Revert "misc: fastrpc: Restrict untrusted app to attach to privileged…

… PD"

This reverts commit bab2f5e.

Joel reported that this commit breaks userspace and stops sensors in
SDM845 from working. Also breaks other qcom SoC devices running postmarketOS.

Cc: stable <stable@kernel.org>
Cc: Ekansh Gupta <quic_ekangupt@quicinc.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Reported-by: Joel Selvaraj <joelselvaraj.oss@gmail.com>
Link: https://lore.kernel.org/r/9a9f5646-a554-4b65-8122-d212bb665c81@umsystem.edu
Signed-off-by: Griffin Kroah-Hartman <griffin@kroah.com>
Acked-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Fixes: bab2f5e ("misc: fastrpc: Restrict untrusted app to attach to privileged PD")
Link: https://lore.kernel.org/r/20240815094920.8242-1-griffin@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/fastrpc.c

@@ -2085,16 +2085,6 @@ static int fastrpc_req_mem_map(struct fastrpc_user *fl, char __user *argp)
 	return err;
 }
 
-static int is_attach_rejected(struct fastrpc_user *fl)
-{
-	/* Check if the device node is non-secure */
-	if (!fl->is_secure_dev) {
-		dev_dbg(&fl->cctx->rpdev->dev, "untrusted app trying to attach to privileged DSP PD\n");
-		return -EACCES;
-	}
-	return 0;
-}
-
 static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
 				 unsigned long arg)
 {
@@ -2107,19 +2097,13 @@ static long fastrpc_device_ioctl(struct file *file, unsigned int cmd,
 		err = fastrpc_invoke(fl, argp);
 		break;
 	case FASTRPC_IOCTL_INIT_ATTACH:
-		err = is_attach_rejected(fl);
-		if (!err)
-			err = fastrpc_init_attach(fl, ROOT_PD);
+		err = fastrpc_init_attach(fl, ROOT_PD);
 		break;
 	case FASTRPC_IOCTL_INIT_ATTACH_SNS:
-		err = is_attach_rejected(fl);
-		if (!err)
-			err = fastrpc_init_attach(fl, SENSORS_PD);
+		err = fastrpc_init_attach(fl, SENSORS_PD);
 		break;
 	case FASTRPC_IOCTL_INIT_CREATE_STATIC:
-		err = is_attach_rejected(fl);
-		if (!err)
-			err = fastrpc_init_create_static_process(fl, argp);
+		err = fastrpc_init_create_static_process(fl, argp);
 		break;
 	case FASTRPC_IOCTL_INIT_CREATE:
 		err = fastrpc_init_create_process(fl, argp);

include/uapi/misc/fastrpc.h

@@ -8,14 +8,11 @@
 #define FASTRPC_IOCTL_ALLOC_DMA_BUFF	_IOWR('R', 1, struct fastrpc_alloc_dma_buf)
 #define FASTRPC_IOCTL_FREE_DMA_BUFF	_IOWR('R', 2, __u32)
 #define FASTRPC_IOCTL_INVOKE		_IOWR('R', 3, struct fastrpc_invoke)
-/* This ioctl is only supported with secure device nodes */
 #define FASTRPC_IOCTL_INIT_ATTACH	_IO('R', 4)
 #define FASTRPC_IOCTL_INIT_CREATE	_IOWR('R', 5, struct fastrpc_init_create)
 #define FASTRPC_IOCTL_MMAP		_IOWR('R', 6, struct fastrpc_req_mmap)
 #define FASTRPC_IOCTL_MUNMAP		_IOWR('R', 7, struct fastrpc_req_munmap)
-/* This ioctl is only supported with secure device nodes */
 #define FASTRPC_IOCTL_INIT_ATTACH_SNS	_IO('R', 8)
-/* This ioctl is only supported with secure device nodes */
 #define FASTRPC_IOCTL_INIT_CREATE_STATIC _IOWR('R', 9, struct fastrpc_init_create_static)
 #define FASTRPC_IOCTL_MEM_MAP		_IOWR('R', 10, struct fastrpc_mem_map)
 #define FASTRPC_IOCTL_MEM_UNMAP		_IOWR('R', 11, struct fastrpc_mem_unmap)