[PATCH 1/2] part: Check all partitions in part_get_info_by_name()
In part_get_info_by_name() the inability to get some partition info shouldn't be a reason for dropping out of the loop. That might happen e.g. if the partition is hidden or unused. An example of such case are Samsung devices, where they use the "unused" GUID type (00000000-0000-0000-0000-000000000000) to indicate that the partition should be hidden from the OS. Such partitions might not be seen in "part list" output, which creates "gaps" in numbering in between of the visible partitions:
Part Start LBA End LBA Name 1 0x00000400 0x0000a3ff "efs" 5 0x00026420 0x00026c1f "dtbo" 12 0x0003f390 0x0074738f "super"
In that case, the loop in part_get_info_by_name() would break after partition #1, so any attempt to obtain "dtbo" or "super" partition will fail. Fix that by continuing to iterate over the remaining partitions to make sure none of the visible ones is missed. That makes "part" command (e.g. "part start", "part size") able to work with such tables.
Fixes: 87b8530fe244 ("disk: part: implement generic function part_get_info_by_name()") Signed-off-by: Sam Protsenko semen.protsenko@linaro.org --- disk/part.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/disk/part.c b/disk/part.c index 36b88205eca7..08c9331e059c 100644 --- a/disk/part.c +++ b/disk/part.c @@ -717,8 +717,11 @@ int part_get_info_by_name(struct blk_desc *desc, const char *name, for (i = 1; i < part_drv->max_entries; i++) { ret = part_drv->get_info(desc, i, info); if (ret != 0) { - /* no more entries in table */ - break; + /* + * Partition with this index can't be obtained, but + * further partitions might be, so keep checking. + */ + continue; } if (strcmp(name, (const char *)info->name) == 0) { /* matched */
Some platforms use the "unused" (all-zero) GUID as a partition type GUID to make some partitions hidden from the OS. For example, Samsung phones and other devices often have GPT partition tables like that, created by their "gpt_builder" tool [1]. All partitions with FILESYS=0 value (second column in [2] file) will be created in a way that: 1. Partition type GUID will be all-zero ("unused") 2. Attributes[48:49] bits will be set to 0 (whereas non-zero values mean the partition is visible to the OS: 1=raw, 2=ext4, 3=f2fs)
Although it's true that Linux kernel verifies the partition type GUID to be non-zero (in block/partitions/efi.c, is_pte_valid() function), where its U-Boot counterpart code was borrowed from originally, in case of U-Boot we want to handle partitions with "unused" GUIDs the same way as any other valid partitions, to allow the user to interact with those (e.g. list partitions using "part list", be able to flash those via fastboot, etc).
[1] https://gitlab.com/Linaro/96boards/e850-96/tools/gpt/ [2] https://gitlab.com/Linaro/96boards/e850-96/tools/gpt/-/blob/master/gpt_layou...
Fixes: 07f3d789b9be ("Add support for CONFIG_EFI_PARTITION (GUID Partition Table)") Signed-off-by: Sam Protsenko semen.protsenko@linaro.org --- disk/part_efi.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-)
diff --git a/disk/part_efi.c b/disk/part_efi.c index 4ce9243ef25c..6b138abae0a6 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -1166,28 +1166,17 @@ static gpt_entry *alloc_read_gpt_entries(struct blk_desc *desc, */ static int is_pte_valid(gpt_entry * pte) { - efi_guid_t unused_guid; + /* + * NOTE: Do not check unused (zero) GUIDs here, it's considered a valid + * case in U-Boot. + */
if (!pte) { log_debug("Invalid Argument(s)\n"); return 0; }
- /* Only one validation for now: - * The GUID Partition Type != Unused Entry (ALL-ZERO) - */ - memset(unused_guid.b, 0, sizeof(unused_guid.b)); - - if (memcmp(pte->partition_type_guid.b, unused_guid.b, - sizeof(unused_guid.b)) == 0) { - - log_debug("Found an unused PTE GUID at 0x%08X\n", - (unsigned int)(uintptr_t)pte); - - return 0; - } else { - return 1; - } + return 1; }
/*
On 3/28/24 23:29, Sam Protsenko wrote:
Some platforms use the "unused" (all-zero) GUID as a partition type GUID to make some partitions hidden from the OS. For example, Samsung phones and other devices often have GPT partition tables like that, created by their "gpt_builder" tool [1]. All partitions with FILESYS=0 value (second column in [2] file) will be created in a way that:
- Partition type GUID will be all-zero ("unused")
- Attributes[48:49] bits will be set to 0 (whereas non-zero values mean the partition is visible to the OS: 1=raw, 2=ext4, 3=f2fs)
The UEFI specification is defining what a GPT partition table has to look like.
According the specification partition type GUID 00000000-0000-0000-0000-000000000000 marks an "unused entry" in the partition table.
An unused partition table entry cannot define a partition. It is one of the entries, that you skip over when enumerating via your patch 1/2.
With this patch 128 partition table entries are printed for an image having a single partition.
=> part list host 0
Partition Map for HOST device 0 -- Partition Type: EFI
Part Start LBA End LBA Name Attributes Type GUID Partition GUID 1 0x00000800 0x0001f7ff "EFI system partition" attrs: 0x0000000000000005 type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b (system) guid: ee474198-4601-4d5c-81f0-54acf904dd40 2 0x00000000 0x00000000 "" attrs: 0x0000000000000000 type: 00000000-0000-0000-0000-000000000000 (00000000-0000-0000-0000-000000000000) guid: 00000000-0000-0000-0000-000000000000 ...
128 0x00000000 0x00000000 "" attrs: 0x0000000000000000 type: 00000000-0000-0000-0000-000000000000 (00000000-0000-0000-0000-000000000000) guid: 00000000-0000-0000-0000-000000000000
This is definitively wrong.
Although it's true that Linux kernel verifies the partition type GUID to be non-zero (in block/partitions/efi.c, is_pte_valid() function), where its U-Boot counterpart code was borrowed from originally, in case of U-Boot we want to handle partitions with "unused" GUIDs the same way as any other valid partitions, to allow the user to interact with those (e.g. list partitions using "part list", be able to flash those via fastboot, etc).
You cannot interact with a non-existing partition.
You may create a new partition in any empty slot that Samsung's tool has left in the partition table and then write to it. No patch is needed for this.
Best regards
Heinrich
[1] https://gitlab.com/Linaro/96boards/e850-96/tools/gpt/ [2] https://gitlab.com/Linaro/96boards/e850-96/tools/gpt/-/blob/master/gpt_layou...
Fixes: 07f3d789b9be ("Add support for CONFIG_EFI_PARTITION (GUID Partition Table)") Signed-off-by: Sam Protsenko semen.protsenko@linaro.org
disk/part_efi.c | 21 +++++---------------- 1 file changed, 5 insertions(+), 16 deletions(-)
diff --git a/disk/part_efi.c b/disk/part_efi.c index 4ce9243ef25c..6b138abae0a6 100644 --- a/disk/part_efi.c +++ b/disk/part_efi.c @@ -1166,28 +1166,17 @@ static gpt_entry *alloc_read_gpt_entries(struct blk_desc *desc, */ static int is_pte_valid(gpt_entry * pte) {
- efi_guid_t unused_guid;
/*
* NOTE: Do not check unused (zero) GUIDs here, it's considered a valid* case in U-Boot.*/if (!pte) { log_debug("Invalid Argument(s)\n"); return 0; }
- /* Only one validation for now:
* The GUID Partition Type != Unused Entry (ALL-ZERO)*/- memset(unused_guid.b, 0, sizeof(unused_guid.b));
- if (memcmp(pte->partition_type_guid.b, unused_guid.b,
sizeof(unused_guid.b)) == 0) {log_debug("Found an unused PTE GUID at 0x%08X\n",(unsigned int)(uintptr_t)pte);return 0;- } else {
return 1;- }
return 1; }
/*
On Thu, Mar 28, 2024 at 8:07 PM Heinrich Schuchardt xypron.glpk@gmx.de wrote:
On 3/28/24 23:29, Sam Protsenko wrote:
Some platforms use the "unused" (all-zero) GUID as a partition type GUID to make some partitions hidden from the OS. For example, Samsung phones and other devices often have GPT partition tables like that, created by their "gpt_builder" tool [1]. All partitions with FILESYS=0 value (second column in [2] file) will be created in a way that:
- Partition type GUID will be all-zero ("unused")
- Attributes[48:49] bits will be set to 0 (whereas non-zero values mean the partition is visible to the OS: 1=raw, 2=ext4, 3=f2fs)
The UEFI specification is defining what a GPT partition table has to look like.
According the specification partition type GUID 00000000-0000-0000-0000-000000000000 marks an "unused entry" in the partition table.
An unused partition table entry cannot define a partition. It is one of the entries, that you skip over when enumerating via your patch 1/2.
With this patch 128 partition table entries are printed for an image having a single partition.
=> part list host 0
Partition Map for HOST device 0 -- Partition Type: EFI
Part Start LBA End LBA Name Attributes Type GUID Partition GUID 1 0x00000800 0x0001f7ff "EFI system partition" attrs: 0x0000000000000005 type: c12a7328-f81f-11d2-ba4b-00a0c93ec93b (system) guid: ee474198-4601-4d5c-81f0-54acf904dd40 2 0x00000000 0x00000000 "" attrs: 0x0000000000000000 type: 00000000-0000-0000-0000-000000000000 (00000000-0000-0000-0000-000000000000) guid: 00000000-0000-0000-0000-000000000000 ...
128 0x00000000 0x00000000 "" attrs: 0x0000000000000000 type: 00000000-0000-0000-0000-000000000000 (00000000-0000-0000-0000-000000000000) guid: 00000000-0000-0000-0000-000000000000
This is definitively wrong.
Although it's true that Linux kernel verifies the partition type GUID to be non-zero (in block/partitions/efi.c, is_pte_valid() function), where its U-Boot counterpart code was borrowed from originally, in case of U-Boot we want to handle partitions with "unused" GUIDs the same way as any other valid partitions, to allow the user to interact with those (e.g. list partitions using "part list", be able to flash those via fastboot, etc).
You cannot interact with a non-existing partition.
You may create a new partition in any empty slot that Samsung's tool has left in the partition table and then write to it. No patch is needed for this.
Thanks for reviewing! In case of Samsung's way of creating GPT tables, those are actually real partitions (they just "hide" those by means of setting their type GUIDs to 0), and it's possible to flash those and interact with them in other ways. But I can see how it's not a standard way of doing things. And because (as you pointed out) this patch leads to undesirable effects on other platforms, I also think it should be NAKed. That of course means it won't be possible to access all partitions on downstream Samsung devices, but with upstream U-Boot people will probably want to create an appropriate GPT table anyways.
Best regards
Heinrich
[snip]
On 3/28/24 23:29, Sam Protsenko wrote:
In part_get_info_by_name() the inability to get some partition info shouldn't be a reason for dropping out of the loop. That might happen e.g. if the partition is hidden or unused. An example of such case are Samsung devices, where they use the "unused" GUID type (00000000-0000-0000-0000-000000000000) to indicate that the partition should be hidden from the OS. Such partitions might not be seen in "part list" output, which creates "gaps" in numbering in between of the visible partitions:
Part Start LBA End LBA Name 1 0x00000400 0x0000a3ff "efs" 5 0x00026420 0x00026c1f "dtbo" 12 0x0003f390 0x0074738f "super"In that case, the loop in part_get_info_by_name() would break after partition #1, so any attempt to obtain "dtbo" or "super" partition will fail. Fix that by continuing to iterate over the remaining partitions to make sure none of the visible ones is missed. That makes "part" command (e.g. "part start", "part size") able to work with such tables.
Fixes: 87b8530fe244 ("disk: part: implement generic function part_get_info_by_name()") Signed-off-by: Sam Protsenko semen.protsenko@linaro.org
Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de
disk/part.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/disk/part.c b/disk/part.c index 36b88205eca7..08c9331e059c 100644 --- a/disk/part.c +++ b/disk/part.c @@ -717,8 +717,11 @@ int part_get_info_by_name(struct blk_desc *desc, const char *name, for (i = 1; i < part_drv->max_entries; i++) { ret = part_drv->get_info(desc, i, info); if (ret != 0) {
/* no more entries in table */break;
/** Partition with this index can't be obtained, but* further partitions might be, so keep checking.*/continue;
On Thu, Mar 28, 2024 at 05:29:50PM -0500, Sam Protsenko wrote:
In part_get_info_by_name() the inability to get some partition info shouldn't be a reason for dropping out of the loop. That might happen e.g. if the partition is hidden or unused. An example of such case are Samsung devices, where they use the "unused" GUID type (00000000-0000-0000-0000-000000000000) to indicate that the partition should be hidden from the OS. Such partitions might not be seen in "part list" output, which creates "gaps" in numbering in between of the visible partitions:
Part Start LBA End LBA Name 1 0x00000400 0x0000a3ff "efs" 5 0x00026420 0x00026c1f "dtbo" 12 0x0003f390 0x0074738f "super"In that case, the loop in part_get_info_by_name() would break after partition #1, so any attempt to obtain "dtbo" or "super" partition will fail. Fix that by continuing to iterate over the remaining partitions to make sure none of the visible ones is missed. That makes "part" command (e.g. "part start", "part size") able to work with such tables.
Fixes: 87b8530fe244 ("disk: part: implement generic function part_get_info_by_name()") Signed-off-by: Sam Protsenko semen.protsenko@linaro.org Reviewed-by: Heinrich Schuchardt xypron.glpk@gmx.de
Applied to u-boot/master, thanks!
participants (3)
-
Heinrich Schuchardt -
Sam Protsenko -
Tom Rini