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git/fsck.h
Jeff King 0fbcaef6b4 fsck: detect very large tree pathnames
In general, Git tries not to arbitrarily limit what it will store, and
there are currently no limits at all on the size of the path we find in
a tree. In theory you could have one that is gigabytes long.

But in practice this freedom is not really helping anybody, and is
potentially harmful:

  1. Most operating systems have much lower limits for the size of a
     single pathname component (e.g., on Linux you'll generally get
     ENAMETOOLONG for anything over 255 bytes). And while you _can_ use
     Git in a way that never touches the filesystem (manipulating the
     index and trees directly), it's still probably not a good idea to
     have gigantic tree names. Many operations load and traverse them,
     so any clever Git-as-a-database scheme is likely to perform poorly
     in that case.

  2. We still have a lot of code which assumes strings are reasonably
     sized, and I won't be at all surprised if you can trigger some
     interesting integer overflows with gigantic pathnames. Stopping
     malicious trees from entering the repository provides an extra line
     of defense, protecting downstream code.

This patch implements an fsck check so that such trees can be rejected
by transfer.fsckObjects. I've picked a reasonably high maximum depth
here (4096) that hopefully should not bother anybody in practice. I've
also made it configurable, as an escape hatch.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-08-31 15:51:07 -07:00

246 lines
7.5 KiB
C

#ifndef GIT_FSCK_H
#define GIT_FSCK_H
#include "object.h"
#include "oidset.h"
enum fsck_msg_type {
/* for internal use only */
FSCK_IGNORE,
FSCK_INFO,
FSCK_FATAL,
/* "public", fed to e.g. error_func callbacks */
FSCK_ERROR,
FSCK_WARN,
};
/*
* Documentation/fsck-msgids.txt documents these; when
* modifying this list in any way, make sure to keep the
* two in sync.
*/
#define FOREACH_FSCK_MSG_ID(FUNC) \
/* fatal errors */ \
FUNC(NUL_IN_HEADER, FATAL) \
FUNC(UNTERMINATED_HEADER, FATAL) \
/* errors */ \
FUNC(BAD_DATE, ERROR) \
FUNC(BAD_DATE_OVERFLOW, ERROR) \
FUNC(BAD_EMAIL, ERROR) \
FUNC(BAD_NAME, ERROR) \
FUNC(BAD_OBJECT_SHA1, ERROR) \
FUNC(BAD_PARENT_SHA1, ERROR) \
FUNC(BAD_TIMEZONE, ERROR) \
FUNC(BAD_TREE, ERROR) \
FUNC(BAD_TREE_SHA1, ERROR) \
FUNC(BAD_TYPE, ERROR) \
FUNC(DUPLICATE_ENTRIES, ERROR) \
FUNC(MISSING_AUTHOR, ERROR) \
FUNC(MISSING_COMMITTER, ERROR) \
FUNC(MISSING_EMAIL, ERROR) \
FUNC(MISSING_NAME_BEFORE_EMAIL, ERROR) \
FUNC(MISSING_OBJECT, ERROR) \
FUNC(MISSING_SPACE_BEFORE_DATE, ERROR) \
FUNC(MISSING_SPACE_BEFORE_EMAIL, ERROR) \
FUNC(MISSING_TAG, ERROR) \
FUNC(MISSING_TAG_ENTRY, ERROR) \
FUNC(MISSING_TREE, ERROR) \
FUNC(MISSING_TYPE, ERROR) \
FUNC(MISSING_TYPE_ENTRY, ERROR) \
FUNC(MULTIPLE_AUTHORS, ERROR) \
FUNC(TREE_NOT_SORTED, ERROR) \
FUNC(UNKNOWN_TYPE, ERROR) \
FUNC(ZERO_PADDED_DATE, ERROR) \
FUNC(GITMODULES_MISSING, ERROR) \
FUNC(GITMODULES_BLOB, ERROR) \
FUNC(GITMODULES_LARGE, ERROR) \
FUNC(GITMODULES_NAME, ERROR) \
FUNC(GITMODULES_SYMLINK, ERROR) \
FUNC(GITMODULES_URL, ERROR) \
FUNC(GITMODULES_PATH, ERROR) \
FUNC(GITMODULES_UPDATE, ERROR) \
FUNC(GITATTRIBUTES_MISSING, ERROR) \
FUNC(GITATTRIBUTES_LARGE, ERROR) \
FUNC(GITATTRIBUTES_LINE_LENGTH, ERROR) \
FUNC(GITATTRIBUTES_BLOB, ERROR) \
/* warnings */ \
FUNC(EMPTY_NAME, WARN) \
FUNC(FULL_PATHNAME, WARN) \
FUNC(HAS_DOT, WARN) \
FUNC(HAS_DOTDOT, WARN) \
FUNC(HAS_DOTGIT, WARN) \
FUNC(NULL_SHA1, WARN) \
FUNC(ZERO_PADDED_FILEMODE, WARN) \
FUNC(NUL_IN_COMMIT, WARN) \
FUNC(LARGE_PATHNAME, WARN) \
/* infos (reported as warnings, but ignored by default) */ \
FUNC(BAD_FILEMODE, INFO) \
FUNC(GITMODULES_PARSE, INFO) \
FUNC(GITIGNORE_SYMLINK, INFO) \
FUNC(GITATTRIBUTES_SYMLINK, INFO) \
FUNC(MAILMAP_SYMLINK, INFO) \
FUNC(BAD_TAG_NAME, INFO) \
FUNC(MISSING_TAGGER_ENTRY, INFO) \
/* ignored (elevated when requested) */ \
FUNC(EXTRA_HEADER_ENTRY, IGNORE)
#define MSG_ID(id, msg_type) FSCK_MSG_##id,
enum fsck_msg_id {
FOREACH_FSCK_MSG_ID(MSG_ID)
FSCK_MSG_MAX
};
#undef MSG_ID
struct fsck_options;
struct object;
void fsck_set_msg_type_from_ids(struct fsck_options *options,
enum fsck_msg_id msg_id,
enum fsck_msg_type msg_type);
void fsck_set_msg_type(struct fsck_options *options,
const char *msg_id, const char *msg_type);
void fsck_set_msg_types(struct fsck_options *options, const char *values);
int is_valid_msg_type(const char *msg_id, const char *msg_type);
/*
* callback function for fsck_walk
* type is the expected type of the object or OBJ_ANY
* the return value is:
* 0 everything OK
* <0 error signaled and abort
* >0 error signaled and do not abort
*/
typedef int (*fsck_walk_func)(struct object *obj, enum object_type object_type,
void *data, struct fsck_options *options);
/* callback for fsck_object, type is FSCK_ERROR or FSCK_WARN */
typedef int (*fsck_error)(struct fsck_options *o,
const struct object_id *oid, enum object_type object_type,
enum fsck_msg_type msg_type, enum fsck_msg_id msg_id,
const char *message);
int fsck_error_function(struct fsck_options *o,
const struct object_id *oid, enum object_type object_type,
enum fsck_msg_type msg_type, enum fsck_msg_id msg_id,
const char *message);
int fsck_error_cb_print_missing_gitmodules(struct fsck_options *o,
const struct object_id *oid,
enum object_type object_type,
enum fsck_msg_type msg_type,
enum fsck_msg_id msg_id,
const char *message);
struct fsck_options {
fsck_walk_func walk;
fsck_error error_func;
unsigned strict:1;
enum fsck_msg_type *msg_type;
struct oidset skiplist;
struct oidset gitmodules_found;
struct oidset gitmodules_done;
struct oidset gitattributes_found;
struct oidset gitattributes_done;
kh_oid_map_t *object_names;
};
#define FSCK_OPTIONS_DEFAULT { \
.skiplist = OIDSET_INIT, \
.gitmodules_found = OIDSET_INIT, \
.gitmodules_done = OIDSET_INIT, \
.gitattributes_found = OIDSET_INIT, \
.gitattributes_done = OIDSET_INIT, \
.error_func = fsck_error_function \
}
#define FSCK_OPTIONS_STRICT { \
.strict = 1, \
.gitmodules_found = OIDSET_INIT, \
.gitmodules_done = OIDSET_INIT, \
.gitattributes_found = OIDSET_INIT, \
.gitattributes_done = OIDSET_INIT, \
.error_func = fsck_error_function, \
}
#define FSCK_OPTIONS_MISSING_GITMODULES { \
.strict = 1, \
.gitmodules_found = OIDSET_INIT, \
.gitmodules_done = OIDSET_INIT, \
.gitattributes_found = OIDSET_INIT, \
.gitattributes_done = OIDSET_INIT, \
.error_func = fsck_error_cb_print_missing_gitmodules, \
}
/* descend in all linked child objects
* the return value is:
* -1 error in processing the object
* <0 return value of the callback, which lead to an abort
* >0 return value of the first signaled error >0 (in the case of no other errors)
* 0 everything OK
*/
int fsck_walk(struct object *obj, void *data, struct fsck_options *options);
/*
* Blob objects my pass a NULL data pointer, which indicates they are too large
* to fit in memory. All other types must pass a real buffer.
*/
int fsck_object(struct object *obj, void *data, unsigned long size,
struct fsck_options *options);
/*
* Same as fsck_object(), but for when the caller doesn't have an object
* struct.
*/
int fsck_buffer(const struct object_id *oid, enum object_type,
void *data, unsigned long size,
struct fsck_options *options);
/*
* fsck a tag, and pass info about it back to the caller. This is
* exposed fsck_object() internals for git-mktag(1).
*/
int fsck_tag_standalone(const struct object_id *oid, const char *buffer,
unsigned long size, struct fsck_options *options,
struct object_id *tagged_oid,
int *tag_type);
/*
* Some fsck checks are context-dependent, and may end up queued; run this
* after completing all fsck_object() calls in order to resolve any remaining
* checks.
*/
int fsck_finish(struct fsck_options *options);
/*
* Subsystem for storing human-readable names for each object.
*
* If fsck_enable_object_names() has not been called, all other functions are
* noops.
*
* Use fsck_put_object_name() to seed initial names (e.g. from refnames); the
* fsck code will extend that while walking trees, etc.
*
* Use fsck_get_object_name() to get a single name (or NULL if none). Or the
* more convenient describe_object(), which always produces an output string
* with the oid combined with the name (if any). Note that the return value
* points to a rotating array of static buffers, and may be invalidated by a
* subsequent call.
*/
void fsck_enable_object_names(struct fsck_options *options);
const char *fsck_get_object_name(struct fsck_options *options,
const struct object_id *oid);
__attribute__((format (printf,3,4)))
void fsck_put_object_name(struct fsck_options *options,
const struct object_id *oid,
const char *fmt, ...);
const char *fsck_describe_object(struct fsck_options *options,
const struct object_id *oid);
struct key_value_info;
/*
* git_config() callback for use by fsck-y tools that want to support
* fsck.<msg> fsck.skipList etc.
*/
int git_fsck_config(const char *var, const char *value,
const struct config_context *ctx, void *cb);
#endif