add_inode: handle LXSS symlinks properly

maharmstone · Sep 27, 2021 · d30191a · d30191a
1 parent a8f27e8
commit d30191a
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Showing 2 changed files with 56 additions and 14 deletions.
diff --git a/src/ntfs.h b/src/ntfs.h
@@ -295,9 +295,19 @@ typedef struct {
  struct {
  uint8_t DataBuffer[1];
  } GenericReparseBuffer;
+
+ struct {
+ uint32_t unknown;
+ char name[1];
+ } LxSymlink; // undocumented
  };
 } REPARSE_DATA_BUFFER;
 
+typedef struct {
+ uint32_t unknown;
+ char name[1];
+} REPARSE_DATA_BUFFER_LX_SYMLINK;
+
 #ifndef IO_REPARSE_TAG_SYMLINK
 #define IO_REPARSE_TAG_SYMLINK 0xa000000c
 #endif

diff --git a/src/ntfs2btrfs.cpp b/src/ntfs2btrfs.cpp
@@ -2142,7 +2142,7 @@ static void add_inode(root& r, uint64_t inode, uint64_t ntfs_inode, bool& is_dir
  break;
  }
 
- case ntfs_attribute::SYMBOLIC_LINK:
+ case ntfs_attribute::SYMBOLIC_LINK: {
  if (att.FormCode == NTFS_ATTRIBUTE_FORM::NONRESIDENT_FORM)
  throw formatted_error("Error - SYMBOLIC_LINK is non-resident"); // FIXME - can this happen?
 
@@ -2151,24 +2151,40 @@ static void add_inode(root& r, uint64_t inode, uint64_t ntfs_inode, bool& is_dir
 
  symlink.clear();
 
- if (!is_dir && reparse_point.size() > offsetof(REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer)) {
- auto rpb = reinterpret_cast<const REPARSE_DATA_BUFFER*>(reparse_point.data());
+ if (is_dir)
+ break;
+
+ const auto& rpb = *reinterpret_cast<const REPARSE_DATA_BUFFER*>(reparse_point.data());
+
+ if (reparse_point.size() < offsetof(REPARSE_DATA_BUFFER, Reserved) ||
+ reparse_point.size() < rpb.ReparseDataLength + offsetof(REPARSE_DATA_BUFFER, GenericReparseBuffer.DataBuffer)) {
+ clear_line();
+
+ if (filename.empty())
+ filename = f.get_filename();
+
+ warnings.emplace_back(fmt::format("Reparse point buffer of {} was truncated.", filename));
 
- if ((rpb->ReparseTag == IO_REPARSE_TAG_SYMLINK && rpb->SymbolicLinkReparseBuffer.Flags & SYMLINK_FLAG_RELATIVE) ||
-  rpb->ReparseTag == IO_REPARSE_TAG_LX_SYMLINK) {
+ break;
+ }
 
- if (reparse_point.size() < offsetof(REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer) +
- rpb->SymbolicLinkReparseBuffer.PrintNameOffset +
- rpb->SymbolicLinkReparseBuffer.PrintNameLength) {
+ auto len = rpb.ReparseDataLength + offsetof(REPARSE_DATA_BUFFER, GenericReparseBuffer.DataBuffer);
+
+ switch (rpb.ReparseTag) {
+ case IO_REPARSE_TAG_SYMLINK:
+ if (len < offsetof(REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer) ||
+ (len < offsetof(REPARSE_DATA_BUFFER, SymbolicLinkReparseBuffer.PathBuffer) +
+ rpb.SymbolicLinkReparseBuffer.PrintNameOffset +
+ rpb.SymbolicLinkReparseBuffer.PrintNameLength)) {
  clear_line();
 
  if (filename.empty())
  filename = f.get_filename();
 
- warnings.emplace_back(fmt::format("Reparse point buffer of {} was truncated.", filename));
- } else {
- symlink = convert.to_bytes(&rpb->SymbolicLinkReparseBuffer.PathBuffer[rpb->SymbolicLinkReparseBuffer.PrintNameOffset / sizeof(char16_t)],
- &rpb->SymbolicLinkReparseBuffer.PathBuffer[(rpb->SymbolicLinkReparseBuffer.PrintNameOffset + rpb->SymbolicLinkReparseBuffer.PrintNameLength) / sizeof(char16_t)]);
+ warnings.emplace_back(fmt::format("Symlink reparse point buffer of {} was truncated.", filename));
+ } else if (rpb.SymbolicLinkReparseBuffer.Flags & SYMLINK_FLAG_RELATIVE) {
+ symlink = convert.to_bytes(&rpb.SymbolicLinkReparseBuffer.PathBuffer[rpb.SymbolicLinkReparseBuffer.PrintNameOffset / sizeof(char16_t)],
+ &rpb.SymbolicLinkReparseBuffer.PathBuffer[(rpb.SymbolicLinkReparseBuffer.PrintNameOffset + rpb.SymbolicLinkReparseBuffer.PrintNameLength) / sizeof(char16_t)]);
 
  for (auto& c : symlink) {
  if (c == '\\')
@@ -2177,9 +2193,25 @@ static void add_inode(root& r, uint64_t inode, uint64_t ntfs_inode, bool& is_dir
 
  reparse_point.clear();
  }
- }
+ break;
+
+ case IO_REPARSE_TAG_LX_SYMLINK:
+ if (len < offsetof(REPARSE_DATA_BUFFER, LxSymlink.name)) {
+ clear_line();
+
+ if (filename.empty())
+ filename = f.get_filename();
+
+ warnings.emplace_back(fmt::format("LXSS reparse point buffer of {} was truncated.", filename));
+ } else {
+ symlink = string_view(rpb.LxSymlink.name, len - offsetof(REPARSE_DATA_BUFFER, LxSymlink.name));
+ reparse_point.clear();
+ }
+ break;
  }
- break;
+
+ break;
+ }
 
  case ntfs_attribute::SECURITY_DESCRIPTOR: {
  auto max_sd_size = (uint32_t)(tree_size - sizeof(tree_header) - sizeof(leaf_node) - offsetof(DIR_ITEM, name[0]) - sizeof(EA_NTACL) + 1);