From ed286bc80e9d237dd1732ced037427e7d9a277a0 Mon Sep 17 00:00:00 2001 From: Utkarsh Gupta Date: Tue, 20 Feb 2018 01:19:24 +0000 Subject: [PATCH] imx: hab: Check if CSF is valid before authenticating image For proper authentication the HAB code must check if the CSF is valid. Users must call the csf_is_valid() function to parse the CSF prior to authenticating any additional images. The function will return a failure if any of the following invalid conditions are met: - CSF pointer is NULL - CSF Header does not exist - CSF does not lie within the image bounds - CSF command length zero Signed-off-by: Utkarsh Gupta Signed-off-by: Breno Lima Reviewed-by: Fabio Estevam --- arch/arm/include/asm/mach-imx/hab.h | 8 +++ arch/arm/mach-imx/hab.c | 81 +++++++++++++++++++++++++++++ 2 files changed, 89 insertions(+) diff --git a/arch/arm/include/asm/mach-imx/hab.h b/arch/arm/include/asm/mach-imx/hab.h index a0cb19db2f..bb732030e9 100644 --- a/arch/arm/include/asm/mach-imx/hab.h +++ b/arch/arm/include/asm/mach-imx/hab.h @@ -38,6 +38,12 @@ struct ivt { uint32_t reserved2; /* Reserved should be zero */ }; +struct __packed hab_hdr { + u8 tag; /* Tag field */ + u8 len[2]; /* Length field in bytes (big-endian) */ + u8 par; /* Parameters field */ +}; + /* -------- start of HAB API updates ------------*/ /* The following are taken from HAB4 SIS */ @@ -182,6 +188,8 @@ typedef void hapi_clock_init_t(void); #define HAB_CID_ROM 0 /**< ROM Caller ID */ #define HAB_CID_UBOOT 1 /**< UBOOT Caller ID*/ +#define HAB_CMD_HDR 0xD4 /* CSF Header */ + #define IVT_SIZE 0x20 #define CSF_PAD_SIZE 0x2000 diff --git a/arch/arm/mach-imx/hab.c b/arch/arm/mach-imx/hab.c index ba6b31d490..7f66965af5 100644 --- a/arch/arm/mach-imx/hab.c +++ b/arch/arm/mach-imx/hab.c @@ -453,6 +453,83 @@ U_BOOT_CMD( #endif /* !defined(CONFIG_SPL_BUILD) */ +/* Get CSF Header length */ +static int get_hab_hdr_len(struct hab_hdr *hdr) +{ + return (size_t)((hdr->len[0] << 8) + (hdr->len[1])); +} + +/* Check whether addr lies between start and + * end and is within the length of the image + */ +static int chk_bounds(u8 *addr, size_t bytes, u8 *start, u8 *end) +{ + size_t csf_size = (size_t)((end + 1) - addr); + + return (addr && (addr >= start) && (addr <= end) && + (csf_size >= bytes)); +} + +/* Get Length of each command in CSF */ +static int get_csf_cmd_hdr_len(u8 *csf_hdr) +{ + if (*csf_hdr == HAB_CMD_HDR) + return sizeof(struct hab_hdr); + + return get_hab_hdr_len((struct hab_hdr *)csf_hdr); +} + +/* Check if CSF is valid */ +static bool csf_is_valid(struct ivt *ivt, ulong start_addr, size_t bytes) +{ + u8 *start = (u8 *)start_addr; + u8 *csf_hdr; + u8 *end; + + size_t csf_hdr_len; + size_t cmd_hdr_len; + size_t offset = 0; + + if (bytes != 0) + end = start + bytes - 1; + else + end = start; + + /* Verify if CSF pointer content is zero */ + if (!ivt->csf) { + puts("Error: CSF pointer is NULL\n"); + return false; + } + + csf_hdr = (u8 *)ivt->csf; + + /* Verify if CSF Header exist */ + if (*csf_hdr != HAB_CMD_HDR) { + puts("Error: CSF header command not found\n"); + return false; + } + + csf_hdr_len = get_hab_hdr_len((struct hab_hdr *)csf_hdr); + + /* Check if the CSF lies within the image bounds */ + if (!chk_bounds(csf_hdr, csf_hdr_len, start, end)) { + puts("Error: CSF lies outside the image bounds\n"); + return false; + } + + do { + cmd_hdr_len = get_csf_cmd_hdr_len(&csf_hdr[offset]); + if (!cmd_hdr_len) { + puts("Error: Invalid command length\n"); + return false; + } + offset += cmd_hdr_len; + + } while (offset < csf_hdr_len); + + return true; +} + bool imx_hab_is_enabled(void) { struct imx_sec_config_fuse_t *fuse = @@ -525,6 +602,10 @@ int imx_hab_authenticate_image(uint32_t ddr_start, uint32_t image_size, start = ddr_start; bytes = image_size; + /* Verify CSF */ + if (!csf_is_valid(ivt, start, bytes)) + goto hab_authentication_exit; + if (hab_rvt_entry() != HAB_SUCCESS) { puts("hab entry function fail\n"); goto hab_exit_failure_print_status; -- 2.25.1