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>

Author: griffinkh

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)