When creating the core image with an unaligned appended signature size (e.g., 479) for PowerPC, the grub-mkimage aligns the appended signature size to a multiple of 4 bytes, but it does not find and add the padding needed to align a multiple of 4 bytes appended signature size in the appended signature ELF note. Therefore, After signing and installing this core image, the firmware tries to read the magic string "~Module signature appended~" from the appended signature ELF note but gets the partial magic string like "Module signature appended~", and it leads to the appended signature magic string matching failing.
Example: grub-mkimage -O powerpc-ieee1275 -o core.elf -d grub-core -p /grub2 -x \ kernel.der --appended-signature-size 479 ... sign-file SHA256 ./grub.key ./grub.pem ./core.elf ./core.elf.signed Without padding: hexdump -C ./core.elf.signed . . 00383550 00 00 00 13 00 00 01 e0 41 53 69 67 41 70 70 65 |........ASigAppe| 00383560 6e 64 65 64 2d 53 69 67 6e 61 74 75 72 65 00 00 |nded-Signature..| . . 003836f0 dd 47 cd ed 02 8e 15 af 5b 09 2e 44 6f da 67 88 |.G......[..Do.g.| 00383700 4d 94 17 31 26 9d 47 95 d8 7c ad 36 00 d2 9c 53 |M..1&.G..|.6...S| 00383710 20 e0 af 60 78 cd 22 e6 ed 45 1e b1 e7 7e cf b5 | ..`x."..E...~..| 00383720 fc 58 ec df 1b ab 7a 00 00 02 00 00 00 00 00 00 |.X....z.........| 00383730 00 01 b7 7e 4d 6f 64 75 6c 65 20 73 69 67 6e 61 |...~Module signa| 00383740 74 75 72 65 20 61 70 70 65 6e 64 65 64 7e 0a |ture appended~.| To fix this, find and include the padding required to align a multiple of 4 bytes of appended signature size in the appended signature ELF note. Example: grub-mkimage -O powerpc-ieee1275 -o core.elf -d grub-core -p /grub2 -x \ kernel.der --appended-signature-size 479 ... sign-file SHA256 ./grub.key ./grub.pem ./core.elf ./core.elf.signed With padding: hexdump -C ./core.elf.signed . . 00137460 62 00 00 00 00 00 00 13 00 00 01 ec 41 53 69 67 |b...........ASig| 00137470 41 70 70 65 6e 64 65 64 2d 53 69 67 6e 61 74 75 |Appended-Signatu| . . 00137610 b7 07 cd b6 c8 ca 9a 5b 7c 13 8c 75 1d 1c 54 81 |.......[|..u..T.| 00137620 7f c4 9a 8b bd d7 73 8d 2f 7d d2 e6 d1 3c 52 a9 |......s./}...<R.| 00137630 4e 0b e5 24 ba 0a 82 aa 8e c5 86 fa e1 19 50 ec |N..$..........P.| 00137640 9f a7 9a ed e5 ed 13 35 00 00 02 00 00 00 00 00 |.......5........| 00137650 00 00 01 c2 7e 4d 6f 64 75 6c 65 20 73 69 67 6e |....~Module sign| 00137660 61 74 75 72 65 20 61 70 70 65 6e 64 65 64 7e 0a |ature appended~.| Signed-off-by: Sudhakar Kuppusamy <[email protected]> --- util/grub-mkimagexx.c | 1 + 1 file changed, 1 insertion(+) diff --git a/util/grub-mkimagexx.c b/util/grub-mkimagexx.c index 7fe2e35e6..1a453a5e8 100644 --- a/util/grub-mkimagexx.c +++ b/util/grub-mkimagexx.c @@ -249,6 +249,7 @@ SUFFIX (grub_mkimage_generate_elf) (const struct grub_install_image_target_desc { phnum++; footer_size += ALIGN_UP (sizeof (struct grub_appended_signature_note), 4); + footer_size += ALIGN_UP_OVERHEAD (appsig_size, 4); } if (image_target->id != IMAGE_LOONGSON_ELF) -- 2.50.1 (Apple Git-155) _______________________________________________ Grub-devel mailing list [email protected] https://lists.gnu.org/mailman/listinfo/grub-devel
