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authorJohannes Schindelin <johannes.schindelin@gmx.de>2019-09-23 06:58:11 (GMT)
committerJohannes Schindelin <johannes.schindelin@gmx.de>2019-12-05 14:36:50 (GMT)
commit288a74bcd28229a00c3632f18cba92dbfdf73ee9 (patch)
tree86984af16137a62e6062503f5d3d2278eeed6519 /read-cache.c
parenta62f9d1ace8c6556cbc1bb7df69eff0a0bb9e774 (diff)
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is_ntfs_dotgit(): only verify the leading segment
The config setting `core.protectNTFS` is specifically designed to work not only on Windows, but anywhere, to allow for repositories hosted on, say, Linux servers to be protected against NTFS-specific attack vectors. As a consequence, `is_ntfs_dotgit()` manually splits backslash-separated paths (but does not do the same for paths separated by forward slashes), under the assumption that the backslash might not be a valid directory separator on the _current_ Operating System. However, the two callers, `verify_path()` and `fsck_tree()`, are supposed to feed only individual path segments to the `is_ntfs_dotgit()` function. This causes a lot of duplicate scanning (and very inefficient scanning, too, as the inner loop of `is_ntfs_dotgit()` was optimized for readability rather than for speed. Let's simplify the design of `is_ntfs_dotgit()` by putting the burden of splitting the paths by backslashes as directory separators on the callers of said function. Consequently, the `verify_path()` function, which already splits the path by directory separators, now treats backslashes as directory separators _explicitly_ when `core.protectNTFS` is turned on, even on platforms where the backslash is _not_ a directory separator. Note that we have to repeat some code in `verify_path()`: if the backslash is not a directory separator on the current Operating System, we want to allow file names like `\`, but we _do_ want to disallow paths that are clearly intended to cause harm when the repository is cloned on Windows. The `fsck_tree()` function (the other caller of `is_ntfs_dotgit()`) now needs to look for backslashes in tree entries' names specifically when `core.protectNTFS` is turned on. While it would be tempting to completely disallow backslashes in that case (much like `fsck` reports names containing forward slashes as "full paths"), this would be overzealous: when `core.protectNTFS` is turned on in a non-Windows setup, backslashes are perfectly valid characters in file names while we _still_ want to disallow tree entries that are clearly designed to exploit NTFS-specific behavior. This simplification will make subsequent changes easier to implement, such as turning `core.protectNTFS` on by default (not only on Windows) or protecting against attack vectors involving NTFS Alternate Data Streams. Incidentally, this change allows for catching malicious repositories that contain tree entries of the form `dir\.gitmodules` already on the server side rather than only on the client side (and previously only on Windows): in contrast to `is_ntfs_dotgit()`, the `is_ntfs_dotgitmodules()` function already expects the caller to split the paths by directory separators. Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Diffstat (limited to 'read-cache.c')
-rw-r--r--read-cache.c8
1 files changed, 8 insertions, 0 deletions
diff --git a/read-cache.c b/read-cache.c
index 5b57b36..bde1e70 100644
--- a/read-cache.c
+++ b/read-cache.c
@@ -874,7 +874,15 @@ inside:
if ((c == '.' && !verify_dotfile(path, mode)) ||
is_dir_sep(c) || c == '\0')
return 0;
+ } else if (c == '\\' && protect_ntfs) {
+ if (is_ntfs_dotgit(path))
+ return 0;
+ if (S_ISLNK(mode)) {
+ if (is_ntfs_dotgitmodules(path))
+ return 0;
+ }
}
+
c = *path++;
}
}