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![Taylor Blau](/assets/img/avatar_default.png)
When using the dir_iterator API, we first stat(2) the base path, and
then use that as a starting point to enumerate the directory's contents.
If the directory contains symbolic links, we will immediately die() upon
encountering them without the `FOLLOW_SYMLINKS` flag. The same is not
true when resolving the top-level directory, though.
As explained in a previous commit, this oversight in 6f054f9fb3
(builtin/clone.c: disallow `--local` clones with symlinks, 2022-07-28)
can be used as an attack vector to include arbitrary files on a victim's
filesystem from outside of the repository.
Prevent resolving top-level symlinks unless the FOLLOW_SYMLINKS flag is
given, which will cause clones of a repository with a symlink'd
"$GIT_DIR/objects" directory to fail.
Signed-off-by: Taylor Blau <me@ttaylorr.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
133 lines
4.5 KiB
C
133 lines
4.5 KiB
C
#ifndef DIR_ITERATOR_H
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#define DIR_ITERATOR_H
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#include "strbuf.h"
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/*
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* Iterate over a directory tree.
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*
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* Iterate over a directory tree, recursively, including paths of all
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* types and hidden paths. Skip "." and ".." entries and don't follow
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* symlinks except for the original path. Note that the original path
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* is not included in the iteration.
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*
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* Every time dir_iterator_advance() is called, update the members of
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* the dir_iterator structure to reflect the next path in the
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* iteration. The order that paths are iterated over within a
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* directory is undefined, directory paths are always given before
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* their contents.
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*
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* A typical iteration looks like this:
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*
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* int ok;
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* unsigned int flags = DIR_ITERATOR_PEDANTIC;
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* struct dir_iterator *iter = dir_iterator_begin(path, flags);
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*
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* if (!iter)
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* goto error_handler;
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*
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* while ((ok = dir_iterator_advance(iter)) == ITER_OK) {
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* if (want_to_stop_iteration()) {
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* ok = dir_iterator_abort(iter);
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* break;
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* }
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*
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* // Access information about the current path:
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* if (S_ISDIR(iter->st.st_mode))
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* printf("%s is a directory\n", iter->relative_path);
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* }
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*
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* if (ok != ITER_DONE)
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* handle_error();
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*
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* Callers are allowed to modify iter->path while they are working,
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* but they must restore it to its original contents before calling
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* dir_iterator_advance() again.
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*/
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/*
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* Flags for dir_iterator_begin:
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*
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* - DIR_ITERATOR_PEDANTIC: override dir-iterator's default behavior
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* in case of an error at dir_iterator_advance(), which is to keep
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* looking for a next valid entry. With this flag, resources are freed
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* and ITER_ERROR is returned immediately. In both cases, a meaningful
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* warning is emitted. Note: ENOENT errors are always ignored so that
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* the API users may remove files during iteration.
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*
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* - DIR_ITERATOR_FOLLOW_SYMLINKS: make dir-iterator follow symlinks.
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* i.e., linked directories' contents will be iterated over and
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* iter->base.st will contain information on the referred files,
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* not the symlinks themselves, which is the default behavior. Broken
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* symlinks are ignored.
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*
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* Note: setting DIR_ITERATOR_FOLLOW_SYMLINKS affects resolving the
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* starting path as well (e.g., attempting to iterate starting at a
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* symbolic link pointing to a directory without FOLLOW_SYMLINKS will
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* result in an error).
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*
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* Warning: circular symlinks are also followed when
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* DIR_ITERATOR_FOLLOW_SYMLINKS is set. The iteration may end up with
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* an ELOOP if they happen and DIR_ITERATOR_PEDANTIC is set.
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*/
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#define DIR_ITERATOR_PEDANTIC (1 << 0)
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#define DIR_ITERATOR_FOLLOW_SYMLINKS (1 << 1)
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struct dir_iterator {
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/* The current path: */
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struct strbuf path;
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/*
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* The current path relative to the starting path. This part
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* of the path always uses "/" characters to separate path
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* components:
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*/
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const char *relative_path;
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/* The current basename: */
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const char *basename;
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/*
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* The result of calling lstat() on path; or stat(), if the
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* DIR_ITERATOR_FOLLOW_SYMLINKS flag was set at
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* dir_iterator's initialization.
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*/
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struct stat st;
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};
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/*
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* Start a directory iteration over path with the combination of
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* options specified by flags. On success, return a dir_iterator
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* that holds the internal state of the iteration. In case of
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* failure, return NULL and set errno accordingly.
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*
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* The iteration includes all paths under path, not including path
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* itself and not including "." or ".." entries.
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*
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* Parameters are:
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* - path is the starting directory. An internal copy will be made.
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* - flags is a combination of the possible flags to initialize a
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* dir-iterator or 0 for default behavior.
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*/
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struct dir_iterator *dir_iterator_begin(const char *path, unsigned int flags);
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/*
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* Advance the iterator to the first or next item and return ITER_OK.
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* If the iteration is exhausted, free the dir_iterator and any
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* resources associated with it and return ITER_DONE.
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*
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* It is a bug to use iterator or call this function again after it
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* has returned ITER_DONE or ITER_ERROR (which may be returned iff
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* the DIR_ITERATOR_PEDANTIC flag was set).
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*/
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int dir_iterator_advance(struct dir_iterator *iterator);
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/*
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* End the iteration before it has been exhausted. Free the
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* dir_iterator and any associated resources and return ITER_DONE. On
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* error, free the dir_iterator and return ITER_ERROR.
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*/
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int dir_iterator_abort(struct dir_iterator *iterator);
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#endif
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