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| author | James Morse <james.morse@arm.com> | 2022-03-03 19:53:56 +0300 |
|---|---|---|
| committer | James Morse <james.morse@arm.com> | 2022-03-07 20:25:52 +0300 |
| commit | 58c9a5060cb7cd529d49c93954cdafe81c1d642a (patch) | |
| tree | 85b2116c1f354ba0195aefa668b72ac598721436 /arch | |
| parent | 228a26b912287934789023b4132ba76065d9491c (diff) | |
| download | linux-58c9a5060cb7cd529d49c93954cdafe81c1d642a.tar.xz | |
arm64: proton-pack: Include unprivileged eBPF status in Spectre v2 mitigation reporting
The mitigations for Spectre-BHB are only applied when an exception is
taken from user-space. The mitigation status is reported via the spectre_v2
sysfs vulnerabilities file.
When unprivileged eBPF is enabled the mitigation in the exception vectors
can be avoided by an eBPF program.
When unprivileged eBPF is enabled, print a warning and report vulnerable
via the sysfs vulnerabilities file.
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: James Morse <james.morse@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/kernel/proton-pack.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/arch/arm64/kernel/proton-pack.c b/arch/arm64/kernel/proton-pack.c index d3fbff00993d..6d45c63c6454 100644 --- a/arch/arm64/kernel/proton-pack.c +++ b/arch/arm64/kernel/proton-pack.c @@ -18,6 +18,7 @@ */ #include <linux/arm-smccc.h> +#include <linux/bpf.h> #include <linux/cpu.h> #include <linux/device.h> #include <linux/nospec.h> @@ -111,6 +112,15 @@ static const char *get_bhb_affected_string(enum mitigation_state bhb_state) } } +static bool _unprivileged_ebpf_enabled(void) +{ +#ifdef CONFIG_BPF_SYSCALL + return !sysctl_unprivileged_bpf_disabled; +#else + return false; +#endif +} + ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, char *buf) { @@ -130,6 +140,9 @@ ssize_t cpu_show_spectre_v2(struct device *dev, struct device_attribute *attr, v2_str = "CSV2"; fallthrough; case SPECTRE_MITIGATED: + if (bhb_state == SPECTRE_MITIGATED && _unprivileged_ebpf_enabled()) + return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); + return sprintf(buf, "Mitigation: %s%s\n", v2_str, bhb_str); case SPECTRE_VULNERABLE: fallthrough; @@ -1125,3 +1138,16 @@ void __init spectre_bhb_patch_clearbhb(struct alt_instr *alt, *updptr++ = cpu_to_le32(aarch64_insn_gen_nop()); *updptr++ = cpu_to_le32(aarch64_insn_gen_nop()); } + +#ifdef CONFIG_BPF_SYSCALL +#define EBPF_WARN "Unprivileged eBPF is enabled, data leaks possible via Spectre v2 BHB attacks!\n" +void unpriv_ebpf_notify(int new_state) +{ + if (spectre_v2_state == SPECTRE_VULNERABLE || + spectre_bhb_state != SPECTRE_MITIGATED) + return; + + if (!new_state) + pr_err("WARNING: %s", EBPF_WARN); +} +#endif |