mdadm: Follow POSIX Portable Character Set

When the user creates a device with a name that contains whitespace,
mdadm timeouts and throws an error. This issue is caused by udev, which
truncates /dev/md link until the first whitespace.

This patch introduces prohibition of characters other than A-Za-z0-9.-_
in the device name. Also, it prohibits using leading "-" in device name,
so name won't be confused with cli parameter.
Set of allowed characters is taken from POSIX 3.280 Portable Character
Set. Also, device name length now is limited to NAME_MAX.

In some places, there are other requirements for string length (e.g. size
up to MD_NAME_MAX for device name). This routine is made to follow POSIX
and other, more strict limitations should be checked separately.
We are aware of the risk of regression in exceptional cases (as
escape_devname function is removed) that should be fixed by updating
the array name.

The POSIX validation is added for:
- 'name' parameter in every mode.
- first devlist entry, for Build, Create, Assemble, Manage, Grow.
- config entries, both devname and "name=".

Additionally, some manual cleanups are made.

Signed-off-by: Mariusz Tkaczyk <mariusz.tkaczyk@linux.intel.com>
Signed-off-by: Jes Sorensen <jes@trained-monkey.org>

1 files changed, 30 insertions, 40 deletions

diff --git a/mdadm.8.in b/mdadm.8.in
index b7159509..3142436f 100644
--- a/mdadm.8.in
+++ b/mdadm.8.in
@@ -364,7 +364,7 @@ Use the Intel(R) Matrix Storage Manager metadata format.  This creates a
 which is managed in a similar manner to DDF, and is supported by an
 option-rom on some platforms:
 .IP
-.B https://www.intel.com/content/www/us/en/support/products/122484/memory-and-storage/ssd-software/intel-virtual-raid-on-cpu-intel-vroc.html
+.B https://www.intel.com/content/www/us/en/support/products/122484
 .PP
 .RE
 
@@ -932,17 +932,14 @@ option will be ignored.
 .BR \-N ", " \-\-name=
 Set a
 .B name
-for the array.  This is currently only effective when creating an
-array with a version-1 superblock, or an array in a DDF container.
-The name is a simple textual string that can be used to identify array
-components when assembling.  If name is needed but not specified, it
-is taken from the basename of the device that is being created.
-e.g. when creating
-.I /dev/md/home
-the
-.B name
-will default to
-.IR home .
+for the array. It must be
+.BR "POSIX PORTABLE NAME"
+compatible and cannot be longer than 32 chars. This is effective when creating an array
+with a v1 metadata, or an external array.
+
+If name is needed but not specified, it is taken from the basename of the device
+that is being created. See
+.BR "DEVICE NAMES"
 
 .TP
 .BR \-R ", " \-\-run
@@ -1132,8 +1129,10 @@ is much safer.
 
 .TP
 .BR \-N ", " \-\-name=
-Specify the name of the array to assemble.  This must be the name
-that was specified when creating the array.  It must either match
+Specify the name of the array to assemble. It must be
+.BR "POSIX PORTABLE NAME"
+compatible and cannot be longer than 32 chars. This must be the name
+that was specified when creating the array. It must either match
 the name stored in the superblock exactly, or it must match
 with the current
 .I homehost
@@ -2179,14 +2178,17 @@ Usage:
 .I md-device
 .BI \-\-chunk= X
 .BI \-\-level= Y
-.br
 .BI \-\-raid\-devices= Z
 .I devices
 
 .PP
-This usage will initialise a new md array, associate some devices with
+This usage will initialize a new md array, associate some devices with
 it, and activate the array.
 
+.I md-device
+is a new device. This could be standard name or chosen name. For details see:
+.BR "DEVICE NAMES"
+
 The named device will normally not exist when
 .I "mdadm \-\-create"
 is run, but will be created by
@@ -2227,24 +2229,6 @@ array.  This feature can be overridden with the
 .B \-\-force
 option.
 
-When creating an array with version-1 metadata a name for the array is
-required.
-If this is not given with the
-.B \-\-name
-option,
-.I mdadm
-will choose a name based on the last component of the name of the
-device being created.  So if
-.B /dev/md3
-is being created, then the name
-.B 3
-will be chosen.
-If
-.B /dev/md/home
-is being created, then the name
-.B home
-will be used.
-
 When creating a partition based array, using
 .I mdadm
 with version-1.x metadata, the partition type should be set to
@@ -2429,12 +2413,10 @@ and
 
 The
 .B name
-option updates the subarray name in the metadata, it may not affect the
-device node name or the device node symlink until the subarray is
-re\-assembled.  If updating
-.B name
-would change the UUID of an active subarray this operation is blocked,
-and the command will end in an error.
+option updates the subarray name in the metadata. It must be
+.BR "POSIX PORTABLE NAME"
+compatible and cannot be longer than 32 chars. If successes, new value will be respected after
+next assembly.
 
 The
 .B ppl
@@ -3395,6 +3377,10 @@ When
 .B \-\-incremental
 mode is used, this file gets a list of arrays currently being created.
 
+.SH POSIX PORTABLE NAME
+A valid name can only consist of characters "A-Za-z0-9.-_".
+The name cannot start with a leading "-" and cannot exceed 255 chars.
+
 .SH DEVICE NAMES
 
 .I mdadm
@@ -3416,6 +3402,10 @@ can be given, or just the suffix of the second sort of name, such as
 .I home
 can be given.
 
+In every style, raw name must be compatible with
+.BR "POSIX PORTABLE NAME"
+and has to be no longer than 32 chars.
+
 When
 .I mdadm
 chooses device names during auto-assembly or incremental assembly, it