From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: linux-kernel@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
stable@vger.kernel.org, Josh Poimboeuf <jpoimboe@redhat.com>,
Borislav Petkov <bp@suse.de>,
Thomas Gleixner <tglx@linutronix.de>,
Frank van der Linden <fllinden@amazon.com>
Subject: [PATCH 5.10 05/43] x86/speculation: Include unprivileged eBPF status in Spectre v2 mitigation reporting
Date: Wed, 9 Mar 2022 16:59:38 +0100 [thread overview]
Message-ID: <20220309155859.398788962@linuxfoundation.org> (raw)
In-Reply-To: <20220309155859.239810747@linuxfoundation.org>
From: Josh Poimboeuf <jpoimboe@redhat.com>
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 <jpoimboe@redhat.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
[fllinden@amazon.com: backported to 5.10]
Signed-off-by: Frank van der Linden <fllinden@amazon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/kernel/cpu/bugs.c | 35 +++++++++++++++++++++++++++++------
include/linux/bpf.h | 12 ++++++++++++
kernel/sysctl.c | 7 +++++++
3 files changed, 48 insertions(+), 6 deletions(-)
--- a/arch/x86/kernel/cpu/bugs.c
+++ b/arch/x86/kernel/cpu/bugs.c
@@ -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>
@@ -613,6 +614,16 @@ static inline const char *spectre_v2_mod
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);
@@ -957,6 +968,9 @@ static void __init spectre_v2_select_mit
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;
@@ -1710,6 +1724,20 @@ 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]);
@@ -1735,12 +1763,7 @@ static ssize_t cpu_show_common(struct de
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]);
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -1485,6 +1485,12 @@ struct bpf_prog *bpf_prog_by_id(u32 id);
struct bpf_link *bpf_link_by_id(u32 id);
const struct bpf_func_proto *bpf_base_func_proto(enum bpf_func_id func_id);
+
+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)
{
@@ -1679,6 +1685,12 @@ bpf_base_func_proto(enum bpf_func_id fun
{
return NULL;
}
+
+static inline bool unprivileged_ebpf_enabled(void)
+{
+ return false;
+}
+
#endif /* CONFIG_BPF_SYSCALL */
static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -234,6 +234,10 @@ static int bpf_stats_handler(struct ctl_
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)
{
@@ -251,6 +255,9 @@ static int bpf_unpriv_handler(struct ctl
return -EPERM;
*(int *)table->data = unpriv_enable;
}
+
+ unpriv_ebpf_notify(unpriv_enable);
+
return ret;
}
#endif /* CONFIG_BPF_SYSCALL && CONFIG_SYSCTL */
next prev parent reply other threads:[~2022-03-09 16:11 UTC|newest]
Thread overview: 50+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-03-09 15:59 [PATCH 5.10 00/43] 5.10.105-rc1 review Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 01/43] x86,bugs: Unconditionally allow spectre_v2=retpoline,amd Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 02/43] x86/speculation: Rename RETPOLINE_AMD to RETPOLINE_LFENCE Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 03/43] x86/speculation: Add eIBRS + Retpoline options Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 04/43] Documentation/hw-vuln: Update spectre doc Greg Kroah-Hartman
2022-03-09 15:59 ` Greg Kroah-Hartman [this message]
2022-03-09 15:59 ` [PATCH 5.10 06/43] x86/speculation: Use generic retpoline by default on AMD Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 07/43] x86/speculation: Update link to AMD speculation whitepaper Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 08/43] x86/speculation: Warn about Spectre v2 LFENCE mitigation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 09/43] x86/speculation: Warn about eIBRS + LFENCE + Unprivileged eBPF + SMT Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 10/43] ARM: report Spectre v2 status through sysfs Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 11/43] ARM: early traps initialisation Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 12/43] ARM: use LOADADDR() to get load address of sections Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 13/43] ARM: Spectre-BHB workaround Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 14/43] ARM: include unprivileged BPF status in Spectre V2 reporting Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 15/43] arm64: cputype: Add CPU implementor & types for the Apple M1 cores Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 16/43] arm64: Add Neoverse-N2, Cortex-A710 CPU part definition Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 17/43] arm64: Add Cortex-X2 " Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 18/43] arm64: Add Cortex-A510 " Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 19/43] arm64: Add HWCAP for self-synchronising virtual counter Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 20/43] arm64: add ID_AA64ISAR2_EL1 sys register Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 21/43] arm64: cpufeature: add HWCAP for FEAT_AFP Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 22/43] arm64: cpufeature: add HWCAP for FEAT_RPRES Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 23/43] arm64: entry.S: Add ventry overflow sanity checks Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 24/43] arm64: spectre: Rename spectre_v4_patch_fw_mitigation_conduit Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 25/43] arm64: entry: Make the trampoline cleanup optional Greg Kroah-Hartman
2022-03-09 15:59 ` [PATCH 5.10 26/43] arm64: entry: Free up another register on kptis tramp_exit path Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 27/43] arm64: entry: Move the trampoline data page before the text page Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 28/43] arm64: entry: Allow tramp_alias to access symbols after the 4K boundary Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 29/43] arm64: entry: Dont assume tramp_vectors is the start of the vectors Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 30/43] arm64: entry: Move trampoline macros out of ifdefd section Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 31/43] arm64: entry: Make the kpti trampolines kpti sequence optional Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 32/43] arm64: entry: Allow the trampoline text to occupy multiple pages Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 33/43] arm64: entry: Add non-kpti __bp_harden_el1_vectors for mitigations Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 34/43] arm64: entry: Add vectors that have the bhb mitigation sequences Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 35/43] arm64: entry: Add macro for reading symbol addresses from the trampoline Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 36/43] arm64: Add percpu vectors for EL1 Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 37/43] arm64: proton-pack: Report Spectre-BHB vulnerabilities as part of Spectre-v2 Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 38/43] KVM: arm64: Allow indirect vectors to be used without SPECTRE_V3A Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 39/43] arm64: Mitigate spectre style branch history side channels Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 40/43] KVM: arm64: Allow SMCCC_ARCH_WORKAROUND_3 to be discovered and migrated Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 41/43] arm64: Use the clearbhb instruction in mitigations Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 42/43] arm64: proton-pack: Include unprivileged eBPF status in Spectre v2 mitigation reporting Greg Kroah-Hartman
2022-03-09 16:00 ` [PATCH 5.10 43/43] ARM: fix build error when BPF_SYSCALL is disabled Greg Kroah-Hartman
2022-03-09 21:10 ` [PATCH 5.10 00/43] 5.10.105-rc1 review Daniel Díaz
2022-03-09 23:56 ` Fox Chen
2022-03-10 3:56 ` Samuel Zou
2022-03-10 4:19 ` Florian Fainelli
2022-03-10 6:22 ` Bagas Sanjaya
2022-03-10 11:35 ` Pavel Machek
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