[PATCH 09/37] imx: HAB: Validate IVT before authenticating image

[Peng Fan (OSS)]

From: Utkarsh Gupta <utkarsh.gupta at nxp.com>

Calling csf_is_valid() with an un-signed image may lead to data abort
as the CSF pointer could be pointing to a garbage address when accessed
in HAB_HDR_LEN(*(const struct hab_hdr *)(ulong)ivt_initial->csf).

Authenticate image from DDR location 0x80800000...
Check CSF for Write Data command before authenticating image
data abort
pc : [<fff5494c>]          lr : [<fff54910>]
reloc pc : [<8780294c>]    lr : [<87802910>]
sp : fdf45dc8  ip : 00000214     fp : 00000000
r10: fffb6170  r9 : fdf4fec0     r8 : 00722020
r7 : 80f20000  r6 : 80800000     r5 : 80800000  r4 : 00720000
r3 : 17a5aca3  r2 : 00000000     r1 : 80f2201f  r0 : 00000019
Flags: NzcV  IRQs off  FIQs off  Mode SVC_32
Resetting CPU ...

resetting ...

To avoid such errors during authentication process, validate IVT structure
by calling validate_ivt function which checks the following values in an IVT:

IVT_HEADER = 0x4X2000D1
ENTRY != 0x0
RES1 = 0x0
DCD = 0x0       /* Recommended */
SELF != 0x0     /* Absoulute address of IVT */
CSF != 0x0
RES2 = 0x0

This commit also checks if Image's start address is 4 byte aligned.

commit "0088d127 MLK-14945 HAB: Check if IVT valid before authenticating image"
removed as this patch addresses the issue.

Signed-off-by: Utkarsh Gupta <utkarsh.gupta at nxp.com>
Signed-off-by: Ye Li <ye.li at nxp.com>
Signed-off-by: Peng Fan <peng.fan at nxp.com>
---
 arch/arm/mach-imx/hab.c | 59 ++++++++++++++++++++++++++++++-----------
 1 file changed, 43 insertions(+), 16 deletions(-)

diff --git a/arch/arm/mach-imx/hab.c b/arch/arm/mach-imx/hab.c
index 9ebdbe6ac3..f2d5f744e8 100644
--- a/arch/arm/mach-imx/hab.c
+++ b/arch/arm/mach-imx/hab.c
@@ -728,6 +728,48 @@ static bool csf_is_valid(struct ivt *ivt, ulong start_addr, size_t bytes)
 	return true;
 }
 
+/*
+ * Validate IVT structure of the image being authenticated
+ */
+static int validate_ivt(struct ivt *ivt_initial)
+{
+	struct ivt_header *ivt_hdr = &ivt_initial->hdr;
+
+	if ((ulong)ivt_initial & 0x3) {
+		puts("Error: Image's start address is not 4 byte aligned\n");
+		return 0;
+	}
+
+	/* Check IVT fields before allowing authentication */
+	if ((!verify_ivt_header(ivt_hdr)) && \
+	    (ivt_initial->entry != 0x0) && \
+	    (ivt_initial->reserved1 == 0x0) && \
+	    (ivt_initial->self == \
+		   (uint32_t)((ulong)ivt_initial & 0xffffffff)) && \
+	    (ivt_initial->csf != 0x0) && \
+	    (ivt_initial->reserved2 == 0x0)) {
+		/* Report boot failure if DCD pointer is found in IVT */
+		if (ivt_initial->dcd != 0x0)
+			puts("Error: DCD pointer must be 0\n");
+		else
+			return 1;
+	}
+
+	puts("Error: Invalid IVT structure\n");
+	debug("\nAllowed IVT structure:\n");
+	debug("IVT HDR       = 0x4X2000D1\n");
+	debug("IVT ENTRY     = 0xXXXXXXXX\n");
+	debug("IVT RSV1      = 0x0\n");
+	debug("IVT DCD       = 0x0\n");		/* Recommended */
+	debug("IVT BOOT_DATA = 0xXXXXXXXX\n");	/* Commonly 0x0 */
+	debug("IVT SELF      = 0xXXXXXXXX\n");	/* = ddr_start + ivt_offset */
+	debug("IVT CSF       = 0xXXXXXXXX\n");
+	debug("IVT RSV2      = 0x0\n");
+
+	/* Invalid IVT structure */
+	return 0;
+}
+
 bool imx_hab_is_enabled(void)
 {
 	struct imx_sec_config_fuse_t *fuse =
@@ -753,7 +795,6 @@ int imx_hab_authenticate_image(uint32_t ddr_start, uint32_t image_size,
 	int result = 1;
 	ulong start;
 	struct ivt *ivt;
-	struct ivt_header *ivt_hdr;
 	enum hab_status status;
 
 	if (!imx_hab_is_enabled()) {
@@ -769,24 +810,10 @@ int imx_hab_authenticate_image(uint32_t ddr_start, uint32_t image_size,
 	/* Calculate IVT address header */
 	ivt_addr = (ulong) (ddr_start + ivt_offset);
 	ivt = (struct ivt *)ivt_addr;
-	ivt_hdr = &ivt->hdr;
 
 	/* Verify IVT header bugging out on error */
-	if (verify_ivt_header(ivt_hdr))
-		goto hab_authentication_exit;
-
-	/* Verify IVT body */
-	if (ivt->self != ivt_addr) {
-		printf("ivt->self 0x%08x pointer is 0x%08lx\n",
-		       ivt->self, ivt_addr);
+	if (!validate_ivt(ivt))
 		goto hab_authentication_exit;
-	}
-
-	/* Verify if IVT DCD pointer is NULL */
-	if (ivt->dcd) {
-		puts("Error: DCD pointer must be NULL\n");
-		goto hab_authentication_exit;
-	}
 
 	start = ddr_start;
 	bytes = image_size;
-- 
2.25.1