renegade-project/linux-next
2
0
Fork 0
mirror of https://github.com/edk2-porting/linux-next.git synced 2024-12-17 01:34:00 +08:00
Code

x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting

Browse Source 
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 <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Josh Poimboeuf 2022-02-18 11:49:08 -08:00 committed by Borislav Petkov
parent 5ad3eb1132
commit 44a3918c82
3 changed files with 47 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

35
arch/x86/kernel/cpu/bugs.c
View File

@ -16,6 +16,7 @@
#include <linux/prctl.h>
#include <linux/sched/smt.h>
#include <linux/pgtable.h>
#include <linux/bpf.h>
#include <asm/spec-ctrl.h>
#include <asm/cmdline.h>
@ -650,6 +651,16 @@ 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);
@ -994,6 +1005,9 @@ 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;
@ -1780,6 +1794,20 @@ 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]);
@ -1805,12 +1833,7 @@ 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]);

11
include/linux/bpf.h
View File

@ -1793,6 +1793,11 @@ struct bpf_core_ctx {
int bpf_core_apply(struct bpf_core_ctx *ctx, const struct bpf_core_relo *relo,
int relo_idx, void *insn);
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)
{
@ -2012,6 +2017,12 @@ bpf_jit_find_kfunc_model(const struct bpf_prog *prog,
{
return NULL;
}
static inline bool unprivileged_ebpf_enabled(void)
{
return false;
}
#endif /* CONFIG_BPF_SYSCALL */
void __bpf_free_used_btfs(struct bpf_prog_aux *aux,

7
kernel/sysctl.c
View File

@ -180,6 +180,10 @@ static int bpf_stats_handler(struct ctl_table *table, int write,
return ret;
}
void __weak unpriv_ebpf_notify(int new_state)
{
}
static int bpf_unpriv_handler(struct ctl_table *table, int write,
void *buffer, size_t *lenp, loff_t *ppos)
{
@ -197,6 +201,9 @@ static int bpf_unpriv_handler(struct ctl_table *table, int write,
return -EPERM;
*(int *)table->data = unpriv_enable;
}
unpriv_ebpf_notify(unpriv_enable);
return ret;
}
#endif /* CONFIG_BPF_SYSCALL && CONFIG_SYSCTL */