From: Rick Edgecombe <rick.p.edgecombe@intel.com>
To: 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>,
Peter Zijlstra <peterz@infradead.org>,
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,
Nadav Amit <namit@vmware.com>,
Daniel Borkmann <daniel@iogearbox.net>,
Alexei Starovoitov <ast@kernel.org>,
Rick Edgecombe <rick.p.edgecombe@intel.com>
Subject: [PATCH v4 23/23] bpf: Fail bpf_probe_write_user() while mm is switched
Date: Mon, 22 Apr 2019 11:58:05 -0700 [thread overview]
Message-ID: <20190422185805.1169-24-rick.p.edgecombe@intel.com> (raw)
In-Reply-To: <20190422185805.1169-1-rick.p.edgecombe@intel.com>
From: Nadav Amit <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:[~2019-04-22 18:59 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-04-22 18:57 [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 01/23] Fix "x86/alternatives: Lockdep-enforce text_mutex in text_poke*()" Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 02/23] x86/jump_label: Use text_poke_early() during early init Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 03/23] x86/mm: Introduce temporary mm structs Rick Edgecombe
2019-04-25 16:26 ` Borislav Petkov
2019-04-25 17:37 ` Nadav Amit
2019-04-25 17:49 ` Andy Lutomirski
2019-04-22 18:57 ` [PATCH v4 04/23] x86/mm: Save DRs when loading a temporary mm Rick Edgecombe
2019-04-25 16:36 ` Borislav Petkov
2019-04-25 18:17 ` Peter Zijlstra
2019-04-22 18:57 ` [PATCH v4 05/23] fork: Provide a function for copying init_mm Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 06/23] x86/alternative: Initialize temporary mm for patching Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 07/23] x86/alternative: Use temporary mm for text poking Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 08/23] x86/kgdb: Avoid redundant comparison of patched code Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 09/23] x86/ftrace: Set trampoline pages as executable Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 10/23] x86/kprobes: Set instruction page " Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 11/23] x86/module: Avoid breaking W^X while loading modules Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 12/23] x86/jump-label: Remove support for custom poker Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 13/23] x86/alternative: Remove the return value of text_poke_*() Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 14/23] x86/mm/cpa: Add set_direct_map_ functions Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 15/23] mm: Make hibernate handle unmapped pages Rick Edgecombe
2019-04-22 18:57 ` [PATCH v4 16/23] vmalloc: Add flag for free of special permsissions Rick Edgecombe
2019-04-25 20:38 ` Peter Zijlstra
2019-04-25 21:22 ` Edgecombe, Rick P
2019-04-22 18:57 ` [PATCH v4 17/23] modules: Use vmalloc special flag Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 18/23] bpf: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 19/23] x86/ftrace: " Rick Edgecombe
2019-04-25 18:28 ` Steven Rostedt
2019-04-25 19:19 ` Edgecombe, Rick P
2019-04-22 18:58 ` [PATCH v4 20/23] x86/kprobes: " Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 21/23] x86/alternative: Comment about module removal races Rick Edgecombe
2019-04-22 18:58 ` [PATCH v4 22/23] tlb: provide default nmi_uaccess_okay() Rick Edgecombe
2019-04-22 18:58 ` Rick Edgecombe [this message]
2019-04-25 20:48 ` [PATCH v4 00/23] Merge text_poke fixes and executable lockdowns Peter Zijlstra
2019-04-25 20:49 ` Peter Zijlstra
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