Quick Intro to RCS and AFS File Permissions

1
Quick Intro toRCS and AFS File Permissions

• Ref man pages for fs, pts,
• CIS Memo RPI.114Sharing Files in RCS Unix

2
Access Control List - ACL

• Each directory in an AFS file system has an
  access control list that determines who can
  access the files in the directory.
• Within a directory you can use the traditional
  Unix permissions to further restrict access.

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Types of Permissions

• r read - users can view contents of file
• l list - users can names of files in a directory.
• i insert - users can add files to directory
• d delete - users can delete files.
• w write - users can change contents of files.
• k lock - users can lock files (flock()).
• a administer - users can change permissions.

4
The fs command

• The fs command can be used to display and change
  an ACL.
• fs does lots of other things also!
• try fs help for details

5
Displaying file permissions

• fs listacl dirname(s)
• fs la dirname(s)
• Shows the access control list for the named
  directories.

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fs la (pronounced "fuse lay")

• gt fs la public
• Access list for public is
• Normal rights
• systembackup l
• systemanyuser rl
• hollid2 rlidwka
• gt

Not really (I made that up!)
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Setting Permissions

• fs setacl -d dirname -acl aclentries
• fs sa -d dirname -acl aclentries
• fs sa dirname username permissions
• Changes the ACL for the named directory.

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aclentries

• Each acl entry is a username (or group) followed
  by any combination of the seven access privileges
  (rlidwka)
• Examples
• hollid2 rlidwka
• systemanyuser rl
• hollid none

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fs sa (pronounced "fusy")

• fs sa . systemanyuser all
• fs sa tmp joe rl
• fs sa foo sam none

10
Negative Permissions

• fs sa dirname -negative aclentry
• example
• fs sa . -negative faustn2 rl

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negativity

• gt fs sa . systemanyuser all
• gt fs sa . -negative faustn2 all
• gt fs la .
• Normal rights
• systembackup l
• systemanyuser rlidwka
• hollid2 rlidwka
• Negative rights
• faustn2 rlidwka

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Groups

• You can create your own groups of users to
  simplify setting up permissions.
• These are not the traditional "Unix groups",
  these are just for AFS file permissions!
• Each group name you create starts with the prefix
  "yourid"

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Creating a group

• pts creategroup youridgroupname
• example
• pts creategroup hollid2students

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Adding a user to a group

• pts adduser username groupname
• examples
• pts adduser god hollid2closefriends

15
pts removeuser (pronounced "puts fillybog")

• pts removeuser username groupname
• example
• pts removeuser joe hollid2research

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Listing a group

• pts membership groupname
• example
• gt pts membership hollid2blah
• Members of hollid2blah (id -3128) are
• ingalr
• faustn2