diff options
| author | Ming Lei <[email protected]> | 2024-10-16 21:48:47 +0800 |
|---|---|---|
| committer | Jens Axboe <[email protected]> | 2024-10-16 08:08:18 -0600 |
| commit | 42aafd8b48adac1c3b20fe5892b1b91b80c1a1e6 (patch) | |
| tree | b34db3afc3a7f0315d0afb18a0430ea85f7a8239 | |
| parent | e972b08b91ef48488bae9789f03cfedb148667fb (diff) | |
ublk: don't allow user copy for unprivileged device
UBLK_F_USER_COPY requires userspace to call write() on ublk char
device for filling request buffer, and unprivileged device can't
be trusted.
So don't allow user copy for unprivileged device.
Cc: [email protected]
Fixes: 1172d5b8beca ("ublk: support user copy")
Signed-off-by: Ming Lei <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jens Axboe <[email protected]>
| -rw-r--r-- | drivers/block/ublk_drv.c | 11 | ||||
| -rw-r--r-- | include/uapi/linux/ublk_cmd.h | 8 |
2 files changed, 17 insertions, 2 deletions
diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index a6c8e5cc6051..6ba2c1dd1d87 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -2380,10 +2380,19 @@ static int ublk_ctrl_add_dev(struct io_uring_cmd *cmd) * TODO: provide forward progress for RECOVERY handler, so that * unprivileged device can benefit from it */ - if (info.flags & UBLK_F_UNPRIVILEGED_DEV) + if (info.flags & UBLK_F_UNPRIVILEGED_DEV) { info.flags &= ~(UBLK_F_USER_RECOVERY_REISSUE | UBLK_F_USER_RECOVERY); + /* + * For USER_COPY, we depends on userspace to fill request + * buffer by pwrite() to ublk char device, which can't be + * used for unprivileged device + */ + if (info.flags & UBLK_F_USER_COPY) + return -EINVAL; + } + /* the created device is always owned by current user */ ublk_store_owner_uid_gid(&info.owner_uid, &info.owner_gid); diff --git a/include/uapi/linux/ublk_cmd.h b/include/uapi/linux/ublk_cmd.h index c8dc5f8ea699..12873639ea96 100644 --- a/include/uapi/linux/ublk_cmd.h +++ b/include/uapi/linux/ublk_cmd.h @@ -175,7 +175,13 @@ /* use ioctl encoding for uring command */ #define UBLK_F_CMD_IOCTL_ENCODE (1UL << 6) -/* Copy between request and user buffer by pread()/pwrite() */ +/* + * Copy between request and user buffer by pread()/pwrite() + * + * Not available for UBLK_F_UNPRIVILEGED_DEV, otherwise userspace may + * deceive us by not filling request buffer, then kernel uninitialized + * data may be leaked. + */ #define UBLK_F_USER_COPY (1UL << 7) /* |