|
 |
9119d9 |
From 03a842c7997b0e299a6b044f4822024e9be2bc7d Mon Sep 17 00:00:00 2001
|
|
|
9119d9 |
Message-Id: <03a842c7997b0e299a6b044f4822024e9be2bc7d@dist-git>
|
|
|
9119d9 |
From: Michal Privoznik <mprivozn@redhat.com>
|
|
|
9119d9 |
Date: Wed, 15 Oct 2014 12:55:00 +0200
|
|
|
9119d9 |
Subject: [PATCH] security_selinux: Don't relabel /dev/net/tun
|
|
|
9119d9 |
|
|
|
9119d9 |
RHEL-7: https://bugzilla.redhat.com/show_bug.cgi?id=1095636
|
|
|
9119d9 |
Fedora: https://bugzilla.redhat.com/show_bug.cgi?id=1147057
|
|
|
9119d9 |
|
|
|
9119d9 |
The code for relabelling the TAP FD is there due to a race. When
|
|
|
9119d9 |
libvirt creates a /dev/tapN device it's labeled as
|
|
|
9119d9 |
'system_u:object_r:device_t:s0' by default. Later, when
|
|
|
9119d9 |
udev/systemd reacts to this device, it's relabelled to the
|
|
|
9119d9 |
expected label 'system_u:object_r:tun_tap_device_t:s0'. Hence, we
|
|
|
9119d9 |
have a code that relabels the device, to cut the race down. For
|
|
|
9119d9 |
more info see ae368ebfcc4.
|
|
|
9119d9 |
|
|
|
9119d9 |
But the problem is, the relabel function is called on all TUN/TAP
|
|
|
9119d9 |
devices. Yes, on /dev/net/tun too. This is however a special kind
|
|
|
9119d9 |
of device - other processes uses it too. We shouldn't touch it's
|
|
|
9119d9 |
label then.
|
|
|
9119d9 |
|
|
|
9119d9 |
Ideally, there would an API in SELinux that would label just the
|
|
|
9119d9 |
passed FD and not the underlying path. That way, we wouldn't need
|
|
|
9119d9 |
to care as we would be not labeling /dev/net/tun but the FD
|
|
|
9119d9 |
passed to the domain. Unfortunately, there's no such API so we
|
|
|
9119d9 |
have to workaround until then.
|
|
|
9119d9 |
|
|
|
9119d9 |
Tested-by: Richard W.M. Jones <rjones@redhat.com>
|
|
|
9119d9 |
Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
|
|
|
9119d9 |
(cherry picked from commit ebc05263960f41065fa7d882959ea754b9281ab1)
|
|
|
9119d9 |
Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
|
|
|
9119d9 |
---
|
|
|
9119d9 |
src/security/security_selinux.c | 23 +++++++++++++++++++++--
|
|
|
9119d9 |
1 file changed, 21 insertions(+), 2 deletions(-)
|
|
|
9119d9 |
|
|
|
9119d9 |
diff --git a/src/security/security_selinux.c b/src/security/security_selinux.c
|
|
|
9119d9 |
index b7c1015..352f1ab 100644
|
|
|
9119d9 |
--- a/src/security/security_selinux.c
|
|
|
9119d9 |
+++ b/src/security/security_selinux.c
|
|
|
9119d9 |
@@ -2352,7 +2352,7 @@ virSecuritySELinuxSetTapFDLabel(virSecurityManagerPtr mgr,
|
|
|
9119d9 |
struct stat buf;
|
|
|
9119d9 |
security_context_t fcon = NULL;
|
|
|
9119d9 |
virSecurityLabelDefPtr secdef;
|
|
|
9119d9 |
- char *str = NULL;
|
|
|
9119d9 |
+ char *str = NULL, *proc = NULL, *fd_path = NULL;
|
|
|
9119d9 |
int rc = -1;
|
|
|
9119d9 |
|
|
|
9119d9 |
secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_SELINUX_NAME);
|
|
|
9119d9 |
@@ -2370,7 +2370,24 @@ virSecuritySELinuxSetTapFDLabel(virSecurityManagerPtr mgr,
|
|
|
9119d9 |
goto cleanup;
|
|
|
9119d9 |
}
|
|
|
9119d9 |
|
|
|
9119d9 |
- if (getContext(mgr, "/dev/tap.*", buf.st_mode, &fcon) < 0) {
|
|
|
9119d9 |
+ /* Label /dev/tap.* devices only. Leave /dev/net/tun alone! */
|
|
|
9119d9 |
+ if (virAsprintf(&proc, "/proc/self/fd/%d", fd) == -1)
|
|
|
9119d9 |
+ goto cleanup;
|
|
|
9119d9 |
+
|
|
|
9119d9 |
+ if (virFileResolveLink(proc, &fd_path) < 0) {
|
|
|
9119d9 |
+ virReportSystemError(errno,
|
|
|
9119d9 |
+ _("Unable to resolve link: %s"), proc);
|
|
|
9119d9 |
+ goto cleanup;
|
|
|
9119d9 |
+ }
|
|
|
9119d9 |
+
|
|
|
9119d9 |
+ if (!STRPREFIX(fd_path, "/dev/tap")) {
|
|
|
9119d9 |
+ VIR_DEBUG("fd=%d points to %s not setting SELinux label",
|
|
|
9119d9 |
+ fd, fd_path);
|
|
|
9119d9 |
+ rc = 0;
|
|
|
9119d9 |
+ goto cleanup;
|
|
|
9119d9 |
+ }
|
|
|
9119d9 |
+
|
|
|
9119d9 |
+ if (getContext(mgr, "/dev/tap*", buf.st_mode, &fcon) < 0) {
|
|
|
9119d9 |
virReportError(VIR_ERR_INTERNAL_ERROR,
|
|
|
9119d9 |
_("cannot lookup default selinux label for tap fd %d"), fd);
|
|
|
9119d9 |
goto cleanup;
|
|
|
9119d9 |
@@ -2384,6 +2401,8 @@ virSecuritySELinuxSetTapFDLabel(virSecurityManagerPtr mgr,
|
|
|
9119d9 |
|
|
|
9119d9 |
cleanup:
|
|
|
9119d9 |
freecon(fcon);
|
|
|
9119d9 |
+ VIR_FREE(fd_path);
|
|
|
9119d9 |
+ VIR_FREE(proc);
|
|
|
9119d9 |
VIR_FREE(str);
|
|
|
9119d9 |
return rc;
|
|
|
9119d9 |
}
|
|
|
9119d9 |
--
|
|
|
9119d9 |
2.1.3
|
|
|
9119d9 |
|