On Tue, Jan 18, 2011 at 10:34:56AM +0100, Milan Broz wrote:
> On 01/18/2011 10:01 AM, Xavier Nicollet wrote:
> > I did something like that:
> > cryptsetup luksOpen /dev/mapper/lv_device crypto_device
> >
> > I would like to find a way, given /dev/mapper/crypto_device, to find
> > which lv_device it was built from.
>
> cryptsetup status crypto_device (for active mapping)?
>
> (But note this device name is not always the same you used, for LV you can
> have several symlinks /dev/mapper/vg-lv or /dev/vg/lv or /dev/by-uuid/...
> so there are hardcoded priorities)
I have a Python script, that does a traversal of /dev/
to find all devices mapped to the same object as a node
in /dev/mapper/ for each node in /dev/mapper/. This works
by comparing not names, but major and minor device number.
It does not work for symlinks though, only for duplicate
device special files. Symliks could be added easily though.
Not very elegant, but works. Copy for current cryptsetup
is attached. Sample output:
/dev/mapper/c1 is active and is in use.
type: PLAIN
cipher: aes-cbc-essiv:sha256
keysize: 256 bits
devices: (9, 6) /dev/md6
offset: 0 sectors
size: 387462831 sectors
mode: read/write
mounted: /opt
Gruesse,
Arno
--
Arno Wagner, Dr. sc. techn., Dipl. Inform., CISSP -- Email: arno@xxxxxxxxxxx
GnuPG: ID: 1E25338F FP: 0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F
----
Cuddly UI's are the manifestation of wishful thinking. -- Dylan Evans
If it's in the news, don't worry about it. The very definition of
"news" is "something that hardly ever happens." -- Bruce Schneier
#!/usr/bin/python
# cryptstat.py
# Displays all matching devices in /dev/ for a cryptsetup target
# Calls "cryptsetup status <target>" to get the initial info,
# then determines major/minor of the reported device and does
# a traversal of /dev/ to find all matches.
# Reports an augemented result of "cryptsetup status", also
# including mount points.
# Arguments are any number of cryptsetup targets. Does a validity
# check and refuses targets not found in /dev/mapper/
# Without argument, displays info on all targets found in /dev/mapper/
# (c) Arno Wagner 2010, distributed under the modified BSD license.
# Version 0.03
# Version history
# 0.03 Adjustments for cryptsrtup 1.2.0
# 0.02 fixed error on unmounted but mapped devices
import sys, os, stat, subprocess, re
dev_path = '/dev'
mapper_path = '/dev/mapper'
cryptsetup_path = '/usr/sbin/cryptsetup'
# Utility functions
def normalize_path(path):
"""Replaces any number of occurences of '/' with a single '/'"""
# Note: INefficient, but should not matter
while path.find('//') > -1:
path = path.replace('//','/')
return(path)
def dir_walk(dir):
"""Returns a list of all filenames with full paths
(including dirs, specials, etc.) below the argument.
"." and ".." are omitted. Does not follow symblinks
to avoid loops, but there is no real loop prevention."""
names = []
dir = normalize_path(dir)
# process current directory
current = os.listdir(dir)
for d in current:
d = dir + '/' + d
# Test whether d is a directory. If so, recurse.
s = os.lstat(d)
if stat.S_ISDIR( s[stat.ST_MODE] ):
names.extend(dir_walk(d))
else:
names.append(d)
return(names)
def dir_walk_block(dir):
"""Returns the names of all block devices in the subtree at dir"""
names = dir_walk(dir)
block_dev = []
for n in names:
if stat.S_ISBLK(os.lstat(n)[stat.ST_MODE]):
block_dev.append(n)
return(block_dev)
def special_dev_major_minor(n):
"""Returns (major,minor) for a device special file name"""
s = os.lstat(n)
if not stat.S_ISBLK(s[stat.ST_MODE]) and \
not stat.S_ISCHR(s[stat.ST_MODE]) :
return None
else:
maj = os.major(s.st_rdev)
min = os.minor(s.st_rdev)
return (maj, min)
def build_block_major_minor_tables(dir):
"""Returns
1) a table of filenames that are all block special files
2) a dict mapping each name to (major,minor)
3) a dict mapping each (major,minor) pair to a table of filenames"""
names = []
name2pair = {}
pair2name = {}
names = dir_walk_block(dir)
for n in names:
maj, min = special_dev_major_minor(n)
name2pair[n] = (maj, min)
if (maj, min) not in pair2name:
pair2name[(maj, min)] = [n]
else:
pair2name[(maj, min)].append(n)
return (names, name2pair, pair2name)
# Start of main action
# determine list of targets to be processed
targets = []
# first get all in mapper_path except 'control'
mapper_targets = []
mapper_entries = os.listdir(mapper_path)
tmp = []
for e in mapper_entries:
if e != 'control':
tmp.append(e)
mapper_entries = tmp
# if argument list empty, copy mapper_entries
if len(sys.argv) == 1:
targets = mapper_entries
targets.sort()
else:
targets = sys.argv[1:]
# Make sure all targets are in mapper_entries
tbl = {}
for e in mapper_entries:
tbl[e] = None
for e in targets:
if e not in tbl:
print '\nError: Command argument "'+e+'" is not present in '+\
'mapper dir '+mapper_path+'!\nAborting\n'
sys.exit(1)
# print targets
# Create mappings (major,minor) <-> name
names, name2pair, pair2names = build_block_major_minor_tables(dev_path)
print
for t in targets:
# do call to "cryptsetup status"
cmd = cryptsetup_path + ' status ' + t
# print 'calling "' + cmd + '"'
p = subprocess.Popen(cmd, shell=True, bufsize=0,
stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, close_fds=True)
(out, err) = p.communicate()
out_lines = out.splitlines()
if (p.returncode != 0): raise IOError(p.returncode, err)
# print('command output = [' + out + ']')
# check output line 7 for ' device: <device name>'
if not re.match('\ \ device\:\ \ \S+', out_lines[4]):
print '\nError: Line 7 of cryptsetup output has unexpected form'
print 'Expected: " device: <device name>'
print 'found: [' + out_lines[4]+ ']'
print 'complete cryptsetup output:\m'
print out
print '\nAborting!\n'
sys.exit(1)
device = out_lines[4][11:]
# print 'device found: [' + device + ']'
(maj, min) = name2pair[device]
# print '(maj, min) = ', (maj, min)
devices = pair2names[(maj, min)]
dev_str = ''
for d in devices: dev_str = dev_str + d + ' '
# print 'devices: ', dev_str
out_lines[4] = ' devices: '+str((maj, min))+' '+dev_str
for l in out_lines: print l
# determine mounts and print them
mounts = ' mounted:'
# ';echo' in next command is so that we have at least one line
# of output to avoid an error from subprocess
cmd = 'mount | grep '+mapper_path+'/'+t+'; echo'
# print 'calling "' + cmd + '"'
p = subprocess.Popen(cmd, shell=True, bufsize=0,
stdin=subprocess.PIPE, stdout=subprocess.PIPE,
stderr=subprocess.PIPE, close_fds=True)
(out, err) = p.communicate()
out_lines = out.splitlines()
# print('command output = [' + out + ']')
if (p.returncode != 0): raise IOError(p.returncode, err)
if len(out_lines) == 1:
mounts = mounts + ' not mounted'
else:
for l in out_lines:
# print 'l = ', l
match = re.search(' on (\S+) type', l)
if match != None:
mounts = mounts + ' ' + match.group(1)
print mounts
print
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