76 lines
2.2 KiB
Diff
76 lines
2.2 KiB
Diff
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From 2011a616aa533c336f9242f25017ce7043557e4c Mon Sep 17 00:00:00 2001
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From: =?UTF-8?q?Thomas=20Wei=C3=9Fschuh?= <thomas@t-8ch.de>
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Date: Tue, 6 Aug 2024 19:07:48 +0200
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Subject: [PATCH] libblkid: apfs: validate checksums
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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The apfs superblock contains a checksum based on Fletcher-64.
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Validate the checksum to make the probing more robust.
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Signed-off-by: Thomas Weißschuh <thomas@t-8ch.de>
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Reference:https://github.com/util-linux/util-linux/commit/2011a616aa533c336f9242f25017ce7043557e4c
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Conflict:NA
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---
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libblkid/src/superblocks/apfs.c | 36 ++++++++++++++++++++++++++++++++-
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1 file changed, 35 insertions(+), 1 deletion(-)
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diff --git a/libblkid/src/superblocks/apfs.c b/libblkid/src/superblocks/apfs.c
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index b7f09f33..4557abcb 100644
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--- a/libblkid/src/superblocks/apfs.c
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+++ b/libblkid/src/superblocks/apfs.c
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@@ -35,7 +35,38 @@ struct apfs_super_block {
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uint64_t read_only_features;
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uint64_t incompatible_features;
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uint8_t uuid[16];
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-};
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+
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+ uint8_t padding[4008]; // Pad to 4096 bytes for checksum
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+} __attribute__((packed));
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+
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+static uint64_t apfs_fletcher64(const uint8_t *buf, size_t size)
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+{
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+ uint64_t lo32 = 0, hi32 = 0, csum_hi;
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+ uint32_t csum_low;
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+ size_t i;
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+
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+ for (i = 0; i < size / 4; i++) {
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+ lo32 += le32_to_cpu(((uint32_t *)buf)[i]);
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+ hi32 += lo32;
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+ }
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+
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+ csum_low = ~((lo32 + hi32) % UINT32_MAX);
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+ csum_hi = ~((lo32 + csum_low) % UINT32_MAX);
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+
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+ return csum_hi << 32 | csum_low;
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+}
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+
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+static int apfs_verify_checksum(blkid_probe pr,
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+ const struct apfs_super_block *sb)
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+{
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+ const size_t csummed_start_offset = offsetof(__typeof__(*sb), oid);
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+ uint64_t csum;
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+
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+ csum = apfs_fletcher64(((const uint8_t *)sb) + csummed_start_offset,
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+ sizeof(*sb) - csummed_start_offset);
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+
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+ return blkid_probe_verify_csum(pr, csum, le64_to_cpu(sb->checksum));
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+}
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static int probe_apfs(blkid_probe pr, const struct blkid_idmag *mag)
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{
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@@ -45,6 +76,9 @@ static int probe_apfs(blkid_probe pr, const struct blkid_idmag *mag)
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if (!sb)
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return errno ? -errno : BLKID_PROBE_NONE;
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+ if (!apfs_verify_checksum(pr, sb))
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+ return BLKID_PROBE_NONE;
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+
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if (le16_to_cpu(sb->type) != APFS_CONTAINER_SUPERBLOCK_TYPE)
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return BLKID_PROBE_NONE;
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--
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2.33.0
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