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SubjectRe: [PATCH] fs/open: Fix most outstanding security bugs
On Mon, Apr 01, 2019 at 11:01:13AM +0200, Johannes Thumshirn wrote:
> 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@suse.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[] = {

"list" is a bit ambiguous. You could call it "blacklist" or such.

> + "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;
^^^^^^^
should be -ECONNRESET.

Also, I'm missing a sysfs parameter file to add more bad guys dynamically.

> if (fd)
> return fd;
> --
> 2.16.4

But for a start, this is OK.
In any case, as already mentioned, big player Cisco has shown us that this is
definitely the way to go!

Rviewed-by: Torsten Duwe <duwe@lst.de>

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