[PATCH v2] media: rc: bpf attach/detach requires write permission

[PATCH v2] media: rc: bpf attach/detach requires write permission

[Sean Young]

Note that bpf attach/detach also requires CAP_NET_ADMIN.

Cc: stable@vger.kernel.org
Signed-off-by: Sean Young <sean@mess.org>
---
 drivers/media/rc/bpf-lirc.c     | 6 +++---
 drivers/media/rc/lirc_dev.c     | 5 ++++-
 drivers/media/rc/rc-core-priv.h | 2 +-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/drivers/media/rc/bpf-lirc.c b/drivers/media/rc/bpf-lirc.c
index fe17c7f98e81..52d82cbe7685 100644
--- a/drivers/media/rc/bpf-lirc.c
+++ b/drivers/media/rc/bpf-lirc.c
@@ -253,7 +253,7 @@ int lirc_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 	if (attr->attach_flags)
 		return -EINVAL;
 
-	rcdev = rc_dev_get_from_fd(attr->target_fd);
+	rcdev = rc_dev_get_from_fd(attr->target_fd, true);
 	if (IS_ERR(rcdev))
 		return PTR_ERR(rcdev);
 
@@ -278,7 +278,7 @@ int lirc_prog_detach(const union bpf_attr *attr)
 	if (IS_ERR(prog))
 		return PTR_ERR(prog);
 
-	rcdev = rc_dev_get_from_fd(attr->target_fd);
+	rcdev = rc_dev_get_from_fd(attr->target_fd, true);
 	if (IS_ERR(rcdev)) {
 		bpf_prog_put(prog);
 		return PTR_ERR(rcdev);
@@ -303,7 +303,7 @@ int lirc_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
 	if (attr->query.query_flags)
 		return -EINVAL;
 
-	rcdev = rc_dev_get_from_fd(attr->query.target_fd);
+	rcdev = rc_dev_get_from_fd(attr->query.target_fd, false);
 	if (IS_ERR(rcdev))
 		return PTR_ERR(rcdev);
 
diff --git a/drivers/media/rc/lirc_dev.c b/drivers/media/rc/lirc_dev.c
index 25ab61dae126..d9b316eb86dd 100644
--- a/drivers/media/rc/lirc_dev.c
+++ b/drivers/media/rc/lirc_dev.c
@@ -810,7 +810,7 @@ void __exit lirc_dev_exit(void)
 	unregister_chrdev_region(lirc_base_dev, RC_DEV_MAX);
 }
 
-struct rc_dev *rc_dev_get_from_fd(int fd)
+struct rc_dev *rc_dev_get_from_fd(int fd, bool write)
 {
 	struct fd f = fdget(fd);
 	struct lirc_fh *fh;
@@ -824,6 +824,9 @@ struct rc_dev *rc_dev_get_from_fd(int fd)
 		return ERR_PTR(-EINVAL);
 	}
 
+	if (write && !(f.file->f_mode & FMODE_WRITE))
+		return ERR_PTR(-EPERM);
+
 	fh = f.file->private_data;
 	dev = fh->rc;
 
diff --git a/drivers/media/rc/rc-core-priv.h b/drivers/media/rc/rc-core-priv.h
index ef1e95e1af7f..7df949fc65e2 100644
--- a/drivers/media/rc/rc-core-priv.h
+++ b/drivers/media/rc/rc-core-priv.h
@@ -325,7 +325,7 @@ void lirc_raw_event(struct rc_dev *dev, struct ir_raw_event ev);
 void lirc_scancode_event(struct rc_dev *dev, struct lirc_scancode *lsc);
 int lirc_register(struct rc_dev *dev);
 void lirc_unregister(struct rc_dev *dev);
-struct rc_dev *rc_dev_get_from_fd(int fd);
+struct rc_dev *rc_dev_get_from_fd(int fd, bool write);
 #else
 static inline int lirc_dev_init(void) { return 0; }
 static inline void lirc_dev_exit(void) {}
-- 
2.39.2

Re: [PATCH v2] media: rc: bpf attach/detach requires write permission

[Greg KH]

On Thu, Apr 13, 2023 at 09:50:32AM +0100, Sean Young wrote:
> Note that bpf attach/detach also requires CAP_NET_ADMIN.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Sean Young <sean@mess.org>
> ---
>  drivers/media/rc/bpf-lirc.c     | 6 +++---
>  drivers/media/rc/lirc_dev.c     | 5 ++++-
>  drivers/media/rc/rc-core-priv.h | 2 +-
>  3 files changed, 8 insertions(+), 5 deletions(-)
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/process/submitting-patches.rst for what
  needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot