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ANDROID: KVM: arm64: Block module loading based on cmdline or HVC

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Disable module loading, based on the cmdline option
kvm-arm.protected_modules. If enabled, the feature can later be
irreversibly disabled with the HVC __pkvm_close_module_registration().

Bug: 357781595
Bug: 244543039
Bug: 244373730
Change-Id: I693a1db350ae15bcaab59103a68b60f087dcc6b4
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Quentin Perret <qperret@google.com>
This commit is contained in:
Vincent Donnefort
2022-11-24 15:23:26 +00:00
committed by Keir Fraser
parent a871b30b2d
commit 7089457a75
7 changed files with 117 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files
arch/arm64/include/asm/kvm_asm.h
+5 -4
View File
@@ -66,10 +66,6 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid,
__KVM_HOST_SMCCC_FUNC___kvm_tlb_flush_vmid_range,
__KVM_HOST_SMCCC_FUNC___kvm_flush_cpu_context,
__KVM_HOST_SMCCC_FUNC___pkvm_alloc_module_va,
__KVM_HOST_SMCCC_FUNC___pkvm_map_module_page,
__KVM_HOST_SMCCC_FUNC___pkvm_unmap_module_page,
__KVM_HOST_SMCCC_FUNC___pkvm_init_module,
__KVM_HOST_SMCCC_FUNC___pkvm_prot_finalize,
/* Hypercalls available after pKVM finalisation */
@@ -98,6 +94,11 @@ enum __kvm_host_smccc_func {
__KVM_HOST_SMCCC_FUNC___pkvm_enable_event,
__KVM_HOST_SMCCC_FUNC___pkvm_selftest_event,
__KVM_HOST_SMCCC_FUNC___pkvm_register_hcall,
__KVM_HOST_SMCCC_FUNC___pkvm_alloc_module_va,
__KVM_HOST_SMCCC_FUNC___pkvm_map_module_page,
__KVM_HOST_SMCCC_FUNC___pkvm_unmap_module_page,
__KVM_HOST_SMCCC_FUNC___pkvm_init_module,
__KVM_HOST_SMCCC_FUNC___pkvm_close_module_registration,
/*
* Start of the dynamically registered hypercalls. Start a bit
arch/arm64/include/asm/kvm_hyp.h
+3
View File
@@ -147,4 +147,7 @@ extern u64 kvm_nvhe_sym(id_aa64smfr0_el1_sys_val);
extern unsigned long kvm_nvhe_sym(__icache_flags);
extern unsigned int kvm_nvhe_sym(kvm_arm_vmid_bits);
extern unsigned int kvm_nvhe_sym(kvm_host_sve_max_vl);
extern bool kvm_nvhe_sym(__pkvm_modules_enabled);
#endif /* __ARM64_KVM_HYP_H__ */
arch/arm64/kvm/hyp/include/nvhe/modules.h
+8
View File
@@ -7,6 +7,10 @@
int __pkvm_init_module(void *module_init);
int __pkvm_register_hcall(unsigned long hfn_hyp_va);
int handle_host_dynamic_hcall(struct kvm_cpu_context *host_ctxt);
void pkvm_modules_lock(void);
void pkvm_modules_unlock(void);
bool pkvm_modules_enabled(void);
int __pkvm_close_module_registration(void);
#else
static inline int __pkvm_init_module(void *module_init) { return -EOPNOTSUPP; }
static inline int
@@ -15,4 +19,8 @@ static inline int handle_host_dynamic_hcall(struct kvm_cpu_context *host_ctxt)
{
return HCALL_UNHANDLED;
}
static inline void pkvm_modules_lock(void) { }
static inline void pkvm_modules_unlock(void) { }
static inline bool pkvm_modules_enabled(void) { return false; }
static inline int __pkvm_close_module_registration(void) { return -EOPNOTSUPP; }
#endif
arch/arm64/kvm/hyp/nvhe/hyp-main.c
+7
View File
@@ -1318,6 +1318,12 @@ static void handle___pkvm_register_hcall(struct kvm_cpu_context *host_ctxt)
cpu_reg(host_ctxt, 1) = __pkvm_register_hcall(hfn_hyp_va);
}
static void
handle___pkvm_close_module_registration(struct kvm_cpu_context *host_ctxt)
{
cpu_reg(host_ctxt, 1) = __pkvm_close_module_registration();
}
typedef void (*hcall_t)(struct kvm_cpu_context *);
#define HANDLE_FUNC(x) [__KVM_HOST_SMCCC_FUNC_##x] = (hcall_t)handle_##x
@@ -1368,6 +1374,7 @@ static const hcall_t host_hcall[] = {
HANDLE_FUNC(__pkvm_unmap_module_page),
HANDLE_FUNC(__pkvm_init_module),
HANDLE_FUNC(__pkvm_register_hcall),
HANDLE_FUNC(__pkvm_close_module_registration),
};
static void handle_host_hcall(struct kvm_cpu_context *host_ctxt)
arch/arm64/kvm/hyp/nvhe/mm.c
+25 -9
View File
@@ -16,6 +16,7 @@
#include <nvhe/memory.h>
#include <nvhe/mem_protect.h>
#include <nvhe/mm.h>
#include <nvhe/modules.h>
#include <nvhe/spinlock.h>
struct kvm_pgtable pkvm_pgtable;
@@ -112,29 +113,44 @@ int __pkvm_create_private_mapping(phys_addr_t phys, size_t size,
void *__pkvm_alloc_module_va(u64 nr_pages)
{
unsigned long addr;
int ret;
unsigned long addr = 0;
ret = pkvm_alloc_private_va_range(nr_pages << PAGE_SHIFT, &addr);
pkvm_modules_lock();
if (pkvm_modules_enabled())
pkvm_alloc_private_va_range(nr_pages << PAGE_SHIFT, &addr);
pkvm_modules_unlock();
return ret ? NULL : (void *)addr;
return (void *)addr;
}
int __pkvm_map_module_page(u64 pfn, void *va, enum kvm_pgtable_prot prot)
{
int ret;
int ret = -EACCES;
pkvm_modules_lock();
if (!pkvm_modules_enabled())
goto err;
ret = __pkvm_host_donate_hyp(pfn, 1);
if (ret)
return ret;
goto err;
return __pkvm_create_mappings((unsigned long)va, PAGE_SIZE, hyp_pfn_to_phys(pfn), prot);
ret = __pkvm_create_mappings((unsigned long)va, PAGE_SIZE, hyp_pfn_to_phys(pfn), prot);
err:
pkvm_modules_unlock();
return ret;
}
void __pkvm_unmap_module_page(u64 pfn, void *va)
{
WARN_ON(__pkvm_hyp_donate_host(pfn, 1));
pkvm_remove_mappings(va, va + PAGE_SIZE);
pkvm_modules_lock();
if (pkvm_modules_enabled()) {
WARN_ON(__pkvm_hyp_donate_host(pfn, 1));
pkvm_remove_mappings(va, va + PAGE_SIZE);
}
pkvm_modules_unlock();
}
int pkvm_create_mappings_locked(void *from, void *to, enum kvm_pgtable_prot prot)
arch/arm64/kvm/hyp/nvhe/modules.c
+58 -4
View File
@@ -11,6 +11,42 @@
#include <nvhe/spinlock.h>
#include <nvhe/trap_handler.h>
DEFINE_HYP_SPINLOCK(modules_lock);
bool __pkvm_modules_enabled __ro_after_init;
void pkvm_modules_lock(void)
{
hyp_spin_lock(&modules_lock);
}
void pkvm_modules_unlock(void)
{
hyp_spin_unlock(&modules_lock);
}
bool pkvm_modules_enabled(void)
{
return __pkvm_modules_enabled;
}
int __pkvm_close_module_registration(void)
{
int ret;
pkvm_modules_lock();
ret = __pkvm_modules_enabled ? 0 : -EACCES;
if (!ret) {
void *addr = hyp_fixmap_map(__hyp_pa(&__pkvm_modules_enabled));
*(bool *)addr = false;
hyp_fixmap_unmap();
}
pkvm_modules_unlock();
/* The fuse is blown! No way back until reset */
return ret;
}
const struct pkvm_module_ops module_ops = {
.create_private_mapping = __pkvm_create_private_mapping,
.register_serial_driver = __pkvm_register_serial_driver,
@@ -24,7 +60,15 @@ int __pkvm_init_module(void *module_init)
int (*do_module_init)(const struct pkvm_module_ops *ops) = module_init;
int ret;
pkvm_modules_lock();
if (!pkvm_modules_enabled()) {
ret = -EACCES;
goto err;
}
ret = do_module_init(&module_ops);
err:
pkvm_modules_unlock();
return ret;
}
@@ -72,15 +116,21 @@ end:
int __pkvm_register_hcall(unsigned long hvn_hyp_va)
{
dyn_hcall_t hfn = (void *)hvn_hyp_va;
int reserved_id;
int reserved_id, ret;
pkvm_modules_lock();
if (!pkvm_modules_enabled()) {
ret = -EACCES;
goto err;
}
hyp_spin_lock(&dyn_hcall_lock);
reserved_id = atomic_read(&num_dynamic_hcalls);
if (reserved_id >= MAX_DYNAMIC_HCALLS) {
hyp_spin_unlock(&dyn_hcall_lock);
return -ENOMEM;
ret = -ENOMEM;
goto err_hcall_unlock;
}
WRITE_ONCE(host_dynamic_hcalls[reserved_id], hfn);
@@ -91,7 +141,11 @@ int __pkvm_register_hcall(unsigned long hvn_hyp_va)
*/
atomic_set_release(&num_dynamic_hcalls, reserved_id + 1);
ret = reserved_id + __KVM_HOST_SMCCC_FUNC___dynamic_hcalls;
err_hcall_unlock:
hyp_spin_unlock(&dyn_hcall_lock);
err:
pkvm_modules_unlock();
return reserved_id + __KVM_HOST_SMCCC_FUNC___dynamic_hcalls;
return ret;
};
arch/arm64/kvm/pkvm.c
+11
View File
@@ -15,6 +15,7 @@
#include <linux/of_reserved_mem.h>
#include <linux/sort.h>
#include <asm/kvm_hyp.h>
#include <asm/kvm_mmu.h>
#include <asm/kvm_pkvm.h>
#include <asm/kvm_pkvm_module.h>
@@ -480,6 +481,16 @@ int pkvm_vm_ioctl_enable_cap(struct kvm *kvm, struct kvm_enable_cap *cap)
return 0;
}
#ifdef CONFIG_MODULES
static int __init early_pkvm_enable_modules(char *arg)
{
kvm_nvhe_sym(__pkvm_modules_enabled) = true;
return 0;
}
early_param("kvm-arm.protected_modules", early_pkvm_enable_modules);
#endif
struct pkvm_mod_sec_mapping {
struct pkvm_module_section *sec;
enum kvm_pgtable_prot prot;