Linux Page Cache Status - linux

I'm able to list page cache statuses in my OS by using page-types tool in Linux kernel source tree. Such as:
referenced,uptodate,lru,mappedtodisk
referenced,uptodate,lru,active,private
In source code there is whole list:
[KPF_LOCKED] = "L:locked",
[KPF_ERROR] = "E:error",
[KPF_REFERENCED]= "R:referenced",
[KPF_UPTODATE] = "U:uptodate",
[KPF_DIRTY] = "D:dirty",
[KPF_LRU] = "l:lru",
[KPF_ACTIVE] = "A:active",
[KPF_SLAB] = "S:slab",
[KPF_WRITEBACK] = "W:writeback",
[KPF_RECLAIM] = "I:reclaim",
[KPF_BUDDY] = "B:buddy",
.......
But I couldn't find any information about what they mean, how kernel uses them etc. How can I find further information about types of page caches?

Try (in the kernel src tree)
Documentation/vm/pagemap.txt
-has some explanation on page flags..

Related

Custom file generation using cuckoo sandbox

I am trying to generate custom result file which will contain system information gathered using python psutil library.I searched, followed the documentation but couldn't get the answer. All I want to do is, I have written code to collect system information in python psutil library, this code should run along with malware file in cuckoo sandbox and result should be saved in ubuntu host machine.
I don't know where should i put my code and how to save the results.
Here is my code to collect system information
import psutil
pids = psutil.pids()
max_pid = max(pids)
total_id = len(pids)
psutil.cpu_times_percent()
cputimes = psutil.cpu_times_percent(0.1)
usertime = cputimes.user
systemtime = cputimes.system
memuse = psutil.virtual_memory().used
swapuse = psutil.swap_memory().used
net = psutil.net_io_counters()
packsent = net.packets_sent
packrecv = net.packets_recv
bytessent = net.bytes_sent
bytesrecv = net.bytes_recv
result={"maxpid":max_pip,"totalid":total_id,"usertime":usertime,"systemtime":systemtime,"memuse":memuse,"swapuse":swapuse,"packsent":packsent,"packrecv":packrecv,"bytessent":bytessent,"bytesrecv":bytesrecv}
I want to save this result dictionary to be saved in json file in host machine.

Getting owner of file from smb share, by using python on linux

I need to find out for a script I'm writing who is the true owner of a file in an smb share (mounted using mount -t cifs of course on my server and using net use through windows machines).
Turns out it is a real challenge finding this information out using python on a linux server.
I tried using many many smb libraries (such as smbprotocol, smbclient and others), nothing worked.
I find few solutions for windows, they all use pywin32 or another windows specific package.
And I also managed to do it from bash using smbcalcs but couldn't do it cleanly but using subprocess.popen('smbcacls')..
Any idea on how to solve it?
This was unbelievably not a trivial task, and unfortunately the answer isn't simple as I hoped it would be..
I'm posting this answer if someone will be stuck with this same problem in the future, but hope maybe someone would post a better solution earlier
In order to find the owner I used this library with its examples:
from smb.SMBConnection import SMBConnection
conn = SMBConnection(username='<username>', password='<password>', domain=<domain>', my_name='<some pc name>', remote_name='<server name>')
conn.connect('<server name>')
sec_att = conn.getSecurity('<share name>', r'\some\file\path')
owner_sid = sec_att.owner
The problem is that pysmb package will only give you the owner's SID and not his name.
In order to get his name you need to make an ldap query like in this answer (reposting the code):
from ldap3 import Server, Connection, ALL
from ldap3.utils.conv import escape_bytes
s = Server('my_server', get_info=ALL)
c = Connection(s, 'my_user', 'my_password')
c.bind()
binary_sid = b'....' # your sid must be in binary format
c.search('my_base', '(objectsid=' + escape_bytes(binary_sid) + ')', attributes=['objectsid', 'samaccountname'])
print(c.entries)
But of course nothing will be easy, it took me hours to find a way to convert a string SID to binary SID in python, and in the end this solved it:
# posting the needed functions and omitting the class part
def byte(strsid):
'''
Convert a SID into bytes
strdsid - SID to convert into bytes
'''
sid = str.split(strsid, '-')
ret = bytearray()
sid.remove('S')
for i in range(len(sid)):
sid[i] = int(sid[i])
sid.insert(1, len(sid)-2)
ret += longToByte(sid[0], size=1)
ret += longToByte(sid[1], size=1)
ret += longToByte(sid[2], False, 6)
for i in range(3, len(sid)):
ret += cls.longToByte(sid[i])
return ret
def byteToLong(byte, little_endian=True):
'''
Convert bytes into a Python integer
byte - bytes to convert
little_endian - True (default) or False for little or big endian
'''
if len(byte) > 8:
raise Exception('Bytes too long. Needs to be <= 8 or 64bit')
else:
if little_endian:
a = byte.ljust(8, b'\x00')
return struct.unpack('<q', a)[0]
else:
a = byte.rjust(8, b'\x00')
return struct.unpack('>q', a)[0]
... AND finally you have the full solution! enjoy :(
I'm adding this answer to let you know of the option of using smbprotocol; as well as expand in case of misunderstood terminology.
SMBProtocol Owner Info
It is possible to get the SID using the smbprotocol library as well (just like with the pysmb library).
This was brought up in the github issues section of the smbprotocol repo, along with an example of how to do it. The example provided is fantastic and works perfectly. An extremely stripped down version
However, this also just retrieves a SID and will need a secondary library to perform a lookup.
Here's a function to get the owner SID (just wrapped what's in the gist in a function. Including here in case the gist is deleted or lost for any reason).
import smbclient
from ldap3 import Server, Connection, ALL,NTLM,SUBTREE
def getFileOwner(smb: smbclient, conn: Connection, filePath: str):
from smbprotocol.file_info import InfoType
from smbprotocol.open import FilePipePrinterAccessMask,SMB2QueryInfoRequest, SMB2QueryInfoResponse
from smbprotocol.security_descriptor import SMB2CreateSDBuffer
class SecurityInfo:
# 100% just pulled from gist example
Owner = 0x00000001
Group = 0x00000002
Dacl = 0x00000004
Sacl = 0x00000008
Label = 0x00000010
Attribute = 0x00000020
Scope = 0x00000040
Backup = 0x00010000
def guid2hex(text_sid):
"""convert the text string SID to a hex encoded string"""
s = ['\\{:02X}'.format(ord(x)) for x in text_sid]
return ''.join(s)
def get_sd(fd, info):
""" Get the Security Descriptor for the opened file. """
query_req = SMB2QueryInfoRequest()
query_req['info_type'] = InfoType.SMB2_0_INFO_SECURITY
query_req['output_buffer_length'] = 65535
query_req['additional_information'] = info
query_req['file_id'] = fd.file_id
req = fd.connection.send(query_req, sid=fd.tree_connect.session.session_id, tid=fd.tree_connect.tree_connect_id)
resp = fd.connection.receive(req)
query_resp = SMB2QueryInfoResponse()
query_resp.unpack(resp['data'].get_value())
security_descriptor = SMB2CreateSDBuffer()
security_descriptor.unpack(query_resp['buffer'].get_value())
return security_descriptor
with smbclient.open_file(filePath, mode='rb', buffering=0,
desired_access=FilePipePrinterAccessMask.READ_CONTROL) as fd:
sd = get_sd(fd.fd, SecurityInfo.Owner | SecurityInfo.Dacl)
# returns SID
_sid = sd.get_owner()
try:
# Don't forget to convert the SID string-like object to a string
# or you get an error related to "0" not existing
sid = guid2hex(str(_sid))
except:
print(f"Failed to convert SID {_sid} to HEX")
raise
conn.search('DC=dell,DC=com',f"(&(objectSid={sid}))",SUBTREE)
# Will return an empty array if no results are found
return [res['dn'].split(",")[0].replace("CN=","") for res in conn.response if 'dn' in res]
to use:
# Client config is required if on linux, not if running on windows
smbclient.ClientConfig(username=username, password=password)
# Setup LDAP session
server = Server('mydomain.com',get_info=ALL,use_ssl = True)
# you can turn off raise_exceptions, or leave it out of the ldap connection
# but I prefer to know when there are issues vs. silently failing
conn = Connection(server, user="domain\username", password=password, raise_exceptions=True,authentication=NTLM)
conn.start_tls()
conn.open()
conn.bind()
# Run the check
fileCheck = r"\\shareserver.server.com\someNetworkShare\someFile.txt"
owner = getFileOwner(smbclient, conn, fileCheck)
# Unbind ldap session
# I'm not clear if this is 100% required, I don't THINK so
# but better safe than sorry
conn.unbind()
# Print results
print(owner)
Now, this isn't super efficient. It takes 6 seconds for me to run this one a SINGLE file. So if you wanted to run some kind of ownership scan, then you probably want to just write the program in C++ or some other low-level language instead of trying to use python. But for something quick and dirty this does work. You could also setup a threading pool and run batches. The piece that takes longest is connecting to the file itself, not running the ldap query, so if you can find a more efficient way to do that you'll be golden.
Terminology Warning, Owner != Creator/Author
Last note on this. Owner != File Author. Many domain environments, and in particular SMB shares, automatically alter ownership from the creator to a group. In my case the results of the above is:
What I was actually looking for was the creator of the file. File creator and modifier aren't attributes which windows keeps track of by default. An administrator can enable policies to audit file changes in a share, or auditing can be enabled on a file-by-file basis using the Security->Advanced->Auditing functionality for an individual file (which does nothing to help you determine the creator).
That being said, some applications store that information for themselves. For example, if you're looking for Excel this answer provides a method for which to get the creator of any xls or xlsx files (doesn't work for xlsb due to the binary nature of the files). Unfortunately few files store this kind of information. In my case I was hoping to get that info for tblu, pbix, and other reporting type files. However, they don't contain this information (which is good from a privacy perspective).
So in case anyone finds this answer trying to solve the same kind of thing I did - Your best bet (to get actual authorship information) is to work with your domain IT administrators to get auditing setup.

How does a ioctl() call the driver code

I am working on a testing tool for nvme-cli(written in c and can run on linux).
For SSD validation purpose, i was actually looking for a custom command(For e.g. I/O command, write and then read the same and finally compare if both the data are same)
For read the ioctl() function is used as shown in the below code.
struct nvme_user_io io = {
.opcode = opcode,
.flags = 0,
.control = control,
.nblocks = nblocks,
.rsvd = 0,
.metadata = (__u64)(uintptr_t) metadata,
.addr = (__u64)(uintptr_t) data,
.slba = slba,
.dsmgmt = dsmgmt,
.reftag = reftag,
.appmask = appmask,
.apptag = apptag,
};
err = ioctl(fd, NVME_IOCTL_SUBMIT_IO, &io);
Can I to where exactly the control of execution goes in order to understand the read.
Also I want to have another command that looks like
err = ioctl(fd,NVME_IOCTL_WRITE_AND_COMPARE_IO, &io);
so that I can internally do a write, then read the same location and finally compare the both data to ensure that the disk contains only the data that I wanted to write.
Since I am new to this nvme/ioctl(), if there is any mistakes please correct me.
nvme_io() is a main command handler that accepts as a parameter the NVMe opcode that you want to send to your device. According to the standard, you have separate commands (opcodes) for read, write and compare. You could either send those commands separately, or add a vendor specific command to calculate what you need.

Purpose of /usr/lib/python3.4/plat-x86_64-linux-gnu

Hello I'm poking around in python3.4 packages and found a file called CDROM.py with a list like:
CDROMPAUSE = 0x5301
CDROMRESUME = 0x5302
CDROMPLAYMSF = 0x5303
CDROMPLAYTRKIND = 0x5304
CDROMREADTOCHDR = 0x5305
CDROMREADTOCENTRY = 0x5306
CDROMSTOP = 0x5307
CDROMSTART = 0x5308
CDROMEJECT = 0x5309
CDROMVOLCTRL = 0x530a
What do these numbers mean??
These are the ioctl codes for the Linux CD-ROM interface. The file was generated from cdrom.h in the Linux kernel.
https://github.com/torvalds/linux/blob/master/include/uapi/linux/cdrom.h

How to use dcmtk/dcmprscp in Windows

How can I use dcmprscp to receive from SCU Printer a DICOM file and save it, I'm using dcmtk 3.6 & I've some trouble to use it with the default help, this's what I'm doing in CMD:
dcmprscp.exe --config dcmpstat.cfg --printer PRINT2FILE
each time I receive this messagebut (database\index.da) don't exsist in windows
W: $dcmtk: dcmprscp v3.6.0 2011-01-06 $
W: 2016-02-21 00:08:09
W: started
E: database\index.dat: No such file or directory
F: Unable to access database 'database'
I try to follow some tip, but the same result :
http://www.programmershare.com/2468333/
http://www.programmershare.com/3020601/
and this's my printer's PRINT2FILE config :
[PRINT2FILE]
hostname = localhost
type = LOCALPRINTER
description = PRINT2FILE
port = 20006
aetitle = PRINT2FILE
DisableNewVRs = true
FilmDestination = MAGAZINE\PROCESSOR\BIN_1\BIN_2
SupportsPresentationLUT = true
PresentationLUTinFilmSession = true
PresentationLUTMatchRequired = true
PresentationLUTPreferSCPRendering = false
SupportsImageSize = true
SmoothingType = 0\1\2\3\4\5\6\7\8\9\10\11\12\13\14\15
BorderDensity = BLACK\WHITE\150
EmptyImageDensity = BLACK\WHITE\150
MaxDensity = 320\310\300\290\280\270
MinDensity = 20\25\30\35\40\45\50
Annotation = 2\ANNOTATION
Configuration_1 = PERCEPTION_LUT=OEM001
Configuration_2 = PERCEPTION_LUT=KANAMORI
Configuration_3 = ANNOTATION1=FILE1
Configuration_4 = ANNOTATION1=PATID
Configuration_5 = WINDOW_WIDTH=256\WINDOW_CENTER=128
Supports12Bit = true
SupportsDecimateCrop = false
SupportsTrim = true
DisplayFormat=1,1\2,1\1,2\2,2\3,2\2,3\3,3\4,3\5,3\3,4\4,4\5,4\6,4\3,5\4,5\5,5\6,5\4,6\5,6
FilmSizeID = 8INX10IN\11INX14IN\14INX14IN\14INX17IN
MediumType = PAPER\CLEAR FILM\BLUE FILM
MagnificationType = REPLICATE\BILINEAR\CUBIC
The documentation of the "dcmprscp" tool says:
The dcmprscp utility implements the DICOM Basic Grayscale Print
Management Service Class as SCP. It also supports the optional
Presentation LUT SOP Class. The utility is intended for use within the
DICOMscope viewer.
That means, it is usually not run from the command line (as most of the other DCMTK tools) but started automatically in the background by DICOMscope.
Anyway, I think the error message is clear:
E: database\index.dat: No such file or directory
F: Unable to access database 'database'
Did you check whether there is a subdirectory "database" and whether the "index.dat" file exists in this directory? If you should ask why there is a need for a "database" then please read the next paragraph of the documentation:
The dcmprscp utility accepts print jobs from a remote Print SCU.
It does not create real hardcopies but stores print jobs in the local
DICOMscope database as a set of Stored Print objects (one per page)
and Hardcopy Grayscale images (one per film box N-SET)

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