, print a warning and report vulnerable |
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via the sysfs vulnerabilities file. |
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|
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Acked-by: Catalin Marinas <catalin.marinas@arm.com> |
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Signed-off-by: James Morse <james.morse@arm.com> |
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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--- |
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arch/arm64/kernel/proton-pack.c | 26 ++++++++++++++++++++++++++ |
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1 file changed, 26 insertions(+) |
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|
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--- a/arch/arm64/kernel/proton-pack.c |
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+++ b/arch/arm64/kernel/proton-pack.c |
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@@ -18,6 +18,7 @@ |
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*/ |
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|
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#include <linux/arm-smccc.h> |
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+#include <linux/bpf.h> |
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#include <linux/cpu.h> |
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#include <linux/device.h> |
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#include <linux/nospec.h> |
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@@ -111,6 +112,15 @@ static const char *get_bhb_affected_stri |
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} |
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} |
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|
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+static bool _unprivileged_ebpf_enabled(void) |
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+{ |
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+#ifdef CONFIG_BPF_SYSCALL |
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+ return !sysctl_unprivileged_bpf_disabled; |
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+#else |
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+ return false; |
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+#endif |
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+} |
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+ |
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ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, |
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char *buf) |
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{ |
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@@ -130,6 +140,9 @@ ssize_t cpu_show_spectre_v2(struct devic |
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v2_str = "CSV2"; |
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fallthrough; |
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case SPECTRE_MITIGATED: |
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+ if (bhb_state == SPECTRE_MITIGATED && _unprivileged_ebpf_enabled()) |
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+ return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); |
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+ |
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return sprintf(buf, "Mitigation: %s%s\n", v2_str, bhb_str); |
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case SPECTRE_VULNERABLE: |
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fallthrough; |
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@@ -1125,3 +1138,16 @@ void __init spectre_bhb_patch_clearbhb(s |
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*updptr++ = cpu_to_le32(aarch64_insn_gen_nop()); |
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*updptr++ = cpu_to_le32(aarch64_insn_gen_nop()); |
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} |
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+ |
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+#ifdef CONFIG_BPF_SYSCALL |
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+#define EBPF_WARN "Unprivileged eBPF is enabled, data leaks possible via Spectre v2 BHB attacks!\n" |
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+void unpriv_ebpf_notify(int new_state) |
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+{ |
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+ if (spectre_v2_state == SPECTRE_VULNERABLE || |
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+ spectre_bhb_state != SPECTRE_MITIGATED) |
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+ return; |
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+ |
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+ if (!new_state) |
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+ pr_err("WARNING: %s", EBPF_WARN); |
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+} |
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+#endif |
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