[U-Boot] [PATCH] drivers: optee: rpmb: fix returning CID to TEE
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io --- drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id); + int i;
if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND; @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
- memcpy(info->cid, mmc->cid, sizeof(info->cid)); + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); + info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;
Hi Jorge,
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);
So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
AFAICS U-boot should be providing the same CID than Linux does, and whatever OP-TEE might be masking out on the receiving end is orthogonal to such value, isnt it? maybe I am not understanding your point?
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
AFAICS U-boot should be providing the same CID than Linux does, and whatever OP-TEE might be masking out on the receiving end is orthogonal to such value, isnt it? maybe I am not understanding your point?
I agree that something must be done so it works with Linux. However, I'm a bit surprised that we haven't seen this earlier.
If there's an error in how it's done in Linux we may need to implement some workaround in tee-supplicant or perhaps in secure world. If we wait with that until after we have some workarounds in U-Boot too, stuff will become even more messy.
Cheers, Jens
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
AFAICS U-boot should be providing the same CID than Linux does, and whatever OP-TEE might be masking out on the receiving end is orthogonal to such value, isnt it? maybe I am not understanding your point?
I agree that something must be done so it works with Linux. However, I'm a bit surprised that we haven't seen this earlier.
could be that accessing rpmb has never been done from both linux and u-boot?
in fact when I was trying to access rpmb values from uboot via AVB I also noticed that the current code (at least in my imx7 platform) wouldnt work due to cache alignment issues...so needed an additional patch (which I still need to send to this ML) to use aligned buffers on the stack in the read/write rpmb functions.
If there's an error in how it's done in Linux we may need to implement some workaround in tee-supplicant or perhaps in secure world. If we wait with that until after we have some workarounds in U-Boot too, stuff will become even more messy.
Cheers, Jens
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
AFAICS U-boot should be providing the same CID than Linux does, and whatever OP-TEE might be masking out on the receiving end is orthogonal to such value, isnt it? maybe I am not understanding your point?
I agree that something must be done so it works with Linux. However, I'm a bit surprised that we haven't seen this earlier.
could be that accessing rpmb has never been done from both linux and u-boot?
I'm sure I've tested that on Hikey when I implemented this stuff. I know I wrote the key using Linux since I didn't have the complete chain in U-Boot to start with then.
in fact when I was trying to access rpmb values from uboot via AVB I also noticed that the current code (at least in my imx7 platform) wouldnt work due to cache alignment issues...so needed an additional patch (which I still need to send to this ML) to use aligned buffers on the stack in the read/write rpmb functions.
If there's an error in how it's done in Linux we may need to implement some workaround in tee-supplicant or perhaps in secure world. If we wait with that until after we have some workarounds in U-Boot too, stuff will become even more messy.
Cheers, Jens
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote:
The MMC CID value is one of the input parameters to unequivocally provision the the RPMB key.
Before this patch, the value returned by the mmc driver in the Linux kernel differs from the one returned by uboot to optee.
This means that if Linux provisions the RPMB key, uboot wont be able to access it (and the other way around).
Fix it so both uboot and linux can access the RPMB partition independently of who provisions the key.
Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io
drivers/tee/optee/rpmb.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)
diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c index 955155b3f8..5dbb1eae4a 100644 --- a/drivers/tee/optee/rpmb.c +++ b/drivers/tee/optee/rpmb.c @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) { struct mmc *mmc = find_mmc_device(dev_id);
int i; if (!mmc) return TEE_ERROR_ITEM_NOT_FOUND;@@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) if (!mmc->ext_csd) return TEE_ERROR_GENERIC;
memcpy(info->cid, mmc->cid, sizeof(info->cid));
for (i = 0; i < ARRAY_SIZE(mmc->cid); i++)((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]);So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
I had a quick look at the linux driver and both are using LE operations when reading from the corresponding registers.
Moreover, when interpreting the CID response (ie RSP_136) they both perform the same arithmetics:
uboot: fsl_esdhc_imx.c ------ if (cmd->resp_type & MMC_RSP_136) { u32 cmdrsp3, cmdrsp2, cmdrsp1, cmdrsp0;
cmdrsp3 = esdhc_read32(®s->cmdrsp3); cmdrsp2 = esdhc_read32(®s->cmdrsp2); cmdrsp1 = esdhc_read32(®s->cmdrsp1); cmdrsp0 = esdhc_read32(®s->cmdrsp0); cmd->response[0] = (cmdrsp3 << 8) | (cmdrsp2 >> 24); cmd->response[1] = (cmdrsp2 << 8) | (cmdrsp1 >> 24); cmd->response[2] = (cmdrsp1 << 8) | (cmdrsp0 >> 24); cmd->response[3] = (cmdrsp0 << 8); }
linux: ------ static void sdhci_read_rsp_136(struct sdhci_host *host, struct mmc_command *cmd) { int i, reg;
for (i = 0; i < 4; i++) { reg = SDHCI_RESPONSE + (3 - i) * 4; cmd->resp[i] = sdhci_readl(host, reg); }
if (host->quirks2 & SDHCI_QUIRK2_RSP_136_HAS_CRC) return;
/* CRC is stripped so we need to do some shifting */ for (i = 0; i < 4; i++) { cmd->resp[i] <<= 8; if (i != 3) cmd->resp[i] |= cmd->resp[i + 1] >> 24; } }
so it seems to me that both drivers are doing the same thing.
I'll try to have another look towards the end of the week, maybe adding some extra debug.
AFAICS U-boot should be providing the same CID than Linux does, and whatever OP-TEE might be masking out on the receiving end is orthogonal to such value, isnt it? maybe I am not understanding your point?
I agree that something must be done so it works with Linux. However, I'm a bit surprised that we haven't seen this earlier.
could be that accessing rpmb has never been done from both linux and u-boot?
I'm sure I've tested that on Hikey when I implemented this stuff. I know I wrote the key using Linux since I didn't have the complete chain in U-Boot to start with then.
um ok. hikey is also little endian (in byteorder.h)
in fact when I was trying to access rpmb values from uboot via AVB I also noticed that the current code (at least in my imx7 platform) wouldnt work due to cache alignment issues...so needed an additional patch (which I still need to send to this ML) to use aligned buffers on the stack in the read/write rpmb functions.
If there's an error in how it's done in Linux we may need to implement some workaround in tee-supplicant or perhaps in secure world. If we wait with that until after we have some workarounds in U-Boot too, stuff will become even more messy.
yes I understand your point. ok.
Cheers, Jens
CID is a uint8_t[16] here /* * PRV/CRC would be changed when doing eMMC FFU * The following fields should be masked off when deriving RPMB key * * CID [55: 48]: PRV (Product revision) * CID [07: 01]: CRC (CRC7 checksum) * CID [00]: not used */
Will this work as expected on a big endian machine?
Cheers, Jens
info->rel_wr_sec_c = mmc->ext_csd[222]; info->rpmb_size_mult = mmc->ext_csd[168]; info->ret_code = RPMB_CMD_GET_DEV_INFO_RET_OK;-- 2.23.0
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote:
Hi Jorge,
hey!
On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: > The MMC CID value is one of the input parameters to unequivocally > provision the the RPMB key. > > Before this patch, the value returned by the mmc driver in the Linux > kernel differs from the one returned by uboot to optee. > > This means that if Linux provisions the RPMB key, uboot wont be able > to access it (and the other way around). > > Fix it so both uboot and linux can access the RPMB partition > independently of who provisions the key. > > Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io > --- > drivers/tee/optee/rpmb.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c > index 955155b3f8..5dbb1eae4a 100644 > --- a/drivers/tee/optee/rpmb.c > +++ b/drivers/tee/optee/rpmb.c > @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) > static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) > { > struct mmc *mmc = find_mmc_device(dev_id); > + int i; > > if (!mmc) > return TEE_ERROR_ITEM_NOT_FOUND; > @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) > if (!mmc->ext_csd) > return TEE_ERROR_GENERIC; > > - memcpy(info->cid, mmc->cid, sizeof(info->cid)); > + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) > + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); > + So it seems to be a byte order issue. I can't find the place in the Linux kernel (or in tee-supplicant) where the corresponding byte swapping is done. Have you been able to find it or you just tried to swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
I'm not yet convinced that be32_to_cpu() is the correct function here. OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
However in the trusted environment the situation is a bit different:
1) when Linux reports it to sysfs, Linux displays the CID as _four_ concatenated u32 values (not as an array of sixteen u8 values).
2) The Linux TEE supplicant reads said entry as an array of u8 therefore discarding the endianess.
3) In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8 therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 10:36 AM, Jens Wiklander wrote: > Hi Jorge,
hey!
> > On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >> The MMC CID value is one of the input parameters to unequivocally >> provision the the RPMB key. >> >> Before this patch, the value returned by the mmc driver in the Linux >> kernel differs from the one returned by uboot to optee. >> >> This means that if Linux provisions the RPMB key, uboot wont be able >> to access it (and the other way around). >> >> Fix it so both uboot and linux can access the RPMB partition >> independently of who provisions the key. >> >> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >> --- >> drivers/tee/optee/rpmb.c | 5 ++++- >> 1 file changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >> index 955155b3f8..5dbb1eae4a 100644 >> --- a/drivers/tee/optee/rpmb.c >> +++ b/drivers/tee/optee/rpmb.c >> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >> { >> struct mmc *mmc = find_mmc_device(dev_id); >> + int i; >> >> if (!mmc) >> return TEE_ERROR_ITEM_NOT_FOUND; >> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >> if (!mmc->ext_csd) >> return TEE_ERROR_GENERIC; >> >> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >> + > So it seems to be a byte order issue. I can't find the place in the > Linux kernel (or in tee-supplicant) where the corresponding byte > swapping is done. Have you been able to find it or you just tried to > swap the bytes and it seemed to work?
I compared against the full CID output from Linux and noticed that in order to match that exact same output this swap seemed to be required. I didnt dig any deeper since a similar swap operation is done on other -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
> > I'm not yet convinced that be32_to_cpu() is the correct function here. > OP-TEE masks out a few fields from the CID when deriving the key:
sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed. However, I think that cpu_to_be32() should be used instead for clarity. Then there's the issue of alignment with the casting you do. It works today due to how the function is called, but the compiler can't guarantee that since the struct rpmb_dev_info only contains u8:s so it's only byte aligned. You need to handle that inside the function.
Cheers, Jens
On 11/20/19 8:20 AM, Jens Wiklander wrote:
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote:
[+ Igor and Sam]
On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote: > On 11/18/19 10:36 AM, Jens Wiklander wrote: >> Hi Jorge, > > > hey! > >> >> On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >>> The MMC CID value is one of the input parameters to unequivocally >>> provision the the RPMB key. >>> >>> Before this patch, the value returned by the mmc driver in the Linux >>> kernel differs from the one returned by uboot to optee. >>> >>> This means that if Linux provisions the RPMB key, uboot wont be able >>> to access it (and the other way around). >>> >>> Fix it so both uboot and linux can access the RPMB partition >>> independently of who provisions the key. >>> >>> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >>> --- >>> drivers/tee/optee/rpmb.c | 5 ++++- >>> 1 file changed, 4 insertions(+), 1 deletion(-) >>> >>> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >>> index 955155b3f8..5dbb1eae4a 100644 >>> --- a/drivers/tee/optee/rpmb.c >>> +++ b/drivers/tee/optee/rpmb.c >>> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >>> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>> { >>> struct mmc *mmc = find_mmc_device(dev_id); >>> + int i; >>> >>> if (!mmc) >>> return TEE_ERROR_ITEM_NOT_FOUND; >>> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>> if (!mmc->ext_csd) >>> return TEE_ERROR_GENERIC; >>> >>> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >>> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >>> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >>> + >> So it seems to be a byte order issue. I can't find the place in the >> Linux kernel (or in tee-supplicant) where the corresponding byte >> swapping is done. Have you been able to find it or you just tried to >> swap the bytes and it seemed to work? > > > I compared against the full CID output from Linux and noticed that in > order to match that exact same output this swap seemed to be required. I > didnt dig any deeper since a similar swap operation is done on other > -different - values returned from U-boot to OP-TEE.
So we don't know if the byte swap is always needed, only on little endian machines or perhaps only with certain devices.
right, I dont know.
By the way, where are the other byte swaps you're mentioning? I did a quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
> > >> >> I'm not yet convinced that be32_to_cpu() is the correct function here. >> OP-TEE masks out a few fields from the CID when deriving the key: > > > sure but isnt that a different matter?
No, it's important that OP-TEE masks out the correct fields. That's why we must make sure to understand the problem so we don't just push the problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed.
which incidentally is exactly the same thing that linux does when the MMC host talks the SPI protocol ie, be32_to_cpu on each of the 4 cid words.
static int mmc_spi_send_cid(struct mmc_host *host, u32 *cid) { int ret, i; __be32 *cid_tmp;
cid_tmp = kzalloc(16, GFP_KERNEL); if (!cid_tmp) return -ENOMEM;
ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16); if (ret) goto err;
for (i = 0; i < 4; i++) cid[i] = be32_to_cpu(cid_tmp[i]);
err: kfree(cid_tmp); return ret; }
However, I think that cpu_to_be32() should be used
instead for clarity.
sorry what do you mean? cpu_to_be32 instead of be32_to_cpu?
Then there's the issue of alignment with the
casting you do. It works today due to how the function is called, but the compiler can't guarantee that since the struct rpmb_dev_info only contains u8:s so it's only byte aligned. You need to handle that inside the function.
but why does the optee supplicant in uboot igonres the alignment request made by optee (cmd_shm_alloc in uboot sets alignment to 0 while thread_rpc_alloc_payload in optee requested 8)
also any reason why we cant ask some other alignment from optee when allocating the response buffer for the mmc dev info? then we dont have to jump through hoops in uboot?
Cheers, Jens
On Wed, Nov 20, 2019 at 09:21:35AM +0100, Jorge Ramirez-Ortiz wrote:
On 11/20/19 8:20 AM, Jens Wiklander wrote:
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/18/19 1:42 PM, Jens Wiklander wrote: > [+ Igor and Sam] > > On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote: >> On 11/18/19 10:36 AM, Jens Wiklander wrote: >>> Hi Jorge, >> >> >> hey! >> >>> >>> On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >>>> The MMC CID value is one of the input parameters to unequivocally >>>> provision the the RPMB key. >>>> >>>> Before this patch, the value returned by the mmc driver in the Linux >>>> kernel differs from the one returned by uboot to optee. >>>> >>>> This means that if Linux provisions the RPMB key, uboot wont be able >>>> to access it (and the other way around). >>>> >>>> Fix it so both uboot and linux can access the RPMB partition >>>> independently of who provisions the key. >>>> >>>> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >>>> --- >>>> drivers/tee/optee/rpmb.c | 5 ++++- >>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>> >>>> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >>>> index 955155b3f8..5dbb1eae4a 100644 >>>> --- a/drivers/tee/optee/rpmb.c >>>> +++ b/drivers/tee/optee/rpmb.c >>>> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >>>> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>> { >>>> struct mmc *mmc = find_mmc_device(dev_id); >>>> + int i; >>>> >>>> if (!mmc) >>>> return TEE_ERROR_ITEM_NOT_FOUND; >>>> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>> if (!mmc->ext_csd) >>>> return TEE_ERROR_GENERIC; >>>> >>>> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >>>> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >>>> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >>>> + >>> So it seems to be a byte order issue. I can't find the place in the >>> Linux kernel (or in tee-supplicant) where the corresponding byte >>> swapping is done. Have you been able to find it or you just tried to >>> swap the bytes and it seemed to work? >> >> >> I compared against the full CID output from Linux and noticed that in >> order to match that exact same output this swap seemed to be required. I >> didnt dig any deeper since a similar swap operation is done on other >> -different - values returned from U-boot to OP-TEE. > > So we don't know if the byte swap is always needed, only on little > endian machines or perhaps only with certain devices.
right, I dont know. > > By the way, where are the other byte swaps you're mentioning? I did a > quick grep under drivers/tee/ and didn't find anything.
um my bad...let me clarify: when I was hacking around the issues I had with the rpmb uboot driver, I was merging/testing some of the code from the emulation mode in the linux tee-supplicant (rpbm values are converted to network byte order); doing so allowed me to moved through the response validation stage in optee so I figured that CID probably was missing some sort of conversion as well.
> >> >> >>> >>> I'm not yet convinced that be32_to_cpu() is the correct function here. >>> OP-TEE masks out a few fields from the CID when deriving the key: >> >> >> sure but isnt that a different matter? > > No, it's important that OP-TEE masks out the correct fields. That's why > we must make sure to understand the problem so we don't just push the > problem around.
ok. if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed.
which incidentally is exactly the same thing that linux does when the MMC host talks the SPI protocol ie, be32_to_cpu on each of the 4 cid words.
static int mmc_spi_send_cid(struct mmc_host *host, u32 *cid) { int ret, i; __be32 *cid_tmp;
cid_tmp = kzalloc(16, GFP_KERNEL); if (!cid_tmp) return -ENOMEM;
ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16); if (ret) goto err;
for (i = 0; i < 4; i++) cid[i] = be32_to_cpu(cid_tmp[i]);
err: kfree(cid_tmp); return ret; }
However, I think that cpu_to_be32() should be used
instead for clarity.
sorry what do you mean? cpu_to_be32 instead of be32_to_cpu?
Yes, the words are in little endian but we need them to be in big endian when making it an array of u8.
Then there's the issue of alignment with the
casting you do. It works today due to how the function is called, but the compiler can't guarantee that since the struct rpmb_dev_info only contains u8:s so it's only byte aligned. You need to handle that inside the function.
but why does the optee supplicant in uboot igonres the alignment request made by optee (cmd_shm_alloc in uboot sets alignment to 0 while thread_rpc_alloc_payload in optee requested 8)
Good question, looks like a bug to me. In this case it doesn't make much difference though since malloc() is required to return buffers which are at least 8 byte aligned.
also any reason why we cant ask some other alignment from optee when allocating the response buffer for the mmc dev info? then we dont have to jump through hoops in uboot?
You mean the cache line aligned buffers? I don't see a problem with that, a patch is welcome. :-)
Any way, the suspicious cast which you're doing will cause a compiler warning with the right flags enabled. If you'd rather write a long comment explaining why it's perfectly safe to cast like that do so instead.
Cheers, Jens
On 20/11/19 11:33:10, Jens Wiklander wrote:
On Wed, Nov 20, 2019 at 09:21:35AM +0100, Jorge Ramirez-Ortiz wrote:
On 11/20/19 8:20 AM, Jens Wiklander wrote:
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote:
On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote: > On 11/18/19 1:42 PM, Jens Wiklander wrote: >> [+ Igor and Sam] >> >> On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote: >>> On 11/18/19 10:36 AM, Jens Wiklander wrote: >>>> Hi Jorge, >>> >>> >>> hey! >>> >>>> >>>> On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >>>>> The MMC CID value is one of the input parameters to unequivocally >>>>> provision the the RPMB key. >>>>> >>>>> Before this patch, the value returned by the mmc driver in the Linux >>>>> kernel differs from the one returned by uboot to optee. >>>>> >>>>> This means that if Linux provisions the RPMB key, uboot wont be able >>>>> to access it (and the other way around). >>>>> >>>>> Fix it so both uboot and linux can access the RPMB partition >>>>> independently of who provisions the key. >>>>> >>>>> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >>>>> --- >>>>> drivers/tee/optee/rpmb.c | 5 ++++- >>>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >>>>> index 955155b3f8..5dbb1eae4a 100644 >>>>> --- a/drivers/tee/optee/rpmb.c >>>>> +++ b/drivers/tee/optee/rpmb.c >>>>> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >>>>> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>> { >>>>> struct mmc *mmc = find_mmc_device(dev_id); >>>>> + int i; >>>>> >>>>> if (!mmc) >>>>> return TEE_ERROR_ITEM_NOT_FOUND; >>>>> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>> if (!mmc->ext_csd) >>>>> return TEE_ERROR_GENERIC; >>>>> >>>>> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >>>>> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >>>>> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >>>>> + >>>> So it seems to be a byte order issue. I can't find the place in the >>>> Linux kernel (or in tee-supplicant) where the corresponding byte >>>> swapping is done. Have you been able to find it or you just tried to >>>> swap the bytes and it seemed to work? >>> >>> >>> I compared against the full CID output from Linux and noticed that in >>> order to match that exact same output this swap seemed to be required. I >>> didnt dig any deeper since a similar swap operation is done on other >>> -different - values returned from U-boot to OP-TEE. >> >> So we don't know if the byte swap is always needed, only on little >> endian machines or perhaps only with certain devices. > > right, I dont know. >> >> By the way, where are the other byte swaps you're mentioning? I did a >> quick grep under drivers/tee/ and didn't find anything. > > um my bad...let me clarify: when I was hacking around the issues I had > with the rpmb uboot driver, I was merging/testing some of the code from > the emulation mode in the linux tee-supplicant (rpbm values are > converted to network byte order); doing so allowed me to moved through > the response validation stage in optee so I figured that CID probably > was missing some sort of conversion as well. > > >> >>> >>> >>>> >>>> I'm not yet convinced that be32_to_cpu() is the correct function here. >>>> OP-TEE masks out a few fields from the CID when deriving the key: >>> >>> >>> sure but isnt that a different matter? >> >> No, it's important that OP-TEE masks out the correct fields. That's why >> we must make sure to understand the problem so we don't just push the >> problem around. > > ok. > if there is anything you'd like me to test or validate please let me know
I'm not convinced that this is a generic problem. I don't doubt that it's a problem on the hardware you're using. Perhaps there's some byteswap missing in the driver for you hardware. So if you could figure out why the CID is in the wrong byte order with you're hardware it would help a lot. Or confirm that CID always is supposed to be stored in big endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed.
right, because the supplicant is implicitly doing the swap by picking one byte at a time since the linux kernel wrote u32s and not bytes to sysfs.so between them things balanced out.
which incidentally is exactly the same thing that linux does when the MMC host talks the SPI protocol ie, be32_to_cpu on each of the 4 cid words.
static int mmc_spi_send_cid(struct mmc_host *host, u32 *cid) { int ret, i; __be32 *cid_tmp;
cid_tmp = kzalloc(16, GFP_KERNEL); if (!cid_tmp) return -ENOMEM;
ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16); if (ret) goto err;
for (i = 0; i < 4; i++) cid[i] = be32_to_cpu(cid_tmp[i]);
err: kfree(cid_tmp); return ret; }
However, I think that cpu_to_be32() should be used
instead for clarity.
sorry what do you mean? cpu_to_be32 instead of be32_to_cpu?
Yes, the words are in little endian but we need them to be in big endian when making it an array of u8.
no, sorry, I dont understand this. it would not work: we have to have be32_to_cpu
really it is either the linux supplicant or uboot that have to change. I supose uboot will be the preferred choice since it will have less impact on current users.
Then there's the issue of alignment with the
casting you do. It works today due to how the function is called, but the compiler can't guarantee that since the struct rpmb_dev_info only contains u8:s so it's only byte aligned. You need to handle that inside the function.
but why does the optee supplicant in uboot igonres the alignment request made by optee (cmd_shm_alloc in uboot sets alignment to 0 while thread_rpc_alloc_payload in optee requested 8)
Good question, looks like a bug to me. In this case it doesn't make much difference though since malloc() is required to return buffers which are at least 8 byte aligned.
also any reason why we cant ask some other alignment from optee when allocating the response buffer for the mmc dev info? then we dont have to jump through hoops in uboot?
You mean the cache line aligned buffers? I don't see a problem with that, a patch is welcome. :-)
Any way, the suspicious cast which you're doing will cause a compiler warning with the right flags enabled. If you'd rather write a long comment explaining why it's perfectly safe to cast like that do so instead.
Cheers, Jens
On Tue, Nov 26, 2019 at 09:22:38AM +0100, Jorge Ramirez-Ortiz, Foundries wrote:
On 20/11/19 11:33:10, Jens Wiklander wrote:
On Wed, Nov 20, 2019 at 09:21:35AM +0100, Jorge Ramirez-Ortiz wrote:
On 11/20/19 8:20 AM, Jens Wiklander wrote:
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote:
On 11/19/19 10:02 AM, Jens Wiklander wrote: > On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote: >> On 11/18/19 1:42 PM, Jens Wiklander wrote: >>> [+ Igor and Sam] >>> >>> On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote: >>>> On 11/18/19 10:36 AM, Jens Wiklander wrote: >>>>> Hi Jorge, >>>> >>>> >>>> hey! >>>> >>>>> >>>>> On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >>>>>> The MMC CID value is one of the input parameters to unequivocally >>>>>> provision the the RPMB key. >>>>>> >>>>>> Before this patch, the value returned by the mmc driver in the Linux >>>>>> kernel differs from the one returned by uboot to optee. >>>>>> >>>>>> This means that if Linux provisions the RPMB key, uboot wont be able >>>>>> to access it (and the other way around). >>>>>> >>>>>> Fix it so both uboot and linux can access the RPMB partition >>>>>> independently of who provisions the key. >>>>>> >>>>>> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >>>>>> --- >>>>>> drivers/tee/optee/rpmb.c | 5 ++++- >>>>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>>>> >>>>>> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >>>>>> index 955155b3f8..5dbb1eae4a 100644 >>>>>> --- a/drivers/tee/optee/rpmb.c >>>>>> +++ b/drivers/tee/optee/rpmb.c >>>>>> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >>>>>> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>>> { >>>>>> struct mmc *mmc = find_mmc_device(dev_id); >>>>>> + int i; >>>>>> >>>>>> if (!mmc) >>>>>> return TEE_ERROR_ITEM_NOT_FOUND; >>>>>> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>>> if (!mmc->ext_csd) >>>>>> return TEE_ERROR_GENERIC; >>>>>> >>>>>> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >>>>>> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >>>>>> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >>>>>> + >>>>> So it seems to be a byte order issue. I can't find the place in the >>>>> Linux kernel (or in tee-supplicant) where the corresponding byte >>>>> swapping is done. Have you been able to find it or you just tried to >>>>> swap the bytes and it seemed to work? >>>> >>>> >>>> I compared against the full CID output from Linux and noticed that in >>>> order to match that exact same output this swap seemed to be required. I >>>> didnt dig any deeper since a similar swap operation is done on other >>>> -different - values returned from U-boot to OP-TEE. >>> >>> So we don't know if the byte swap is always needed, only on little >>> endian machines or perhaps only with certain devices. >> >> right, I dont know. >>> >>> By the way, where are the other byte swaps you're mentioning? I did a >>> quick grep under drivers/tee/ and didn't find anything. >> >> um my bad...let me clarify: when I was hacking around the issues I had >> with the rpmb uboot driver, I was merging/testing some of the code from >> the emulation mode in the linux tee-supplicant (rpbm values are >> converted to network byte order); doing so allowed me to moved through >> the response validation stage in optee so I figured that CID probably >> was missing some sort of conversion as well. >> >> >>> >>>> >>>> >>>>> >>>>> I'm not yet convinced that be32_to_cpu() is the correct function here. >>>>> OP-TEE masks out a few fields from the CID when deriving the key: >>>> >>>> >>>> sure but isnt that a different matter? >>> >>> No, it's important that OP-TEE masks out the correct fields. That's why >>> we must make sure to understand the problem so we don't just push the >>> problem around. >> >> ok. >> if there is anything you'd like me to test or validate please let me know > > I'm not convinced that this is a generic problem. I don't doubt that > it's a problem on the hardware you're using. Perhaps there's some > byteswap missing in the driver for you hardware. So if you could figure > out why the CID is in the wrong byte order with you're hardware it would > help a lot. Or confirm that CID always is supposed to be stored in big > endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed.
right, because the supplicant is implicitly doing the swap by picking one byte at a time since the linux kernel wrote u32s and not bytes to sysfs.so between them things balanced out.
which incidentally is exactly the same thing that linux does when the MMC host talks the SPI protocol ie, be32_to_cpu on each of the 4 cid words.
static int mmc_spi_send_cid(struct mmc_host *host, u32 *cid) { int ret, i; __be32 *cid_tmp;
cid_tmp = kzalloc(16, GFP_KERNEL); if (!cid_tmp) return -ENOMEM;
ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16); if (ret) goto err;
for (i = 0; i < 4; i++) cid[i] = be32_to_cpu(cid_tmp[i]);
err: kfree(cid_tmp); return ret; }
However, I think that cpu_to_be32() should be used
instead for clarity.
sorry what do you mean? cpu_to_be32 instead of be32_to_cpu?
Yes, the words are in little endian but we need them to be in big endian when making it an array of u8.
no, sorry, I dont understand this. it would not work: we have to have be32_to_cpu
On a little endian system cpu_to_be32() and be32_to_cpu() are both implemented using uswap_32(). The only difference is in usage. With cpu_to_be32() you have something in native byte order and convert it to big endian, with be32_to_cpu() it's the other way around.
In this case (in rpmb_get_dev_info() far up in this conversion) we have the 4 words in native endian and we need to convert them into big endian.
Cheers, Jens
On 26/11/19 12:46:04, Jens Wiklander wrote:
On Tue, Nov 26, 2019 at 09:22:38AM +0100, Jorge Ramirez-Ortiz, Foundries wrote:
On 20/11/19 11:33:10, Jens Wiklander wrote:
On Wed, Nov 20, 2019 at 09:21:35AM +0100, Jorge Ramirez-Ortiz wrote:
On 11/20/19 8:20 AM, Jens Wiklander wrote:
On Tue, Nov 19, 2019 at 06:21:34PM +0100, Jorge Ramirez-Ortiz wrote:
On 11/19/19 12:53 PM, Jorge Ramirez-Ortiz wrote: > On 11/19/19 10:02 AM, Jens Wiklander wrote: >> On Mon, Nov 18, 2019 at 02:18:55PM +0100, Jorge Ramirez-Ortiz wrote: >>> On 11/18/19 1:42 PM, Jens Wiklander wrote: >>>> [+ Igor and Sam] >>>> >>>> On Mon, Nov 18, 2019 at 12:18:27PM +0100, Jorge Ramirez-Ortiz wrote: >>>>> On 11/18/19 10:36 AM, Jens Wiklander wrote: >>>>>> Hi Jorge, >>>>> >>>>> >>>>> hey! >>>>> >>>>>> >>>>>> On Fri, Nov 15, 2019 at 10:37 PM Jorge Ramirez-Ortiz jorge@foundries.io wrote: >>>>>>> The MMC CID value is one of the input parameters to unequivocally >>>>>>> provision the the RPMB key. >>>>>>> >>>>>>> Before this patch, the value returned by the mmc driver in the Linux >>>>>>> kernel differs from the one returned by uboot to optee. >>>>>>> >>>>>>> This means that if Linux provisions the RPMB key, uboot wont be able >>>>>>> to access it (and the other way around). >>>>>>> >>>>>>> Fix it so both uboot and linux can access the RPMB partition >>>>>>> independently of who provisions the key. >>>>>>> >>>>>>> Signed-off-by: Jorge Ramirez-Ortiz jorge@foundries.io >>>>>>> --- >>>>>>> drivers/tee/optee/rpmb.c | 5 ++++- >>>>>>> 1 file changed, 4 insertions(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/drivers/tee/optee/rpmb.c b/drivers/tee/optee/rpmb.c >>>>>>> index 955155b3f8..5dbb1eae4a 100644 >>>>>>> --- a/drivers/tee/optee/rpmb.c >>>>>>> +++ b/drivers/tee/optee/rpmb.c >>>>>>> @@ -98,6 +98,7 @@ static struct mmc *get_mmc(struct optee_private *priv, int dev_id) >>>>>>> static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>>>> { >>>>>>> struct mmc *mmc = find_mmc_device(dev_id); >>>>>>> + int i; >>>>>>> >>>>>>> if (!mmc) >>>>>>> return TEE_ERROR_ITEM_NOT_FOUND; >>>>>>> @@ -105,7 +106,9 @@ static u32 rpmb_get_dev_info(u16 dev_id, struct rpmb_dev_info *info) >>>>>>> if (!mmc->ext_csd) >>>>>>> return TEE_ERROR_GENERIC; >>>>>>> >>>>>>> - memcpy(info->cid, mmc->cid, sizeof(info->cid)); >>>>>>> + for (i = 0; i < ARRAY_SIZE(mmc->cid); i++) >>>>>>> + ((u32 *) info->cid)[i] = be32_to_cpu(mmc->cid[i]); >>>>>>> + >>>>>> So it seems to be a byte order issue. I can't find the place in the >>>>>> Linux kernel (or in tee-supplicant) where the corresponding byte >>>>>> swapping is done. Have you been able to find it or you just tried to >>>>>> swap the bytes and it seemed to work? >>>>> >>>>> >>>>> I compared against the full CID output from Linux and noticed that in >>>>> order to match that exact same output this swap seemed to be required. I >>>>> didnt dig any deeper since a similar swap operation is done on other >>>>> -different - values returned from U-boot to OP-TEE. >>>> >>>> So we don't know if the byte swap is always needed, only on little >>>> endian machines or perhaps only with certain devices. >>> >>> right, I dont know. >>>> >>>> By the way, where are the other byte swaps you're mentioning? I did a >>>> quick grep under drivers/tee/ and didn't find anything. >>> >>> um my bad...let me clarify: when I was hacking around the issues I had >>> with the rpmb uboot driver, I was merging/testing some of the code from >>> the emulation mode in the linux tee-supplicant (rpbm values are >>> converted to network byte order); doing so allowed me to moved through >>> the response validation stage in optee so I figured that CID probably >>> was missing some sort of conversion as well. >>> >>> >>>> >>>>> >>>>> >>>>>> >>>>>> I'm not yet convinced that be32_to_cpu() is the correct function here. >>>>>> OP-TEE masks out a few fields from the CID when deriving the key: >>>>> >>>>> >>>>> sure but isnt that a different matter? >>>> >>>> No, it's important that OP-TEE masks out the correct fields. That's why >>>> we must make sure to understand the problem so we don't just push the >>>> problem around. >>> >>> ok. >>> if there is anything you'd like me to test or validate please let me know >> >> I'm not convinced that this is a generic problem. I don't doubt that >> it's a problem on the hardware you're using. Perhaps there's some >> byteswap missing in the driver for you hardware. So if you could figure >> out why the CID is in the wrong byte order with you're hardware it would >> help a lot. Or confirm that CID always is supposed to be stored in big >> endian in struct mmc and that eventual deviations from that is wrong.
Yeah, actually it is: but perhaps should be fixed in the Linux supplicant instead.
Both u-boot and Linux do read the CID properly from MMC and they both hold the same values in four u32 variables so I can confirm that the MMC drivers for the imx do the right thing
Good
However in the trusted environment the situation is a bit different:
- when Linux reports it to sysfs, Linux displays the CID as _four_
concatenated u32 values (not as an array of sixteen u8 values).
- The Linux TEE supplicant reads said entry as an array of u8 therefore
discarding the endianess.
- In U-boot the rpmb.c driver does memcpy the cid uint32 array into u8
therefore keeping the endiannes.
It is clear that at this point, the value that will reach the OPTEE's rpmb driver from linux will be different to the one from uboot.
So we could either fix it in u-boot's RPMB driver (with the patch I posted) or in the Linux supplicant in the read_cid(..) function.
But one of the two has to change not only for consistency but to enable both u-boot and Linux to access rpmb during the boot process on any endian systems.
what do you think? does this make sense?
Thanks for digging into this, now the problem is clear to me. At the Linux side I think the CID is received by secure world with the bytes in the expected order. You're original patch fixes this by byte swapping the words as needed.
right, because the supplicant is implicitly doing the swap by picking one byte at a time since the linux kernel wrote u32s and not bytes to sysfs.so between them things balanced out.
which incidentally is exactly the same thing that linux does when the MMC host talks the SPI protocol ie, be32_to_cpu on each of the 4 cid words.
static int mmc_spi_send_cid(struct mmc_host *host, u32 *cid) { int ret, i; __be32 *cid_tmp;
cid_tmp = kzalloc(16, GFP_KERNEL); if (!cid_tmp) return -ENOMEM;
ret = mmc_send_cxd_data(NULL, host, MMC_SEND_CID, cid_tmp, 16); if (ret) goto err;
for (i = 0; i < 4; i++) cid[i] = be32_to_cpu(cid_tmp[i]);
err: kfree(cid_tmp); return ret; }
However, I think that cpu_to_be32() should be used
instead for clarity.
sorry what do you mean? cpu_to_be32 instead of be32_to_cpu?
Yes, the words are in little endian but we need them to be in big endian when making it an array of u8.
no, sorry, I dont understand this. it would not work: we have to have be32_to_cpu
On a little endian system cpu_to_be32() and be32_to_cpu() are both implemented using uswap_32(). The only difference is in usage. With cpu_to_be32() you have something in native byte order and convert it to big endian, with be32_to_cpu() it's the other way around.
In this case (in rpmb_get_dev_info() far up in this conversion) we have the 4 words in native endian and we need to convert them into big endian.
yes, of course you are right (I double checked those implementations in LE and I am with you now).
will repost the patch
thanks!
Cheers, Jens
participants (3)
-
Jens Wiklander -
Jorge Ramirez-Ortiz -
Jorge Ramirez-Ortiz, Foundries