From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 10 Jun 2021 22:19:59 +0000 (+0200)
Subject: 5.10-stable patches
X-Git-Tag: v4.4.273~62
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=db1438437becd463c6cc68ebb490a20b3870205c;p=thirdparty%2Fkernel%2Fstable-queue.git

5.10-stable patches

added patches:
	proc-track-proc-pid-attr-opener-mm_struct.patch
---

diff --git a/queue-5.10/proc-track-proc-pid-attr-opener-mm_struct.patch b/queue-5.10/proc-track-proc-pid-attr-opener-mm_struct.patch
new file mode 100644
index 00000000000..96dc04e6c65
--- /dev/null
+++ b/queue-5.10/proc-track-proc-pid-attr-opener-mm_struct.patch
@@ -0,0 +1,65 @@
+From 591a22c14d3f45cc38bd1931c593c221df2f1881 Mon Sep 17 00:00:00 2001
+From: Kees Cook <keescook@chromium.org>
+Date: Tue, 8 Jun 2021 10:12:21 -0700
+Subject: proc: Track /proc/$pid/attr/ opener mm_struct
+
+From: Kees Cook <keescook@chromium.org>
+
+commit 591a22c14d3f45cc38bd1931c593c221df2f1881 upstream.
+
+Commit bfb819ea20ce ("proc: Check /proc/$pid/attr/ writes against file opener")
+tried to make sure that there could not be a confusion between the opener of
+a /proc/$pid/attr/ file and the writer. It used struct cred to make sure
+the privileges didn't change. However, there were existing cases where a more
+privileged thread was passing the opened fd to a differently privileged thread
+(during container setup). Instead, use mm_struct to track whether the opener
+and writer are still the same process. (This is what several other proc files
+already do, though for different reasons.)
+
+Reported-by: Christian Brauner <christian.brauner@ubuntu.com>
+Reported-by: Andrea Righi <andrea.righi@canonical.com>
+Tested-by: Andrea Righi <andrea.righi@canonical.com>
+Fixes: bfb819ea20ce ("proc: Check /proc/$pid/attr/ writes against file opener")
+Cc: stable@vger.kernel.org
+Signed-off-by: Kees Cook <keescook@chromium.org>
+Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ fs/proc/base.c |    9 ++++++++-
+ 1 file changed, 8 insertions(+), 1 deletion(-)
+
+--- a/fs/proc/base.c
++++ b/fs/proc/base.c
+@@ -2675,6 +2675,11 @@ out:
+ }
+ 
+ #ifdef CONFIG_SECURITY
++static int proc_pid_attr_open(struct inode *inode, struct file *file)
++{
++	return __mem_open(inode, file, PTRACE_MODE_READ_FSCREDS);
++}
++
+ static ssize_t proc_pid_attr_read(struct file * file, char __user * buf,
+ 				  size_t count, loff_t *ppos)
+ {
+@@ -2705,7 +2710,7 @@ static ssize_t proc_pid_attr_write(struc
+ 	int rv;
+ 
+ 	/* A task may only write when it was the opener. */
+-	if (file->f_cred != current_real_cred())
++	if (file->private_data != current->mm)
+ 		return -EPERM;
+ 
+ 	rcu_read_lock();
+@@ -2755,9 +2760,11 @@ out:
+ }
+ 
+ static const struct file_operations proc_pid_attr_operations = {
++	.open		= proc_pid_attr_open,
+ 	.read		= proc_pid_attr_read,
+ 	.write		= proc_pid_attr_write,
+ 	.llseek		= generic_file_llseek,
++	.release	= mem_release,
+ };
+ 
+ #define LSM_DIR_OPS(LSM) \