[PATCH v2] nvme: remove unprivileged passthrough support

[Kanchan Joshi]

On 10/27/2023 12:36 PM, Shinichiro Kawasaki wrote:
> On Oct 16, 2023 / 11:35, Kanchan Joshi wrote:
>> Passthrough has got a hole that can be exploited to cause kernel memory
>> corruption. This is about making the device do larger DMA into
>> short meta/data buffer owned by kernel [1].
>>
>> As a stopgap measure, disable the support of unprivileged passthrough.
>>
>> This patch brings back coarse-granular CAP_SYS_ADMIN checks by reverting
>> following patches:
>>
>> - 7d9d7d59d44 ("nvme: replace the fmode_t argument to the nvme ioctl handlers with a simple bool")
>> - 313c08c72ee ("nvme: don't allow unprivileged passthrough on partitions")
>> - 6f99ac04c46 ("nvme: consult the CSE log page for unprivileged passthrough")
>> - ea43fceea41 ("nvme: allow unprivileged passthrough of Identify Controller")
>> - e4fbcf32c86 ("nvme: identify-namespace without CAP_SYS_ADMIN")
>> - 855b7717f44 ("nvme: fine-granular CAP_SYS_ADMIN for nvme io commands")
>>
>> [1] https://lore.kernel.org/linux-nvme/20231013051458.39987-1-joshi.k@samsung.com/
> 
> This change looks affecting the blktests test case nvme/046. Should we adjust
> the test case for the coarse-granular CAP_SYS_ADMIN checks?

Nothing to adjust in the test, as there is no change in the kernel (at 
this point). I have made a note to revisit the test if anything changes.