git/fsck.h
Patrick Steinhardt 27ab4784d5 fsck: implement checks for gitattributes
Recently, a vulnerability was reported that can lead to an out-of-bounds
write when reading an unreasonably large gitattributes file. The root
cause of this error are multiple integer overflows in different parts of
the code when there are either too many lines, when paths are too long,
when attribute names are too long, or when there are too many attributes
declared for a pattern.

As all of these are related to size, it seems reasonable to restrict the
size of the gitattributes file via git-fsck(1). This allows us to both
stop distributing known-vulnerable objects via common hosting platforms
that have fsck enabled, and users to protect themselves by enabling the
`fetch.fsckObjects` config.

There are basically two checks:

    1. We verify that size of the gitattributes file is smaller than
       100MB.

    2. We verify that the maximum line length does not exceed 2048
       bytes.

With the preceding commits, both of these conditions would cause us to
either ignore the complete gitattributes file or blob in the first case,
or the specific line in the second case. Now with these consistency
checks added, we also grow the ability to stop distributing such files
in the first place when `receive.fsckObjects` is enabled.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2022-12-09 17:07:04 +09:00

230 lines
7.1 KiB
C

#ifndef GIT_FSCK_H
#define GIT_FSCK_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,
};
#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_TAG_OBJECT, 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_TREE_OBJECT, 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(BAD_FILEMODE, WARN) \
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) \
/* infos (reported as warnings, but ignored by default) */ \
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);
/*
* 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);
/*
* 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, void *cb);
#endif