[xen staging] sysctl/XSM: drop .readconsole() hook

[patchbot@xxxxxxx]

commit 4b249cba4b25ad1b5c86bf3b2ff9cc685b47fa67
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Mon Jul 20 16:28:18 2026 +0100
Commit:     Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
CommitDate: Tue Jul 28 12:40:10 2026 +0100

    sysctl/XSM: drop .readconsole() hook
    
    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.
    
    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>
---
 xen/common/sysctl.c     |  4 ----
 xen/include/xsm/dummy.h |  6 ------
 xen/include/xsm/xsm.h   |  6 ------
 xen/xsm/dummy.c         |  1 -
 xen/xsm/flask/hooks.c   | 18 ++++++------------
 5 files changed, 6 insertions(+), 29 deletions(-)

diff --git a/xen/common/sysctl.c b/xen/common/sysctl.c
index 2df2426762..ea5ad0efa9 100644
--- a/xen/common/sysctl.c
+++ b/xen/common/sysctl.c
@@ -59,10 +59,6 @@ long do_sysctl(XEN_GUEST_HANDLE_PARAM(xen_sysctl_t) u_sysctl)
     switch ( op->cmd )
     {
     case XEN_SYSCTL_readconsole:
-        ret = xsm_readconsole(XSM_HOOK, op->u.readconsole.clear);
-        if ( ret )
-            break;
-
         ret = read_console_ring(&op->u.readconsole);
         break;
 
diff --git a/xen/include/xsm/dummy.h b/xen/include/xsm/dummy.h
index 30a6f86e70..1cc248d710 100644
--- a/xen/include/xsm/dummy.h
+++ b/xen/include/xsm/dummy.h
@@ -181,12 +181,6 @@ static XSM_INLINE int cf_check xsm_sysctl(
     return xsm_default_action(action, current->domain, NULL);
 }
 
-static XSM_INLINE int cf_check xsm_readconsole(XSM_DEFAULT_ARG uint32_t clear)
-{
-    XSM_ASSERT_ACTION(XSM_HOOK);
-    return xsm_default_action(action, current->domain, NULL);
-}
-
 static XSM_INLINE int cf_check xsm_alloc_security_domain(struct domain *d)
 {
     return 0;
diff --git a/xen/include/xsm/xsm.h b/xen/include/xsm/xsm.h
index 4e2cae51f0..7609c4c5db 100644
--- a/xen/include/xsm/xsm.h
+++ b/xen/include/xsm/xsm.h
@@ -60,7 +60,6 @@ struct xsm_ops {
     int (*domctl)(struct domain *d, struct xen_domctl *op);
 #ifdef CONFIG_SYSCTL
     int (*sysctl)(const struct xen_sysctl *op);
-    int (*readconsole)(uint32_t clear);
 #endif
 
     int (*evtchn_unbound)(struct domain *d, struct evtchn *chn, domid_t id2);
@@ -245,11 +244,6 @@ static inline int xsm_sysctl(xsm_default_t def, const 
struct xen_sysctl *op)
 {
     return alternative_call(xsm_ops.sysctl, op);
 }
-
-static inline int xsm_readconsole(xsm_default_t def, uint32_t clear)
-{
-    return alternative_call(xsm_ops.readconsole, clear);
-}
 #endif
 
 static inline int xsm_evtchn_unbound(
diff --git a/xen/xsm/dummy.c b/xen/xsm/dummy.c
index 98bf9a73eb..89d37b6537 100644
--- a/xen/xsm/dummy.c
+++ b/xen/xsm/dummy.c
@@ -22,7 +22,6 @@ static const struct xsm_ops __initconst_cf_clobber dummy_ops 
= {
     .domctl                        = xsm_domctl,
 #ifdef CONFIG_SYSCTL
     .sysctl                        = xsm_sysctl,
-    .readconsole                   = xsm_readconsole,
 #endif
 
     .evtchn_unbound                = xsm_evtchn_unbound,
diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
index 4e5b75dfaf..b37d4bf2a2 100644
--- a/xen/xsm/flask/hooks.c
+++ b/xen/xsm/flask/hooks.c
@@ -877,13 +877,18 @@ static int cf_check flask_sysctl(const struct xen_sysctl 
*op)
     switch ( op->cmd )
     {
     /* These have individual XSM hooks */
-    case XEN_SYSCTL_readconsole:
     case XEN_SYSCTL_page_offline_op:
 #ifdef CONFIG_X86
     case XEN_SYSCTL_cpu_hotplug:
 #endif
         return 0;
 
+    case XEN_SYSCTL_readconsole:
+        return domain_has_xen(current->domain,
+                              XEN__READCONSOLE |
+                              (op->u.readconsole.clear ? XEN__CLEARCONSOLE
+                                                       : 0));
+
     case XEN_SYSCTL_tbuf_op:
         return domain_has_xen(current->domain, XEN__TBUFCONTROL);
 
@@ -949,16 +954,6 @@ static int cf_check flask_sysctl(const struct xen_sysctl 
*op)
         return avc_unknown_permission("sysctl", op->cmd);
     }
 }
-
-static int cf_check flask_readconsole(uint32_t clear)
-{
-    uint32_t perms = XEN__READCONSOLE;
-
-    if ( clear )
-        perms |= XEN__CLEARCONSOLE;
-
-    return domain_has_xen(current->domain, perms);
-}
 #endif /* CONFIG_SYSCTL */
 
 static inline uint32_t resource_to_perm(uint8_t access)
@@ -1903,7 +1898,6 @@ static const struct xsm_ops __initconst_cf_clobber 
flask_ops = {
     .domctl = flask_domctl,
 #ifdef CONFIG_SYSCTL
     .sysctl = flask_sysctl,
-    .readconsole = flask_readconsole,
 #endif
 
     .evtchn_unbound = flask_evtchn_unbound,
--
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