linux-kernel - [PATCH] fs/open: Fix most outstanding security bugs

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Date:   Mon,  1 Apr 2019 11:01:13 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Linux FSDEVEL Mailinglist <linux-fsdevel@...r.kernel.org>
Cc:     Johannes Thumshirn <jthumshirn@...e.de>
Subject: [PATCH] fs/open: Fix most outstanding security bugs

Over the last 20 years, the Linux kernel has accumulated hundreds if not
thousands of security vulnerabilities.

One common pattern in most of these security related reports is processes
called "syzkaller", "trinity" or "syz-executor" opening files and then
abuse kernel interfaces causing kernel crashes or even worse threats using
memory overwrites or by exploiting race conditions.

Hunting down these bugs has become time consuming and very expensive, so
I've decided to put an end to it.

If one of the above mentioned processes tries opening a file, return -EPERM
indicating this process does not have the permission to open files on Linux
anymore.

Signed-off-by: Johannes Thumshirn <jthumshirn@...e.de>
---
 fs/open.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/open.c b/fs/open.c
index f1c2f855fd43..3a3b460beccd 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -1056,6 +1056,20 @@ long do_sys_open(int dfd, const char __user *filename, int flags, umode_t mode)
 	struct open_flags op;
 	int fd = build_open_flags(flags, mode, &op);
 	struct filename *tmp;
+	char comm[TASK_COMM_LEN];
+	int i;
+	static const char * const list[] = {
+		"syzkaller",
+		"syz-executor,"
+		"trinity",
+		NULL
+	};
+
+	get_task_comm(comm, current);
+
+	for (i = 0; i < ARRAY_SIZE(list); i++)
+		if (!strncmp(comm, list[i], strlen(list[i])))
+			return -EPERM;

 	if (fd)
 		return fd;
-- 
2.16.4