From: Nicușor Cîțu <ncitu@xxxxxxxxxxxxxxx>
This event is sent when IDTR, GDTR, LDTR or TR are accessed.
These could be used to implement a tiny agent which runs in the context
of an introspected guest and uses virtualized exceptions (#VE) and
alternate EPT views (VMFUNC #0) to filter converted VMEXITS. The events
of interested will be suppressed (after some appropriate guest-side
handling) while the rest will be sent to the introspector via a VMCALL.
Signed-off-by: Nicușor Cîțu <ncitu@xxxxxxxxxxxxxxx>
Co-developed-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
Documentation/virtual/kvm/kvmi.rst | 38 +++++++++++++++
arch/x86/include/asm/kvm_host.h | 1 +
arch/x86/include/uapi/asm/kvmi.h | 11 +++++
arch/x86/kvm/kvmi.c | 70 ++++++++++++++++++++++++++++
arch/x86/kvm/svm.c | 74 ++++++++++++++++++++++++++++++
arch/x86/kvm/vmx/vmx.c | 59 +++++++++++++++++++++++-
arch/x86/kvm/vmx/vmx.h | 2 +
arch/x86/kvm/x86.c | 6 +++
include/linux/kvm_host.h | 1 +
include/linux/kvmi.h | 4 ++
virt/kvm/kvmi.c | 2 +-
virt/kvm/kvmi_int.h | 3 ++
virt/kvm/kvmi_msg.c | 17 +++++++
13 files changed, 285 insertions(+), 3 deletions(-)
diff --git a/Documentation/virtual/kvm/kvmi.rst b/Documentation/virtual/kvm/kvmi.rst
index 2603813d1ee6..8721a470de87 100644
--- a/Documentation/virtual/kvm/kvmi.rst
+++ b/Documentation/virtual/kvm/kvmi.rst
@@ -1536,3 +1536,41 @@ It is used by the code residing inside the introspected guest to call the
introspection tool and to report certain details about its operation. For
example, a classic antimalware remediation tool can report what it has
found during a scan.
+
+11. KVMI_EVENT_DESCRIPTOR
+-------------------------
+
+:Architecture: x86
+:Versions: >= 1
+:Actions: CONTINUE, RETRY, CRASH
+:Parameters:
+
+::
+
+ struct kvmi_event;
+ struct kvmi_event_descriptor {
+ __u8 descriptor;
+ __u8 write;
+ __u8 padding[6];
+ };
+
+:Returns:
+
+::
+
+ struct kvmi_vcpu_hdr;
+ struct kvmi_event_reply;
+
+This event is sent when a descriptor table register is accessed and the
+introspection has been enabled for this event (see **KVMI_CONTROL_EVENTS**).
+
+``kvmi_event`` and ``kvmi_event_descriptor`` are sent to the introspector.
+
+``descriptor`` can be one of::
+
+ KVMI_DESC_IDTR
+ KVMI_DESC_GDTR
+ KVMI_DESC_LDTR
+ KVMI_DESC_TR
+
+``write`` is 1 if the descriptor was written, 0 otherwise.
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 91cd43a7a7bf..ad36a5fc2048 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -1015,6 +1015,7 @@ struct kvm_x86_ops {
void (*msr_intercept)(struct kvm_vcpu *vcpu, unsigned int msr,
bool enable);
+ bool (*desc_intercept)(struct kvm_vcpu *vcpu, bool enable);
void (*cr3_write_exiting)(struct kvm_vcpu *vcpu, bool enable);
bool (*nested_pagefault)(struct kvm_vcpu *vcpu);
bool (*spt_fault)(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/include/uapi/asm/kvmi.h b/arch/x86/include/uapi/asm/kvmi.h
index c3c96e6e2a26..0fa4ac3ed5d1 100644
--- a/arch/x86/include/uapi/asm/kvmi.h
+++ b/arch/x86/include/uapi/asm/kvmi.h
@@ -110,4 +110,15 @@ struct kvmi_get_mtrr_type_reply {
__u8 padding[7];
};
+#define KVMI_DESC_IDTR 1
+#define KVMI_DESC_GDTR 2
+#define KVMI_DESC_LDTR 3
+#define KVMI_DESC_TR 4
+
+struct kvmi_event_descriptor {
+ __u8 descriptor;
+ __u8 write;
+ __u8 padding[6];
+};
+
#endif /* _UAPI_ASM_X86_KVMI_H */
diff --git a/arch/x86/kvm/kvmi.c b/arch/x86/kvm/kvmi.c
index 02e026ef5ed7..04cac5b8a4d0 100644
--- a/arch/x86/kvm/kvmi.c
+++ b/arch/x86/kvm/kvmi.c
@@ -161,6 +161,38 @@ bool kvmi_monitored_msr(struct kvm_vcpu *vcpu, u32 msr)
}
EXPORT_SYMBOL(kvmi_monitored_msr);
+static int kvmi_control_event_desc(struct kvm_vcpu *vcpu, bool enable)
+{
+ int err = 0;
+
+ if (enable) {
+ if (!is_event_enabled(vcpu, KVMI_EVENT_DESCRIPTOR))
+ if (!kvm_arch_vcpu_intercept_desc(vcpu, true))
+ err = -KVM_EOPNOTSUPP;
+ } else if (is_event_enabled(vcpu, KVMI_EVENT_DESCRIPTOR)) {
+ kvm_arch_vcpu_intercept_desc(vcpu, false);
+ }
+
+ return err;
+}
+
+int kvmi_arch_cmd_control_event(struct kvm_vcpu *vcpu, unsigned int event_id,
+ bool enable)
+{
+ int err;
+
+ switch (event_id) {
+ case KVMI_EVENT_DESCRIPTOR:
+ err = kvmi_control_event_desc(vcpu, enable);
+ break;
+ default:
+ err = 0;
+ break;
+ }
+
+ return err;
+}
+
static void *alloc_get_registers_reply(const struct kvmi_msg_hdr *msg,
const struct kvmi_get_registers *req,
size_t *rpl_size)
@@ -604,6 +636,44 @@ void kvmi_arch_trap_event(struct kvm_vcpu *vcpu)
}
}
+static bool __kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor,
+ u8 write)
+{
+ u32 action;
+ bool ret = false;
+
+ action = kvmi_msg_send_descriptor(vcpu, descriptor, write);
+ switch (action) {
+ case KVMI_EVENT_ACTION_CONTINUE:
+ ret = true;
+ break;
+ case KVMI_EVENT_ACTION_RETRY:
+ break;
+ default:
+ kvmi_handle_common_event_actions(vcpu, action, "DESC");
+ }
+
+ return ret;
+}
+
+bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write)
+{
+ struct kvmi *ikvm;
+ bool ret = true;
+
+ ikvm = kvmi_get(vcpu->kvm);
+ if (!ikvm)
+ return true;
+
+ if (is_event_enabled(vcpu, KVMI_EVENT_DESCRIPTOR))
+ ret = __kvmi_descriptor_event(vcpu, descriptor, write);
+
+ kvmi_put(vcpu->kvm);
+
+ return ret;
+}
+EXPORT_SYMBOL(kvmi_descriptor_event);
+
int kvmi_arch_cmd_get_cpuid(struct kvm_vcpu *vcpu,
const struct kvmi_get_cpuid *req,
struct kvmi_get_cpuid_reply *rpl)
diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c
index b4e59ef040b7..b178b8900660 100644
--- a/arch/x86/kvm/svm.c
+++ b/arch/x86/kvm/svm.c
@@ -52,6 +52,7 @@
#include <asm/kvm_para.h>
#include <asm/irq_remapping.h>
#include <asm/spec-ctrl.h>
+#include <asm/kvmi.h>
#include <asm/virtext.h>
#include "trace.h"
@@ -4754,6 +4755,41 @@ static int avic_unaccelerated_access_interception(struct vcpu_svm *svm)
return ret;
}
+#ifdef CONFIG_KVM_INTROSPECTION
+static int descriptor_access_interception(struct vcpu_svm *svm)
+{
+ struct kvm_vcpu *vcpu = &svm->vcpu;
+ struct vmcb_control_area *c = &svm->vmcb->control;
+
+ switch (c->exit_code) {
+ case SVM_EXIT_IDTR_READ:
+ case SVM_EXIT_IDTR_WRITE:
+ kvmi_descriptor_event(vcpu, KVMI_DESC_IDTR,
+ c->exit_code == SVM_EXIT_IDTR_WRITE);
+ break;
+ case SVM_EXIT_GDTR_READ:
+ case SVM_EXIT_GDTR_WRITE:
+ kvmi_descriptor_event(vcpu, KVMI_DESC_GDTR,
+ c->exit_code == SVM_EXIT_GDTR_WRITE);
+ break;
+ case SVM_EXIT_LDTR_READ:
+ case SVM_EXIT_LDTR_WRITE:
+ kvmi_descriptor_event(vcpu, KVMI_DESC_LDTR,
+ c->exit_code == SVM_EXIT_LDTR_WRITE);
+ break;
+ case SVM_EXIT_TR_READ:
+ case SVM_EXIT_TR_WRITE:
+ kvmi_descriptor_event(vcpu, KVMI_DESC_TR,
+ c->exit_code == SVM_EXIT_TR_WRITE);
+ break;
+ default:
+ break;
+ }
+
+ return 1;
+}
+#endif /* CONFIG_KVM_INTROSPECTION */
+
static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_READ_CR0] = cr_interception,
[SVM_EXIT_READ_CR3] = cr_interception,
@@ -4819,6 +4855,16 @@ static int (*const svm_exit_handlers[])(struct vcpu_svm *svm) = {
[SVM_EXIT_RSM] = rsm_interception,
[SVM_EXIT_AVIC_INCOMPLETE_IPI] = avic_incomplete_ipi_interception,
[SVM_EXIT_AVIC_UNACCELERATED_ACCESS] = avic_unaccelerated_access_interception,
+#ifdef CONFIG_KVM_INTROSPECTION
+ [SVM_EXIT_IDTR_READ] = descriptor_access_interception,
+ [SVM_EXIT_GDTR_READ] = descriptor_access_interception,
+ [SVM_EXIT_LDTR_READ] = descriptor_access_interception,
+ [SVM_EXIT_TR_READ] = descriptor_access_interception,
+ [SVM_EXIT_IDTR_WRITE] = descriptor_access_interception,
+ [SVM_EXIT_GDTR_WRITE] = descriptor_access_interception,
+ [SVM_EXIT_LDTR_WRITE] = descriptor_access_interception,
+ [SVM_EXIT_TR_WRITE] = descriptor_access_interception,
+#endif /* CONFIG_KVM_INTROSPECTION */
};
static void dump_vmcb(struct kvm_vcpu *vcpu)
@@ -7141,6 +7187,33 @@ static void svm_cr3_write_exiting(struct kvm_vcpu *vcpu, bool enable)
{
}
+static bool svm_desc_intercept(struct kvm_vcpu *vcpu, bool enable)
+{
+ struct vcpu_svm *svm = to_svm(vcpu);
+
+ if (enable) {
+ set_intercept(svm, INTERCEPT_STORE_IDTR);
+ set_intercept(svm, INTERCEPT_STORE_GDTR);
+ set_intercept(svm, INTERCEPT_STORE_LDTR);
+ set_intercept(svm, INTERCEPT_STORE_TR);
+ set_intercept(svm, INTERCEPT_LOAD_IDTR);
+ set_intercept(svm, INTERCEPT_LOAD_GDTR);
+ set_intercept(svm, INTERCEPT_LOAD_LDTR);
+ set_intercept(svm, INTERCEPT_LOAD_TR);
+ } else {
+ clr_intercept(svm, INTERCEPT_STORE_IDTR);
+ clr_intercept(svm, INTERCEPT_STORE_GDTR);
+ clr_intercept(svm, INTERCEPT_STORE_LDTR);
+ clr_intercept(svm, INTERCEPT_STORE_TR);
+ clr_intercept(svm, INTERCEPT_LOAD_IDTR);
+ clr_intercept(svm, INTERCEPT_LOAD_GDTR);
+ clr_intercept(svm, INTERCEPT_LOAD_LDTR);
+ clr_intercept(svm, INTERCEPT_LOAD_TR);
+ }
+
+ return true;
+}
+
static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.cpu_has_kvm_support = has_svm,
.disabled_by_bios = is_disabled,
@@ -7154,6 +7227,7 @@ static struct kvm_x86_ops svm_x86_ops __ro_after_init = {
.cr3_write_exiting = svm_cr3_write_exiting,
.msr_intercept = svm_msr_intercept,
+ .desc_intercept = svm_desc_intercept,
.nested_pagefault = svm_nested_pagefault,
.spt_fault = svm_spt_fault,
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index d560b583bf30..7d1e341b51ad 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -22,6 +22,7 @@
#include <linux/kernel.h>
#include <linux/kvm_host.h>
#include <asm/kvmi_host.h>
+#include <uapi/linux/kvmi.h>
#include <linux/kvmi.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
@@ -2922,8 +2923,9 @@ int vmx_set_cr4(struct kvm_vcpu *vcpu, unsigned long cr4)
hw_cr4 &= ~X86_CR4_UMIP;
} else if (!is_guest_mode(vcpu) ||
!nested_cpu_has2(get_vmcs12(vcpu), SECONDARY_EXEC_DESC))
- vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL,
- SECONDARY_EXEC_DESC);
+ if (!to_vmx(vcpu)->tracking_desc)
+ vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL,
+ SECONDARY_EXEC_DESC);
}
if (cr4 & X86_CR4_VMXE) {
@@ -4691,7 +4693,43 @@ static int handle_set_cr4(struct kvm_vcpu *vcpu, unsigned long val)
static int handle_desc(struct kvm_vcpu *vcpu)
{
+#ifdef CONFIG_KVM_INTROSPECTION
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+ u32 exit_reason = vmx->exit_reason;
+ u32 vmx_instruction_info = vmcs_read32(VMX_INSTRUCTION_INFO);
+ u8 store = (vmx_instruction_info >> 29) & 0x1;
+ u8 descriptor = 0;
+
+ if (!vmx->tracking_desc)
+ goto emulate;
+
+ if (exit_reason == EXIT_REASON_GDTR_IDTR) {
+ if ((vmx_instruction_info >> 28) & 0x1)
+ descriptor = KVMI_DESC_IDTR;
+ else
+ descriptor = KVMI_DESC_GDTR;
+ } else {
+ if ((vmx_instruction_info >> 28) & 0x1)
+ descriptor = KVMI_DESC_TR;
+ else
+ descriptor = KVMI_DESC_LDTR;
+ }
+
+ /*
+ * For now, this function returns false only when the guest
+ * is ungracefully stopped (crashed) or the current instruction
+ * is skipped by the introspection tool.
+ */
+ if (!kvmi_descriptor_event(vcpu, descriptor, store))
+ return 1;
+emulate:
+ /*
+ * We are here because X86_CR4_UMIP was set or
+ * KVMI enabled the interception.
+ */
+#else
WARN_ON(!(vcpu->arch.cr4 & X86_CR4_UMIP));
+#endif /* CONFIG_KVM_INTROSPECTION */
return kvm_emulate_instruction(vcpu, 0) == EMULATE_DONE;
}
@@ -7840,6 +7878,22 @@ static bool vmx_spt_fault(struct kvm_vcpu *vcpu)
return (vmx->exit_reason == EXIT_REASON_EPT_VIOLATION);
}
+static bool vmx_desc_intercept(struct kvm_vcpu *vcpu, bool enable)
+{
+ struct vcpu_vmx *vmx = to_vmx(vcpu);
+
+ if (!cpu_has_secondary_exec_ctrls())
+ return false;
+
+ if (enable)
+ vmcs_set_bits(SECONDARY_VM_EXEC_CONTROL, SECONDARY_EXEC_DESC);
+ else
+ vmcs_clear_bits(SECONDARY_VM_EXEC_CONTROL, SECONDARY_EXEC_DESC);
+
+ vmx->tracking_desc = enable;
+ return true;
+}
+
static bool vmx_get_spp_status(void)
{
return spp_supported;
@@ -7875,6 +7929,7 @@ static struct kvm_x86_ops vmx_x86_ops __ro_after_init = {
.msr_intercept = vmx_msr_intercept,
.cr3_write_exiting = vmx_cr3_write_exiting,
+ .desc_intercept = vmx_desc_intercept,
.nested_pagefault = vmx_nested_pagefault,
.spt_fault = vmx_spt_fault,
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 0ac0a64c7790..580b02f86011 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -268,6 +268,8 @@ struct vcpu_vmx {
u64 msr_ia32_feature_control_valid_bits;
u64 ept_pointer;
+ bool tracking_desc;
+
struct pt_desc pt_desc;
};
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index d568e60ae568..38aaddadb93a 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10140,6 +10140,12 @@ bool kvm_spt_fault(struct kvm_vcpu *vcpu)
}
EXPORT_SYMBOL(kvm_spt_fault);
+bool kvm_arch_vcpu_intercept_desc(struct kvm_vcpu *vcpu, bool enable)
+{
+ return kvm_x86_ops->desc_intercept(vcpu, enable);
+}
+EXPORT_SYMBOL(kvm_arch_vcpu_intercept_desc);
+
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_exit);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_fast_mmio);
EXPORT_TRACEPOINT_SYMBOL_GPL(kvm_inj_virq);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index b77914e944a4..6c57291414d0 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -806,6 +806,7 @@ int kvm_arch_vcpu_ioctl_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg);
int kvm_arch_vcpu_set_guest_debug(struct kvm_vcpu *vcpu,
struct kvm_guest_debug *dbg);
+bool kvm_arch_vcpu_intercept_desc(struct kvm_vcpu *vcpu, bool enable);
int kvm_arch_vcpu_ioctl_run(struct kvm_vcpu *vcpu, struct kvm_run *kvm_run);
void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
struct kvm_xsave *guest_xsave);
diff --git a/include/linux/kvmi.h b/include/linux/kvmi.h
index 59d83d2d0cca..5d162b9e67f2 100644
--- a/include/linux/kvmi.h
+++ b/include/linux/kvmi.h
@@ -20,6 +20,7 @@ bool kvmi_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva, u8 insn_len);
bool kvmi_hypercall_event(struct kvm_vcpu *vcpu);
bool kvmi_queue_exception(struct kvm_vcpu *vcpu);
void kvmi_trap_event(struct kvm_vcpu *vcpu);
+bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor, u8 write);
void kvmi_handle_requests(struct kvm_vcpu *vcpu);
void kvmi_init_emulate(struct kvm_vcpu *vcpu);
void kvmi_activate_rep_complete(struct kvm_vcpu *vcpu);
@@ -35,6 +36,9 @@ static inline int kvmi_vcpu_init(struct kvm_vcpu *vcpu) { return 0; }
static inline bool kvmi_breakpoint_event(struct kvm_vcpu *vcpu, u64 gva,
u8 insn_len)
{ return true; }
+static inline bool kvmi_descriptor_event(struct kvm_vcpu *vcpu, u8 descriptor,
+ u8 write)
+ { return true; }
static inline void kvmi_vcpu_uninit(struct kvm_vcpu *vcpu) { }
static inline void kvmi_handle_requests(struct kvm_vcpu *vcpu) { }
static inline bool kvmi_hypercall_event(struct kvm_vcpu *vcpu) { return false; }
diff --git a/virt/kvm/kvmi.c b/virt/kvm/kvmi.c
index d04e13a0b244..d47a725a4045 100644
--- a/virt/kvm/kvmi.c
+++ b/virt/kvm/kvmi.c
@@ -1529,7 +1529,7 @@ int kvmi_cmd_control_events(struct kvm_vcpu *vcpu, unsigned int event_id,
err = kvmi_control_event_breakpoint(vcpu, enable);
break;
default:
- err = 0;
+ err = kvmi_arch_cmd_control_event(vcpu, event_id, enable);
break;
}
diff --git a/virt/kvm/kvmi_int.h b/virt/kvm/kvmi_int.h
index 793ec269b9fa..d7f9858d3e97 100644
--- a/virt/kvm/kvmi_int.h
+++ b/virt/kvm/kvmi_int.h
@@ -189,6 +189,7 @@ u32 kvmi_msg_send_hypercall(struct kvm_vcpu *vcpu);
u32 kvmi_msg_send_pf(struct kvm_vcpu *vcpu, u64 gpa, u64 gva, u8 access,
bool *singlestep, bool *rep_complete,
u64 *ctx_addr, u8 *ctx, u32 *ctx_size);
+u32 kvmi_msg_send_descriptor(struct kvm_vcpu *vcpu, u8 descriptor, u8 write);
u32 kvmi_msg_send_create_vcpu(struct kvm_vcpu *vcpu);
u32 kvmi_msg_send_pause_vcpu(struct kvm_vcpu *vcpu);
int kvmi_msg_send_unhook(struct kvmi *ikvm);
@@ -228,6 +229,8 @@ void kvmi_handle_common_event_actions(struct kvm_vcpu *vcpu, u32 action,
void kvmi_arch_update_page_tracking(struct kvm *kvm,
struct kvm_memory_slot *slot,
struct kvmi_mem_access *m);
+int kvmi_arch_cmd_control_event(struct kvm_vcpu *vcpu, unsigned int event_id,
+ bool enable);
int kvmi_arch_cmd_get_registers(struct kvm_vcpu *vcpu,
const struct kvmi_msg_hdr *msg,
const struct kvmi_get_registers *req,
diff --git a/virt/kvm/kvmi_msg.c b/virt/kvm/kvmi_msg.c
index 89f63f40f5cc..3e381f95b686 100644
--- a/virt/kvm/kvmi_msg.c
+++ b/virt/kvm/kvmi_msg.c
@@ -1163,6 +1163,23 @@ u32 kvmi_msg_send_pf(struct kvm_vcpu *vcpu, u64 gpa, u64 gva, u8 access,
return action;
}
+u32 kvmi_msg_send_descriptor(struct kvm_vcpu *vcpu, u8 descriptor, u8 write)
+{
+ struct kvmi_event_descriptor e;
+ int err, action;
+
+ memset(&e, 0, sizeof(e));
+ e.descriptor = descriptor;
+ e.write = write;
+
+ err = kvmi_send_event(vcpu, KVMI_EVENT_DESCRIPTOR, &e, sizeof(e),
+ NULL, 0, &action);
+ if (err)
+ return KVMI_EVENT_ACTION_CONTINUE;
+
+ return action;
+}
+
u32 kvmi_msg_send_create_vcpu(struct kvm_vcpu *vcpu)
{
int err, action;
