99 lines
3.7 KiB
Diff
99 lines
3.7 KiB
Diff
From 3c75dc1ed9a32fff16c84f60536ee21ff8e9e19f Mon Sep 17 00:00:00 2001
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From: Michal Privoznik <mprivozn@redhat.com>
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Date: Thu, 18 Sep 2014 15:17:29 +0200
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Subject: [PATCH] virSecuritySELinuxSetTapFDLabel: Temporarily revert to old
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behavior
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https://bugzilla.redhat.com/show_bug.cgi?id=1141879
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A long time ago I've implemented support for so called multiqueue
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net. The idea was to let guest network traffic be processed by
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multiple host CPUs and thus increasing performance. However, this
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behavior is enabled by QEMU via special ioctl() iterated over the
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all tap FDs passed in by libvirt. Unfortunately, SELinux comes in
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and disallows the ioctl() call because the /dev/net/tun has label
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system_u:object_r:tun_tap_device_t:s0 and 'attach_queue' ioctl()
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is not allowed on tun_tap_device_t type. So after discussion with
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a SELinux developer we've decided that the FDs passed to the QEMU
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should be labelled with svirt_t type and SELinux policy will
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allow the ioctl(). Therefore I've made a patch
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(cf976d9dcf4e592261b14f03572) that does exactly this. The patch
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was fixed then by a4431931393aeb1ac5893f121151fa3df4fde612 and
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b635b7a1af0e64754016d758376f382470bc11e7. However, things are not
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that easy - even though the API to label FD is called
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(fsetfilecon_raw) the underlying file is labelled too! So
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effectively we are mangling /dev/net/tun label. Yes, that broke
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dozen of other application from openvpn, or boxes, to qemu
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running other domains.
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The best solution would be if SELinux provides a way to label an
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FD only, which could be then labeled when passed to the qemu.
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However that's a long path to go and we should fix this
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regression AQAP. So I went to talk to the SELinux developer again
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and we agreed on temporary solution that:
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1) All the three patches are reverted
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2) SELinux temporarily allows 'attach_queue' on the
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tun_tap_device_t
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Signed-off-by: Michal Privoznik <mprivozn@redhat.com>
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(cherry picked from commit ba7468dbb13f552a9177d01ea8bad155f9877bc3)
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---
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src/security/security_selinux.c | 34 ++++++++++++++++++++++++++++++++--
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1 file changed, 32 insertions(+), 2 deletions(-)
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diff --git a/src/security/security_selinux.c b/src/security/security_selinux.c
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index e8c13db..c078cab 100644
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--- a/src/security/security_selinux.c
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+++ b/src/security/security_selinux.c
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@@ -2330,17 +2330,47 @@ virSecuritySELinuxSetImageFDLabel(virSecurityManagerPtr mgr ATTRIBUTE_UNUSED,
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}
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static int
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-virSecuritySELinuxSetTapFDLabel(virSecurityManagerPtr mgr ATTRIBUTE_UNUSED,
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+virSecuritySELinuxSetTapFDLabel(virSecurityManagerPtr mgr,
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virDomainDefPtr def,
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int fd)
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{
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+ struct stat buf;
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+ security_context_t fcon = NULL;
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virSecurityLabelDefPtr secdef;
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+ char *str = NULL;
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+ int rc = -1;
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secdef = virDomainDefGetSecurityLabelDef(def, SECURITY_SELINUX_NAME);
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if (!secdef || !secdef->label)
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return 0;
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- return virSecuritySELinuxFSetFilecon(fd, secdef->imagelabel);
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+ if (fstat(fd, &buf) < 0) {
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+ virReportSystemError(errno, _("cannot stat tap fd %d"), fd);
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+ goto cleanup;
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+ }
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+
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+ if ((buf.st_mode & S_IFMT) != S_IFCHR) {
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+ virReportError(VIR_ERR_INTERNAL_ERROR,
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+ _("tap fd %d is not character device"), fd);
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+ goto cleanup;
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+ }
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+
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+ if (getContext(mgr, "/dev/tap.*", buf.st_mode, &fcon) < 0) {
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+ virReportError(VIR_ERR_INTERNAL_ERROR,
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+ _("cannot lookup default selinux label for tap fd %d"), fd);
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+ goto cleanup;
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+ }
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+
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+ if (!(str = virSecuritySELinuxContextAddRange(secdef->label, fcon))) {
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+ goto cleanup;
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+ } else {
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+ rc = virSecuritySELinuxFSetFilecon(fd, str);
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+ }
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+
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+ cleanup:
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+ freecon(fcon);
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+ VIR_FREE(str);
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+ return rc;
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}
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static char *
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