sys-boot/grub: fix issue with XFS v4 superblocks

Signed-off-by: Mike Gilbert <floppym@gentoo.org>

2 files changed, 121 insertions, 0 deletions

diff --git a/sys-boot/grub/files/grub-2.06-xfs-v4.patch b/sys-boot/grub/files/grub-2.06-xfs-v4.patch
new file mode 100644
index 000000000000..fe8223780384
--- /dev/null
+++ b/sys-boot/grub/files/grub-2.06-xfs-v4.patch
@@ -0,0 +1,120 @@
+From a4b495520e4dc41a896a8b916a64eda9970c50ea Mon Sep 17 00:00:00 2001
+From: Erwan Velu <erwanaliasr1@gmail.com>
+Date: Wed, 25 Aug 2021 15:31:52 +0200
+Subject: fs/xfs: Fix unreadable filesystem with v4 superblock
+
+The commit 8b1e5d193 (fs/xfs: Add bigtime incompat feature support)
+introduced the bigtime support by adding some features in v3 inodes.
+This change extended grub_xfs_inode struct by 76 bytes but also changed
+the computation of XFS_V2_INODE_SIZE and XFS_V3_INODE_SIZE. Prior this
+commit, XFS_V2_INODE_SIZE was 100 bytes. After the commit it's 84 bytes
+XFS_V2_INODE_SIZE becomes 16 bytes too small.
+
+As a result, the data structures aren't properly aligned and the GRUB
+generates "attempt to read or write outside of partition" errors when
+trying to read the XFS filesystem:
+
+                             GNU GRUB  version 2.11
+	....
+	grub> set debug=efi,gpt,xfs
+	grub> insmod part_gpt
+	grub> ls (hd0,gpt1)/
+	partmap/gpt.c:93: Read a valid GPT header
+	partmap/gpt.c:115: GPT entry 0: start=4096, length=1953125
+	fs/xfs.c:931: Reading sb
+	fs/xfs.c:270: Validating superblock
+	fs/xfs.c:295: XFS v4 superblock detected
+	fs/xfs.c:962: Reading root ino 128
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:515: Reading inode (739521961424144223) - 344365866970255880, 3840
+	error: attempt to read or write outside of partition.
+
+This commit change the XFS_V2_INODE_SIZE computation by subtracting 76
+bytes instead of 92 bytes from the actual size of grub_xfs_inode struct.
+This 76 bytes value comes from added members:
+	20 grub_uint8_t   unused5
+	 1 grub_uint64_t  flags2
+        48 grub_uint8_t   unused6
+
+This patch explicitly splits the v2 and v3 parts of the structure.
+The unused4 is still ending of the v2 structures and the v3 starts
+at unused5. Thanks to this we will avoid future corruptions of v2
+or v3 inodes.
+
+The XFS_V2_INODE_SIZE is returning to its expected size and the
+filesystem is back to a readable state:
+
+                      GNU GRUB  version 2.11
+	....
+	grub> set debug=efi,gpt,xfs
+	grub> insmod part_gpt
+	grub> ls (hd0,gpt1)/
+	partmap/gpt.c:93: Read a valid GPT header
+	partmap/gpt.c:115: GPT entry 0: start=4096, length=1953125
+	fs/xfs.c:931: Reading sb
+	fs/xfs.c:270: Validating superblock
+	fs/xfs.c:295: XFS v4 superblock detected
+	fs/xfs.c:962: Reading root ino 128
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:931: Reading sb
+	fs/xfs.c:270: Validating superblock
+	fs/xfs.c:295: XFS v4 superblock detected
+	fs/xfs.c:962: Reading root ino 128
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:515: Reading inode (128) - 64, 0
+	fs/xfs.c:515: Reading inode (131) - 64, 768
+	efi/ fs/xfs.c:515: Reading inode (3145856) - 1464904, 0
+	grub2/ fs/xfs.c:515: Reading inode (132) - 64, 1024
+	grub/ fs/xfs.c:515: Reading inode (139) - 64, 2816
+	grub>
+
+Fixes: 8b1e5d193 (fs/xfs: Add bigtime incompat feature support)
+
+Signed-off-by: Erwan Velu <e.velu@criteo.com>
+Tested-by: Carlos Maiolino <cmaiolino@redhat.com>
+Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
+---
+ grub-core/fs/xfs.c | 14 ++++++++++----
+ 1 file changed, 10 insertions(+), 4 deletions(-)
+
+diff --git a/grub-core/fs/xfs.c b/grub-core/fs/xfs.c
+index 0f524c3a8..e3816d1ec 100644
+--- a/grub-core/fs/xfs.c
++++ b/grub-core/fs/xfs.c
+@@ -192,6 +192,11 @@ struct grub_xfs_time_legacy
+   grub_uint32_t nanosec;
+ } GRUB_PACKED;
+ 
++/*
++ * The struct grub_xfs_inode layout was taken from the
++ * struct xfs_dinode_core which is described here:
++ * https://mirrors.edge.kernel.org/pub/linux/utils/fs/xfs/docs/xfs_filesystem_structure.pdf
++ */
+ struct grub_xfs_inode
+ {
+   grub_uint8_t magic[2];
+@@ -208,14 +213,15 @@ struct grub_xfs_inode
+   grub_uint32_t nextents;
+   grub_uint16_t unused3;
+   grub_uint8_t fork_offset;
+-  grub_uint8_t unused4[37];
++  grub_uint8_t unused4[17]; /* Last member of inode v2. */
++  grub_uint8_t unused5[20]; /* First member of inode v3. */
+   grub_uint64_t flags2;
+-  grub_uint8_t unused5[48];
++  grub_uint8_t unused6[48]; /* Last member of inode v3. */
+ } GRUB_PACKED;
+ 
+ #define XFS_V3_INODE_SIZE	sizeof(struct grub_xfs_inode)
+-/* Size of struct grub_xfs_inode until fork_offset (included). */
+-#define XFS_V2_INODE_SIZE	(XFS_V3_INODE_SIZE - 92)
++/* Size of struct grub_xfs_inode v2, up to unused4 member included. */
++#define XFS_V2_INODE_SIZE	(XFS_V3_INODE_SIZE - 76)
+ 
+ struct grub_xfs_dirblock_tail
+ {
+-- 
+cgit v1.2.1
+
diff --git a/sys-boot/grub/grub-2.06.ebuild b/sys-boot/grub/grub-2.06-r1.ebuild
index f5286ca3d6b9..3c49ad5db1f0 100644
--- a/sys-boot/grub/grub-2.06.ebuild
+++ b/sys-boot/grub/grub-2.06-r1.ebuild
@@ -38,6 +38,7 @@ else
 fi
 
 PATCHES=(
+	"${FILESDIR}"/grub-2.06-xfs-v4.patch
 	"${FILESDIR}"/gfxpayload.patch
 	"${FILESDIR}"/grub-2.02_beta2-KERNEL_GLOBS.patch
 	"${FILESDIR}"/grub-2.06-test-words.patch