Implement support for encrypting/decrypting the environment block into the tools/env/fw_* tools. The cipher used is AES 128 CBC and the implementation depends solely on components internal to U-Boot.
To allow building against the internal AES library, the library did need minor adjustments to not include U-Boot's headers which are not wanted to be included and define missing types.
Signed-off-by: Marek Vasut marex@denx.de --- include/aes.h | 7 +++ lib/aes.c | 4 ++ tools/env/Makefile | 2 +- tools/env/fw_env.c | 129 +++++++++++++++++++++++++++++++++++++++++++++++- tools/env/fw_env_main.c | 17 +++++-- 5 files changed, 151 insertions(+), 8 deletions(-)
V2: Checkpatch cleanup
diff --git a/include/aes.h b/include/aes.h index 4897e6f..ee0e6c2 100644 --- a/include/aes.h +++ b/include/aes.h @@ -8,6 +8,13 @@ #ifndef _AES_REF_H_ #define _AES_REF_H_
+#ifdef USE_HOSTCC +/* Define compat stuff for use in fw_* tools. */ +typedef unsigned char u8; +typedef unsigned int u32; +#define debug(...) do {} while (0) +#endif + /* * AES encryption library, with small code size, supporting only 128-bit AES * diff --git a/lib/aes.c b/lib/aes.c index 9dadb22..05c97cd 100644 --- a/lib/aes.c +++ b/lib/aes.c @@ -22,7 +22,11 @@ * REDISTRIBUTION OF THIS SOFTWARE. */
+#ifndef USE_HOSTCC #include <common.h> +#else +#include <string.h> +#endif #include "aes.h"
/* forward s-box */ diff --git a/tools/env/Makefile b/tools/env/Makefile index 6ad81fd..fa4c258 100644 --- a/tools/env/Makefile +++ b/tools/env/Makefile @@ -25,7 +25,7 @@ hostprogs-y := fw_printenv_unstripped
fw_printenv_unstripped-objs := fw_env.o fw_env_main.o \ crc32.o ctype.o linux_string.o \ - env_attr.o env_flags.o + env_attr.o env_flags.o aes.o
quiet_cmd_strip = STRIP $@ cmd_strip = $(STRIP) -o $@ $< diff --git a/tools/env/fw_env.c b/tools/env/fw_env.c index 577ce2d..acf0fa5 100644 --- a/tools/env/fw_env.c +++ b/tools/env/fw_env.c @@ -31,6 +31,10 @@
#include "fw_env.h"
+#include <aes.h> + +#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d)) + #define WHITESPACE(c) ((c == '\t') || (c == ' '))
#define min(x, y) ({ \ @@ -98,6 +102,11 @@ static struct environment environment = { .flag_scheme = FLAG_NONE, };
+/* Is AES encryption used? */ +static int aes_flag; +static uint8_t aes_key[AES_KEY_LENGTH] = { 0 }; +static int env_aes_cbc_crypt(char *data, const int enc); + static int HaveRedundEnv = 0;
static unsigned char active_flag = 1; @@ -120,6 +129,10 @@ static inline ulong getenvsize (void)
if (HaveRedundEnv) rc -= sizeof (char); + + if (aes_flag) + rc &= ~(AES_KEY_LENGTH - 1); + return rc; }
@@ -191,6 +204,36 @@ char *fw_getdefenv(char *name) return NULL; }
+static int parse_aes_key(char *key) +{ + char tmp[5] = { '0', 'x', 0, 0, 0 }; + unsigned long ul; + int i; + + if (strnlen(key, 64) != 32) { + fprintf(stderr, + "## Error: '-a' option requires 16-byte AES key\n"); + return -1; + } + + for (i = 0; i < 16; i++) { + tmp[2] = key[0]; + tmp[3] = key[1]; + errno = 0; + ul = strtoul(tmp, NULL, 16); + if (errno) { + fprintf(stderr, + "## Error: '-a' option requires valid AES key\n"); + return -1; + } + aes_key[i] = ul & 0xff; + key += 2; + } + aes_flag = 1; + + return 0; +} + /* * Print the current definition of one, or more, or all * environment variables @@ -201,6 +244,19 @@ int fw_printenv (int argc, char *argv[]) int i, n_flag; int rc = 0;
+ if (argc >= 2 && strcmp(argv[1], "-a") == 0) { + if (argc < 3) { + fprintf(stderr, + "## Error: '-a' option requires AES key\n"); + return -1; + } + rc = parse_aes_key(argv[2]); + if (rc) + return rc; + argv += 2; + argc -= 2; + } + if (fw_env_open()) return -1;
@@ -266,6 +322,16 @@ int fw_printenv (int argc, char *argv[])
int fw_env_close(void) { + int ret; + if (aes_flag) { + ret = env_aes_cbc_crypt(environment.data, 1); + if (ret) { + fprintf(stderr, + "Error: can't encrypt env for flash\n"); + return ret; + } + } + /* * Update CRC */ @@ -413,7 +479,7 @@ int fw_env_write(char *name, char *value) */ int fw_setenv(int argc, char *argv[]) { - int i; + int i, rc; size_t len; char *name; char *value = NULL; @@ -423,6 +489,24 @@ int fw_setenv(int argc, char *argv[]) return -1; }
+ if (strcmp(argv[1], "-a") == 0) { + if (argc < 3) { + fprintf(stderr, + "## Error: '-a' option requires AES key\n"); + return -1; + } + rc = parse_aes_key(argv[2]); + if (rc) + return rc; + argv += 2; + argc -= 2; + } + + if (argc < 2) { + errno = EINVAL; + return -1; + } + if (fw_env_open()) { fprintf(stderr, "Error: environment not initialized\n"); return -1; @@ -900,6 +984,28 @@ static int flash_flag_obsolete (int dev, int fd, off_t offset) return rc; }
+/* Encrypt or decrypt the environment before writing or reading it. */ +static int env_aes_cbc_crypt(char *payload, const int enc) +{ + uint8_t *data = (uint8_t *)payload; + const int len = getenvsize(); + uint8_t key_exp[AES_EXPAND_KEY_LENGTH]; + uint32_t aes_blocks; + + /* First we expand the key. */ + aes_expand_key(aes_key, key_exp); + + /* Calculate the number of AES blocks to encrypt. */ + aes_blocks = DIV_ROUND_UP(len, AES_KEY_LENGTH); + + if (enc) + aes_cbc_encrypt_blocks(key_exp, data, data, aes_blocks); + else + aes_cbc_decrypt_blocks(key_exp, data, data, aes_blocks); + + return 0; +} + static int flash_write (int fd_current, int fd_target, int dev_target) { int rc; @@ -923,6 +1029,7 @@ static int flash_write (int fd_current, int fd_target, int dev_target) fprintf(stderr, "Writing new environment at 0x%lx on %s\n", DEVOFFSET (dev_target), DEVNAME (dev_target)); #endif + rc = flash_write_buf(dev_target, fd_target, environment.image, CUR_ENVSIZE, DEVOFFSET(dev_target), DEVTYPE(dev_target)); @@ -981,8 +1088,10 @@ static int flash_read (int fd)
rc = flash_read_buf(dev_current, fd, environment.image, CUR_ENVSIZE, DEVOFFSET (dev_current), mtdinfo.type); + if (rc != CUR_ENVSIZE) + return -1;
- return (rc != CUR_ENVSIZE) ? -1 : 0; + return 0; }
static int flash_io (int mode) @@ -1075,6 +1184,8 @@ int fw_env_open(void) unsigned char flag1; void *addr1;
+ int ret; + struct env_image_single *single; struct env_image_redundant *redundant;
@@ -1109,6 +1220,13 @@ int fw_env_open(void) return -1;
crc0 = crc32 (0, (uint8_t *) environment.data, ENV_SIZE); + + if (aes_flag) { + ret = env_aes_cbc_crypt(environment.data, 0); + if (ret) + return ret; + } + crc0_ok = (crc0 == *environment.crc); if (!HaveRedundEnv) { if (!crc0_ok) { @@ -1159,6 +1277,13 @@ int fw_env_open(void) }
crc1 = crc32 (0, (uint8_t *) redundant->data, ENV_SIZE); + + if (aes_flag) { + ret = env_aes_cbc_crypt(redundant->data, 0); + if (ret) + return ret; + } + crc1_ok = (crc1 == redundant->crc); flag1 = redundant->flags;
diff --git a/tools/env/fw_env_main.c b/tools/env/fw_env_main.c index 2b85d78..ce50d58 100644 --- a/tools/env/fw_env_main.c +++ b/tools/env/fw_env_main.c @@ -9,18 +9,22 @@ * Command line user interface to firmware (=U-Boot) environment. * * Implements: - * fw_printenv [[ -n name ] | [ name ... ]] + * fw_printenv [ -a key ] [[ -n name ] | [ name ... ]] * - prints the value of a single environment variable * "name", the ``name=value'' pairs of one or more * environment variables "name", or the whole * environment if no names are specified. - * fw_setenv name [ value ... ] + * fw_setenv [ -a key ] name [ value ... ] * - If a name without any values is given, the variable * with this name is deleted from the environment; * otherwise, all "value" arguments are concatenated, * separated by single blank characters, and the * resulting string is assigned to the environment * variable "name" + * + * If '-a key' is specified, the env block is encrypted with AES 128 CBC. + * The 'key' argument is in the format of 32 hexadecimal numbers (16 bytes + * of AES key), eg. '-a aabbccddeeff00112233445566778899'. */
#include <fcntl.h> @@ -46,8 +50,8 @@ void usage(void)
fprintf(stderr, "fw_printenv/fw_setenv, " "a command line interface to U-Boot environment\n\n" - "usage:\tfw_printenv [-n] [variable name]\n" - "\tfw_setenv [variable name] [variable value]\n" + "usage:\tfw_printenv [-a key] [-n] [variable name]\n" + "\tfw_setenv [-a key] [variable name] [variable value]\n" "\tfw_setenv -s [ file ]\n" "\tfw_setenv -s - < [ file ]\n\n" "The file passed as argument contains only pairs " @@ -94,9 +98,12 @@ int main(int argc, char *argv[]) cmdname = p + 1; }
- while ((c = getopt_long (argc, argv, "ns:h", + while ((c = getopt_long (argc, argv, "a:ns:h", long_options, NULL)) != EOF) { switch (c) { + case 'a': + /* AES key, handled later */ + break; case 'n': /* handled in fw_printenv */ break;