[RFC 2/2] nvme: Use CAP_FIRMWARE_UPGRADE to check user commands

[Mario Limonciello]

Software that is running with CAP_FIRMWARE_UPGRADE needs a limited
set of opcode access:
* Identify the disk
* Download firmware to the disk
* Commit the firmwware to the disk

Signed-off-by: Mario Limonciello <mario.limoncie...@dell.com>
---
 drivers/nvme/host/core.c | 28 ++++++++++++++++++++++++----
 1 file changed, 24 insertions(+), 4 deletions(-)

diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index f13eb4ded95f..80be3d6b7437 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1593,13 +1593,23 @@ static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct 
nvme_ns *ns,
        u64 result;
        int status;
 
-       if (!capable(CAP_SYS_ADMIN))
-               return -EACCES;
        if (copy_from_user(&cmd, ucmd, sizeof(cmd)))
                return -EFAULT;
        if (cmd.flags)
                return -EINVAL;
 
+       switch (cmd.opcode) {
+       case nvme_admin_identify:
+       case nvme_admin_activate_fw:
+       case nvme_admin_download_fw:
+               if (!firmware_upgrade_capable())
+                       return -EACCES;
+               break;
+       default:
+               if (!capable(CAP_SYS_ADMIN))
+                       return -EACCES;
+       }
+
        memset(&c, 0, sizeof(c));
        c.common.opcode = cmd.opcode;
        c.common.flags = cmd.flags;
@@ -1637,13 +1647,23 @@ static int nvme_user_cmd64(struct nvme_ctrl *ctrl, 
struct nvme_ns *ns,
        unsigned timeout = 0;
        int status;
 
-       if (!capable(CAP_SYS_ADMIN))
-               return -EACCES;
        if (copy_from_user(&cmd, ucmd, sizeof(cmd)))
                return -EFAULT;
        if (cmd.flags)
                return -EINVAL;
 
+       switch (cmd.opcode) {
+       case nvme_admin_identify:
+       case nvme_admin_activate_fw:
+       case nvme_admin_download_fw:
+               if (!firmware_upgrade_capable())
+                       return -EACCES;
+               break;
+       default:
+               if (!capable(CAP_SYS_ADMIN))
+                       return -EACCES;
+       }
+
        memset(&c, 0, sizeof(c));
        c.common.opcode = cmd.opcode;
        c.common.flags = cmd.flags;
-- 
2.25.1