[PATCH for-next 2/2] nvme: Make CAP_SYS_ADMIN fine-granular

[Kanchan Joshi]

On Tue, Sep 27, 2022 at 09:32:50AM +0200, Christoph Hellwig wrote:
>On Mon, Sep 26, 2022 at 08:24:30PM +0530, Kanchan Joshi wrote:
>> Change all the callers of CAP_SYS_ADMIN to go through nvme_cmd_allowed
>> for any decision making.
>> Since file open mode is taken into consideration for any
>> approval/denial, change at various places to keep file-mode information
>> handy.
>>
>> Signed-off-by: Kanchan Joshi <joshi.k at samsung.com>
>> ---
>>  drivers/nvme/host/ioctl.c | 70 +++++++++++++++++++++------------------
>>  1 file changed, 38 insertions(+), 32 deletions(-)
>>
>> diff --git a/drivers/nvme/host/ioctl.c b/drivers/nvme/host/ioctl.c
>> index 6ca6477dd899..4e53a01e702d 100644
>> --- a/drivers/nvme/host/ioctl.c
>> +++ b/drivers/nvme/host/ioctl.c
>> @@ -259,7 +259,7 @@ static bool nvme_validate_passthru_nsid(struct nvme_ctrl *ctrl,
>>  }
>>
>>  static int nvme_user_cmd(struct nvme_ctrl *ctrl, struct nvme_ns *ns,
>> -			struct nvme_passthru_cmd __user *ucmd)
>> +			struct nvme_passthru_cmd __user *ucmd, fmode_t mode)
>>  {
>>  	struct nvme_passthru_cmd cmd;
>>  	struct nvme_command c;
>> @@ -267,10 +267,10 @@ 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 (!nvme_cmd_allowed(ns, cmd.opcode, mode))
>> +		return -EACCES;
>
>Btw, what speaks against moving this check a little bit later,
>so that we can pass the nvme_command to nvme_cmd_allowed, and thus
>can simply use nvme_is_write?

Moving down is good to me. Just after we have put the opcode into
nvme_command. Will do that in v2.