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udev: add /dev/disk/by-diskseq symlink for block devices

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This adds another symlink for block devices:

    /dev/disk/by-diskseq/<number>

where the number is the diskseq number as exposed by the kernel. It's
useful for apps because they can use it to open a device by diskseq, in
a way that is safe against device node reuse. I.e. if a device node path
like this is passed to an app it could open the device node via the
symlink and also parse the diskseq from the path. Once the device is
opened it could compare the parsed diskseq with the one returned by
BLKGETDISKSEQ on the open node, and if it matches they know they are
talking to the right device.

Fixes: #22906
This commit is contained in:
Lennart Poettering 2022-03-31 10:10:37 +02:00 committed by Yu Watanabe
parent 37ebfe49de
commit 0d08db7f89
1 changed files with 5 additions and 0 deletions
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5
rules.d/60-persistent-storage.rules
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@ -121,4 +121,9 @@ ENV{DEVTYPE}=="partition", ENV{ID_WWN_WITH_EXTENSION}=="?*", SYMLINK+="disk/by-i
ENV{ID_PART_ENTRY_UUID}=="?*", SYMLINK+="disk/by-partuuid/$env{ID_PART_ENTRY_UUID}"
ENV{ID_PART_ENTRY_SCHEME}=="gpt", ENV{ID_PART_ENTRY_NAME}=="?*", SYMLINK+="disk/by-partlabel/$env{ID_PART_ENTRY_NAME}"
# by-diskseq link (if an app is told to open a path like this, they may parse
# the diskseq number from the path, then issue BLKGETDISKSEQ to verify they really got
# the right device, to access specific disks in a race-free fashion)
ENV{DISKSEQ}=="?*", ENV{DEVTYPE}!="partition", SYMLINK+="disk/by-diskseq/$env{DISKSEQ}"
LABEL="persistent_storage_end"