From: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
These commands allows the introspection tool to read/write from/to the
guest memory.
Signed-off-by: Mihai Donțu <mdontu@xxxxxxxxxxxxxxx>
Co-developed-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
Signed-off-by: Adalbert Lazăr <alazar@xxxxxxxxxxxxxxx>
---
Documentation/virtual/kvm/kvmi.rst | 60 ++++++++++++++++
include/uapi/linux/kvmi.h | 11 +++
virt/kvm/kvmi.c | 107 +++++++++++++++++++++++++++++
virt/kvm/kvmi_int.h | 7 ++
virt/kvm/kvmi_msg.c | 42 +++++++++++
5 files changed, 227 insertions(+)
diff --git a/Documentation/virtual/kvm/kvmi.rst b/Documentation/virtual/kvm/kvmi.rst
index 69557c63ff94..eef32107837a 100644
--- a/Documentation/virtual/kvm/kvmi.rst
+++ b/Documentation/virtual/kvm/kvmi.rst
@@ -760,6 +760,66 @@ corresponding bit set to 1.
* -KVM_EAGAIN - the selected vCPU can't be introspected yet
* -KVM_ENOMEM - not enough memory to add the page tracking structures
+14. KVMI_READ_PHYSICAL
+----------------------
+
+:Architectures: all
+:Versions: >= 1
+:Parameters:
+
+::
+
+ struct kvmi_read_physical {
+ __u64 gpa;
+ __u64 size;
+ };
+
+:Returns:
+
+::
+
+ struct kvmi_error_code;
+ __u8 data[0];
+
+Reads from the guest memory.
+
+Currently, the size must be non-zero and the read must be restricted to
+one page (offset + size <= PAGE_SIZE).
+
+:Errors:
+
+* -KVM_EINVAL - the specified gpa is invalid
+
+15. KVMI_WRITE_PHYSICAL
+-----------------------
+
+:Architectures: all
+:Versions: >= 1
+:Parameters:
+
+::
+
+ struct kvmi_write_physical {
+ __u64 gpa;
+ __u64 size;
+ __u8 data[0];
+ };
+
+:Returns:
+
+::
+
+ struct kvmi_error_code
+
+Writes into the guest memory.
+
+Currently, the size must be non-zero and the write must be restricted to
+one page (offset + size <= PAGE_SIZE).
+
+:Errors:
+
+* -KVM_EINVAL - the specified gpa is invalid
+
Events
======
diff --git a/include/uapi/linux/kvmi.h b/include/uapi/linux/kvmi.h
index 0b3139c52a30..be3f066f314e 100644
--- a/include/uapi/linux/kvmi.h
+++ b/include/uapi/linux/kvmi.h
@@ -191,6 +191,17 @@ struct kvmi_control_vm_events {
__u32 padding2;
};
+struct kvmi_read_physical {
+ __u64 gpa;
+ __u64 size;
+};
+
+struct kvmi_write_physical {
+ __u64 gpa;
+ __u64 size;
+ __u8 data[0];
+};
+
struct kvmi_vcpu_hdr {
__u16 vcpu;
__u16 padding1;
diff --git a/virt/kvm/kvmi.c b/virt/kvm/kvmi.c
index d2bebef98d8d..a84eb150e116 100644
--- a/virt/kvm/kvmi.c
+++ b/virt/kvm/kvmi.c
@@ -5,6 +5,7 @@
* Copyright (C) 2017-2019 Bitdefender S.R.L.
*
*/
+#include <linux/mmu_context.h>
#include <uapi/linux/kvmi.h>
#include "kvmi_int.h"
#include <linux/kthread.h>
@@ -1220,6 +1221,112 @@ int kvmi_cmd_set_page_write_bitmap(struct kvmi *ikvm, u64 gpa,
return kvmi_set_gfn_access(ikvm->kvm, gfn, access, write_bitmap);
}
+unsigned long gfn_to_hva_safe(struct kvm *kvm, gfn_t gfn)
+{
+ unsigned long hva;
+ int srcu_idx;
+
+ srcu_idx = srcu_read_lock(&kvm->srcu);
+ hva = gfn_to_hva(kvm, gfn);
+ srcu_read_unlock(&kvm->srcu, srcu_idx);
+
+ return hva;
+}
+
+static long get_user_pages_remote_unlocked(struct mm_struct *mm,
+ unsigned long start,
+ unsigned long nr_pages,
+ unsigned int gup_flags,
+ struct page **pages)
+{
+ long ret;
+ struct task_struct *tsk = NULL;
+ struct vm_area_struct **vmas = NULL;
+ int locked = 1;
+
+ down_read(&mm->mmap_sem);
+ ret = get_user_pages_remote(tsk, mm, start, nr_pages, gup_flags,
+ pages, vmas, &locked);
+ if (locked)
+ up_read(&mm->mmap_sem);
+ return ret;
+}
+
+static void *get_page_ptr(struct kvm *kvm, gpa_t gpa, struct page **page,
+ bool write)
+{
+ unsigned int flags = write ? FOLL_WRITE : 0;
+ unsigned long hva;
+
+ *page = NULL;
+
+ hva = gfn_to_hva_safe(kvm, gpa_to_gfn(gpa));
+
+ if (kvm_is_error_hva(hva)) {
+ kvmi_err(IKVM(kvm), "Invalid gpa %llx\n", gpa);
+ return NULL;
+ }
+
+ if (get_user_pages_remote_unlocked(kvm->mm, hva, 1, flags, page) != 1) {
+ kvmi_err(IKVM(kvm),
+ "Failed to get the page for hva %lx gpa %llx\n",
+ hva, gpa);
+ return NULL;
+ }
+
+ return kmap_atomic(*page);
+}
+
+static void put_page_ptr(void *ptr, struct page *page)
+{
+ if (ptr)
+ kunmap_atomic(ptr);
+ if (page)
+ put_page(page);
+}
+
+int kvmi_cmd_read_physical(struct kvm *kvm, u64 gpa, u64 size, int(*send)(
+ struct kvmi *, const struct kvmi_msg_hdr *,
+ int err, const void *buf, size_t),
+ const struct kvmi_msg_hdr *ctx)
+{
+ int err, ec = 0;
+ struct page *page = NULL;
+ void *ptr_page = NULL, *ptr = NULL;
+ size_t ptr_size = 0;
+
+ ptr_page = get_page_ptr(kvm, gpa, &page, false);
+ if (!ptr_page) {
+ ec = -KVM_EINVAL;
+ goto out;
+ }
+
+ ptr = ptr_page + (gpa & ~PAGE_MASK);
+ ptr_size = size;
+
+out:
+ err = send(IKVM(kvm), ctx, ec, ptr, ptr_size);
+
+ put_page_ptr(ptr_page, page);
+ return err;
+}
+
+int kvmi_cmd_write_physical(struct kvm *kvm, u64 gpa, u64 size, const void *buf)
+{
+ struct page *page;
+ void *ptr;
+
+ ptr = get_page_ptr(kvm, gpa, &page, true);
+ if (!ptr)
+ return -KVM_EINVAL;
+
+ memcpy(ptr + (gpa & ~PAGE_MASK), buf, size);
+
+ put_page_ptr(ptr, page);
+
+ return 0;
+}
+
int kvmi_cmd_control_events(struct kvm_vcpu *vcpu, unsigned int event_id,
bool enable)
{
diff --git a/virt/kvm/kvmi_int.h b/virt/kvm/kvmi_int.h
index 18c00dae0f2f..7bdff70d4309 100644
--- a/virt/kvm/kvmi_int.h
+++ b/virt/kvm/kvmi_int.h
@@ -174,6 +174,13 @@ int kvmi_cmd_get_page_access(struct kvmi *ikvm, u64 gpa, u8 *access);
int kvmi_cmd_set_page_access(struct kvmi *ikvm, u64 gpa, u8 access);
int kvmi_cmd_get_page_write_bitmap(struct kvmi *ikvm, u64 gpa, u32 *bitmap);
int kvmi_cmd_set_page_write_bitmap(struct kvmi *ikvm, u64 gpa, u32 bitmap);
+int kvmi_cmd_read_physical(struct kvm *kvm, u64 gpa, u64 size,
+ int (*send)(struct kvmi *,
+ const struct kvmi_msg_hdr*,
+ int err, const void *buf, size_t),
+ const struct kvmi_msg_hdr *ctx);
+int kvmi_cmd_write_physical(struct kvm *kvm, u64 gpa, u64 size,
+ const void *buf);
int kvmi_cmd_control_events(struct kvm_vcpu *vcpu, unsigned int event_id,
bool enable);
int kvmi_cmd_control_vm_events(struct kvmi *ikvm, unsigned int event_id,
diff --git a/virt/kvm/kvmi_msg.c b/virt/kvm/kvmi_msg.c
index f9efb52d49c3..9c20a9cfda42 100644
--- a/virt/kvm/kvmi_msg.c
+++ b/virt/kvm/kvmi_msg.c
@@ -34,8 +34,10 @@ static const char *const msg_IDs[] = {
[KVMI_GET_PAGE_WRITE_BITMAP] = "KVMI_GET_PAGE_WRITE_BITMAP",
[KVMI_GET_VCPU_INFO] = "KVMI_GET_VCPU_INFO",
[KVMI_GET_VERSION] = "KVMI_GET_VERSION",
+ [KVMI_READ_PHYSICAL] = "KVMI_READ_PHYSICAL",
[KVMI_SET_PAGE_ACCESS] = "KVMI_SET_PAGE_ACCESS",
[KVMI_SET_PAGE_WRITE_BITMAP] = "KVMI_SET_PAGE_WRITE_BITMAP",
+ [KVMI_WRITE_PHYSICAL] = "KVMI_WRITE_PHYSICAL",
};
static bool is_known_message(u16 id)
@@ -303,6 +305,44 @@ static int kvmi_get_vcpu(struct kvmi *ikvm, unsigned int vcpu_idx,
return 0;
}
+static bool invalid_page_access(u64 gpa, u64 size)
+{
+ u64 off = gpa & ~PAGE_MASK;
+
+ return (size == 0 || size > PAGE_SIZE || off + size > PAGE_SIZE);
+}
+
+static int handle_read_physical(struct kvmi *ikvm,
+ const struct kvmi_msg_hdr *msg,
+ const void *_req)
+{
+ const struct kvmi_read_physical *req = _req;
+
+ if (invalid_page_access(req->gpa, req->size))
+ return -EINVAL;
+
+ return kvmi_cmd_read_physical(ikvm->kvm, req->gpa, req->size,
+ kvmi_msg_vm_maybe_reply, msg);
+}
+
+static int handle_write_physical(struct kvmi *ikvm,
+ const struct kvmi_msg_hdr *msg,
+ const void *_req)
+{
+ const struct kvmi_write_physical *req = _req;
+ int ec;
+
+ if (invalid_page_access(req->gpa, req->size))
+ return -EINVAL;
+
+ if (msg->size < sizeof(*req) + req->size)
+ return -EINVAL;
+
+ ec = kvmi_cmd_write_physical(ikvm->kvm, req->gpa, req->size, req->data);
+
+ return kvmi_msg_vm_maybe_reply(ikvm, msg, ec, NULL, 0);
+}
+
static bool enable_spp(struct kvmi *ikvm)
{
if (!ikvm->spp.initialized) {
@@ -431,8 +471,10 @@ static int(*const msg_vm[])(struct kvmi *, const struct kvmi_msg_hdr *,
[KVMI_GET_PAGE_ACCESS] = handle_get_page_access,
[KVMI_GET_PAGE_WRITE_BITMAP] = handle_get_page_write_bitmap,
[KVMI_GET_VERSION] = handle_get_version,
+ [KVMI_READ_PHYSICAL] = handle_read_physical,
[KVMI_SET_PAGE_ACCESS] = handle_set_page_access,
[KVMI_SET_PAGE_WRITE_BITMAP] = handle_set_page_write_bitmap,
+ [KVMI_WRITE_PHYSICAL] = handle_write_physical,
};
static int handle_event_reply(struct kvm_vcpu *vcpu,
