PM: hibernate: don't use early_lookup_bdev in resume_store

resume_store is a sysfs attribute written during normal kernel runtime,
and it should not use the early_lookup_bdev API that bypasses all normal
path based permission checking, and might cause problems with certain
container environments renaming devices.

Switch to lookup_bdev, which does a normal path lookup instead, and fall
back to trying to parse a numeric dev_t just like early_lookup_bdev did.

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.

Fixes: 421a5fa1a6cf ("PM / hibernate: use name_to_dev_t to parse resume")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: Rafael J. Wysocki <rafael@kernel.org>
Link: https://lore.kernel.org/r/20230531125535.676098-22-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index c52dedb..7ae95ec 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -1178,7 +1178,23 @@ static ssize_t resume_store(struct kobject *kobj, struct kobj_attribute *attr,
        if (!name)
                return -ENOMEM;
 
-       error = early_lookup_bdev(name, &dev);
+       error = lookup_bdev(name, &dev);
+       if (error) {
+               unsigned maj, min, offset;
+               char *p, dummy;
+
+               if (sscanf(name, "%u:%u%c", &maj, &min, &dummy) == 2 ||
+                   sscanf(name, "%u:%u:%u:%c", &maj, &min, &offset,
+                               &dummy) == 3) {
+                       dev = MKDEV(maj, min);
+                       if (maj != MAJOR(dev) || min != MINOR(dev))
+                               error = -EINVAL;
+               } else {
+                       dev = new_decode_dev(simple_strtoul(name, &p, 16));
+                       if (*p)
+                               error = -EINVAL;
+               }
+       }
        kfree(name);
        if (error)
                return error;