From 8fbdf654b00fdf629be3b94c4f64182b9522774a Mon Sep 17 00:00:00 2001 From: Josh Poimboeuf Date: Wed, 20 Apr 2022 11:53:26 +0000 Subject: [PATCH] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting stable inclusion from stable-v4.19.234 commit 995629e1d8e6751936c6e2b738f70b392b0461de category: bugfix bugzilla: 186453, https://gitee.com/src-openeuler/kernel/issues/I50WBM CVE: CVE-2022-0001 -------------------------------- commit 44a3918c8245ab10c6c9719dd12e7a8d291980d8 upstream. With unprivileged eBPF enabled, eIBRS (without retpoline) is vulnerable to Spectre v2 BHB-based attacks. When both are enabled, print a warning message and report it in the 'spectre_v2' sysfs vulnerabilities file. Signed-off-by: Josh Poimboeuf Signed-off-by: Borislav Petkov Reviewed-by: Thomas Gleixner [fllinden@amazon.com: backported to 4.19] Signed-off-by: Frank van der Linden Signed-off-by: Greg Kroah-Hartman Conflicts: kernel/sysctl.c Signed-off-by: Chen Jiahao Reviewed-by: Hanjun Guo Reviewed-by: Liao Chang Signed-off-by: Yongqiang Liu --- arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++------ include/linux/bpf.h | 11 +++++++++++ 2 files changed, 40 insertions(+), 6 deletions(-) diff --git a/arch/x86/kernel/cpu/bugs.c b/arch/x86/kernel/cpu/bugs.c index 9da94659e89f..9a9e5ac44bd5 100644 --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -31,6 +31,7 @@ #include #include #include +#include #include "cpu.h" @@ -607,6 +608,16 @@ static inline const char *spectre_v2_module_string(void) static inline const char *spectre_v2_module_string(void) { return ""; } #endif +#define SPECTRE_V2_EIBRS_EBPF_MSG "WARNING: Unprivileged eBPF is enabled with eIBRS on, data leaks possible via Spectre v2 BHB attacks!\n" + +#ifdef CONFIG_BPF_SYSCALL +void unpriv_ebpf_notify(int new_state) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && !new_state) + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); +} +#endif + static inline bool match_option(const char *arg, int arglen, const char *opt) { int len = strlen(opt); @@ -950,6 +961,9 @@ static void __init spectre_v2_select_mitigation(void) break; } + if (mode == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + pr_err(SPECTRE_V2_EIBRS_EBPF_MSG); + if (spectre_v2_in_eibrs_mode(mode)) { /* Force it so VMEXIT will restore correctly */ x86_spec_ctrl_base |= SPEC_CTRL_IBRS; @@ -1672,6 +1686,20 @@ static char *ibpb_state(void) return ""; } +static ssize_t spectre_v2_show_state(char *buf) +{ + if (spectre_v2_enabled == SPECTRE_V2_EIBRS && unprivileged_ebpf_enabled()) + return sprintf(buf, "Vulnerable: Unprivileged eBPF enabled\n"); + + return sprintf(buf, "%s%s%s%s%s%s\n", + spectre_v2_strings[spectre_v2_enabled], + ibpb_state(), + boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", + stibp_state(), + boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", + spectre_v2_module_string()); +} + static ssize_t srbds_show_state(char *buf) { return sprintf(buf, "%s\n", srbds_strings[srbds_mitigation]); @@ -1697,12 +1725,7 @@ static ssize_t cpu_show_common(struct device *dev, struct device_attribute *attr return sprintf(buf, "%s\n", spectre_v1_strings[spectre_v1_mitigation]); case X86_BUG_SPECTRE_V2: - return sprintf(buf, "%s%s%s%s%s%s\n", spectre_v2_strings[spectre_v2_enabled], - ibpb_state(), - boot_cpu_has(X86_FEATURE_USE_IBRS_FW) ? ", IBRS_FW" : "", - stibp_state(), - boot_cpu_has(X86_FEATURE_RSB_CTXSW) ? ", RSB filling" : "", - spectre_v2_module_string()); + return spectre_v2_show_state(buf); case X86_BUG_SPEC_STORE_BYPASS: return sprintf(buf, "%s\n", ssb_strings[ssb_mode]); diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c40fa25cf2ca..30fcf812df9d 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -546,6 +546,11 @@ static inline int bpf_map_attr_numa_node(const union bpf_attr *attr) struct bpf_prog *bpf_prog_get_type_path(const char *name, enum bpf_prog_type type); int array_map_alloc_check(union bpf_attr *attr); +static inline bool unprivileged_ebpf_enabled(void) +{ + return !sysctl_unprivileged_bpf_disabled; +} + #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { @@ -657,6 +662,12 @@ static inline struct bpf_prog *bpf_prog_get_type_path(const char *name, { return ERR_PTR(-EOPNOTSUPP); } + +static inline bool unprivileged_ebpf_enabled(void) +{ + return false; +} + #endif /* CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get_type(u32 ufd, -- GitLab