[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <tip-c7b6f29b6257532792fc722b68fcc0e00b5a856c@git.kernel.org>
Date: Tue, 30 Apr 2019 04:15:13 -0700
From: tip-bot for Nadav Amit <tipbot@...or.com>
To: linux-tip-commits@...r.kernel.org
Cc: luto@...nel.org, namit@...are.com, linux_dti@...oud.com,
ard.biesheuvel@...aro.org, will.deacon@....com, jannh@...gle.com,
riel@...riel.com, rick.p.edgecombe@...el.com,
kernel-hardening@...ts.openwall.com, torvalds@...ux-foundation.org,
linux-kernel@...r.kernel.org, daniel@...earbox.net,
deneen.t.dock@...el.com, tglx@...utronix.de, ast@...nel.org,
akpm@...ux-foundation.org, mingo@...nel.org, kristen@...ux.intel.com,
peterz@...radead.org, bp@...en8.de, hpa@...or.com,
dave.hansen@...ux.intel.com
Subject: [tip:x86/mm] bpf: Fail bpf_probe_write_user() while mm is switched
Commit-ID: c7b6f29b6257532792fc722b68fcc0e00b5a856c
Gitweb: https://git.kernel.org/tip/c7b6f29b6257532792fc722b68fcc0e00b5a856c
Author: Nadav Amit <namit@...are.com>
AuthorDate: Thu, 25 Apr 2019 17:11:43 -0700
Committer: Ingo Molnar <mingo@...nel.org>
CommitDate: Tue, 30 Apr 2019 12:37:48 +0200
bpf: Fail bpf_probe_write_user() while mm is switched
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.
Suggested-by: Jann Horn <jannh@...gle.com>
Reported-by: Jann Horn <jannh@...gle.com>
Signed-off-by: Nadav Amit <namit@...are.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>
Cc: <akpm@...ux-foundation.org>
Cc: <ard.biesheuvel@...aro.org>
Cc: <deneen.t.dock@...el.com>
Cc: <kernel-hardening@...ts.openwall.com>
Cc: <kristen@...ux.intel.com>
Cc: <linux_dti@...oud.com>
Cc: <will.deacon@....com>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andy Lutomirski <luto@...nel.org>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: H. Peter Anvin <hpa@...or.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Rik van Riel <riel@...riel.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Link: https://lkml.kernel.org/r/20190426001143.4983-24-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
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;
Powered by blists - more mailing lists
Confused about mailing lists and their use?
Read about mailing lists on Wikipedia
and check out these
guidelines on proper formatting of your messages.
