Operating Systems 2018F: Tutorial 8 - Revision history

Soma at 22:19, 11 November 2018

2018-11-11T22:19:54Z

← Older revision		Revision as of 22:19, 11 November 2018
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	~~'''This tutorial is not yet finalized.'''~~

	In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply]. The exercises below have been tested in the class openstack VM. It should also work in the virtualbox VM (as long as you don't run out of disk space while installing/updating packages). It should also work on any ubuntu 18.04 installation. Other linux distributions are likely to work but there may be glitches.		In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply]. The exercises below have been tested in the class openstack VM. It should also work in the virtualbox VM (as long as you don't run out of disk space while installing/updating packages). It should also work on any ubuntu 18.04 installation. Other linux distributions are likely to work but there may be glitches.

Soma: /* Tasks */

2018-11-11T22:19:16Z

Tasks

← Older revision		Revision as of 22:19, 11 November 2018
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	# What permissions do you need to "mount" the filesystem? What about to "umount" it?		# What permissions do you need to "mount" the filesystem? What about to "umount" it?
	# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)		# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)
			# Modify the code so that file renames don't delete the old file but instead just create a new name for it.
			# Modify the code so that when read, files are converted to upper case.
	# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/opensnoop.ply opensnoop.ply] and run it with the command "sudo ply opensnoop.ply". Cancel the script by entering Ctrl-C. What does this ply script output?		# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/opensnoop.ply opensnoop.ply] and run it with the command "sudo ply opensnoop.ply". Cancel the script by entering Ctrl-C. What does this ply script output?
	# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/fusesnoop.ply fusesnoop.ply] and run it with the command "sudo ply fusesnoop.ply". What does this ply script output?		# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/fusesnoop.ply fusesnoop.ply] and run it with the command "sudo ply fusesnoop.ply". What does this ply script output?
	# Create a ply script to monitor other functions in the Linux kernel. Try looking at functions in [https://elixir.bootlin.com/linux/latest/source/fs/fuse fs/fuse] and general filesystem operations such as [https://elixir.bootlin.com/linux/latest/source/fs/read_write.c fs/read_write.c].		# Create a ply script to monitor other functions in the Linux kernel. Try looking at functions in [https://elixir.bootlin.com/linux/latest/source/fs/fuse fs/fuse] and general filesystem operations such as [https://elixir.bootlin.com/linux/latest/source/fs/read_write.c fs/read_write.c].
	~~# Modify the code so that file renames don't delete the old file but instead just create a new name for it.~~
	~~# Modify the code so that when read, files are converted to upper case.~~

	==Code==		==Code==

Housedhorse: /* Tasks */

2018-11-11T21:17:35Z

Tasks

← Older revision		Revision as of 21:17, 11 November 2018
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	# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)		# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)
	# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/opensnoop.ply opensnoop.ply] and run it with the command "sudo ply opensnoop.ply". Cancel the script by entering Ctrl-C. What does this ply script output?		# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/opensnoop.ply opensnoop.ply] and run it with the command "sudo ply opensnoop.ply". Cancel the script by entering Ctrl-C. What does this ply script output?
	# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/fusesnoop.ply fusesnoop.ply] and run it with the command "sudo ply ~~opensnoop~~.ply". What does this ply script output?		# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/fusesnoop.ply fusesnoop.ply] and run it with the command "sudo ply fusesnoop.ply". What does this ply script output?
	# Create a ply script to monitor other functions in the Linux kernel. Try looking at functions in [https://elixir.bootlin.com/linux/latest/source/fs/fuse fs/fuse] and general filesystem operations such as [https://elixir.bootlin.com/linux/latest/source/fs/read_write.c fs/read_write.c].		# Create a ply script to monitor other functions in the Linux kernel. Try looking at functions in [https://elixir.bootlin.com/linux/latest/source/fs/fuse fs/fuse] and general filesystem operations such as [https://elixir.bootlin.com/linux/latest/source/fs/read_write.c fs/read_write.c].
	# Modify the code so that file renames don't delete the old file but instead just create a new name for it.		# Modify the code so that file renames don't delete the old file but instead just create a new name for it.

Soma: /* ply */

2018-11-09T16:05:20Z

ply

← Older revision		Revision as of 16:05, 9 November 2018
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	After this, you should have ply installed in /usr/local/sbin/.		After this, you should have ply installed in /usr/local/sbin/.

			For documentation, check out [https://wkz.github.io/ply/ply.1.html ply's man page] and [https://github.com/iovisor/ply/blob/master/README.md ply's README].

	==Tasks==		==Tasks==

Soma: /* Tasks */

2018-11-09T16:03:50Z

Tasks

← Older revision		Revision as of 16:03, 9 November 2018
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	# When you make files in mnt, are they normal files? Can they be accessed by regular programs?		# When you make files in mnt, are they normal files? Can they be accessed by regular programs?
	# What permissions do you need to "mount" the filesystem? What about to "umount" it?		# What permissions do you need to "mount" the filesystem? What about to "umount" it?
	~~# What happens to these files when you terminate the memoryll.py script? Can you get the files back?~~
	# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)		# What system calls are associated with which functions in memoryll.py? How close is the correspondence between system calls made and python function invocations? (Note that if you want to use strace you'll have to do everything as root.)
			# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/opensnoop.ply opensnoop.ply] and run it with the command "sudo ply opensnoop.ply". Cancel the script by entering Ctrl-C. What does this ply script output?
			# Download [https://homeostasis.scs.carleton.ca/~soma/os-2018f/code/tut8/fusesnoop.ply fusesnoop.ply] and run it with the command "sudo ply opensnoop.ply". What does this ply script output?
			# Create a ply script to monitor other functions in the Linux kernel. Try looking at functions in [https://elixir.bootlin.com/linux/latest/source/fs/fuse fs/fuse] and general filesystem operations such as [https://elixir.bootlin.com/linux/latest/source/fs/read_write.c fs/read_write.c].
	# Modify the code so that file renames don't delete the old file but instead just create a new name for it.		# Modify the code so that file renames don't delete the old file but instead just create a new name for it.
	# Modify the code so that when read, files are converted to upper case.		# Modify the code so that when read, files are converted to upper case.

Soma at 15:55, 9 November 2018

2018-11-09T15:55:23Z

@@ Line 88: / Line 88: @@
+{
 	printf("%16s(%5d): %s\n", comm(), pid(), mem(arg(1), "128s"));
+}
 </source>

Soma: /* Code */

2018-11-09T15:33:01Z

Code

← Older revision		Revision as of 15:33, 9 November 2018
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	==Code==		==Code==

			===opensnoop.ply===
			<source lang="C" line>
			#!/usr/bin/env ply

			kprobe:do_sys_open
			{
			printf("%16s(%5d): %s\n", comm(), pid(), mem(arg(1), "128s"));
			}
			</source>

	===memoryll.py===		===memoryll.py===

	<source lang="python" line>		<source lang="python" line>
	#!/usr/bin/env python		#!/usr/bin/env python

Soma at 15:08, 9 November 2018

2018-11-09T15:08:33Z

← Older revision		Revision as of 15:08, 9 November 2018
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	==memoryll & fusell==		==memoryll & fusell==

			The memoryll script (which depends on fusell) creates an in-memory filesystem. You can store what you want in this filesystem and the data will be recorded in python data structures. When the script terminates all data is lost.

	The memoryll and fusell example code are written in Python, not C. The code should be readable even if you are not familiar with Python. When you make changes, keep in mind the following:		The memoryll and fusell example code are written in Python, not C. The code should be readable even if you are not familiar with Python. When you make changes, keep in mind the following:

Soma at 15:06, 9 November 2018

2018-11-09T15:06:43Z

← Older revision		Revision as of 15:06, 9 November 2018
Line 1:		Line 1:
			'''This tutorial is not yet finalized.'''

	In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply]. The exercises below have been tested in the class openstack VM. It should also work in the virtualbox VM (as long as you don't run out of disk space while installing/updating packages). It should also work on any ubuntu 18.04 installation. Other linux distributions are likely to work but there may be glitches.		In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply]. The exercises below have been tested in the class openstack VM. It should also work in the virtualbox VM (as long as you don't run out of disk space while installing/updating packages). It should also work on any ubuntu 18.04 installation. Other linux distributions are likely to work but there may be glitches.

Soma at 15:06, 9 November 2018

2018-11-09T15:06:25Z

← Older revision		Revision as of 15:06, 9 November 2018
Line 1:		Line 1:
	In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply].		In this tutorial you will be learning about [https://github.com/libfuse/libfuse filesystem in userspace (FUSE)] using an example from [https://github.com/terencehonles/fusepy fusepy]. You will also be tracing kernel-level behavior using [https://wkz.github.io/ply/ ply]. The exercises below have been tested in the class openstack VM. It should also work in the virtualbox VM (as long as you don't run out of disk space while installing/updating packages). It should also work on any ubuntu 18.04 installation. Other linux distributions are likely to work but there may be glitches.

	==memoryll & fusell==		==memoryll & fusell==