@@ -224,3 +224,30 @@ device etc.). It is up to the user to determine, using the guest operating
system data structures, the areas that are safe to access (code, stack, heap
etc.).
+Commands
+--------
+
+The following C structures are meant to be used directly when communicating
+over the wire. The peer that detects any size mismatch should simply close
+the connection and report the error.
+
+1. KVMI_GET_VERSION
+-------------------
+
+:Architectures: all
+:Versions: >= 1
+:Parameters: none
+:Returns:
+
+::
+
+ struct kvmi_error_code;
+ struct kvmi_get_version_reply {
+ __u32 version;
+ __u32 padding;
+ };
+
+Returns the introspection API version.
+
+This command is always allowed and successful (if the introspection is
+built in kernel).
@@ -6,11 +6,16 @@
* KVMI structures and definitions
*/
+#include <linux/kernel.h>
+#include <linux/types.h>
+
enum {
KVMI_VERSION = 0x00000001
};
enum {
+ KVMI_GET_VERSION = 2,
+
KVMI_NUM_MESSAGES
};
@@ -33,4 +38,9 @@ struct kvmi_error_code {
__u32 padding;
};
+struct kvmi_get_version_reply {
+ __u32 version;
+ __u32 padding;
+};
+
#endif /* _UAPI__LINUX_KVMI_H */
@@ -177,12 +177,37 @@ static void test_cmd_invalid(void)
-r, kvm_strerror(-r));
}
+static void test_vm_command(int cmd_id, struct kvmi_msg_hdr *req,
+ size_t req_size, void *rpl, size_t rpl_size)
+{
+ int r;
+
+ r = do_command(cmd_id, req, req_size, rpl, rpl_size);
+ TEST_ASSERT(r == 0,
+ "Command %d failed, error %d (%s)\n",
+ cmd_id, -r, kvm_strerror(-r));
+}
+
+static void test_cmd_get_version(void)
+{
+ struct kvmi_get_version_reply rpl;
+ struct kvmi_msg_hdr req;
+
+ test_vm_command(KVMI_GET_VERSION, &req, sizeof(req), &rpl, sizeof(rpl));
+ TEST_ASSERT(rpl.version == KVMI_VERSION,
+ "Unexpected KVMI version %d, expecting %d\n",
+ rpl.version, KVMI_VERSION);
+
+ DEBUG("KVMI version: %u\n", rpl.version);
+}
+
static void test_introspection(struct kvm_vm *vm)
{
setup_socket();
hook_introspection(vm);
test_cmd_invalid();
+ test_cmd_get_version();
unhook_introspection(vm);
}
@@ -76,6 +76,8 @@ alloc_kvmi(struct kvm *kvm, const struct kvm_introspection_hook *hook)
BUILD_BUG_ON(sizeof(hook->uuid) != sizeof(kvmi->uuid));
memcpy(&kvmi->uuid, &hook->uuid, sizeof(kvmi->uuid));
+ set_bit(KVMI_GET_VERSION, kvmi->cmd_allow_mask);
+
kvmi->kvm = kvm;
return kvmi;
@@ -299,6 +301,18 @@ int kvmi_ioctl_command(struct kvm *kvm, void __user *argp)
bitmap_from_u64(known, KVMI_KNOWN_COMMANDS);
bitmap_and(requested, requested, known, KVMI_NUM_COMMANDS);
+ if (!allow) {
+ DECLARE_BITMAP(always_allowed, KVMI_NUM_COMMANDS);
+
+ if (id == KVMI_GET_VERSION)
+ return -EPERM;
+
+ set_bit(KVMI_GET_VERSION, always_allowed);
+
+ bitmap_andnot(requested, requested, always_allowed,
+ KVMI_NUM_COMMANDS);
+ }
+
off_bitmap = offsetof(struct kvm_introspection, cmd_allow_mask);
return kvmi_ioctl_feature(kvm, allow, requested, off_bitmap,
@@ -20,7 +20,9 @@
#define KVMI_KNOWN_EVENTS 0
-#define KVMI_KNOWN_COMMANDS 0
+#define KVMI_KNOWN_COMMANDS ( \
+ BIT(KVMI_GET_VERSION) \
+ )
#define KVMI(kvm) ((struct kvm_introspection *)((kvm)->kvmi))
@@ -9,6 +9,7 @@
#include "kvmi_int.h"
static const char *const msg_IDs[] = {
+ [KVMI_GET_VERSION] = "KVMI_GET_VERSION",
};
static bool is_known_message(u16 id)
@@ -116,11 +117,23 @@ static bool is_command_allowed(struct kvm_introspection *kvmi, int id)
return test_bit(id, kvmi->cmd_allow_mask);
}
+static int handle_get_version(struct kvm_introspection *kvmi,
+ const struct kvmi_msg_hdr *msg, const void *req)
+{
+ struct kvmi_get_version_reply rpl;
+
+ memset(&rpl, 0, sizeof(rpl));
+ rpl.version = KVMI_VERSION;
+
+ return kvmi_msg_vm_reply(kvmi, msg, 0, &rpl, sizeof(rpl));
+}
+
/*
* These commands are executed by the receiving thread/worker.
*/
static int(*const msg_vm[])(struct kvm_introspection *,
const struct kvmi_msg_hdr *, const void *) = {
+ [KVMI_GET_VERSION] = handle_get_version,
};
static bool is_vm_message(u16 id)
This command should be used by the introspection tool to identify the commands/events supported by the KVMi subsystem and, most important, what messages must be used for event replies. These messages might be extended in future versions. The kernel side will accept smaller/older or bigger/newer command messages, but not bigger/newer event replies. The KVMI_GET_VERSION command is always allowed and any attempt from userspace to explicitly disallow this command through KVM_INTROSPECTION_COMMAND will get -EPERM (unless userspace chooses to disable all commands, using id=-1, in which case KVMI_GET_VERSION is silently allowed, without an error). Signed-off-by: Adalbert Lazăr <alazar@bitdefender.com> --- Documentation/virt/kvm/kvmi.rst | 27 +++++++++++++++++++ include/uapi/linux/kvmi.h | 10 +++++++ .../testing/selftests/kvm/x86_64/kvmi_test.c | 25 +++++++++++++++++ virt/kvm/introspection/kvmi.c | 14 ++++++++++ virt/kvm/introspection/kvmi_int.h | 4 ++- virt/kvm/introspection/kvmi_msg.c | 13 +++++++++ 6 files changed, 92 insertions(+), 1 deletion(-)