On Tue, May 23 2023 at 3:45P -0400,
Christoph Hellwig <hch@xxxxxx> wrote:
> early_lookup_bdev is supposed to only be called from the early boot
> code, but dm_get_device calls it as a general fallback when lookup_bdev
> fails, which is problematic because early_lookup_bdev bypasses all normal
> path based permission checking, and might cause problems with certain
> container environments renaming devices.
>
> Switch to only call early_lookup_bdev when dm is built-in and the system
> state in not running yet. This means it is still available when tables
> are constructed by dm-init.c from the kernel command line, but not
> otherwise.
>
> Note that this strictly speaking changes the kernel ABI as the PARTUUID=
> and PARTLABEL= style syntax is now not available during a running
> systems. They never were intended for that, but this breaks things
> we'll have to figure out a way to make them available again. But if
> avoidable in any way I'd rather avoid that.
>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/md/dm-table.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c
> index e997f4322a9967..c230241a76b374 100644
> --- a/drivers/md/dm-table.c
> +++ b/drivers/md/dm-table.c
> @@ -326,8 +326,11 @@ static int upgrade_mode(struct dm_dev_internal *dd, fmode_t new_mode,
> /*
> * Add a device to the list, or just increment the usage count if
> * it's already present.
> + *
> + * Note: the __ref annotation is because this function can call the __init
> + * marked early_lookup_bdev when called during early boot code from dm-init.c.
> */
> -int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
> +int __ref dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
> struct dm_dev **result)
> {
> int r;
> @@ -346,8 +349,10 @@ int dm_get_device(struct dm_target *ti, const char *path, fmode_t mode,
> return -EOVERFLOW;
> } else {
> r = lookup_bdev(path, &dev);
> - if (r)
> +#ifndef MODULE
> + if (r && system_state < SYSTEM_RUNNING)
> r = early_lookup_bdev(path, &dev);
> +#endif
> if (r)
> return -ENODEV;
> }
> --
> 2.39.2
>
I think/hope this will be fine:
Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
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