git/list-objects.c
Jeff King 670a1dadc7 list-objects: respect max_allowed_tree_depth
The tree traversal in list-objects.c, which is used by "rev-list
--objects", etc, uses recursion and may run out of stack space. Let's
teach it about the new core.maxTreeDepth config option.

We unfortunately can't return an error here, as this code doesn't
produce an error return at all. We'll die() instead, which matches the
behavior when we see an otherwise broken tree.

Note that this will also generally reject such deep trees from entering
the repository from a fetch or push, due to the use of rev-list in the
connectivity check. But it's not foolproof! We stop traversing when we
see an UNINTERESTING object, and the connectivity check marks existing
ref tips as UNINTERESTING. So imagine commit X has a tree
with maximum depth N. If you then create a new commit Y with a tree
entry "Y:subdir" that points to "X^{tree}", then the depth of Y will be
N+1. But a connectivity check running "git rev-list --objects Y --not X"
won't realize that; it will stop traversing at X^{tree}, since that was
already reachable.

So this will stop naive pushes of too-deep trees, but not carefully
crafted malicious ones. Doing it robustly and efficiently would require
caching the maximum depth of each tree (i.e., the longest path to any
leaf entry). That's much more complex and not strictly needed. If each
recursive algorithm limits itself already, then that's sufficient.
Blocking the objects from entering the repo would be a nice
belt-and-suspenders addition, but it's not worth the extra cost.

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

441 lines
11 KiB
C

#include "git-compat-util.h"
#include "tag.h"
#include "commit.h"
#include "gettext.h"
#include "hex.h"
#include "tree.h"
#include "blob.h"
#include "diff.h"
#include "tree-walk.h"
#include "revision.h"
#include "list-objects.h"
#include "list-objects-filter.h"
#include "list-objects-filter-options.h"
#include "packfile.h"
#include "object-store-ll.h"
#include "trace.h"
#include "environment.h"
struct traversal_context {
struct rev_info *revs;
show_object_fn show_object;
show_commit_fn show_commit;
void *show_data;
struct filter *filter;
int depth;
};
static void show_commit(struct traversal_context *ctx,
struct commit *commit)
{
if (!ctx->show_commit)
return;
ctx->show_commit(commit, ctx->show_data);
}
static void show_object(struct traversal_context *ctx,
struct object *object,
const char *name)
{
if (!ctx->show_object)
return;
ctx->show_object(object, name, ctx->show_data);
}
static void process_blob(struct traversal_context *ctx,
struct blob *blob,
struct strbuf *path,
const char *name)
{
struct object *obj = &blob->object;
size_t pathlen;
enum list_objects_filter_result r;
if (!ctx->revs->blob_objects)
return;
if (!obj)
die("bad blob object");
if (obj->flags & (UNINTERESTING | SEEN))
return;
/*
* Pre-filter known-missing objects when explicitly requested.
* Otherwise, a missing object error message may be reported
* later (depending on other filtering criteria).
*
* Note that this "--exclude-promisor-objects" pre-filtering
* may cause the actual filter to report an incomplete list
* of missing objects.
*/
if (ctx->revs->exclude_promisor_objects &&
!repo_has_object_file(the_repository, &obj->oid) &&
is_promisor_object(&obj->oid))
return;
pathlen = path->len;
strbuf_addstr(path, name);
r = list_objects_filter__filter_object(ctx->revs->repo,
LOFS_BLOB, obj,
path->buf, &path->buf[pathlen],
ctx->filter);
if (r & LOFR_MARK_SEEN)
obj->flags |= SEEN;
if (r & LOFR_DO_SHOW)
show_object(ctx, obj, path->buf);
strbuf_setlen(path, pathlen);
}
static void process_tree(struct traversal_context *ctx,
struct tree *tree,
struct strbuf *base,
const char *name);
static void process_tree_contents(struct traversal_context *ctx,
struct tree *tree,
struct strbuf *base)
{
struct tree_desc desc;
struct name_entry entry;
enum interesting match = ctx->revs->diffopt.pathspec.nr == 0 ?
all_entries_interesting : entry_not_interesting;
init_tree_desc(&desc, tree->buffer, tree->size);
while (tree_entry(&desc, &entry)) {
if (match != all_entries_interesting) {
match = tree_entry_interesting(ctx->revs->repo->index,
&entry, base,
&ctx->revs->diffopt.pathspec);
if (match == all_entries_not_interesting)
break;
if (match == entry_not_interesting)
continue;
}
if (S_ISDIR(entry.mode)) {
struct tree *t = lookup_tree(ctx->revs->repo, &entry.oid);
if (!t) {
die(_("entry '%s' in tree %s has tree mode, "
"but is not a tree"),
entry.path, oid_to_hex(&tree->object.oid));
}
t->object.flags |= NOT_USER_GIVEN;
ctx->depth++;
process_tree(ctx, t, base, entry.path);
ctx->depth--;
}
else if (S_ISGITLINK(entry.mode))
; /* ignore gitlink */
else {
struct blob *b = lookup_blob(ctx->revs->repo, &entry.oid);
if (!b) {
die(_("entry '%s' in tree %s has blob mode, "
"but is not a blob"),
entry.path, oid_to_hex(&tree->object.oid));
}
b->object.flags |= NOT_USER_GIVEN;
process_blob(ctx, b, base, entry.path);
}
}
}
static void process_tree(struct traversal_context *ctx,
struct tree *tree,
struct strbuf *base,
const char *name)
{
struct object *obj = &tree->object;
struct rev_info *revs = ctx->revs;
int baselen = base->len;
enum list_objects_filter_result r;
int failed_parse;
if (!revs->tree_objects)
return;
if (!obj)
die("bad tree object");
if (obj->flags & (UNINTERESTING | SEEN))
return;
if (revs->include_check_obj &&
!revs->include_check_obj(&tree->object, revs->include_check_data))
return;
if (ctx->depth > max_allowed_tree_depth)
die("exceeded maximum allowed tree depth");
failed_parse = parse_tree_gently(tree, 1);
if (failed_parse) {
if (revs->ignore_missing_links)
return;
/*
* Pre-filter known-missing tree objects when explicitly
* requested. This may cause the actual filter to report
* an incomplete list of missing objects.
*/
if (revs->exclude_promisor_objects &&
is_promisor_object(&obj->oid))
return;
if (!revs->do_not_die_on_missing_tree)
die("bad tree object %s", oid_to_hex(&obj->oid));
}
strbuf_addstr(base, name);
r = list_objects_filter__filter_object(ctx->revs->repo,
LOFS_BEGIN_TREE, obj,
base->buf, &base->buf[baselen],
ctx->filter);
if (r & LOFR_MARK_SEEN)
obj->flags |= SEEN;
if (r & LOFR_DO_SHOW)
show_object(ctx, obj, base->buf);
if (base->len)
strbuf_addch(base, '/');
if (r & LOFR_SKIP_TREE)
trace_printf("Skipping contents of tree %s...\n", base->buf);
else if (!failed_parse)
process_tree_contents(ctx, tree, base);
r = list_objects_filter__filter_object(ctx->revs->repo,
LOFS_END_TREE, obj,
base->buf, &base->buf[baselen],
ctx->filter);
if (r & LOFR_MARK_SEEN)
obj->flags |= SEEN;
if (r & LOFR_DO_SHOW)
show_object(ctx, obj, base->buf);
strbuf_setlen(base, baselen);
free_tree_buffer(tree);
}
static void process_tag(struct traversal_context *ctx,
struct tag *tag,
const char *name)
{
enum list_objects_filter_result r;
r = list_objects_filter__filter_object(ctx->revs->repo, LOFS_TAG,
&tag->object, NULL, NULL,
ctx->filter);
if (r & LOFR_MARK_SEEN)
tag->object.flags |= SEEN;
if (r & LOFR_DO_SHOW)
show_object(ctx, &tag->object, name);
}
static void mark_edge_parents_uninteresting(struct commit *commit,
struct rev_info *revs,
show_edge_fn show_edge)
{
struct commit_list *parents;
for (parents = commit->parents; parents; parents = parents->next) {
struct commit *parent = parents->item;
if (!(parent->object.flags & UNINTERESTING))
continue;
mark_tree_uninteresting(revs->repo,
repo_get_commit_tree(the_repository, parent));
if (revs->edge_hint && !(parent->object.flags & SHOWN)) {
parent->object.flags |= SHOWN;
show_edge(parent);
}
}
}
static void add_edge_parents(struct commit *commit,
struct rev_info *revs,
show_edge_fn show_edge,
struct oidset *set)
{
struct commit_list *parents;
for (parents = commit->parents; parents; parents = parents->next) {
struct commit *parent = parents->item;
struct tree *tree = repo_get_commit_tree(the_repository,
parent);
if (!tree)
continue;
oidset_insert(set, &tree->object.oid);
if (!(parent->object.flags & UNINTERESTING))
continue;
tree->object.flags |= UNINTERESTING;
if (revs->edge_hint && !(parent->object.flags & SHOWN)) {
parent->object.flags |= SHOWN;
show_edge(parent);
}
}
}
void mark_edges_uninteresting(struct rev_info *revs,
show_edge_fn show_edge,
int sparse)
{
struct commit_list *list;
int i;
if (sparse) {
struct oidset set;
oidset_init(&set, 16);
for (list = revs->commits; list; list = list->next) {
struct commit *commit = list->item;
struct tree *tree = repo_get_commit_tree(the_repository,
commit);
if (commit->object.flags & UNINTERESTING)
tree->object.flags |= UNINTERESTING;
oidset_insert(&set, &tree->object.oid);
add_edge_parents(commit, revs, show_edge, &set);
}
mark_trees_uninteresting_sparse(revs->repo, &set);
oidset_clear(&set);
} else {
for (list = revs->commits; list; list = list->next) {
struct commit *commit = list->item;
if (commit->object.flags & UNINTERESTING) {
mark_tree_uninteresting(revs->repo,
repo_get_commit_tree(the_repository, commit));
if (revs->edge_hint_aggressive && !(commit->object.flags & SHOWN)) {
commit->object.flags |= SHOWN;
show_edge(commit);
}
continue;
}
mark_edge_parents_uninteresting(commit, revs, show_edge);
}
}
if (revs->edge_hint_aggressive) {
for (i = 0; i < revs->cmdline.nr; i++) {
struct object *obj = revs->cmdline.rev[i].item;
struct commit *commit = (struct commit *)obj;
if (obj->type != OBJ_COMMIT || !(obj->flags & UNINTERESTING))
continue;
mark_tree_uninteresting(revs->repo,
repo_get_commit_tree(the_repository, commit));
if (!(obj->flags & SHOWN)) {
obj->flags |= SHOWN;
show_edge(commit);
}
}
}
}
static void add_pending_tree(struct rev_info *revs, struct tree *tree)
{
add_pending_object(revs, &tree->object, "");
}
static void traverse_non_commits(struct traversal_context *ctx,
struct strbuf *base)
{
int i;
assert(base->len == 0);
for (i = 0; i < ctx->revs->pending.nr; i++) {
struct object_array_entry *pending = ctx->revs->pending.objects + i;
struct object *obj = pending->item;
const char *name = pending->name;
const char *path = pending->path;
if (obj->flags & (UNINTERESTING | SEEN))
continue;
if (obj->type == OBJ_TAG) {
process_tag(ctx, (struct tag *)obj, name);
continue;
}
if (!path)
path = "";
if (obj->type == OBJ_TREE) {
ctx->depth = 0;
process_tree(ctx, (struct tree *)obj, base, path);
continue;
}
if (obj->type == OBJ_BLOB) {
process_blob(ctx, (struct blob *)obj, base, path);
continue;
}
die("unknown pending object %s (%s)",
oid_to_hex(&obj->oid), name);
}
object_array_clear(&ctx->revs->pending);
}
static void do_traverse(struct traversal_context *ctx)
{
struct commit *commit;
struct strbuf csp; /* callee's scratch pad */
strbuf_init(&csp, PATH_MAX);
while ((commit = get_revision(ctx->revs)) != NULL) {
enum list_objects_filter_result r;
r = list_objects_filter__filter_object(ctx->revs->repo,
LOFS_COMMIT, &commit->object,
NULL, NULL, ctx->filter);
/*
* an uninteresting boundary commit may not have its tree
* parsed yet, but we are not going to show them anyway
*/
if (!ctx->revs->tree_objects)
; /* do not bother loading tree */
else if (repo_get_commit_tree(the_repository, commit)) {
struct tree *tree = repo_get_commit_tree(the_repository,
commit);
tree->object.flags |= NOT_USER_GIVEN;
add_pending_tree(ctx->revs, tree);
} else if (commit->object.parsed) {
die(_("unable to load root tree for commit %s"),
oid_to_hex(&commit->object.oid));
}
if (r & LOFR_MARK_SEEN)
commit->object.flags |= SEEN;
if (r & LOFR_DO_SHOW)
show_commit(ctx, commit);
if (ctx->revs->tree_blobs_in_commit_order)
/*
* NEEDSWORK: Adding the tree and then flushing it here
* needs a reallocation for each commit. Can we pass the
* tree directory without allocation churn?
*/
traverse_non_commits(ctx, &csp);
}
traverse_non_commits(ctx, &csp);
strbuf_release(&csp);
}
void traverse_commit_list_filtered(
struct rev_info *revs,
show_commit_fn show_commit,
show_object_fn show_object,
void *show_data,
struct oidset *omitted)
{
struct traversal_context ctx = {
.revs = revs,
.show_object = show_object,
.show_commit = show_commit,
.show_data = show_data,
};
if (revs->filter.choice)
ctx.filter = list_objects_filter__init(omitted, &revs->filter);
do_traverse(&ctx);
if (ctx.filter)
list_objects_filter__free(ctx.filter);
}