linux-kernel - [PATCH 3.12 001/116] proc: Fix ptrace-based permission checks for accessing task maps

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Message-Id: <fa69c2b418d7aaae8d14810caecc9bfe3f44b4e5.1457082108.git.jslaby@suse.cz>
Date:	Fri,  4 Mar 2016 10:00:46 +0100
From:	Jiri Slaby <jslaby@...e.cz>
To:	stable@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, Corey Wright <undefined@...ox.com>,
	Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 001/116] proc: Fix ptrace-based permission checks for accessing task maps

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

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

===============

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.

Fixes: caaee6234d ("ptrace: use fsuid, fsgid, effective creds for fs access checks")
Signed-off-by: Corey Wright <undefined@...ox.com>
Acked-by: Jann Horn <jann@...jh.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 fs/proc/task_mmu.c   | 4 ++--
 fs/proc/task_nommu.c | 2 +-
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index d20f37d1c6e7..4fe8b1082cf3 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -172,7 +172,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 	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);
@@ -1186,7 +1186,7 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
 	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;
diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index 56123a6f462e..123c19890b14 100644
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -223,7 +223,7 @@ static void *m_start(struct seq_file *m, loff_t *pos)
 	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;
-- 
2.7.2