[PATCH] nvme: don't allow unprivileged Write Zeroes passthrough on read-only FDs

[Christoph Hellwig]

Unfortunately Write Zeroes is coded as a no data transfer opcode in NVMe,
so don't allow it on a read-only FD for unprivileged users.

Fixes: 855b7717f44b ("nvme: fine-granular CAP_SYS_ADMIN for nvme io commands")
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
 drivers/nvme/host/ioctl.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 9550a69029b368..8aefe9c904dc9a 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -45,7 +45,7 @@ static bool nvme_cmd_allowed(struct nvme_ns *ns, struct nvme_command *c,
 	 * special file is open for writing, but always allow I/O commands that
 	 * transfer data from the controller.
 	 */
-	if (nvme_is_write(c))
+	if (nvme_is_write(c) || c->common.opcode == nvme_cmd_write_zeroes)
 		return mode & FMODE_WRITE;
 	return true;
 }
-- 
2.30.2