Finish Chapter 15

• chown
  • The command
    • chown newuser file
    • chown newuser:newgroup file
    • Must have permission to do so
  • The system call
    int chown(const char *pathname, uid_t owner, gid_t group);
    • lchown, fchown
    • uid and gid, talk about /etc/passwd, /etc/group.
    • The process must be privileged to do this.
• Chmod and file permissions
  • The command
    • chmod [ugo] [+-] [rwxs] file
    • Or give the octal values see page 295
  • setuid bit
    • Allows a process to execute as a different user.
  • setgid bit
    • Allows a process to execute as a different group.
    • Also forces files created in a directory to be owned by a given group.
  • The sticky bit
    • Keep a file memory resident (old)
    • Deny group and other file removal permission on a directory. (new)
  • Setuid and setgid scripts are bad.
  • setuid and setgid programs are sources of problems.
  • What do permissions mean on directories mean?
  • The book notes that the strictest permissions are applied when checking paths.
    • IE User is tested against user, not group and other.