linux-kernel - [PATCH 3.14 023/130] proc: Fix ptrace-based permission checks for accessing task maps

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Message-Id: <20160301234500.584582339@linuxfoundation.org>
Date:	Tue,  1 Mar 2016 15:44:34 -0800
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jann Horn <jann@...jh.net>, Corey Wright <undefined@...ox.com>
Subject: [PATCH 3.14 023/130] proc: Fix ptrace-based permission checks for accessing task maps

3.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Corey Wright <undefined@...ox.com>

Modify mm_access() calls in fs/proc/task_mmu.c and fs/proc/task_nommu.c to
have the mode include PTRACE_MODE_FSCREDS so accessing /proc/pid/maps and
/proc/pid/pagemap is not denied to all users.

In backporting upstream commit caaee623 to pre-3.18 kernel versions it was
overlooked that mm_access() is used in fs/proc/task_*mmu.c as those calls
were removed in 3.18 (by upstream commit 29a40ace) and did not exist at the
time of the original commit.

Signed-off-by: Corey Wright <undefined@...ox.com>
Acked-by: Jann Horn <jann@...jh.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 fs/proc/task_mmu.c   |    4 ++--
 fs/proc/task_nommu.c |    2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -165,7 +165,7 @@ static void *m_start(struct seq_file *m,
 	if (!priv->task)
 		return ERR_PTR(-ESRCH);
 
-	mm = mm_access(priv->task, PTRACE_MODE_READ);
+	mm = mm_access(priv->task, PTRACE_MODE_READ_FSCREDS);
 	if (!mm || IS_ERR(mm))
 		return mm;
 	down_read(&mm->mmap_sem);
@@ -1182,7 +1182,7 @@ static ssize_t pagemap_read(struct file
 	if (!pm.buffer)
 		goto out_task;
 
-	mm = mm_access(task, PTRACE_MODE_READ);
+	mm = mm_access(task, PTRACE_MODE_READ_FSCREDS);
 	ret = PTR_ERR(mm);
 	if (!mm || IS_ERR(mm))
 		goto out_free;
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -216,7 +216,7 @@ static void *m_start(struct seq_file *m,
 	if (!priv->task)
 		return ERR_PTR(-ESRCH);
 
-	mm = mm_access(priv->task, PTRACE_MODE_READ);
+	mm = mm_access(priv->task, PTRACE_MODE_READ_FSCREDS);
 	if (!mm || IS_ERR(mm)) {
 		put_task_struct(priv->task);
 		priv->task = NULL;