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

[Jiri Slaby]

From: Corey Wright <undefi...@pobox.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 <undefi...@pobox.com>
Acked-by: Jann Horn <j...@thejh.net>
Signed-off-by: Jiri Slaby <jsl...@suse.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