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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen stable-4.18] sysctl/XSM: drop .resource_{,un}plug_core() hooks
commit 237dd170340bd9dd6d73ef8513fd5b017acb7b91
Author: Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jul 20 16:44:12 2026 +0100
Commit: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Jul 28 13:10:03 2026 +0100
sysctl/XSM: drop .resource_{,un}plug_core() hooks
Integrate the checking with xsm_sysctl(), now that it has the full op
struct passed. As a positive side effect, permissions are then checked at
the same early point with and without Flask. Note that these were x86-
only, i.e. some dead/unreachable code gets eliminated for (in particular)
Arm.
This is part of CVE-2026-62426 / XSA-499.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-By: Daniel P. Smith <dpsmith@xxxxxxxxxxxxxxxxxxxx>
(cherry picked from commit 0501e1dc047768cba2a458b25f5e9214726c33c8)
---
xen/arch/x86/sysctl.c | 10 +---------
xen/include/xsm/dummy.h | 12 ------------
xen/include/xsm/xsm.h | 12 ------------
xen/xsm/dummy.c | 2 --
xen/xsm/flask/hooks.c | 29 ++++++++++++++++++++++-------
5 files changed, 23 insertions(+), 42 deletions(-)
diff --git a/xen/arch/x86/sysctl.c b/xen/arch/x86/sysctl.c
index c107f40c62..2c6483d903 100644
--- a/xen/arch/x86/sysctl.c
+++ b/xen/arch/x86/sysctl.c
@@ -117,20 +117,17 @@ long arch_do_sysctl(
{
unsigned int cpu = sysctl->u.cpu_hotplug.cpu;
unsigned int op = sysctl->u.cpu_hotplug.op;
- bool plug;
long (*fn)(void *);
void *hcpu;
switch ( op )
{
case XEN_SYSCTL_CPU_HOTPLUG_ONLINE:
- plug = true;
fn = cpu_up_helper;
hcpu = _p(cpu);
break;
case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE:
- plug = false;
fn = cpu_down_helper;
hcpu = _p(cpu);
break;
@@ -150,9 +147,8 @@ long arch_do_sysctl(
if ( CONFIG_NR_CPUS <= 1 )
/* Mimic behavior of smt_up_down_helper(). */
return 0;
- plug = op == XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE;
fn = smt_up_down_helper;
- hcpu = _p(plug);
+ hcpu = _p(op == XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE);
break;
default:
@@ -160,10 +156,6 @@ long arch_do_sysctl(
break;
}
- if ( !ret )
- ret = plug ? xsm_resource_plug_core(XSM_HOOK)
- : xsm_resource_unplug_core(XSM_HOOK);
-
if ( !ret )
ret = continue_hypercall_on_cpu(0, fn, hcpu);
}
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index aacef701a9..b96483d0d8 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -395,18 +395,6 @@ static XSM_INLINE int cf_check xsm_get_device_group(
}
#endif /* HAS_PASSTHROUGH && HAS_PCI */
-static XSM_INLINE int cf_check xsm_resource_plug_core(XSM_DEFAULT_VOID)
-{
- XSM_ASSERT_ACTION(XSM_HOOK);
- return xsm_default_action(action, current->domain, NULL);
-}
-
-static XSM_INLINE int cf_check xsm_resource_unplug_core(XSM_DEFAULT_VOID)
-{
- XSM_ASSERT_ACTION(XSM_HOOK);
- return xsm_default_action(action, current->domain, NULL);
-}
-
static XSM_INLINE int cf_check xsm_resource_plug_pci(
XSM_DEFAULT_ARG uint32_t machine_bdf)
{
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index 87e277aa38..b5d4e9fe43 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -123,8 +123,6 @@ struct xsm_ops {
int (*get_device_group)(uint32_t machine_bdf);
#endif
- int (*resource_plug_core)(void);
- int (*resource_unplug_core)(void);
int (*resource_plug_pci)(uint32_t machine_bdf);
int (*resource_unplug_pci)(uint32_t machine_bdf);
int (*resource_setup_pci)(uint32_t machine_bdf);
@@ -508,16 +506,6 @@ static inline int xsm_resource_unplug_pci(
return alternative_call(xsm_ops.resource_unplug_pci, machine_bdf);
}
-static inline int xsm_resource_plug_core(xsm_default_t def)
-{
- return alternative_call(xsm_ops.resource_plug_core);
-}
-
-static inline int xsm_resource_unplug_core(xsm_default_t def)
-{
- return alternative_call(xsm_ops.resource_unplug_core);
-}
-
static inline int xsm_resource_setup_pci(
xsm_default_t def, uint32_t machine_bdf)
{
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 97c06ee522..bb38d6023d 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -77,8 +77,6 @@ static const struct xsm_ops __initconst_cf_clobber dummy_ops
= {
.get_device_group = xsm_get_device_group,
#endif
- .resource_plug_core = xsm_resource_plug_core,
- .resource_unplug_core = xsm_resource_unplug_core,
.resource_plug_pci = xsm_resource_plug_pci,
.resource_unplug_pci = xsm_resource_unplug_pci,
.resource_setup_pci = xsm_resource_setup_pci,
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 654b8afbea..03d9b8e60f 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -56,6 +56,9 @@ static int flask_deassign_dtdevice(struct domain *d, const
char *dtpath);
#endif
#endif /* CONFIG_HAS_PASSTHROUGH */
+static int flask_resource_plug_core(void);
+static int flask_resource_unplug_core(void);
+
static uint32_t domain_sid(const struct domain *dom)
{
struct domain_security_struct *dsec = dom->ssid;
@@ -898,9 +901,6 @@ static int cf_check flask_sysctl(const struct xen_sysctl
*op)
{
/* These have individual XSM hooks */
case XEN_SYSCTL_page_offline_op:
-#ifdef CONFIG_X86
- case XEN_SYSCTL_cpu_hotplug:
-#endif
return 0;
case XEN_SYSCTL_readconsole:
@@ -952,6 +952,23 @@ static int cf_check flask_sysctl(const struct xen_sysctl
*op)
case XEN_SYSCTL_getdomaininfolist:
return flask_getdomaininfo(dom_xen);
+#ifdef CONFIG_X86
+ case XEN_SYSCTL_cpu_hotplug:
+ switch ( op->u.cpu_hotplug.op )
+ {
+ case XEN_SYSCTL_CPU_HOTPLUG_ONLINE:
+ case XEN_SYSCTL_CPU_HOTPLUG_SMT_ENABLE:
+ return flask_resource_plug_core();
+
+ case XEN_SYSCTL_CPU_HOTPLUG_OFFLINE:
+ case XEN_SYSCTL_CPU_HOTPLUG_SMT_DISABLE:
+ return flask_resource_unplug_core();
+
+ default:
+ return avc_unknown_permission("cpu_hotplug", op->u.cpu_hotplug.op);
+ }
+#endif
+
case XEN_SYSCTL_psr_cmt_op:
return avc_current_has_perm(SECINITSID_XEN, SECCLASS_XEN2,
XEN2__PSR_CMT_OP, NULL);
@@ -1229,12 +1246,12 @@ static int cf_check flask_pci_config_permission(
}
-static int cf_check flask_resource_plug_core(void)
+static int flask_resource_plug_core(void)
{
return avc_current_has_perm(SECINITSID_DOMXEN, SECCLASS_RESOURCE,
RESOURCE__PLUG, NULL);
}
-static int cf_check flask_resource_unplug_core(void)
+static int flask_resource_unplug_core(void)
{
return avc_current_has_perm(SECINITSID_DOMXEN, SECCLASS_RESOURCE,
RESOURCE__UNPLUG, NULL);
}
@@ -1955,8 +1972,6 @@ static const struct xsm_ops __initconst_cf_clobber
flask_ops = {
.iomem_mapping_vpci = flask_iomem_mapping,
.pci_config_permission = flask_pci_config_permission,
- .resource_plug_core = flask_resource_plug_core,
- .resource_unplug_core = flask_resource_unplug_core,
.resource_plug_pci = flask_resource_plug_pci,
.resource_unplug_pci = flask_resource_unplug_pci,
.resource_setup_pci = flask_resource_setup_pci,
--
generated by git-patchbot for /home/xen/git/xen.git#stable-4.18
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