[Trusty SRU][PATCH 1/1] f2fs: do more integrity verification for superblock

[Kleber Sacilotto de Souza]

From: Chao Yu <chao2.yu at samsung.com>

CVE-2017-0750

Do more sanity check for superblock during ->mount.

Signed-off-by: Chao Yu <chao2.yu at samsung.com>
Signed-off-by: Jaegeuk Kim <jaegeuk at kernel.org>
(backported from commit 9a59b62fd88196844cee5fff851bee2cfd7afb6e upstream)
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza at canonical.com>
---
 fs/f2fs/super.c | 97 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)

diff --git a/fs/f2fs/super.c b/fs/f2fs/super.c
index ec70a2176c57..8c017100b7f7 100644
--- a/fs/f2fs/super.c
+++ b/fs/f2fs/super.c
@@ -677,6 +677,79 @@ static loff_t max_file_size(unsigned bits)
 	return result;
 }
 
+static inline bool sanity_check_area_boundary(struct super_block *sb,
+					struct f2fs_super_block *raw_super)
+{
+	u32 segment0_blkaddr = le32_to_cpu(raw_super->segment0_blkaddr);
+	u32 cp_blkaddr = le32_to_cpu(raw_super->cp_blkaddr);
+	u32 sit_blkaddr = le32_to_cpu(raw_super->sit_blkaddr);
+	u32 nat_blkaddr = le32_to_cpu(raw_super->nat_blkaddr);
+	u32 ssa_blkaddr = le32_to_cpu(raw_super->ssa_blkaddr);
+	u32 main_blkaddr = le32_to_cpu(raw_super->main_blkaddr);
+	u32 segment_count_ckpt = le32_to_cpu(raw_super->segment_count_ckpt);
+	u32 segment_count_sit = le32_to_cpu(raw_super->segment_count_sit);
+	u32 segment_count_nat = le32_to_cpu(raw_super->segment_count_nat);
+	u32 segment_count_ssa = le32_to_cpu(raw_super->segment_count_ssa);
+	u32 segment_count_main = le32_to_cpu(raw_super->segment_count_main);
+	u32 segment_count = le32_to_cpu(raw_super->segment_count);
+	u32 log_blocks_per_seg = le32_to_cpu(raw_super->log_blocks_per_seg);
+
+	if (segment0_blkaddr != cp_blkaddr) {
+		f2fs_msg(sb, KERN_INFO,
+			"Mismatch start address, segment0(%u) cp_blkaddr(%u)",
+			segment0_blkaddr, cp_blkaddr);
+		return true;
+	}
+
+	if (cp_blkaddr + (segment_count_ckpt << log_blocks_per_seg) !=
+							sit_blkaddr) {
+		f2fs_msg(sb, KERN_INFO,
+			"Wrong CP boundary, start(%u) end(%u) blocks(%u)",
+			cp_blkaddr, sit_blkaddr,
+			segment_count_ckpt << log_blocks_per_seg);
+		return true;
+	}
+
+	if (sit_blkaddr + (segment_count_sit << log_blocks_per_seg) !=
+							nat_blkaddr) {
+		f2fs_msg(sb, KERN_INFO,
+			"Wrong SIT boundary, start(%u) end(%u) blocks(%u)",
+			sit_blkaddr, nat_blkaddr,
+			segment_count_sit << log_blocks_per_seg);
+		return true;
+	}
+
+	if (nat_blkaddr + (segment_count_nat << log_blocks_per_seg) !=
+							ssa_blkaddr) {
+		f2fs_msg(sb, KERN_INFO,
+			"Wrong NAT boundary, start(%u) end(%u) blocks(%u)",
+			nat_blkaddr, ssa_blkaddr,
+			segment_count_nat << log_blocks_per_seg);
+		return true;
+	}
+
+	if (ssa_blkaddr + (segment_count_ssa << log_blocks_per_seg) !=
+							main_blkaddr) {
+		f2fs_msg(sb, KERN_INFO,
+			"Wrong SSA boundary, start(%u) end(%u) blocks(%u)",
+			ssa_blkaddr, main_blkaddr,
+			segment_count_ssa << log_blocks_per_seg);
+		return true;
+	}
+
+	if (main_blkaddr + (segment_count_main << log_blocks_per_seg) !=
+		segment0_blkaddr + (segment_count << log_blocks_per_seg)) {
+		f2fs_msg(sb, KERN_INFO,
+			"Wrong MAIN_AREA boundary, start(%u) end(%u) blocks(%u)",
+			main_blkaddr,
+			segment0_blkaddr + (segment_count << log_blocks_per_seg),
+			segment_count_main << log_blocks_per_seg);
+		return true;
+	}
+
+	return false;
+}
+
 static int sanity_check_raw_super(struct super_block *sb,
 			struct f2fs_super_block *raw_super)
 {
@@ -706,6 +779,14 @@ static int sanity_check_raw_super(struct super_block *sb,
 		return 1;
 	}
 
+	/* check log blocks per segment */
+	if (le32_to_cpu(raw_super->log_blocks_per_seg) != 9) {
+		f2fs_msg(sb, KERN_INFO,
+			"Invalid log blocks per segment (%u)\n",
+			le32_to_cpu(raw_super->log_blocks_per_seg));
+		return 1;
+	}
+
 	if (le32_to_cpu(raw_super->log_sectorsize) !=
 					F2FS_LOG_SECTOR_SIZE) {
 		f2fs_msg(sb, KERN_INFO, "Invalid log sectorsize");
@@ -724,6 +805,22 @@ static int sanity_check_raw_super(struct super_block *sb,
 		return 1;
 	}
 
+	/* check reserved ino info */
+	if (le32_to_cpu(raw_super->node_ino) != 1 ||
+		le32_to_cpu(raw_super->meta_ino) != 2 ||
+		le32_to_cpu(raw_super->root_ino) != 3) {
+		f2fs_msg(sb, KERN_INFO,
+			"Invalid Fs Meta Ino: node(%u) meta(%u) root(%u)",
+			le32_to_cpu(raw_super->node_ino),
+			le32_to_cpu(raw_super->meta_ino),
+			le32_to_cpu(raw_super->root_ino));
+		return 1;
+	}
+
+	/* check CP/SIT/NAT/SSA/MAIN_AREA area boundary */
+	if (sanity_check_area_boundary(sb, raw_super))
+		return 1;
+
 	return 0;
 }
 
-- 
2.14.1