KVM_INTROSPECTION_COMMAND and KVM_INTROSPECTION_EVENTS ioctls are used
by the device manager to allow/disallow access to specific (or all)
introspection commands and events. The introspection tool will get the
KVM_EPERM error code on any attempt to use a disallowed command.
By default, all events and almost all commands are disallowed.
Some commands, those querying the introspection capabilities,
are always allowed.
Signed-off-by: Adalbert Lazăr <ala...@bitdefender.com>
---
Documentation/virt/kvm/api.rst | 66 ++++++++++
include/linux/kvmi_host.h | 7 ++
include/uapi/linux/kvm.h | 8 ++
include/uapi/linux/kvmi.h | 8 ++
.../testing/selftests/kvm/x86_64/kvmi_test.c | 48 +++++++
virt/kvm/introspection/kvmi.c | 119 ++++++++++++++++++
virt/kvm/kvm_main.c | 14 +++
7 files changed, 270 insertions(+)
diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index e34f20430eb1..174f13f2389d 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4753,6 +4753,72 @@ Errors:
This ioctl is used to free all introspection structures
related to this VM.
+4.128 KVM_INTROSPECTION_COMMAND
+-------------------------------
+
+:Capability: KVM_CAP_INTROSPECTION
+:Architectures: x86
+:Type: vm ioctl
+:Parameters: struct kvm_introspection_feature (in)
+:Returns: 0 on success, a negative value on error
+
+Errors:
+
+ ====== ===========================================================
+ EFAULT the VM is not introspected yet (use KVM_INTROSPECTION_HOOK)
+ EINVAL the command is unknown
+ EPERM the command can't be disallowed (e.g. KVMI_GET_VERSION)
+ ====== ===========================================================
+
+This ioctl is used to allow or disallow introspection commands
+for the current VM. By default, almost all commands are disallowed
+except for those used to query the API.
+
+::
+
+ struct kvm_introspection_feature {
+ __u32 allow;
+ __s32 id;
+ };
+
+If allow is 1, the command specified by id is allowed. If allow is 0,
+the command is disallowed.
+
+Unless set to -1 (meaning all commands), id must be a command ID
+(e.g. KVMI_GET_VERSION)
+
+4.129 KVM_INTROSPECTION_EVENT
+-----------------------------
+
+:Capability: KVM_CAP_INTROSPECTION
+:Architectures: x86
+:Type: vm ioctl
+:Parameters: struct kvm_introspection_feature (in)
+:Returns: 0 on success, a negative value on error
+
+Errors:
+
+ ====== ===========================================================
+ EFAULT the VM is not introspected yet (use KVM_INTROSPECTION_HOOK)
+ EINVAL the event is unknown
+ ====== ===========================================================
+
+This ioctl is used to allow or disallow introspection events
+for the current VM. By default, all events are disallowed.
+
+::
+
+ struct kvm_introspection_feature {
+ __u32 allow;
+ __s32 id;
+ };
+
+If allow is 1, the event specified by id is allowed. If allow is 0,
+the event is disallowed.
+
+Unless set to -1 (meaning all events), id must be a event ID
+(e.g. KVMI_EVENT_UNHOOK, KVMI_EVENT_CR, etc.)
+
5. The kvm_run structure
========================
diff --git a/include/linux/kvmi_host.h b/include/linux/kvmi_host.h
index 55ff571db40d..7efd071e398d 100644
--- a/include/linux/kvmi_host.h
+++ b/include/linux/kvmi_host.h
@@ -14,6 +14,9 @@ struct kvm_introspection {
struct socket *sock;
struct task_struct *recv;
+
+ unsigned long *cmd_allow_mask;
+ unsigned long *event_allow_mask;
};
int kvmi_version(void);
@@ -25,6 +28,10 @@ void kvmi_destroy_vm(struct kvm *kvm);
int kvmi_ioctl_hook(struct kvm *kvm,
const struct kvm_introspection_hook *hook);
int kvmi_ioctl_unhook(struct kvm *kvm);
+int kvmi_ioctl_command(struct kvm *kvm,
+ const struct kvm_introspection_feature *feat);
+int kvmi_ioctl_event(struct kvm *kvm,
+ const struct kvm_introspection_feature *feat);
#else
diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
index dd84ebdfcd6d..17df03ceb483 100644
--- a/include/uapi/linux/kvm.h
+++ b/include/uapi/linux/kvm.h
@@ -1622,6 +1622,14 @@ struct kvm_introspection_hook {
#define KVM_INTROSPECTION_HOOK _IOW(KVMIO, 0xc3, struct
kvm_introspection_hook)
#define KVM_INTROSPECTION_UNHOOK _IO(KVMIO, 0xc4)
+struct kvm_introspection_feature {
+ __u32 allow;
+ __s32 id;
+};
+
+#define KVM_INTROSPECTION_COMMAND _IOW(KVMIO, 0xc5, struct
kvm_introspection_feature)
+#define KVM_INTROSPECTION_EVENT _IOW(KVMIO, 0xc6, struct
kvm_introspection_feature)
+
#define KVM_DEV_ASSIGN_ENABLE_IOMMU (1 << 0)
#define KVM_DEV_ASSIGN_PCI_2_3 (1 << 1)
#define KVM_DEV_ASSIGN_MASK_INTX (1 << 2)
diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h
index 34dda91016db..d7b18ffef4fa 100644
--- a/include/uapi/linux/kvmi.h
+++ b/include/uapi/linux/kvmi.h
@@ -10,4 +10,12 @@ enum {
KVMI_VERSION = 0x00000001
};
+enum {
+ KVMI_NUM_MESSAGES
+};
+
+enum {
+ KVMI_NUM_EVENTS
+};
+
#endif /* _UAPI__LINUX_KVMI_H */
diff --git a/tools/testing/selftests/kvm/x86_64/kvmi_test.c
b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
index 08ca4701c440..09b8989317d7 100644
--- a/tools/testing/selftests/kvm/x86_64/kvmi_test.c
+++ b/tools/testing/selftests/kvm/x86_64/kvmi_test.c
@@ -48,14 +48,62 @@ static void do_hook_ioctl(struct kvm_vm *vm, __s32 fd,
__u32 padding,
errno, strerror(errno), expected_err, fd, padding);
}
+static void set_perm(struct kvm_vm *vm, __s32 id, __u32 allow,
+ int expected_err, int ioctl_id,
+ const char *ioctl_str)
+{
+ struct kvm_introspection_feature feat = {
+ .allow = allow,
+ .id = id
+ };
+ int r;
+
+ r = ioctl(vm->fd, ioctl_id, &feat);
+ TEST_ASSERT(r == 0 || errno == expected_err,
+ "%s failed, id %d, errno %d (%s), expected %d\n",
+ ioctl_str, id, errno, strerror(errno), expected_err);
+}
+
+static void set_event_perm(struct kvm_vm *vm, __s32 id, __u32 allow,
+ int expected_err)
+{
+ set_perm(vm, id, allow, expected_err, KVM_INTROSPECTION_EVENT,
+ "KVM_INTROSPECTION_EVENT");
+}
+
+static void allow_event(struct kvm_vm *vm, __s32 event_id)
+{
+ set_event_perm(vm, event_id, 1, 0);
+}
+
+static void set_command_perm(struct kvm_vm *vm, __s32 id, __u32 allow,
+ int expected_err)
+{
+ set_perm(vm, id, allow, expected_err, KVM_INTROSPECTION_COMMAND,
+ "KVM_INTROSPECTION_COMMAND");
+}
+
static void hook_introspection(struct kvm_vm *vm)
{
+ __u32 allow = 1, disallow = 0, allow_inval = 2;
__u32 padding = 1, no_padding = 0;
+ __s32 all_IDs = -1;
+
+ set_command_perm(vm, all_IDs, allow, EFAULT);
+ set_event_perm(vm, all_IDs, allow, EFAULT);
do_hook_ioctl(vm, Kvm_socket, padding, EINVAL);
do_hook_ioctl(vm, -1, no_padding, EINVAL);
do_hook_ioctl(vm, Kvm_socket, no_padding, 0);
do_hook_ioctl(vm, Kvm_socket, no_padding, EEXIST);
+
+ set_command_perm(vm, all_IDs, allow_inval, EINVAL);
+ set_command_perm(vm, all_IDs, disallow, 0);
+ set_command_perm(vm, all_IDs, allow, 0);
+
+ set_event_perm(vm, all_IDs, allow_inval, EINVAL);
+ set_event_perm(vm, all_IDs, disallow, 0);
+ allow_event(vm, all_IDs);
}
static void unhook_introspection(struct kvm_vm *vm)
diff --git a/virt/kvm/introspection/kvmi.c b/virt/kvm/introspection/kvmi.c
index 5d9bc4ed5060..b1ea39f35481 100644
--- a/virt/kvm/introspection/kvmi.c
+++ b/virt/kvm/introspection/kvmi.c
@@ -8,6 +8,8 @@
#include <linux/kthread.h>
#include "kvmi_int.h"
+#define KVMI_NUM_COMMANDS KVMI_NUM_MESSAGES
+
int kvmi_init(void)
{
return 0;
@@ -24,6 +26,9 @@ void kvmi_uninit(void)
static void free_kvmi(struct kvm *kvm)
{
+ bitmap_free(kvm->kvmi->cmd_allow_mask);
+ bitmap_free(kvm->kvmi->event_allow_mask);
+
kfree(kvm->kvmi);
kvm->kvmi = NULL;
}
@@ -37,6 +42,15 @@ alloc_kvmi(struct kvm *kvm, const struct
kvm_introspection_hook *hook)
if (!kvmi)
return NULL;
+ kvmi->cmd_allow_mask = bitmap_zalloc(KVMI_NUM_COMMANDS, GFP_KERNEL);
+ kvmi->event_allow_mask = bitmap_zalloc(KVMI_NUM_EVENTS, GFP_KERNEL);
+ if (!kvmi->cmd_allow_mask || !kvmi->event_allow_mask) {
+ bitmap_free(kvmi->cmd_allow_mask);
+ bitmap_free(kvmi->event_allow_mask);
+ kfree(kvmi);
+ return NULL;
+ }
+
BUILD_BUG_ON(sizeof(hook->uuid) != sizeof(kvmi->uuid));
memcpy(&kvmi->uuid, &hook->uuid, sizeof(kvmi->uuid));
@@ -185,3 +199,108 @@ void kvmi_destroy_vm(struct kvm *kvm)
{
kvmi_unhook(kvm);
}
+
+static int
+kvmi_ioctl_get_feature(const struct kvm_introspection_feature *feat,
+ bool *allow, s32 *id, unsigned int nbits)
+{
+ s32 all_bits = -1;
+
+ if (feat->id < 0 && feat->id != all_bits)
+ return -EINVAL;
+
+ if (feat->id > 0 && feat->id >= nbits)
+ return -EINVAL;
+
+ if (feat->allow > 1)
+ return -EINVAL;
+
+ *allow = feat->allow == 1;
+ *id = feat->id;
+
+ return 0;
+}
+
+static void kvmi_control_allowed_events(struct kvm_introspection *kvmi,
+ s32 id, bool allow)
+{
+ s32 all_events = -1;
+
+ if (allow) {
+ if (id == all_events)
+ bitmap_fill(kvmi->event_allow_mask, KVMI_NUM_EVENTS);
+ else
+ set_bit(id, kvmi->event_allow_mask);
+ } else {
+ if (id == all_events)
+ bitmap_zero(kvmi->event_allow_mask, KVMI_NUM_EVENTS);
+ else
+ clear_bit(id, kvmi->event_allow_mask);
+ }
+}
+
+int kvmi_ioctl_event(struct kvm *kvm,
+ const struct kvm_introspection_feature *feat)
+{
+ struct kvm_introspection *kvmi;
+ bool allow;
+ int err;
+ s32 id;
+
+ err = kvmi_ioctl_get_feature(feat, &allow, &id, KVMI_NUM_EVENTS);
+ if (err)
+ return err;
+
+ mutex_lock(&kvm->kvmi_lock);
+
+ kvmi = KVMI(kvm);
+ if (kvmi)
+ kvmi_control_allowed_events(kvmi, id, allow);
+ else
+ err = -EFAULT;
+
+ mutex_unlock(&kvm->kvmi_lock);
+ return err;
+}
+
+static void kvmi_control_allowed_commands(struct kvm_introspection *kvmi,
+ s32 id, bool allow)
+{
+ s32 all_commands = -1;
+
+ if (allow) {
+ if (id == all_commands)
+ bitmap_fill(kvmi->cmd_allow_mask, KVMI_NUM_COMMANDS);
+ else
+ set_bit(id, kvmi->cmd_allow_mask);
+ } else {
+ if (id == all_commands)
+ bitmap_zero(kvmi->cmd_allow_mask, KVMI_NUM_COMMANDS);
+ else
+ clear_bit(id, kvmi->cmd_allow_mask);
+ }
+}
+
+int kvmi_ioctl_command(struct kvm *kvm,
+ const struct kvm_introspection_feature *feat)
+{
+ struct kvm_introspection *kvmi;
+ bool allow;
+ int err;
+ s32 id;
+
+ err = kvmi_ioctl_get_feature(feat, &allow, &id, KVMI_NUM_COMMANDS);
+ if (err)
+ return err;
+
+ mutex_lock(&kvm->kvmi_lock);
+
+ kvmi = KVMI(kvm);
+ if (kvmi)
+ kvmi_control_allowed_commands(kvmi, id, allow);
+ else
+ err = -EFAULT;
+
+ mutex_unlock(&kvm->kvmi_lock);
+ return err;
+}
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0d2da77ccb12..9aeb57e93165 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -3847,6 +3847,20 @@ static long kvm_vm_ioctl(struct file *filp,
else
r = -EPERM;
break;
+ case KVM_INTROSPECTION_COMMAND:
+ case KVM_INTROSPECTION_EVENT:
+ r = -EPERM;
+ if (enable_introspection) {
+ struct kvm_introspection_feature feat;
+
+ if (copy_from_user(&feat, argp, sizeof(feat)))
+ r = -EFAULT;
+ else if (ioctl == KVM_INTROSPECTION_EVENT)
+ r = kvmi_ioctl_event(kvm, &feat);
+ else
+ r = kvmi_ioctl_command(kvm, &feat);
+ }
+ break;
#endif /* CONFIG_KVM_INTROSPECTION */
default:
r = kvm_arch_vm_ioctl(filp, ioctl, arg);
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