Hello T J, On Wed, 12 Aug 2026 at 02:11, T.J. Mercier <[email protected]> wrote: > > Write permissions on the /dev/dma_heap/* device files are not required > to issue ioctls and allocate dmabufs. Applications should be opening > these file as O_RDONLY. The BPF dmabuf_iter selftest already does > this. [1] > > Users are pointing to these selftests as examples of how use dmabuf, > and encountering permission errors on systems where write permissions > are not available on /dev/dma_heap/*. Apply the principle of least > privilege to selftests which open dmabuf heaps by removing the write > access mode and using O_RDONLY for the open() instead.
Thanks for the patch. > > The same is true for the vgem test using /dev/dri/card. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c?h=v7.1#n49 > > Signed-off-by: T.J. Mercier <[email protected]> Acked-by: Sumit Semwal <[email protected]> > --- > tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c > b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c > index fc9694fc4e89..45b420e37c97 100644 > --- a/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c > +++ b/tools/testing/selftests/dmabuf-heaps/dmabuf-heap.c > @@ -48,7 +48,7 @@ static int open_vgem(void) > > snprintf(name, 80, "%s%u", drmstr, i); > > - fd = open(name, O_RDWR); > + fd = open(name, O_RDONLY); > if (fd < 0) > continue; > > @@ -96,7 +96,7 @@ static int dmabuf_heap_open(char *name) > if (ret < 0) > ksft_exit_fail_msg("snprintf failed! %d\n", ret); > > - fd = open(buf, O_RDWR); > + fd = open(buf, O_RDONLY); > if (fd < 0) > ksft_exit_fail_msg("open %s failed: %s\n", buf, > strerror(errno)); > > > base-commit: 9a11db68872055e6ead919bad04d6330851c522d > -- > 2.55.0.679.g6767b8d81c-goog >
