[src/trunk]: src Change the way root_owner works: consider the calling proces...

[maxv <maxv%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/97843c974ec8
branches:  trunk
changeset: 460545:97843c974ec8
user:      maxv <maxv%NetBSD.org@localhost>
date:      Sun Oct 27 20:17:36 2019 +0000

description:
Change the way root_owner works: consider the calling process as root_owner
not if it has root privileges, but if the /dev/nvmm device was opened with
write permissions. Introduce the undocumented nvmm_root_init() function to
achieve that.

The goal is to simplify the logic and have more granularity, eg if we want
a monitoring agent to access VMs but don't want to give this agent real
root access on the system.

diffstat:

 lib/libnvmm/libnvmm.c |  25 ++++++++++++++++++++++++-
 lib/libnvmm/nvmm.h    |   3 ++-
 sys/dev/nvmm/nvmm.c   |  29 ++++++++++++++---------------
 3 files changed, 40 insertions(+), 17 deletions(-)

diffs (136 lines):

diff -r 50425805d2d4 -r 97843c974ec8 lib/libnvmm/libnvmm.c
--- a/lib/libnvmm/libnvmm.c     Sun Oct 27 20:11:13 2019 +0000
+++ b/lib/libnvmm/libnvmm.c     Sun Oct 27 20:17:36 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: libnvmm.c,v 1.17 2019/10/27 07:08:15 maxv Exp $        */
+/*     $NetBSD: libnvmm.c,v 1.18 2019/10/27 20:17:36 maxv Exp $        */
 
 /*
  * Copyright (c) 2018-2019 The NetBSD Foundation, Inc.
@@ -180,6 +180,29 @@
 }
 
 int
+nvmm_root_init(void)
+{
+       if (nvmm_fd != -1)
+               return 0;
+       nvmm_fd = open("/dev/nvmm", O_WRONLY | O_CLOEXEC);
+       if (nvmm_fd == -1)
+               return -1;
+       if (nvmm_capability(&__capability) == -1) {
+               close(nvmm_fd);
+               nvmm_fd = -1;
+               return -1;
+       }
+       if (__capability.version != NVMM_KERN_VERSION) {
+               close(nvmm_fd);
+               nvmm_fd = -1;
+               errno = EPROGMISMATCH;
+               return -1;
+       }
+
+       return 0;
+}
+
+int
 nvmm_capability(struct nvmm_capability *cap)
 {
        struct nvmm_ioc_capability args;
diff -r 50425805d2d4 -r 97843c974ec8 lib/libnvmm/nvmm.h
--- a/lib/libnvmm/nvmm.h        Sun Oct 27 20:11:13 2019 +0000
+++ b/lib/libnvmm/nvmm.h        Sun Oct 27 20:17:36 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm.h,v 1.15 2019/10/27 07:08:15 maxv Exp $   */
+/*     $NetBSD: nvmm.h,v 1.16 2019/10/27 20:17:36 maxv Exp $   */
 
 /*
  * Copyright (c) 2018-2019 The NetBSD Foundation, Inc.
@@ -90,6 +90,7 @@
 typedef uint64_t nvmm_prot_t;
 
 int nvmm_init(void);
+int nvmm_root_init(void);
 
 int nvmm_capability(struct nvmm_capability *);
 
diff -r 50425805d2d4 -r 97843c974ec8 sys/dev/nvmm/nvmm.c
--- a/sys/dev/nvmm/nvmm.c       Sun Oct 27 20:11:13 2019 +0000
+++ b/sys/dev/nvmm/nvmm.c       Sun Oct 27 20:17:36 2019 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmm.c,v 1.23 2019/10/23 07:01:11 maxv Exp $   */
+/*     $NetBSD: nvmm.c,v 1.24 2019/10/27 20:17:36 maxv Exp $   */
 
 /*
  * Copyright (c) 2018-2019 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvmm.c,v 1.23 2019/10/23 07:01:11 maxv Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvmm.c,v 1.24 2019/10/27 20:17:36 maxv Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -889,7 +889,7 @@
 /* -------------------------------------------------------------------------- */
 
 static int
-nvmm_ctl_mach_info(struct nvmm_ioc_ctl *args)
+nvmm_ctl_mach_info(struct nvmm_owner *owner, struct nvmm_ioc_ctl *args)
 {
        struct nvmm_ctl_mach_info ctl;
        struct nvmm_machine *mach;
@@ -903,7 +903,7 @@
        if (error)
                return error;
 
-       error = nvmm_machine_get(&root_owner, ctl.machid, &mach, true);
+       error = nvmm_machine_get(owner, ctl.machid, &mach, true);
        if (error)
                return error;
 
@@ -930,16 +930,9 @@
 static int
 nvmm_ctl(struct nvmm_owner *owner, struct nvmm_ioc_ctl *args)
 {
-       int error;
-
-       error = kauth_authorize_device(curlwp->l_cred, KAUTH_DEVICE_NVMM_CTL,
-           NULL, NULL, NULL, NULL);
-       if (error)
-               return error;
-
        switch (args->op) {
        case NVMM_CTL_MACH_INFO:
-               return nvmm_ctl_mach_info(args);
+               return nvmm_ctl_mach_info(owner, args);
        default:
                return EINVAL;
        }
@@ -1047,8 +1040,12 @@
        if (error)
                return error;
 
-       owner = kmem_alloc(sizeof(*owner), KM_SLEEP);
-       owner->pid = l->l_proc->p_pid;
+       if (OFLAGS(flags) & O_WRONLY) {
+               owner = &root_owner;
+       } else {
+               owner = kmem_alloc(sizeof(*owner), KM_SLEEP);
+               owner->pid = l->l_proc->p_pid;
+       }
 
        return fd_clone(fp, fd, flags, &nvmm_fileops, owner);
 }
@@ -1060,7 +1057,9 @@
 
        KASSERT(owner != NULL);
        nvmm_kill_machines(owner);
-       kmem_free(owner, sizeof(*owner));
+       if (owner != &root_owner) {
+               kmem_free(owner, sizeof(*owner));
+       }
        fp->f_data = NULL;
 
        return 0;