[RFC 1/2] nvme: add whitelisting infrastructure

Kanchan Joshi
2022-09-09T16:43:46Z

If CAP_SYS_ADMIN is present, nothing else is checked, as before.
If CAP_SYS_ADMIN is not present, take the decision based on
- type of nvme command (io or admin)
- nature of nvme-command (write or read)
- mode with which file was opened (read-only, read-write etc.)

io-commands that write/read are allowed only if matching file mode is
present.
for admin-commands, few read-only admin command are allowed and that too
when mode matches.

Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
---
drivers/nvme/host/ioctl.c | 36 ++++++++++++++++++++++++++++++++++++
1 file changed, 36 insertions(+)

diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
index 548aca8b5b9f..0d99135a1745 100644
--- a/drivers/nvme/host/ioctl.c
+++ b/drivers/nvme/host/ioctl.c
@@ -20,6 +20,42 @@ static void __user *nvme_to_user_ptr(uintptr_t ptrval)
return (void __user *)ptrval;
}

+bool nvme_io_cmd_allowed(u8 opcode, fmode_t mode)
+{
+ /* allow write/read based on what was allowed for open */
+ /* TBD: try to use nvme_is_write() here */
+ if (opcode & 1)
+ return (mode & FMODE_WRITE);
+ else
+ return (mode & FMODE_READ);
+}
+
+bool nvme_admin_cmd_allowed(u8 opcode, fmode_t mode)
+{
+ /* allowed few read-only commands post the mode check */
+ switch (opcode) {
+ case nvme_admin_identify:
+ case nvme_admin_get_log_page:
+ case nvme_admin_get_features:
+ return (mode & FMODE_READ);
+ default:
+ return false;
+ }
+}
+
+bool nvme_cmd_allowed(struct nvme_ns *ns, u8 opcode, fmode_t mode)
+{
+ bool ret;
+ /* root can do anything */
+ if (capable(CAP_SYS_ADMIN))
+ return true;
+ if (ns == NULL)
+ ret = nvme_admin_cmd_allowed(opcode, mode);
+ else
+ ret = nvme_io_cmd_allowed(opcode, mode);
+ return ret;
+}
+
static void *nvme_add_user_metadata(struct bio *bio, void __user *ubuf,
unsigned len, u32 seed, bool write)
{
--
2.25.1