From: Nadav Amit <namit@vmware.com>
To: Peter Zijlstra <peterz@infradead.org>,
Borislav Petkov <bp@alien8.de>, Andy Lutomirski <luto@kernel.org>,
Ingo Molnar <mingo@redhat.com>
Cc: <linux-kernel@vger.kernel.org>, <x86@kernel.org>, <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Nadav Amit <nadav.amit@gmail.com>,
Dave Hansen <dave.hansen@linux.intel.com>, <linux_dti@icloud.com>,
<linux-integrity@vger.kernel.org>,
<linux-security-module@vger.kernel.org>,
<akpm@linux-foundation.org>,
<kernel-hardening@lists.openwall.com>, <linux-mm@kvack.org>,
<will.deacon@arm.com>, <ard.biesheuvel@linaro.org>,
<kristen@linux.intel.com>, <deneen.t.dock@intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Nadav Amit <namit@vmware.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>
Subject: [PATCH v5 23/23] bpf: Fail bpf_probe_write_user() while mm is switched
Date: Thu, 25 Apr 2019 17:11:43 -0700 [thread overview]
Message-ID: <20190426001143.4983-24-namit@vmware.com> (raw)
In-Reply-To: <20190426001143.4983-1-namit@vmware.com>
When using a temporary mm, bpf_probe_write_user() should not be able to
write to user memory, since user memory addresses may be used to map
kernel memory. Detect these cases and fail bpf_probe_write_user() in
such cases.
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alexei Starovoitov <ast@kernel.org>
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Jann Horn <jannh@google.com>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
---
kernel/trace/bpf_trace.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index d64c00afceb5..94b0e37d90ef 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -14,6 +14,8 @@
#include <linux/syscalls.h>
#include <linux/error-injection.h>
+#include <asm/tlb.h>
+
#include "trace_probe.h"
#include "trace.h"
@@ -163,6 +165,10 @@ BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
* access_ok() should prevent writing to non-user memory, but in
* some situations (nommu, temporary switch, etc) access_ok() does
* not provide enough validation, hence the check on KERNEL_DS.
+ *
+ * nmi_uaccess_okay() ensures the probe is not run in an interim
+ * state, when the task or mm are switched. This is specifically
+ * required to prevent the use of temporary mm.
*/
if (unlikely(in_interrupt() ||
@@ -170,6 +176,8 @@ BPF_CALL_3(bpf_probe_write_user, void *, unsafe_ptr, const void *, src,
return -EPERM;
if (unlikely(uaccess_kernel()))
return -EPERM;
+ if (unlikely(!nmi_uaccess_okay()))
+ return -EPERM;
if (!access_ok(unsafe_ptr, size))
return -EPERM;
--
2.17.1
next prev parent reply other threads:[~2019-04-26 7:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-26 0:11 [PATCH v5 00/23] x86: text_poke() fixes and executable lockdowns Nadav Amit
2019-04-26 0:11 ` [PATCH v5 01/23] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Nadav Amit
2019-04-30 11:13 ` [tip:x86/mm] x86/alternatives: Add text_poke_kgdb() to not assert the lock when debugging tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 02/23] x86/jump_label: Use text_poke_early() during early init Nadav Amit
2019-04-30 11:15 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 03/23] x86/mm: Introduce temporary mm structs Nadav Amit
2019-04-30 11:16 ` [tip:x86/mm] " tip-bot for Andy Lutomirski
2019-04-26 0:11 ` [PATCH v5 04/23] x86/mm: Save debug registers when loading a temporary mm Nadav Amit
2019-04-30 11:17 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 05/23] fork: Provide a function for copying init_mm Nadav Amit
2019-04-30 11:18 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 06/23] x86/alternative: Initialize temporary mm for patching Nadav Amit
2019-04-26 0:11 ` [PATCH v5 07/23] x86/alternative: Use temporary mm for text poking Nadav Amit
2019-04-30 11:20 ` [tip:x86/mm] x86/alternatives: " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 08/23] x86/kgdb: Avoid redundant comparison of patched code Nadav Amit
2019-04-30 11:20 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 09/23] x86/ftrace: Set trampoline pages as executable Nadav Amit
2019-04-30 11:21 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 10/23] x86/kprobes: Set instruction page " Nadav Amit
2019-04-30 11:22 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 11/23] x86/module: Avoid breaking W^X while loading modules Nadav Amit
2019-04-30 11:22 ` [tip:x86/mm] x86/modules: " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 12/23] x86/jump-label: Remove support for custom poker Nadav Amit
2019-04-30 11:23 ` [tip:x86/mm] x86/jump-label: Remove support for custom text poker tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 13/23] x86/alternative: Remove the return value of text_poke_*() Nadav Amit
2019-04-30 11:24 ` [tip:x86/mm] x86/alternatives: " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 14/23] x86/mm/cpa: Add set_direct_map_ functions Nadav Amit
2019-04-26 16:40 ` Linus Torvalds
2019-04-26 16:43 ` Nadav Amit
2019-04-30 11:24 ` [tip:x86/mm] x86/mm/cpa: Add set_direct_map_*() functions tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 15/23] mm: Make hibernate handle unmapped pages Nadav Amit
2019-04-30 11:25 ` [tip:x86/mm] mm/hibernation: Make hibernation " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 16/23] vmalloc: Add flag for free of special permsissions Nadav Amit
2019-04-30 11:26 ` [tip:x86/mm] mm/vmalloc: Add flag for freeing " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 17/23] modules: Use vmalloc special flag Nadav Amit
2019-04-30 11:26 ` [tip:x86/mm] " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 18/23] bpf: " Nadav Amit
2019-04-30 11:27 ` [tip:x86/mm] " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 19/23] x86/ftrace: " Nadav Amit
2019-04-30 11:28 ` [tip:x86/mm] " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 20/23] x86/kprobes: " Nadav Amit
2019-04-30 11:28 ` [tip:x86/mm] " tip-bot for Rick Edgecombe
2019-04-26 0:11 ` [PATCH v5 21/23] x86/alternative: Comment about module removal races Nadav Amit
2019-04-30 11:29 ` [tip:x86/mm] x86/alternatives: Add comment " tip-bot for Nadav Amit
2019-04-26 0:11 ` [PATCH v5 22/23] mm/tlb: Provide default nmi_uaccess_okay() Nadav Amit
2019-04-30 11:14 ` [tip:x86/mm] " tip-bot for Nadav Amit
2019-04-26 0:11 ` Nadav Amit [this message]
2019-04-30 11:15 ` [tip:x86/mm] bpf: Fail bpf_probe_write_user() while mm is switched tip-bot for Nadav Amit
2019-04-26 12:36 ` [PATCH v5 00/23] x86: text_poke() fixes and executable lockdowns Peter Zijlstra
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