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Break out the "see_other_uids" policy check from the various

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method-based inter-process security checks.  To do this, introduce
a new cr_seeotheruids(u1, u2) function, which encapsulates the
"see_other_uids" logic.  Call out to this policy following the
jail security check for all of {debug,sched,see,signal} inter-process
checks.  This more consistently enforces the check, and makes the
check easy to modify.  Eventually, it may be that this check should
become a MAC policy, loaded via a module.

Obtained from:	TrustedBSD Project
Sponsored by:	DARPA, NAI Labs
This commit is contained in:
Robert Watson 2002-03-22 02:28:26 +00:00
parent 3f330d7d1a
commit 1b350b4542
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=92923
1 changed files with 28 additions and 4 deletions
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32
sys/kern/kern_prot.c
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@ -1391,6 +1391,25 @@ SYSCTL_INT(_security_bsd, OID_AUTO, see_other_uids, CTLFLAG_RW,
&see_other_uids, 0,
"Unprivileged processes may see subjects/objects with different real uid");
/*-
* Determine if u1 "can see" the subject specified by u2, according to the
* 'see_other_uids' policy.
* Returns: 0 for permitted, ESRCH otherwise
* Locks: none
* References: *u1 and *u2 must not change during the call
* u1 may equal u2, in which case only one reference is required
*/
static int
cr_seeotheruids(struct ucred *u1, struct ucred *u2)
{
if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) {
if (suser_xxx(u1, NULL, PRISON_ROOT) != 0)
return (ESRCH);
}
return (0);
}
/*-
* Determine if u1 "can see" the subject specified by u2.
* Returns: 0 for permitted, an errno value otherwise
@ -1405,10 +1424,8 @@ cr_cansee(struct ucred *u1, struct ucred *u2)
if ((error = prison_check(u1, u2)))
return (error);
if (!see_other_uids && u1->cr_ruid != u2->cr_ruid) {
if (suser_xxx(u1, NULL, PRISON_ROOT) != 0)
return (ESRCH);
}
if ((error = cr_seeotheruids(u1, u2)))
return (error);
return (0);
}
@ -1444,6 +1461,9 @@ cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
* same jail as cred, if cred is in jail.
*/
error = prison_check(cred, proc->p_ucred);
if (error)
return (error);
error = cr_seeotheruids(cred, proc->p_ucred);
if (error)
return (error);
@ -1539,6 +1559,8 @@ p_cansched(struct proc *p1, struct proc *p2)
return (0);
if ((error = prison_check(p1->p_ucred, p2->p_ucred)))
return (error);
if ((error = cr_seeotheruids(p1->p_ucred, p2->p_ucred)))
return (error);
if (p1->p_ucred->cr_ruid == p2->p_ucred->cr_ruid)
return (0);
if (p1->p_ucred->cr_uid == p2->p_ucred->cr_ruid)
@ -1592,6 +1614,8 @@ p_candebug(struct proc *p1, struct proc *p2)
return (0);
if ((error = prison_check(p1->p_ucred, p2->p_ucred)))
return (error);
if ((error = cr_seeotheruids(p1->p_ucred, p2->p_ucred)))
return (error);
/*
* Is p2's group set a subset of p1's effective group set? This