[patch] unprivileged mlock(2)
- From: Andrey Zonov <zont@xxxxxxxxxxx>
- Date: Tue, 28 Aug 2012 20:37:05 +0400
Hi,
We've got RLIMIT_MEMLOCK for years, but this limit is useless, because
only root may call mlock(2), and root may raise any limits.
I suggest patch that allows to call mlock(2) for unprivileged users.
Are there any objections to got it in tree?
--
Andrey Zonov
- Allow non-root users to call mlock(2)/munlock(2) and
mlockall(2)/munlockall(2). Now RLIMIT_MEMLOCK makes sense.
- Add sysctl security.bsd.unprivileged_mlock to deny ability of calling
mlock(2) to non-root users.
Approved by: kib (mentor)
MFC after: 2 weeks
Index: sys/vm/vm_mmap.c
===================================================================
--- sys/vm/vm_mmap.c (revision 239772)
+++ sys/vm/vm_mmap.c (working copy)
@@ -1015,6 +1015,10 @@ done2:
return (error);
}
+static int unprivileged_mlock = 1;
+SYSCTL_INT(_security_bsd, OID_AUTO, unprivileged_mlock, CTLFLAG_RW,
+ &unprivileged_mlock, 0, "Unprivileged processes may lock the memory");
+
#ifndef _SYS_SYSPROTO_H_
struct mlock_args {
const void *addr;
@@ -1035,9 +1039,11 @@ sys_mlock(td, uap)
unsigned long nsize;
int error;
- error = priv_check(td, PRIV_VM_MLOCK);
- if (error)
- return (error);
+ if (!unprivileged_mlock) {
+ error = priv_check(td, PRIV_VM_MLOCK);
+ if (error)
+ return (error);
+ }
addr = (vm_offset_t)uap->addr;
size = uap->len;
last = addr + size;
@@ -1114,9 +1120,11 @@ sys_mlockall(td, uap)
}
PROC_UNLOCK(td->td_proc);
#else
- error = priv_check(td, PRIV_VM_MLOCK);
- if (error)
- return (error);
+ if (!unprivileged_mlock) {
+ error = priv_check(td, PRIV_VM_MLOCK);
+ if (error)
+ return (error);
+ }
#endif
#ifdef RACCT
PROC_LOCK(td->td_proc);
@@ -1174,9 +1182,11 @@ sys_munlockall(td, uap)
int error;
map = &td->td_proc->p_vmspace->vm_map;
- error = priv_check(td, PRIV_VM_MUNLOCK);
- if (error)
- return (error);
+ if (!unprivileged_mlock) {
+ error = priv_check(td, PRIV_VM_MUNLOCK);
+ if (error)
+ return (error);
+ }
/* Clear the MAP_WIREFUTURE flag from this vm_map. */
vm_map_lock(map);
@@ -1215,9 +1225,11 @@ sys_munlock(td, uap)
vm_size_t size;
int error;
- error = priv_check(td, PRIV_VM_MUNLOCK);
- if (error)
- return (error);
+ if (!unprivileged_mlock) {
+ error = priv_check(td, PRIV_VM_MUNLOCK);
+ if (error)
+ return (error);
+ }
addr = (vm_offset_t)uap->addr;
size = uap->len;
last = addr + size;
Index: lib/libc/sys/mlockall.2
===================================================================
--- lib/libc/sys/mlockall.2 (revision 239772)
+++ lib/libc/sys/mlockall.2 (working copy)
@@ -72,7 +72,9 @@ limit and the per-process
.Dv RLIMIT_MEMLOCK
resource limit.
.Pp
-These calls are only available to the super-user.
+These calls are only available to the super-user, or to anyone when
+.Va security.bsd.unprivileged_mlock
+is set to 1.
.Pp
The
.Fn munlockall
Index: lib/libc/sys/mlock.2
===================================================================
--- lib/libc/sys/mlock.2 (revision 239772)
+++ lib/libc/sys/mlock.2 (working copy)
@@ -99,7 +99,9 @@ the per-process
.Li RLIMIT_MEMLOCK
resource limit.
.Pp
-These calls are only available to the super-user.
+These calls are only available to the super-user, or to anyone when
+.Va security.bsd.unprivileged_mlock
+is set to 1.
.Sh RETURN VALUES
.Rv -std
.Pp
@@ -112,7 +114,9 @@ system call
will fail if:
.Bl -tag -width Er
.It Bq Er EPERM
-The caller is not the super-user.
+The caller is not the super-user and
+.Va security.bsd.unprivileged_mlock
+is set to 0.
.It Bq Er EINVAL
The address given is not page aligned or the length is negative.
.It Bq Er EAGAIN
@@ -129,7 +133,9 @@ system call
will fail if:
.Bl -tag -width Er
.It Bq Er EPERM
-The caller is not the super-user.
+The caller is not the super-user and
+.Va security.bsd.unprivileged_mlock
+is set to 0.
.It Bq Er EINVAL
The address given is not page aligned or the length is negative.
.It Bq Er ENOMEM
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