feat(drtm): add a few DRTM DMA protection APIs
Added DRTM DMA protections APIs, and called them during
the DLME launch and DRTM SMC handling.
Change-Id: I29e7238c04e2ca9f26600276c5c05bff5387789e
Signed-off-by: Manish V Badarkhe <Manish.Badarkhe@arm.com>
diff --git a/services/std_svc/drtm/drtm_dma_prot.c b/services/std_svc/drtm/drtm_dma_prot.c
index 9d014a0..48317fd 100644
--- a/services/std_svc/drtm/drtm_dma_prot.c
+++ b/services/std_svc/drtm/drtm_dma_prot.c
@@ -14,9 +14,30 @@
#include <string.h>
#include <common/debug.h>
-
+#include <drivers/arm/smmu_v3.h>
#include "drtm_dma_prot.h"
+#include "drtm_main.h"
+#include "drtm_remediation.h"
#include <plat/common/platform.h>
+#include <smccc_helpers.h>
+
+/*
+ * ________________________ LAUNCH success ________________________
+ * | Initial | -------------------> | Prot engaged |
+ * |````````````````````````| |````````````````````````|
+ * | request.type == NONE | | request.type != NONE |
+ * | | <------------------- | |
+ * `________________________' UNPROTECT_MEM `________________________'
+ *
+ * Transitions that are not shown correspond to ABI calls that do not change
+ * state and result in an error being returned to the caller.
+ */
+static struct dma_prot active_prot = {
+ .type = PROTECT_NONE,
+};
+
+/* Version-independent type. */
+typedef struct drtm_dl_dma_prot_args_v1 struct_drtm_dl_dma_prot_args;
/*
* This function checks that platform supports complete DMA protection.
@@ -59,3 +80,184 @@
return must_init_fail;
}
+
+/*
+ * Checks that the DMA protection arguments are valid and that the given
+ * protected regions are covered by DMA protection.
+ */
+enum drtm_retc drtm_dma_prot_check_args(const struct_drtm_dl_dma_prot_args *a,
+ int a_dma_prot_type,
+ drtm_mem_region_t p)
+{
+ switch ((enum dma_prot_type)a_dma_prot_type) {
+ case PROTECT_MEM_ALL:
+ if (a->dma_prot_table_paddr || a->dma_prot_table_size) {
+ ERROR("DRTM: invalid launch due to inconsistent"
+ " DMA protection arguments\n");
+ return MEM_PROTECT_INVALID;
+ }
+ /*
+ * Full DMA protection ought to ensure that the DLME and NWd
+ * DCE regions are protected, no further checks required.
+ */
+ return SUCCESS;
+
+ default:
+ ERROR("DRTM: invalid launch due to unsupported DMA protection type\n");
+ return MEM_PROTECT_INVALID;
+ }
+}
+
+enum drtm_retc drtm_dma_prot_engage(const struct_drtm_dl_dma_prot_args *a,
+ int a_dma_prot_type)
+{
+ const uintptr_t *smmus;
+ size_t num_smmus = 0;
+
+ if (active_prot.type != PROTECT_NONE) {
+ ERROR("DRTM: launch denied as previous DMA protection"
+ " is still engaged\n");
+ return DENIED;
+ }
+
+ if (a_dma_prot_type == PROTECT_NONE) {
+ return SUCCESS;
+ /* Only PROTECT_MEM_ALL is supported currently. */
+ } else if (a_dma_prot_type != PROTECT_MEM_ALL) {
+ ERROR("%s(): unimplemented DMA protection type\n", __func__);
+ panic();
+ }
+
+ /*
+ * Engage SMMUs in accordance with the request we have previously received.
+ * Only PROTECT_MEM_ALL is implemented currently.
+ */
+ plat_enumerate_smmus(&smmus, &num_smmus);
+ for (const uintptr_t *smmu = smmus; smmu < smmus+num_smmus; smmu++) {
+ /*
+ * TODO: Invalidate SMMU's Stage-1 and Stage-2 TLB entries. This ensures
+ * that any outstanding device transactions are completed, see Section
+ * 3.21.1, specification IHI_0070_C_a for an approximate reference.
+ */
+ int rc = smmuv3_ns_set_abort_all(*smmu);
+ if (rc != 0) {
+ ERROR("DRTM: SMMU at PA 0x%lx failed to engage DMA protection"
+ " rc=%d\n", *smmu, rc);
+ return INTERNAL_ERROR;
+ }
+ }
+
+ /*
+ * TODO: Restrict DMA from the GIC.
+ *
+ * Full DMA protection may be achieved as follows:
+ *
+ * With a GICv3:
+ * - Set GICR_CTLR.EnableLPIs to 0, for each GICR;
+ * GICR_CTLR.RWP == 0 must be the case before finishing, for each GICR.
+ * - Set GITS_CTLR.Enabled to 0;
+ * GITS_CTLR.Quiescent == 1 must be the case before finishing.
+ *
+ * In addition, with a GICv4:
+ * - Set GICR_VPENDBASER.Valid to 0, for each GICR;
+ * GICR_CTLR.RWP == 0 must be the case before finishing, for each GICR.
+ *
+ * Alternatively, e.g. if some bit values cannot be changed at runtime,
+ * this procedure should return an error if the LPI Pending and
+ * Configuration tables overlap the regions being protected.
+ */
+
+ active_prot.type = a_dma_prot_type;
+
+ return SUCCESS;
+}
+
+/*
+ * Undo what has previously been done in drtm_dma_prot_engage(), or enter
+ * remediation if it is not possible.
+ */
+enum drtm_retc drtm_dma_prot_disengage(void)
+{
+ const uintptr_t *smmus;
+ size_t num_smmus = 0;
+ const char *err_str = "cannot undo PROTECT_MEM_ALL SMMU config";
+
+ if (active_prot.type == PROTECT_NONE) {
+ return SUCCESS;
+ /* Only PROTECT_MEM_ALL is supported currently. */
+ } else if (active_prot.type != PROTECT_MEM_ALL) {
+ ERROR("%s(): unimplemented DMA protection type\n", __func__);
+ panic();
+ }
+
+ /*
+ * For PROTECT_MEM_ALL, undo the SMMU configuration for "abort all" mode
+ * done during engage().
+ */
+ /* Simply enter remediation for now. */
+ (void)smmus;
+ (void)num_smmus;
+ drtm_enter_remediation(1ULL, err_str);
+
+ /* TODO: Undo GIC DMA restrictions. */
+
+ active_prot.type = PROTECT_NONE;
+
+ return SUCCESS;
+}
+
+uint64_t drtm_unprotect_mem(void *ctx)
+{
+ enum drtm_retc ret;
+
+ switch (active_prot.type) {
+ case PROTECT_NONE:
+ ERROR("DRTM: invalid UNPROTECT_MEM, no DMA protection has"
+ " previously been engaged\n");
+ ret = DENIED;
+ break;
+
+ case PROTECT_MEM_ALL:
+ /*
+ * UNPROTECT_MEM is a no-op for PROTECT_MEM_ALL: DRTM must not touch
+ * the NS SMMU as it is expected that the DLME has configured it.
+ */
+ active_prot.type = PROTECT_NONE;
+
+ ret = SUCCESS;
+ break;
+
+ default:
+ ret = drtm_dma_prot_disengage();
+ break;
+ }
+
+ SMC_RET1(ctx, ret);
+}
+
+void drtm_dma_prot_serialise_table(uint8_t *dst, size_t *size_out)
+{
+ if (active_prot.type == PROTECT_NONE) {
+ return;
+ } else if (active_prot.type != PROTECT_MEM_ALL) {
+ ERROR("%s(): unimplemented DMA protection type\n", __func__);
+ panic();
+ }
+
+ struct __packed descr_table_1 {
+ drtm_memory_region_descriptor_table_t header;
+ drtm_mem_region_t regions[1];
+ } prot_table = {
+ .header = {
+ .revision = 1,
+ .num_regions = sizeof(((struct descr_table_1 *)NULL)->regions) /
+ sizeof(((struct descr_table_1 *)NULL)->regions[0])
+ },
+ .regions = {
+ {.region_address = 0, PAGES_AND_TYPE(UINT64_MAX, 0x3)},
+ }
+ };
+
+ memcpy(dst, &prot_table, sizeof(prot_table));
+ *size_out = sizeof(prot_table);
+}
diff --git a/services/std_svc/drtm/drtm_dma_prot.h b/services/std_svc/drtm/drtm_dma_prot.h
index e9b1fe9..79dc9cb 100644
--- a/services/std_svc/drtm/drtm_dma_prot.h
+++ b/services/std_svc/drtm/drtm_dma_prot.h
@@ -8,15 +8,43 @@
#define DRTM_DMA_PROT_H
#include <stdint.h>
+#include <plat/common/platform.h>
+#include <services/drtm_svc.h>
struct __packed drtm_dl_dma_prot_args_v1 {
uint64_t dma_prot_table_paddr;
uint64_t dma_prot_table_size;
};
+/* Values for DRTM_PROTECT_MEMORY */
+enum dma_prot_type {
+ PROTECT_NONE = -1,
+ PROTECT_MEM_ALL = 0,
+ PROTECT_MEM_REGION = 2,
+};
+
+struct dma_prot {
+ enum dma_prot_type type;
+};
+
+#define DRTM_MEM_REGION_PAGES_AND_TYPE(pages, type) \
+ (((uint64_t)(pages) & (((uint64_t)1 << 52) - 1)) \
+ | (((uint64_t)(type) & 0x7) << 52))
+
+#define PAGES_AND_TYPE(pages, type) \
+ .region_size_type = DRTM_MEM_REGION_PAGES_AND_TYPE(pages, type)
+
/* Opaque / encapsulated type. */
typedef struct drtm_dl_dma_prot_args_v1 drtm_dl_dma_prot_args_v1_t;
bool drtm_dma_prot_init(void);
+enum drtm_retc drtm_dma_prot_check_args(const drtm_dl_dma_prot_args_v1_t *a,
+ int a_dma_prot_type,
+ drtm_mem_region_t p);
+enum drtm_retc drtm_dma_prot_engage(const drtm_dl_dma_prot_args_v1_t *a,
+ int a_dma_prot_type);
+enum drtm_retc drtm_dma_prot_disengage(void);
+uint64_t drtm_unprotect_mem(void *ctx);
+void drtm_dma_prot_serialise_table(uint8_t *dst, size_t *size_out);
#endif /* DRTM_DMA_PROT_H */
diff --git a/services/std_svc/drtm/drtm_main.c b/services/std_svc/drtm/drtm_main.c
index 9878887..53aafeb 100644
--- a/services/std_svc/drtm/drtm_main.c
+++ b/services/std_svc/drtm/drtm_main.c
@@ -358,6 +358,7 @@
static uint64_t drtm_dynamic_launch(uint64_t x1, void *handle)
{
enum drtm_retc ret = SUCCESS;
+ enum drtm_retc dma_prot_ret;
struct_drtm_dl_args args;
/* Ensure that only boot PE is powered on */
@@ -380,6 +381,17 @@
SMC_RET1(handle, ret);
}
+ /*
+ * Engage the DMA protections. The launch cannot proceed without the DMA
+ * protections due to potential TOC/TOU vulnerabilities w.r.t. the DLME
+ * region (and to the NWd DCE region).
+ */
+ ret = drtm_dma_prot_engage(&args.dma_prot_args,
+ DL_ARGS_GET_DMA_PROT_TYPE(&args));
+ if (ret != SUCCESS) {
+ SMC_RET1(handle, ret);
+ }
+
SMC_RET1(handle, ret);
}
@@ -497,7 +509,7 @@
case ARM_DRTM_SVC_UNPROTECT_MEM:
INFO("DRTM service handler: unprotect mem\n");
- SMC_RET1(handle, SMC_OK);
+ return drtm_unprotect_mem(handle);
break; /* not reached */
case ARM_DRTM_SVC_DYNAMIC_LAUNCH:
diff --git a/services/std_svc/drtm/drtm_main.h b/services/std_svc/drtm/drtm_main.h
index cccc14f..9bf5400 100644
--- a/services/std_svc/drtm/drtm_main.h
+++ b/services/std_svc/drtm/drtm_main.h
@@ -31,6 +31,7 @@
#define DRTM_PAGE_SIZE (4 * (1 << 10))
#define DRTM_PAGE_SIZE_STR "4-KiB"
+#define DL_ARGS_GET_DMA_PROT_TYPE(a) (((a)->features >> 3) & 0x7U)
#define DL_ARGS_GET_PCR_SCHEMA(a) (((a)->features >> 1) & 0x3U)
#define DL_ARGS_GET_DLME_ENTRY_POINT(a) \
(((a)->dlme_paddr + (a)->dlme_img_off + (a)->dlme_img_ep_off))