[U-Boot] [PATCH] autoboot.c: Add feature to stop autobooting via SHA256 encrypted password
Stefan Roese
sr at denx.de
Wed Mar 11 09:51:37 CET 2015
This patch adds the feature to only stop the autobooting, and therefor
boot into the U-Boot prompt, when the input string / password matches
a values that is encypted via a SHA256 hash and saved in the environment.
This feature is enabled by defined these config options:
CONFIG_AUTOBOOT_KEYED
CONFIG_AUTOBOOT_STOP_STR_SHA256
Signed-off-by: Stefan Roese <sr at denx.de>
---
common/autoboot.c | 45 ++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 44 insertions(+), 1 deletion(-)
diff --git a/common/autoboot.c b/common/autoboot.c
index c27cc2c..4635551 100644
--- a/common/autoboot.c
+++ b/common/autoboot.c
@@ -12,6 +12,7 @@
#include <fdtdec.h>
#include <menu.h>
#include <post.h>
+#include <u-boot/sha256.h>
DECLARE_GLOBAL_DATA_PTR;
@@ -35,6 +36,11 @@ static int abortboot_keyed(int bootdelay)
{
int abort = 0;
uint64_t etime = endtick(bootdelay);
+#if defined(CONFIG_AUTOBOOT_STOP_STR_SHA256)
+ const char *sha_env_str = getenv("bootstopkeysha256");
+ u8 sha_env[SHA256_SUM_LEN];
+ u8 sha[SHA256_SUM_LEN];
+#else
struct {
char *str;
u_int len;
@@ -46,10 +52,11 @@ static int abortboot_keyed(int bootdelay)
{ .str = getenv("bootstopkey"), .retry = 0 },
{ .str = getenv("bootstopkey2"), .retry = 0 },
};
+ u_int presskey_max = 0;
+#endif
char presskey[MAX_DELAY_STOP_STR];
u_int presskey_len = 0;
- u_int presskey_max = 0;
u_int i;
#ifndef CONFIG_ZERO_BOOTDELAY_CHECK
@@ -61,6 +68,41 @@ static int abortboot_keyed(int bootdelay)
printf(CONFIG_AUTOBOOT_PROMPT);
# endif
+#if defined(CONFIG_AUTOBOOT_STOP_STR_SHA256)
+ if (sha_env_str == NULL)
+ sha_env_str = CONFIG_AUTOBOOT_STOP_STR_SHA256;
+
+ /*
+ * Generate the binary value from the environment hash value
+ * so that we can compare this value with the computed hash
+ * from the user input
+ */
+ for (i = 0; i < SHA256_SUM_LEN; i++) {
+ char chr[3];
+
+ strncpy(chr, &sha_env_str[i * 2], 2);
+ sha_env[i] = simple_strtoul(chr, NULL, 16);
+ }
+
+ /*
+ * We don't know how long the stop-string is, so we need to
+ * generate the sha256 hash upon each input character and
+ * compare the value with the one saved in the environment
+ */
+ do {
+ if (tstc()) {
+ presskey[presskey_len++] = getc();
+
+ /* Calculate sha256 upon each new char */
+ sha256_csum_wd((unsigned char *)presskey, presskey_len,
+ sha, CHUNKSZ_SHA256);
+
+ /* And check if sha matches saved value in env */
+ if (memcmp(sha, sha_env, SHA256_SUM_LEN) == 0)
+ abort = 1;
+ }
+ } while (!abort && get_ticks() <= etime);
+#else
# ifdef CONFIG_AUTOBOOT_DELAY_STR
if (delaykey[0].str == NULL)
delaykey[0].str = CONFIG_AUTOBOOT_DELAY_STR;
@@ -124,6 +166,7 @@ static int abortboot_keyed(int bootdelay)
}
}
} while (!abort && get_ticks() <= etime);
+#endif
if (!abort)
debug_bootkeys("key timeout\n");
--
2.3.2
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