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o Introduce kern.suser_permitted, a sysctl that disables the suser_xxx()

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returning anything but EPERM.
o suser is enabled by default; once disabled, cannot be reenabled
o To be used in alternative security models where uid0 does not connote
  additional privileges
o Should be noted that uid0 still has some additional powers as it
  owns many important files and executables, so suffers from the same
  fundamental security flaws as securelevels.  This is fixed with
  MAC integrity protection code (in progress)
o Not safe for consumption unless you are *really* sure you don't want
  things like shutdown to work, et al :-)

Obtained from:	TrustedBSD Project
This commit is contained in:
Robert Watson 2000-06-05 14:53:55 +00:00
parent 192851dbff
commit 0309554711
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=61282
3 changed files with 27 additions and 0 deletions
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24
sys/kern/kern_mib.c
View File

@ -182,6 +182,30 @@ sysctl_kern_securelvl SYSCTL_HANDLER_ARGS
SYSCTL_PROC(_kern, KERN_SECURELVL, securelevel, CTLTYPE_INT|CTLFLAG_RW,
0, 0, sysctl_kern_securelvl, "I", "Current secure level");
int suser_permitted = 1;
static int
sysctl_kern_suser_permitted SYSCTL_HANDLER_ARGS
{
int error, flag;
flag = suser_permitted;
error = sysctl_handle_int(oidp, &flag, 0, req);
if (error || !req->newptr)
return (error);
if (flag != 0 && flag != 1)
return(EPERM);
if (!suser_permitted)
return(EPERM);
suser_permitted = flag;
return (0);
}
SYSCTL_PROC(_kern, OID_AUTO, suser_permitted,
CTLTYPE_INT|CTLFLAG_RW, 0, 0, sysctl_kern_suser_permitted, "I",
"processes with uid 0 have privilege");
char domainname[MAXHOSTNAMELEN];
SYSCTL_STRING(_kern, KERN_NISDOMAINNAME, domainname, CTLFLAG_RW,
&domainname, sizeof(domainname), "Name of the current YP/NIS domain");

2
sys/kern/kern_prot.c
View File

@ -950,6 +950,8 @@ suser_xxx(cred, proc, flag)
struct proc *proc;
int flag;
{
if (!suser_permitted)
return (EPERM);
if (!cred && !proc) {
printf("suser_xxx(): THINK!\n");
return (EPERM);

1
sys/sys/systm.h
View File

@ -47,6 +47,7 @@
#include <sys/callout.h>
extern int securelevel; /* system security level (see init(8)) */
extern int suser_permitted; /* suser_xxx() is permitted to return 0 */
extern int cold; /* nonzero if we are doing a cold boot */
extern const char *panicstr; /* panic message */