KERNEL PATCH: add process hiding (fixed)

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KERNEL PATCH: add process hiding (fixed)

walker_643
(( Resending my last from a client that (hopefully) won't mangle the email.
   Sorry about the noise, folks. ))


Hello OpenBSD Community -

OpenBSD should have the ability to prevent users from seeing each other's processes even if this ability is disabled by default.
In addition to the small security benefit this provides, it also affords each user a much greater amount of privacy. Linux and
FreeBSD already support similar features ( https://www.cyberciti.biz/faq/linux-hide-processes-from-other-users/  &&
https://www.cyberciti.biz/faq/freebsd-disable-ps-sockstat-command-information-leakage/ ) and the implementation itself is fairly
trivial.

Below is a patch which implements basic process hiding for non-superusers and is activated with a sysctl knob. Similar to that of
FreeBSD it is called "kern.see_other_uids¨. The idea is that if process spying is a security or privacy concern for you, you
would add "kern.see_other_uids=0" to sysctl.conf and reboot (assuming securelevel > 0).

I look forward to your comments.

Thanks and cheers all -
Ian Walker



Index: sys/kern/kern_sysctl.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
retrieving revision 1.320
diff -u -p -u -r1.320 kern_sysctl.c
--- sys/kern/kern_sysctl.c    11 Nov 2016 18:59:09 -0000    1.320
+++ sys/kern/kern_sysctl.c    4 Dec 2016 20:43:53 -0000
@@ -263,6 +263,7 @@ size_t disknameslen;
 struct diskstats *diskstats = NULL;
 size_t diskstatslen;
 int securelevel;
+int seeotheruids = 1; /* on by default */
 
 /*
  * kernel related system variables.
@@ -632,6 +633,13 @@ kern_sysctl(int *name, u_int namelen, vo
         dnsjackport = port;
         return 0;
     }
+    case KERN_SEEOTHERUIDS: {
+        if (securelevel > 0)
+            return (sysctl_rdint(oldp, oldlenp, newp,
+                seeotheruids));
+        return (sysctl_int(oldp, oldlenp, newp, newlen,
+            &seeotheruids));
+    }
     default:
         return (EOPNOTSUPP);
     }
@@ -1427,7 +1435,8 @@ sysctl_doproc(int *name, u_int namelen,
     int arg, buflen, doingzomb, elem_size, elem_count;
     int error, needed, op;
     int dothreads = 0;
-    int show_pointers;
+    int is_suser, show_pointers, show_otheruids;
+    uid_t euid;
 
     dp = where;
     buflen = where != NULL ? *sizep : 0;
@@ -1444,7 +1453,10 @@ sysctl_doproc(int *name, u_int namelen,
     dothreads = op & KERN_PROC_SHOW_THREADS;
     op &= ~KERN_PROC_SHOW_THREADS;
 
-    show_pointers = suser(curproc, 0) == 0;
+    is_suser = suser(curproc, 0) == 0;
+    show_pointers = is_suser;
+    show_otheruids = seeotheruids || is_suser;
+    euid = curproc->p_ucred->cr_uid;
 
     if (where != NULL)
         kproc = malloc(sizeof(*kproc), M_TEMP, M_WAITOK);
@@ -1461,6 +1473,9 @@ again:
          * Skip embryonic processes.
          */
         if (pr->ps_flags & PS_EMBRYO)
+            continue;
+
+        if (!show_otheruids && pr->ps_ucred->cr_uid != euid)
             continue;
 
         /*
Index: sys/sys/sysctl.h
===================================================================
RCS file: /cvs/src/sys/sys/sysctl.h,v
retrieving revision 1.170
diff -u -p -u -r1.170 sysctl.h
--- sys/sys/sysctl.h    7 Nov 2016 00:26:32 -0000    1.170
+++ sys/sys/sysctl.h    4 Dec 2016 20:43:55 -0000
@@ -184,7 +184,8 @@ struct ctlname {
 #define    KERN_GLOBAL_PTRACE    81    /* allow ptrace globally */
 #define    KERN_CONSBUFSIZE    82    /* int: console message buffer size */
 #define    KERN_CONSBUF        83    /* console message buffer */
-#define    KERN_MAXID        84    /* number of valid kern ids */
+#define    KERN_SEEOTHERUIDS    84    /* see other users' proceesses */
+#define    KERN_MAXID        85    /* number of valid kern ids */
 
 #define    CTL_KERN_NAMES { \
     { 0, 0 }, \
@@ -269,6 +270,9 @@ struct ctlname {
     { "proc_nobroadcastkill", CTLTYPE_NODE }, \
     { "proc_vmmap", CTLTYPE_NODE }, \
     { "global_ptrace", CTLTYPE_INT }, \
+    { "gap", 0 }, \
+    { "gap", 0 }, \
+    { "see_other_uids", CTLTYPE_INT }, \
 }
 
 /*

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Re: KERNEL PATCH: add process hiding (fixed)

Michael Mikonos
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Re: KERNEL PATCH: add process hiding (fixed)

walker_643
Thanks, Michael. Leave it to me to forget to update the documentation..

Here's the patch with the manpage change:


Index: sys/kern/kern_sysctl.c
===================================================================
RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
retrieving revision 1.320
diff -u -p -u -r1.320 kern_sysctl.c
--- sys/kern/kern_sysctl.c 11 Nov 2016 18:59:09 -0000 1.320
+++ sys/kern/kern_sysctl.c 4 Dec 2016 20:43:53 -0000
@@ -263,6 +263,7 @@ size_t disknameslen;
 struct diskstats *diskstats = NULL;
 size_t diskstatslen;
 int securelevel;
+int seeotheruids = 1; /* on by default */
 
 /*
  * kernel related system variables.
@@ -632,6 +633,13 @@ kern_sysctl(int *name, u_int namelen, vo
  dnsjackport = port;
  return 0;
  }
+ case KERN_SEEOTHERUIDS: {
+ if (securelevel > 0)
+ return (sysctl_rdint(oldp, oldlenp, newp,
+    seeotheruids));
+ return (sysctl_int(oldp, oldlenp, newp, newlen,
+    &seeotheruids));
+ }
  default:
  return (EOPNOTSUPP);
  }
@@ -1427,7 +1435,8 @@ sysctl_doproc(int *name, u_int namelen,
  int arg, buflen, doingzomb, elem_size, elem_count;
  int error, needed, op;
  int dothreads = 0;
- int show_pointers;
+ int is_suser, show_pointers, show_otheruids;
+ uid_t euid;
 
  dp = where;
  buflen = where != NULL ? *sizep : 0;
@@ -1444,7 +1453,10 @@ sysctl_doproc(int *name, u_int namelen,
  dothreads = op & KERN_PROC_SHOW_THREADS;
  op &= ~KERN_PROC_SHOW_THREADS;
 
- show_pointers = suser(curproc, 0) == 0;
+ is_suser = suser(curproc, 0) == 0;
+ show_pointers = is_suser;
+ show_otheruids = seeotheruids || is_suser;
+ euid = curproc->p_ucred->cr_uid;
 
  if (where != NULL)
  kproc = malloc(sizeof(*kproc), M_TEMP, M_WAITOK);
@@ -1461,6 +1473,9 @@ again:
  * Skip embryonic processes.
  */
  if (pr->ps_flags & PS_EMBRYO)
+ continue;
+
+ if (!show_otheruids && pr->ps_ucred->cr_uid != euid)
  continue;
 
  /*
Index: sys/sys/sysctl.h
===================================================================
RCS file: /cvs/src/sys/sys/sysctl.h,v
retrieving revision 1.170
diff -u -p -u -r1.170 sysctl.h
--- sys/sys/sysctl.h 7 Nov 2016 00:26:32 -0000 1.170
+++ sys/sys/sysctl.h 4 Dec 2016 20:43:55 -0000
@@ -184,7 +184,8 @@ struct ctlname {
 #define KERN_GLOBAL_PTRACE 81 /* allow ptrace globally */
 #define KERN_CONSBUFSIZE 82 /* int: console message buffer size */
 #define KERN_CONSBUF 83 /* console message buffer */
-#define KERN_MAXID 84 /* number of valid kern ids */
+#define KERN_SEEOTHERUIDS 84 /* see other users' proceesses */
+#define KERN_MAXID 85 /* number of valid kern ids */
 
 #define CTL_KERN_NAMES { \
  { 0, 0 }, \
@@ -269,6 +270,9 @@ struct ctlname {
  { "proc_nobroadcastkill", CTLTYPE_NODE }, \
  { "proc_vmmap", CTLTYPE_NODE }, \
  { "global_ptrace", CTLTYPE_INT }, \
+ { "gap", 0 }, \
+ { "gap", 0 }, \
+ { "see_other_uids", CTLTYPE_INT }, \
 }
 
 /*
Index: sbin/sysctl/sysctl.8
===================================================================
RCS file: /cvs/src/sbin/sysctl/sysctl.8,v
retrieving revision 1.208
diff -u -p -u -r1.208 sysctl.8
--- sbin/sysctl/sysctl.8        15 Oct 2016 14:43:53 -0000      1.208
+++ sbin/sysctl/sysctl.8        5 Dec 2016 02:04:52 -0000
@@ -194,6 +194,7 @@ and a few require a kernel compiled with
 .It kern.wxabort Ta integer Ta yes
 .It kern.consdev Ta string Ta no
 .It kern.global_ptrace Ta integer Ta yes
+.It kern.see_other_uids Ta integer Ta yes
 .It vm.vmmeter Ta struct Ta no
 .It vm.loadavg Ta struct Ta no
 .It vm.psstrings Ta struct Ta no



On Mon, Dec 05, 2016 at 08:55:19AM +0800, Michael W. Bombardieri wrote:

> Should this patch also add see_other_uids in sysctl(8) manual?
>
> On Sun, Dec 04, 2016 at 07:49:12PM -0500, Ian Walker wrote:
> > (( Resending my last from a client that (hopefully) won't mangle the email.
> >    Sorry about the noise, folks. ))
> >
> >
> > Hello OpenBSD Community -
> >
> > OpenBSD should have the ability to prevent users from seeing each other's processes even if this ability is disabled by default.
> > In addition to the small security benefit this provides, it also affords each user a much greater amount of privacy. Linux and
> > FreeBSD already support similar features ( https://www.cyberciti.biz/faq/linux-hide-processes-from-other-users/  &&
> > https://www.cyberciti.biz/faq/freebsd-disable-ps-sockstat-command-information-leakage/ ) and the implementation itself is fairly
> > trivial.
> >
> > Below is a patch which implements basic process hiding for non-superusers and is activated with a sysctl knob. Similar to that of
> > FreeBSD it is called "kern.see_other_uids¨. The idea is that if process spying is a security or privacy concern for you, you
> > would add "kern.see_other_uids=0" to sysctl.conf and reboot (assuming securelevel > 0).
> >
> > I look forward to your comments.
> >
> > Thanks and cheers all -
> > Ian Walker
> >
> >
> >
> > Index: sys/kern/kern_sysctl.c
> > ===================================================================
> > RCS file: /cvs/src/sys/kern/kern_sysctl.c,v
> > retrieving revision 1.320
> > diff -u -p -u -r1.320 kern_sysctl.c
> > --- sys/kern/kern_sysctl.c    11 Nov 2016 18:59:09 -0000    1.320
> > +++ sys/kern/kern_sysctl.c    4 Dec 2016 20:43:53 -0000
> > @@ -263,6 +263,7 @@ size_t disknameslen;
> >  struct diskstats *diskstats = NULL;
> >  size_t diskstatslen;
> >  int securelevel;
> > +int seeotheruids = 1; /* on by default */
> >  
> >  /*
> >   * kernel related system variables.
> > @@ -632,6 +633,13 @@ kern_sysctl(int *name, u_int namelen, vo
> >          dnsjackport = port;
> >          return 0;
> >      }
> > +    case KERN_SEEOTHERUIDS: {
> > +        if (securelevel > 0)
> > +            return (sysctl_rdint(oldp, oldlenp, newp,
> > +                seeotheruids));
> > +        return (sysctl_int(oldp, oldlenp, newp, newlen,
> > +            &seeotheruids));
> > +    }
> >      default:
> >          return (EOPNOTSUPP);
> >      }
> > @@ -1427,7 +1435,8 @@ sysctl_doproc(int *name, u_int namelen,
> >      int arg, buflen, doingzomb, elem_size, elem_count;
> >      int error, needed, op;
> >      int dothreads = 0;
> > -    int show_pointers;
> > +    int is_suser, show_pointers, show_otheruids;
> > +    uid_t euid;
> >  
> >      dp = where;
> >      buflen = where != NULL ? *sizep : 0;
> > @@ -1444,7 +1453,10 @@ sysctl_doproc(int *name, u_int namelen,
> >      dothreads = op & KERN_PROC_SHOW_THREADS;
> >      op &= ~KERN_PROC_SHOW_THREADS;
> >  
> > -    show_pointers = suser(curproc, 0) == 0;
> > +    is_suser = suser(curproc, 0) == 0;
> > +    show_pointers = is_suser;
> > +    show_otheruids = seeotheruids || is_suser;
> > +    euid = curproc->p_ucred->cr_uid;
> >  
> >      if (where != NULL)
> >          kproc = malloc(sizeof(*kproc), M_TEMP, M_WAITOK);
> > @@ -1461,6 +1473,9 @@ again:
> >           * Skip embryonic processes.
> >           */
> >          if (pr->ps_flags & PS_EMBRYO)
> > +            continue;
> > +
> > +        if (!show_otheruids && pr->ps_ucred->cr_uid != euid)
> >              continue;
> >  
> >          /*
> > Index: sys/sys/sysctl.h
> > ===================================================================
> > RCS file: /cvs/src/sys/sys/sysctl.h,v
> > retrieving revision 1.170
> > diff -u -p -u -r1.170 sysctl.h
> > --- sys/sys/sysctl.h    7 Nov 2016 00:26:32 -0000    1.170
> > +++ sys/sys/sysctl.h    4 Dec 2016 20:43:55 -0000
> > @@ -184,7 +184,8 @@ struct ctlname {
> >  #define    KERN_GLOBAL_PTRACE    81    /* allow ptrace globally */
> >  #define    KERN_CONSBUFSIZE    82    /* int: console message buffer size */
> >  #define    KERN_CONSBUF        83    /* console message buffer */
> > -#define    KERN_MAXID        84    /* number of valid kern ids */
> > +#define    KERN_SEEOTHERUIDS    84    /* see other users' proceesses */
> > +#define    KERN_MAXID        85    /* number of valid kern ids */
> >  
> >  #define    CTL_KERN_NAMES { \
> >      { 0, 0 }, \
> > @@ -269,6 +270,9 @@ struct ctlname {
> >      { "proc_nobroadcastkill", CTLTYPE_NODE }, \
> >      { "proc_vmmap", CTLTYPE_NODE }, \
> >      { "global_ptrace", CTLTYPE_INT }, \
> > +    { "gap", 0 }, \
> > +    { "gap", 0 }, \
> > +    { "see_other_uids", CTLTYPE_INT }, \
> >  }
> >  
> >  /*
> >
>