[U-Boot] [PATCH v2 0/2] Fix signing problems with large keys

[U-Boot] [PATCH v2 0/2] Fix signing problems with large keys

[Mario Six]

This patch series fixes a problem that occurs when signing FIT images with
large keys (e.g. RSA with 4096 bits).

Signing sometimes fails because of unexpected return values from
fit_add_file_data() and the functions called by it.

Some error messages are also removed, since we tolerate failure of the
corresponding functions.

This is probably related to 1152a05 ("tools: Correct error handling in
fit_image_process_hash()") and the corresponding error reported here:

https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html

Mario Six (2):
  tools: Fix return code of fit_image_process_sig()
  rsa: Fix return value and masked error

 lib/rsa/rsa-sign.c | 12 +++++++-----
 tools/image-host.c | 16 +++++++++++-----
 2 files changed, 18 insertions(+), 10 deletions(-)

--
2.9.0

[U-Boot] [PATCH v2 1/2] tools: Fix return code of fit_image_process_sig()

[Mario Six]

When signing images, we repeatedly call fit_add_file_data() with
successively increasing size values to include the keys in the DTB.

Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
process fails sometimes, and mkimage needs to be called repeatedly to
integrate the keys into the DTB.

This is because fit_add_file_data actually returns the wrong error
code, and the loop terminates prematurely, instead of trying again with
a larger size value.

This patch corrects the return value and also removes a error message,
which is misleading, since we actually allow the function to fail. A
(hopefully helpful) comment is also added to explain the lack of error
message.

This is probably related to 1152a05 ("tools: Correct error handling in
fit_image_process_hash()") and the corresponding error reported here:

https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html

Signed-off-by: Mario Six <mario.six@gdsys.cc>
---

Changes in v2:
 - Added an additional NULL check, as suggested by Simon Glass
 - Re-formatted the comment block

---
 tools/image-host.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/image-host.c b/tools/image-host.c
index 3e14fdc..1104695 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -238,12 +238,18 @@ static int fit_image_process_sig(const char *keydir, void *keydest,
 	/* Get keyname again, as FDT has changed and invalidated our pointer */
 	info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);

-	/* Write the public key into the supplied FDT file */
-	if (keydest && info.algo->add_verify_data(&info, keydest)) {
-		printf("Failed to add verification data for '%s' signature node in '%s' image node\n",
-		       node_name, image_name);
+	if (keydest)
+		ret = info.algo->add_verify_data(&info, keydest);
+	else
 		return -1;
-	}
+
+	/*
+	 * Write the public key into the supplied FDT file; this might fail
+	 * several times, since we try signing with successively increasing
+	 * size values
+	 */
+	if (keydest && ret)
+		return ret;

 	return 0;
 }
--
2.9.0

[U-Boot] [PATCH v2 2/2] rsa: Fix return value and masked error

[Mario Six]

When signing images, we repeatedly call fit_add_file_data() with
successively increasing size values to include the keys in the DTB.

Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
process fails sometimes, and mkimage needs to be called repeatedly to
integrate the keys into the DTB.

This is because fit_add_file_data actually returns the wrong error
code, and the loop terminates prematurely, instead of trying again with
a larger size value.

This patch corrects the return value by fixing the return value of
fdt_add_bignum, fixes a case where an error is masked by a unconditional
setting of a return value variable, and also removes a error message,
which is misleading, since we actually allow the function to fail. A
(hopefully helpful) comment is also added to explain the lack of error
message.

This is probably related to 1152a05 ("tools: Correct error handling in
fit_image_process_hash()") and the corresponding error reported here:

https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html

Signed-off-by: Mario Six <mario.six@gdsys.cc>
---

Changes in v2:
 - Re-formatted the comment block

---
 lib/rsa/rsa-sign.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/lib/rsa/rsa-sign.c b/lib/rsa/rsa-sign.c
index 5d9716f..c26f741 100644
--- a/lib/rsa/rsa-sign.c
+++ b/lib/rsa/rsa-sign.c
@@ -420,11 +420,13 @@ static int fdt_add_bignum(void *blob, int noffset, const char *prop_name,
 		BN_rshift(num, num, 32); /*  N = N/B */
 	}

+	/*
+	 * We try signing with successively increasing size values, so this
+	 * might fail several times
+	 */
 	ret = fdt_setprop(blob, noffset, prop_name, buf, size);
-	if (ret) {
-		fprintf(stderr, "Failed to write public key to FIT\n");
-		return -ENOSPC;
-	}
+	if (ret)
+		return -FDT_ERR_NOSPACE;
 	free(buf);
 	BN_free(tmp);
 	BN_free(big2);
@@ -508,7 +510,7 @@ int rsa_add_verify_data(struct image_sign_info *info, void *keydest)
 		ret = fdt_setprop_string(keydest, node, FIT_ALGO_PROP,
 					 info->algo->name);
 	}
-	if (info->require_keys) {
+	if (!ret && info->require_keys) {
 		ret = fdt_setprop_string(keydest, node, "required",
 					 info->require_keys);
 	}
--
2.9.0

[U-Boot] [PATCH v2 2/2] rsa: Fix return value and masked error

[Simon Glass]

On 22 July 2016 at 00:58, Mario Six <mario.six@gdsys.cc> wrote:
> When signing images, we repeatedly call fit_add_file_data() with
> successively increasing size values to include the keys in the DTB.
>
> Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
> process fails sometimes, and mkimage needs to be called repeatedly to
> integrate the keys into the DTB.
>
> This is because fit_add_file_data actually returns the wrong error
> code, and the loop terminates prematurely, instead of trying again with
> a larger size value.
>
> This patch corrects the return value by fixing the return value of
> fdt_add_bignum, fixes a case where an error is masked by a unconditional
> setting of a return value variable, and also removes a error message,
> which is misleading, since we actually allow the function to fail. A
> (hopefully helpful) comment is also added to explain the lack of error
> message.
>
> This is probably related to 1152a05 ("tools: Correct error handling in
> fit_image_process_hash()") and the corresponding error reported here:
>
> https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html
>
> Signed-off-by: Mario Six <mario.six@gdsys.cc>
> ---
>
> Changes in v2:
>  - Re-formatted the comment block
>
> ---
>  lib/rsa/rsa-sign.c | 12 +++++++-----
>  1 file changed, 7 insertions(+), 5 deletions(-)

Reviewed-by: Simon Glass <sjg@chromium.org>

[U-Boot] [U-Boot, v2, 1/2] tools: Fix return code of fit_image_process_sig()

[Tom Rini]

On Fri, Jul 22, 2016 at 08:58:40AM +0200, mario.six at gdsys.cc wrote:

> When signing images, we repeatedly call fit_add_file_data() with
> successively increasing size values to include the keys in the DTB.
> 
> Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
> process fails sometimes, and mkimage needs to be called repeatedly to
> integrate the keys into the DTB.
> 
> This is because fit_add_file_data actually returns the wrong error
> code, and the loop terminates prematurely, instead of trying again with
> a larger size value.
> 
> This patch corrects the return value and also removes a error message,
> which is misleading, since we actually allow the function to fail. A
> (hopefully helpful) comment is also added to explain the lack of error
> message.
> 
> This is probably related to 1152a05 ("tools: Correct error handling in
> fit_image_process_hash()") and the corresponding error reported here:
> 
> https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html
> 
> Signed-off-by: Mario Six <mario.six@gdsys.cc>

The delta between v1 and v2 has been applied to u-boot/master, thanks!

-- 
Tom
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[U-Boot] [U-Boot, v2, 2/2] rsa: Fix return value and masked error

[Tom Rini]

On Fri, Jul 22, 2016 at 08:58:41AM +0200, mario.six at gdsys.cc wrote:

> When signing images, we repeatedly call fit_add_file_data() with
> successively increasing size values to include the keys in the DTB.
> 
> Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
> process fails sometimes, and mkimage needs to be called repeatedly to
> integrate the keys into the DTB.
> 
> This is because fit_add_file_data actually returns the wrong error
> code, and the loop terminates prematurely, instead of trying again with
> a larger size value.
> 
> This patch corrects the return value by fixing the return value of
> fdt_add_bignum, fixes a case where an error is masked by a unconditional
> setting of a return value variable, and also removes a error message,
> which is misleading, since we actually allow the function to fail. A
> (hopefully helpful) comment is also added to explain the lack of error
> message.
> 
> This is probably related to 1152a05 ("tools: Correct error handling in
> fit_image_process_hash()") and the corresponding error reported here:
> 
> https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html
> 
> Signed-off-by: Mario Six <mario.six@gdsys.cc>
> Reviewed-by: Simon Glass <sjg@chromium.org>

The delta between v1 and v2 has been applied to u-boot/master, thanks!

-- 
Tom
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