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Mercier" To: andrew+netdev@lunn.ch, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, bobbyeshleman@meta.com, "T.J. Mercier" Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Write permissions on the /dev/udmabuf device file are not required to issue ioctls and allocate udmabufs. Applications should be opening this file as O_RDONLY. The BPF dmabuf_iter selftest already does this. [1] Users are pointing to these selftests as examples of how use udmabuf, and encountering permission errors on systems where write permissions are not available on /dev/udmabuf. Apply the principle of least privilege to selftests which use udmabuf by removing the write access mode from drivers/dma-buf/udmabuf.c and drivers/net/hw/ncdevmem.c. [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree= /tools/testing/selftests/bpf/prog_tests/dmabuf_iter.c?h=3Dv7.1#n49 Signed-off-by: T.J. Mercier Reviewed-by: Bobby Eshleman --- tools/testing/selftests/drivers/net/hw/ncdevmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/tools/testing/selftests/drivers/net/hw/ncdevmem.c b/tools/test= ing/selftests/drivers/net/hw/ncdevmem.c index d96e8a3b5a65..ffe1d5c1fa4e 100644 --- a/tools/testing/selftests/drivers/net/hw/ncdevmem.c +++ b/tools/testing/selftests/drivers/net/hw/ncdevmem.c @@ -150,7 +150,7 @@ static struct memory_buffer *udmabuf_alloc(size_t size) =20 ctx->size =3D size; =20 - ctx->devfd =3D open("/dev/udmabuf", O_RDWR); + ctx->devfd =3D open("/dev/udmabuf", O_RDONLY); if (ctx->devfd < 0) { pr_err("[skip,no-udmabuf: Unable to access DMA buffer device file]"); goto err_free_ctx; --=20 2.55.0.229.g6434b31f56-goog