/share/doc/papers/sysperf/6.t

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32.\"	@(#)6.t	5.1 (Berkeley) 4/17/91
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34.ds RH Security Tightening
35.NH
36Security Tightening
37.PP
38Since we do not wish to encourage rampant system cracking,
39we describe only briefly the changes made to enhance security.
40.NH 2
41Generic Kernel
42.PP
43Several loopholes in the process tracing facility have been corrected.
44Programs being traced may not be executed;
45executing programs may not be traced.
46Programs may not provide input to terminals to which they do not
47have read permission.
48The handling of process groups has been tightened to eliminate
49some problems.
50When a program attempts to change its process group,
51the system checks to see if the process with the pid of the process 
52group was started by the same user.
53If it exists and was started by a different user the process group
54number change is denied.
55.NH 2
56Security Problems in Utilities
57.PP
58Setuid utilities no longer use the \fIpopen\fP or \fIsystem\fP library routines.
59Access to the kernel's data structures through the kmem device
60is now restricted to programs that are set group id ``kmem''.
61Thus many programs that used to run with root privileges
62no longer need to do so.
63Access to disk devices is now controlled by an ``operator'' group id;
64this permission allows operators to function without being the super-user.
65Only users in group wheel can do ``su root''; this restriction
66allows administrators to define a super-user access list.
67Numerous holes have been closed in the shell to prevent
68users from gaining privileges from set user id shell scripts,
69although use of such scripts is still highly discouraged on systems
70that are concerned about security.