gpu: nvgpu: check capability for reschedule runlist submit flag

NVGPU_SUBMIT_GPFIFO_FLAGS_RESCHEDULE_RUNLIST is only used by realtime
priority EGL context, which checks for CAP_SYS_NICE during context
creation in userspace, so it wasn't secure against unprivileged program
spoofing submit ioctl with this flag to stall GPU progress of others.
This flag does increase duration of submit by approx 16us,
mostly due to register accesses and PMU FIFO mutex.

Bug 1989493
Bug 1854791
Bug 1968813

Change-Id: I086b1d14f286abf8bd2d2dfae5945974b7fe6d1f
Reviewed-on: https://git-master.nvidia.com/r/#/c/1558644
Signed-off-by: David Li <davli@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1558644
Reviewed-by: svc-mobile-coverity <svc-mobile-coverity@nvidia.com>
GVS: Gerrit_Virtual_Submit
Reviewed-by: svccoveritychecker <svccoveritychecker@nvidia.com>
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/drivers/gpu/nvgpu/common/linux/ioctl_channel.c b/drivers/gpu/nvgpu/common/linux/ioctl_channel.c
index 5e09c677..6c66eca0 100644
--- a/drivers/gpu/nvgpu/common/linux/ioctl_channel.c
+++ b/drivers/gpu/nvgpu/common/linux/ioctl_channel.c
@@ -823,6 +823,11 @@ static int gk20a_ioctl_channel_submit_gpfifo(
 #endif
         if (ch->has_timedout)
                 return -ETIMEDOUT;
+
+        if ((NVGPU_SUBMIT_GPFIFO_FLAGS_RESCHEDULE_RUNLIST & args->flags) &&
+                !capable(CAP_SYS_NICE))
+                return -EPERM;
+
         ret = gk20a_submit_channel_gpfifo(ch, NULL, args, args->num_entries,
                                           args->flags, &args->fence,
                                           &fence_out, false, profile);