From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Mon, 21 Aug 2017 00:29:07 +0000 (-0700)
Subject: 4.4-stable patches
X-Git-Tag: v3.18.67~10
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=a0d27d643cb5c421138af6bbe82254e1a1e6ff1f;p=thirdparty%2Fkernel%2Fstable-queue.git

4.4-stable patches

added patches:
	sanitize-move_pages-permission-checks.patch
---

diff --git a/queue-4.4/sanitize-move_pages-permission-checks.patch b/queue-4.4/sanitize-move_pages-permission-checks.patch
new file mode 100644
index 00000000000..0545856a28c
--- /dev/null
+++ b/queue-4.4/sanitize-move_pages-permission-checks.patch
@@ -0,0 +1,75 @@
+From 197e7e521384a23b9e585178f3f11c9fa08274b9 Mon Sep 17 00:00:00 2001
+From: Linus Torvalds <torvalds@linux-foundation.org>
+Date: Sun, 20 Aug 2017 13:26:27 -0700
+Subject: Sanitize 'move_pages()' permission checks
+
+From: Linus Torvalds <torvalds@linux-foundation.org>
+
+commit 197e7e521384a23b9e585178f3f11c9fa08274b9 upstream.
+
+The 'move_paghes()' system call was introduced long long ago with the
+same permission checks as for sending a signal (except using
+CAP_SYS_NICE instead of CAP_SYS_KILL for the overriding capability).
+
+That turns out to not be a great choice - while the system call really
+only moves physical page allocations around (and you need other
+capabilities to do a lot of it), you can check the return value to map
+out some the virtual address choices and defeat ASLR of a binary that
+still shares your uid.
+
+So change the access checks to the more common 'ptrace_may_access()'
+model instead.
+
+This tightens the access checks for the uid, and also effectively
+changes the CAP_SYS_NICE check to CAP_SYS_PTRACE, but it's unlikely that
+anybody really _uses_ this legacy system call any more (we hav ebetter
+NUMA placement models these days), so I expect nobody to notice.
+
+Famous last words.
+
+Reported-by: Otto Ebeling <otto.ebeling@iki.fi>
+Acked-by: Eric W. Biederman <ebiederm@xmission.com>
+Cc: Willy Tarreau <w@1wt.eu>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+
+---
+ mm/migrate.c |   13 ++++---------
+ 1 file changed, 4 insertions(+), 9 deletions(-)
+
+--- a/mm/migrate.c
++++ b/mm/migrate.c
+@@ -38,6 +38,7 @@
+ #include <linux/balloon_compaction.h>
+ #include <linux/mmu_notifier.h>
+ #include <linux/page_idle.h>
++#include <linux/ptrace.h>
+ 
+ #include <asm/tlbflush.h>
+ 
+@@ -1483,7 +1484,6 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid,
+ 		const int __user *, nodes,
+ 		int __user *, status, int, flags)
+ {
+-	const struct cred *cred = current_cred(), *tcred;
+ 	struct task_struct *task;
+ 	struct mm_struct *mm;
+ 	int err;
+@@ -1507,14 +1507,9 @@ SYSCALL_DEFINE6(move_pages, pid_t, pid,
+ 
+ 	/*
+ 	 * Check if this process has the right to modify the specified
+-	 * process. The right exists if the process has administrative
+-	 * capabilities, superuser privileges or the same
+-	 * userid as the target process.
+-	 */
+-	tcred = __task_cred(task);
+-	if (!uid_eq(cred->euid, tcred->suid) && !uid_eq(cred->euid, tcred->uid) &&
+-	    !uid_eq(cred->uid,  tcred->suid) && !uid_eq(cred->uid,  tcred->uid) &&
+-	    !capable(CAP_SYS_NICE)) {
++	 * process. Use the regular "ptrace_may_access()" checks.
++	 */
++	if (!ptrace_may_access(task, PTRACE_MODE_READ_REALCREDS)) {
+ 		rcu_read_unlock();
+ 		err = -EPERM;
+ 		goto out;
diff --git a/queue-4.4/series b/queue-4.4/series
index fe1f1bc39bf..8bc07c8f73e 100644
--- a/queue-4.4/series
+++ b/queue-4.4/series
@@ -13,3 +13,4 @@ xen-fix-bio-vec-merging.patch
 x86-asm-64-clear-ac-on-nmi-entries.patch
 irqchip-atmel-aic-fix-unbalanced-of_node_put-in-aic_common_irq_fixup.patch
 irqchip-atmel-aic-fix-unbalanced-refcount-in-aic_common_rtc_irq_fixup.patch
+sanitize-move_pages-permission-checks.patch