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[Xen-devel] [PATCH 2/3] domctl: perform initial post-XSA-77 auditing

To: "xen-devel" <xen-devel@xxxxxxxxxxxxxxxxxxxx>

From: "Jan Beulich" <JBeulich@xxxxxxxx>

Date: Wed, 30 Apr 2014 15:23:31 +0100

Cc: Ian Campbell <Ian.Campbell@xxxxxxxxxxxxx>, Keir Fraser <keir@xxxxxxx>, Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>, Tim Deegan <tim@xxxxxxx>

Delivery-date: Wed, 30 Apr 2014 14:30:23 +0000

List-id: Xen developer discussion <xen-devel.lists.xen.org>

In a number of cases, loops over each vCPU in a domain are involved here. For large numbers of vCPU-s these may still take some time to complete, but we're limiting them at a couple of thousand at most, so I would think this should not by itself be an issue. I wonder though whether it shouldn't be possible to have XSM restrict the vCPU count that can be set through XEN_DOMCTL_max_vcpus. XEN_DOMCTL_pausedomain: A loop over vcpu_sleep_sync() for each of vCPU in the domain. That function itself has a loop waiting for the subject vCPU to become non- runnable, which ought to complete quickly (involving an IPI to be sent and acted on). No other unbounded resource usage. XEN_DOMCTL_unpausedomain: Simply a loop calling vcpu_wake() (not having any loops or other resource usage itself) for each of vCPU in the domain. XEN_DOMCTL_getdomaininfo: Two loops (one over all domains, i.e. bounded by the limit of 32k domains, and another over all vCPU-s in the domain); no other unbounded resource usage. XEN_DOMCTL_getpageframeinfo: Inquiring just a single MFN, i.e. no loops and no other unbounded resource usage. XEN_DOMCTL_getpageframeinfo{2,3}: Number of inquired MFNs is limited to 1024. Beyond that just like XEN_DOMCTL_getpageframeinfo. XEN_DOMCTL_getvcpuinfo: Only obtaining information on the vCPU, no loops or other resource usage. XEN_DOMCTL_setdomainhandle: Simply a memcpy() of a very limited amount of data. XEN_DOMCTL_setdebugging: A domain_{,un}pause() pair (see XEN_DOMCTL_{,un}pausedomain) framing the setting of a flag. XEN_DOMCTL_hypercall_init: Initializing a guest provided page with hypercall stubs. No other resource consumption. XEN_DOMCTL_arch_setup: IA64 leftover, interface structure being removed from the public header. XEN_DOMCTL_settimeoffset: Setting a couple of guest state fields. No other resource consumption. XEN_DOMCTL_getvcpuaffinity: XEN_DOMCTL_getnodeaffinity: Involve temporary memory allocations (approximately) bounded by the number of CPUs in the system / number of nodes built for, which is okay. Beyond that trivial operation. XEN_DOMCTL_real_mode_area: PPC leftover, interface structure being removed from the public header. XEN_DOMCTL_resumedomain: A domain_{,un}pause() pair framing operation very similar to XEN_DOMCTL_unpausedomain (see above). XEN_DOMCTL_sendtrigger: Injects an interrupt (SCI or NMI) without any other resource consumption. XEN_DOMCTL_subscribe: Updates the suspend event channel, i.e. affecting only the controlled domain. XEN_DOMCTL_disable_migrate: XEN_DOMCTL_suppress_spurious_page_faults: Just setting respective flags on the domain. XEN_DOMCTL_get_address_size: Simply reading the guest property. XEN_DOMCTL_set_opt_feature: Was already tagged IA64-only. XEN_DOMCTL_set_cpuid: MAX_CPUID_INPUT bounded loop, which is okay. No other resource consumption. XEN_DOMCTL_get_machine_address_size: Simply obtaining the value set by XEN_DOMCTL_set_machine_address_size (or the default set at domain creation time). XEN_DOMCTL_gettscinfo: XEN_DOMCTL_settscinfo: Reading/writing of a couple of guest state fields wrapped in a domain_{,un}pause() pair. XEN_DOMCTL_audit_p2m: Enabled only in debug builds. XEN_DOMCTL_set_max_evtchn: While the limit set here implies other (subsequent) resource usage, this is the purpose of the operation. I also verified that all removed domctls' handlers don't leak hypervisor memory contents . Inspected but questionable (and hence left in place for now): XEN_DOMCTL_max_mem: While only setting the field capping a domain's allocation (this implies potential successive resource usage, but that's the purpose of the operation). However, XSM doesn't see the value that's being set here, so the net effect would be potential unbounded memory use. XEN_DOMCTL_set_virq_handler: This modifies a global array. While that is the purpose of the operation, if multiple domains are granted permission they can badly interfere with one another. Hence I'd appreciate a second opinion here. Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx> --- a/docs/misc/xsm-flask.txt +++ b/docs/misc/xsm-flask.txt @@ -64,67 +64,39 @@ __HYPERVISOR_domctl (xen/include/public/ * XEN_DOMCTL_createdomain * XEN_DOMCTL_destroydomain - * XEN_DOMCTL_pausedomain - * XEN_DOMCTL_unpausedomain - * XEN_DOMCTL_getdomaininfo * XEN_DOMCTL_getmemlist - * XEN_DOMCTL_getpageframeinfo - * XEN_DOMCTL_getpageframeinfo2 * XEN_DOMCTL_setvcpuaffinity * XEN_DOMCTL_shadow_op * XEN_DOMCTL_max_mem * XEN_DOMCTL_setvcpucontext * XEN_DOMCTL_getvcpucontext - * XEN_DOMCTL_getvcpuinfo * XEN_DOMCTL_max_vcpus * XEN_DOMCTL_scheduler_op - * XEN_DOMCTL_setdomainhandle - * XEN_DOMCTL_setdebugging * XEN_DOMCTL_irq_permission * XEN_DOMCTL_iomem_permission * XEN_DOMCTL_ioport_permission - * XEN_DOMCTL_hypercall_init - * XEN_DOMCTL_arch_setup - * XEN_DOMCTL_settimeoffset - * XEN_DOMCTL_getvcpuaffinity - * XEN_DOMCTL_real_mode_area - * XEN_DOMCTL_resumedomain - * XEN_DOMCTL_sendtrigger - * XEN_DOMCTL_subscribe * XEN_DOMCTL_gethvmcontext * XEN_DOMCTL_sethvmcontext * XEN_DOMCTL_set_address_size - * XEN_DOMCTL_get_address_size * XEN_DOMCTL_assign_device * XEN_DOMCTL_pin_mem_cacheattr * XEN_DOMCTL_set_ext_vcpucontext * XEN_DOMCTL_get_ext_vcpucontext - * XEN_DOMCTL_set_opt_feature * XEN_DOMCTL_test_assign_device * XEN_DOMCTL_set_target * XEN_DOMCTL_deassign_device - * XEN_DOMCTL_set_cpuid * XEN_DOMCTL_get_device_group * XEN_DOMCTL_set_machine_address_size - * XEN_DOMCTL_get_machine_address_size - * XEN_DOMCTL_suppress_spurious_page_faults * XEN_DOMCTL_debug_op * XEN_DOMCTL_gethvmcontext_partial * XEN_DOMCTL_mem_event_op * XEN_DOMCTL_mem_sharing_op - * XEN_DOMCTL_disable_migrate - * XEN_DOMCTL_gettscinfo - * XEN_DOMCTL_settscinfo - * XEN_DOMCTL_getpageframeinfo3 * XEN_DOMCTL_setvcpuextstate * XEN_DOMCTL_getvcpuextstate * XEN_DOMCTL_set_access_required - * XEN_DOMCTL_audit_p2m * XEN_DOMCTL_set_virq_handler * XEN_DOMCTL_set_broken_page_p2m * XEN_DOMCTL_setnodeaffinity - * XEN_DOMCTL_getnodeaffinity - * XEN_DOMCTL_set_max_evtchn * XEN_DOMCTL_gdbsx_guestmemio * XEN_DOMCTL_gdbsx_pausevcpu * XEN_DOMCTL_gdbsx_unpausevcpu --- a/xen/include/public/domctl.h +++ b/xen/include/public/domctl.h @@ -401,19 +401,6 @@ typedef struct xen_domctl_hypercall_init DEFINE_XEN_GUEST_HANDLE(xen_domctl_hypercall_init_t); -/* XEN_DOMCTL_arch_setup */ -#define _XEN_DOMAINSETUP_hvm_guest 0 -#define XEN_DOMAINSETUP_hvm_guest (1UL<<_XEN_DOMAINSETUP_hvm_guest) -#define _XEN_DOMAINSETUP_query 1 /* Get parameters (for save) */ -#define XEN_DOMAINSETUP_query (1UL<<_XEN_DOMAINSETUP_query) -#define _XEN_DOMAINSETUP_sioemu_guest 2 -#define XEN_DOMAINSETUP_sioemu_guest (1UL<<_XEN_DOMAINSETUP_sioemu_guest) -typedef struct xen_domctl_arch_setup { - uint64_aligned_t flags; /* XEN_DOMAINSETUP_* */ -} xen_domctl_arch_setup_t; -DEFINE_XEN_GUEST_HANDLE(xen_domctl_arch_setup_t); - - /* XEN_DOMCTL_settimeoffset */ struct xen_domctl_settimeoffset { int32_t time_offset_seconds; /* applied to domain wallclock time */ @@ -440,14 +427,6 @@ typedef struct xen_domctl_address_size { DEFINE_XEN_GUEST_HANDLE(xen_domctl_address_size_t); -/* XEN_DOMCTL_real_mode_area */ -struct xen_domctl_real_mode_area { - uint32_t log; /* log2 of Real Mode Area size */ -}; -typedef struct xen_domctl_real_mode_area xen_domctl_real_mode_area_t; -DEFINE_XEN_GUEST_HANDLE(xen_domctl_real_mode_area_t); - - /* XEN_DOMCTL_sendtrigger */ #define XEN_DOMCTL_SENDTRIGGER_NMI 0 #define XEN_DOMCTL_SENDTRIGGER_RESET 1 @@ -940,10 +919,10 @@ struct xen_domctl { #define XEN_DOMCTL_iomem_permission 20 #define XEN_DOMCTL_ioport_permission 21 #define XEN_DOMCTL_hypercall_init 22 -#define XEN_DOMCTL_arch_setup 23 +#define XEN_DOMCTL_arch_setup 23 /* Obsolete IA64 only */ #define XEN_DOMCTL_settimeoffset 24 #define XEN_DOMCTL_getvcpuaffinity 25 -#define XEN_DOMCTL_real_mode_area 26 +#define XEN_DOMCTL_real_mode_area 26 /* Obsolete PPC only */ #define XEN_DOMCTL_resumedomain 27 #define XEN_DOMCTL_sendtrigger 28 #define XEN_DOMCTL_subscribe 29 @@ -1013,11 +992,9 @@ struct xen_domctl { struct xen_domctl_iomem_permission iomem_permission; struct xen_domctl_ioport_permission ioport_permission; struct xen_domctl_hypercall_init hypercall_init; - struct xen_domctl_arch_setup arch_setup; struct xen_domctl_settimeoffset settimeoffset; struct xen_domctl_disable_migrate disable_migrate; struct xen_domctl_tsc_info tsc_info; - struct xen_domctl_real_mode_area real_mode_area; struct xen_domctl_hvmcontext hvmcontext; struct xen_domctl_hvmcontext_partial hvmcontext_partial; struct xen_domctl_address_size address_size;

Attachment: domctl-simple.patch
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