git/fsck.c
Jeff King 8e4309038f fsck: do not assume NUL-termination of buffers
The fsck code operates on an object buffer represented as a pointer/len
combination. However, the parsing of commits and tags is a little bit
loose; we mostly scan left-to-right through the buffer, without checking
whether we've gone past the length we were given.

This has traditionally been OK because the buffers we feed to fsck
always have an extra NUL after the end of the object content, which ends
any left-to-right scan. That has always been true for objects we read
from the odb, and we made it true for incoming index-pack/unpack-objects
checks in a1e920a0a7 (index-pack: terminate object buffers with NUL,
2014-12-08).

However, we recently added an exception: hash-object asks index_fd() to
do fsck checks. That _may_ have an extra NUL (if we read from a pipe
into a strbuf), but it might not (if we read the contents from the
file). Nor can we just teach it to always add a NUL. We may mmap the
on-disk file, which will not have any extra bytes (if it's a multiple of
the page size). Not to mention that this is a rather subtle assumption
for the fsck code to make.

Instead, let's make sure that the fsck parsers don't ever look past the
size of the buffer they've been given. This _almost_ works already,
thanks to earlier work in 4d0d89755e (Make sure fsck_commit_buffer()
does not run out of the buffer, 2014-09-11). The theory there is that we
check up front whether we have the end of header double-newline
separator. And then any left-to-right scanning we do is OK as long as it
stops when it hits that boundary.

However, we later softened that in 84d18c0bcf (fsck: it is OK for a tag
and a commit to lack the body, 2015-06-28), which allows the
double-newline header to be missing, but does require that the header
ends in a newline. That was OK back then, because of the NUL-termination
guarantees (including the one from a1e920a0a7 mentioned above).

Because 84d18c0bcf guarantees that any header line does end in a
newline, we are still OK with most of the left-to-right scanning. We
only need to take care after completing a line, to check that there is
another line (and we didn't run out of buffer).

Most of these checks are just need to check "buffer < buffer_end" (where
buffer is advanced as we parse) before scanning for the next header
line. But here are a few notes:

  - we don't technically need to check for remaining buffer before
    parsing the very first line ("tree" for a commit, or "object" for a
    tag), because verify_headers() rejects a totally empty buffer. But
    we'll do so in the name of consistency and defensiveness.

  - there are some calls to strchr('\n'). These are actually OK by the
    "the final header line must end in a newline" guarantee from
    verify_headers(). They will always find that rather than run off the
    end of the buffer. Curiously, they do check for a NULL return and
    complain, but I believe that condition can never be reached.

    However, I converted them to use memchr() with a proper size and
    retained the NULL checks. Using memchr() is not much longer and
    makes it more obvious what is going on. Likewise, retaining the NULL
    checks serves as a defensive measure in case my analysis is wrong.

  - commit 9a1a3a4d4c (mktag: allow omitting the header/body \n
    separator, 2021-01-05), does check for the end-of-buffer condition,
    but does so with "!*buffer", relying explicitly on the NUL
    termination. We can accomplish the same thing with a pointer
    comparison. I also folded it into the follow-on conditional that
    checks the contents of the buffer, for consistency with the other
    checks.

  - fsck_ident() uses parse_timestamp(), which is based on strtoumax().
    That function will happily skip past leading whitespace, including
    newlines, which makes it a risk. We can fix this by scanning to the
    first digit ourselves, and then using parse_timestamp() to do the
    actual numeric conversion.

    Note that as a side effect this fixes the fact that we missed
    zero-padded timestamps like "<email>   0123" (whereas we would
    complain about "<email> 0123"). I doubt anybody cares, but I
    mention it here for completeness.

  - fsck_tree() does not need any modifications. It relies on
    decode_tree_entry() to do the actual parsing, and that function
    checks both that there are enough bytes in the buffer to represent
    an entry, and that there is a NUL at the appropriate spot (one
    hash-length from the end; this may not be the NUL for the entry we
    are parsing, but we know that in the worst case, everything from our
    current position to that NUL is a filename, so we won't run out of
    bytes).

In addition to fixing the code itself, we'd like to make sure our rather
subtle assumptions are not violated in the future. So this patch does
two more things:

  - add comments around verify_headers() documenting the link between
    what it checks and the memory safety of the callers. I don't expect
    this code to be modified frequently, but this may help somebody from
    accidentally breaking things.

  - add a thorough set of tests covering truncations at various key
    spots (e.g., for a "tree $oid" line, in the middle of the word
    "tree", right after it, after the space, in the middle of the $oid,
    and right at the end of the line. Most of these are fine already (it
    is only truncating right at the end of the line that is currently
    broken). And some of them are not even possible with the current
    code (we parse "tree " as a unit, so truncating before the space is
    equivalent). But I aimed here to consider the code a black box and
    look for any truncations that would be a problem for a left-to-right
    parser.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2023-01-19 15:39:43 -08:00

1414 lines
37 KiB
C

#include "cache.h"
#include "object-store.h"
#include "repository.h"
#include "object.h"
#include "attr.h"
#include "blob.h"
#include "tree.h"
#include "tree-walk.h"
#include "commit.h"
#include "tag.h"
#include "fsck.h"
#include "refs.h"
#include "url.h"
#include "utf8.h"
#include "decorate.h"
#include "oidset.h"
#include "packfile.h"
#include "submodule-config.h"
#include "config.h"
#include "credential.h"
#include "help.h"
#define STR(x) #x
#define MSG_ID(id, msg_type) { STR(id), NULL, NULL, FSCK_##msg_type },
static struct {
const char *id_string;
const char *downcased;
const char *camelcased;
enum fsck_msg_type msg_type;
} msg_id_info[FSCK_MSG_MAX + 1] = {
FOREACH_FSCK_MSG_ID(MSG_ID)
{ NULL, NULL, NULL, -1 }
};
#undef MSG_ID
#undef STR
static void prepare_msg_ids(void)
{
int i;
if (msg_id_info[0].downcased)
return;
/* convert id_string to lower case, without underscores. */
for (i = 0; i < FSCK_MSG_MAX; i++) {
const char *p = msg_id_info[i].id_string;
int len = strlen(p);
char *q = xmalloc(len);
msg_id_info[i].downcased = q;
while (*p)
if (*p == '_')
p++;
else
*(q)++ = tolower(*(p)++);
*q = '\0';
p = msg_id_info[i].id_string;
q = xmalloc(len);
msg_id_info[i].camelcased = q;
while (*p) {
if (*p == '_') {
p++;
if (*p)
*q++ = *p++;
} else {
*q++ = tolower(*p++);
}
}
*q = '\0';
}
}
static int parse_msg_id(const char *text)
{
int i;
prepare_msg_ids();
for (i = 0; i < FSCK_MSG_MAX; i++)
if (!strcmp(text, msg_id_info[i].downcased))
return i;
return -1;
}
void list_config_fsck_msg_ids(struct string_list *list, const char *prefix)
{
int i;
prepare_msg_ids();
for (i = 0; i < FSCK_MSG_MAX; i++)
list_config_item(list, prefix, msg_id_info[i].camelcased);
}
static enum fsck_msg_type fsck_msg_type(enum fsck_msg_id msg_id,
struct fsck_options *options)
{
assert(msg_id >= 0 && msg_id < FSCK_MSG_MAX);
if (!options->msg_type) {
enum fsck_msg_type msg_type = msg_id_info[msg_id].msg_type;
if (options->strict && msg_type == FSCK_WARN)
msg_type = FSCK_ERROR;
return msg_type;
}
return options->msg_type[msg_id];
}
static enum fsck_msg_type parse_msg_type(const char *str)
{
if (!strcmp(str, "error"))
return FSCK_ERROR;
else if (!strcmp(str, "warn"))
return FSCK_WARN;
else if (!strcmp(str, "ignore"))
return FSCK_IGNORE;
else
die("Unknown fsck message type: '%s'", str);
}
int is_valid_msg_type(const char *msg_id, const char *msg_type)
{
if (parse_msg_id(msg_id) < 0)
return 0;
parse_msg_type(msg_type);
return 1;
}
void fsck_set_msg_type_from_ids(struct fsck_options *options,
enum fsck_msg_id msg_id,
enum fsck_msg_type msg_type)
{
if (!options->msg_type) {
int i;
enum fsck_msg_type *severity;
ALLOC_ARRAY(severity, FSCK_MSG_MAX);
for (i = 0; i < FSCK_MSG_MAX; i++)
severity[i] = fsck_msg_type(i, options);
options->msg_type = severity;
}
options->msg_type[msg_id] = msg_type;
}
void fsck_set_msg_type(struct fsck_options *options,
const char *msg_id_str, const char *msg_type_str)
{
int msg_id = parse_msg_id(msg_id_str);
enum fsck_msg_type msg_type = parse_msg_type(msg_type_str);
if (msg_id < 0)
die("Unhandled message id: %s", msg_id_str);
if (msg_type != FSCK_ERROR && msg_id_info[msg_id].msg_type == FSCK_FATAL)
die("Cannot demote %s to %s", msg_id_str, msg_type_str);
fsck_set_msg_type_from_ids(options, msg_id, msg_type);
}
void fsck_set_msg_types(struct fsck_options *options, const char *values)
{
char *buf = xstrdup(values), *to_free = buf;
int done = 0;
while (!done) {
int len = strcspn(buf, " ,|"), equal;
done = !buf[len];
if (!len) {
buf++;
continue;
}
buf[len] = '\0';
for (equal = 0;
equal < len && buf[equal] != '=' && buf[equal] != ':';
equal++)
buf[equal] = tolower(buf[equal]);
buf[equal] = '\0';
if (!strcmp(buf, "skiplist")) {
if (equal == len)
die("skiplist requires a path");
oidset_parse_file(&options->skiplist, buf + equal + 1);
buf += len + 1;
continue;
}
if (equal == len)
die("Missing '=': '%s'", buf);
fsck_set_msg_type(options, buf, buf + equal + 1);
buf += len + 1;
}
free(to_free);
}
static int object_on_skiplist(struct fsck_options *opts,
const struct object_id *oid)
{
return opts && oid && oidset_contains(&opts->skiplist, oid);
}
__attribute__((format (printf, 5, 6)))
static int report(struct fsck_options *options,
const struct object_id *oid, enum object_type object_type,
enum fsck_msg_id msg_id, const char *fmt, ...)
{
va_list ap;
struct strbuf sb = STRBUF_INIT;
enum fsck_msg_type msg_type = fsck_msg_type(msg_id, options);
int result;
if (msg_type == FSCK_IGNORE)
return 0;
if (object_on_skiplist(options, oid))
return 0;
if (msg_type == FSCK_FATAL)
msg_type = FSCK_ERROR;
else if (msg_type == FSCK_INFO)
msg_type = FSCK_WARN;
prepare_msg_ids();
strbuf_addf(&sb, "%s: ", msg_id_info[msg_id].camelcased);
va_start(ap, fmt);
strbuf_vaddf(&sb, fmt, ap);
result = options->error_func(options, oid, object_type,
msg_type, msg_id, sb.buf);
strbuf_release(&sb);
va_end(ap);
return result;
}
void fsck_enable_object_names(struct fsck_options *options)
{
if (!options->object_names)
options->object_names = kh_init_oid_map();
}
const char *fsck_get_object_name(struct fsck_options *options,
const struct object_id *oid)
{
khiter_t pos;
if (!options->object_names)
return NULL;
pos = kh_get_oid_map(options->object_names, *oid);
if (pos >= kh_end(options->object_names))
return NULL;
return kh_value(options->object_names, pos);
}
void fsck_put_object_name(struct fsck_options *options,
const struct object_id *oid,
const char *fmt, ...)
{
va_list ap;
struct strbuf buf = STRBUF_INIT;
khiter_t pos;
int hashret;
if (!options->object_names)
return;
pos = kh_put_oid_map(options->object_names, *oid, &hashret);
if (!hashret)
return;
va_start(ap, fmt);
strbuf_vaddf(&buf, fmt, ap);
kh_value(options->object_names, pos) = strbuf_detach(&buf, NULL);
va_end(ap);
}
const char *fsck_describe_object(struct fsck_options *options,
const struct object_id *oid)
{
static struct strbuf bufs[] = {
STRBUF_INIT, STRBUF_INIT, STRBUF_INIT, STRBUF_INIT
};
static int b = 0;
struct strbuf *buf;
const char *name = fsck_get_object_name(options, oid);
buf = bufs + b;
b = (b + 1) % ARRAY_SIZE(bufs);
strbuf_reset(buf);
strbuf_addstr(buf, oid_to_hex(oid));
if (name)
strbuf_addf(buf, " (%s)", name);
return buf->buf;
}
static int fsck_walk_tree(struct tree *tree, void *data, struct fsck_options *options)
{
struct tree_desc desc;
struct name_entry entry;
int res = 0;
const char *name;
if (parse_tree(tree))
return -1;
name = fsck_get_object_name(options, &tree->object.oid);
if (init_tree_desc_gently(&desc, tree->buffer, tree->size, 0))
return -1;
while (tree_entry_gently(&desc, &entry)) {
struct object *obj;
int result;
if (S_ISGITLINK(entry.mode))
continue;
if (S_ISDIR(entry.mode)) {
obj = (struct object *)lookup_tree(the_repository, &entry.oid);
if (name && obj)
fsck_put_object_name(options, &entry.oid, "%s%s/",
name, entry.path);
result = options->walk(obj, OBJ_TREE, data, options);
}
else if (S_ISREG(entry.mode) || S_ISLNK(entry.mode)) {
obj = (struct object *)lookup_blob(the_repository, &entry.oid);
if (name && obj)
fsck_put_object_name(options, &entry.oid, "%s%s",
name, entry.path);
result = options->walk(obj, OBJ_BLOB, data, options);
}
else {
result = error("in tree %s: entry %s has bad mode %.6o",
fsck_describe_object(options, &tree->object.oid),
entry.path, entry.mode);
}
if (result < 0)
return result;
if (!res)
res = result;
}
return res;
}
static int fsck_walk_commit(struct commit *commit, void *data, struct fsck_options *options)
{
int counter = 0, generation = 0, name_prefix_len = 0;
struct commit_list *parents;
int res;
int result;
const char *name;
if (parse_commit(commit))
return -1;
name = fsck_get_object_name(options, &commit->object.oid);
if (name)
fsck_put_object_name(options, get_commit_tree_oid(commit),
"%s:", name);
result = options->walk((struct object *)get_commit_tree(commit),
OBJ_TREE, data, options);
if (result < 0)
return result;
res = result;
parents = commit->parents;
if (name && parents) {
int len = strlen(name), power;
if (len && name[len - 1] == '^') {
generation = 1;
name_prefix_len = len - 1;
}
else { /* parse ~<generation> suffix */
for (generation = 0, power = 1;
len && isdigit(name[len - 1]);
power *= 10)
generation += power * (name[--len] - '0');
if (power > 1 && len && name[len - 1] == '~')
name_prefix_len = len - 1;
else {
/* Maybe a non-first parent, e.g. HEAD^2 */
generation = 0;
name_prefix_len = len;
}
}
}
while (parents) {
if (name) {
struct object_id *oid = &parents->item->object.oid;
if (counter++)
fsck_put_object_name(options, oid, "%s^%d",
name, counter);
else if (generation > 0)
fsck_put_object_name(options, oid, "%.*s~%d",
name_prefix_len, name,
generation + 1);
else
fsck_put_object_name(options, oid, "%s^", name);
}
result = options->walk((struct object *)parents->item, OBJ_COMMIT, data, options);
if (result < 0)
return result;
if (!res)
res = result;
parents = parents->next;
}
return res;
}
static int fsck_walk_tag(struct tag *tag, void *data, struct fsck_options *options)
{
const char *name = fsck_get_object_name(options, &tag->object.oid);
if (parse_tag(tag))
return -1;
if (name)
fsck_put_object_name(options, &tag->tagged->oid, "%s", name);
return options->walk(tag->tagged, OBJ_ANY, data, options);
}
int fsck_walk(struct object *obj, void *data, struct fsck_options *options)
{
if (!obj)
return -1;
if (obj->type == OBJ_NONE)
parse_object(the_repository, &obj->oid);
switch (obj->type) {
case OBJ_BLOB:
return 0;
case OBJ_TREE:
return fsck_walk_tree((struct tree *)obj, data, options);
case OBJ_COMMIT:
return fsck_walk_commit((struct commit *)obj, data, options);
case OBJ_TAG:
return fsck_walk_tag((struct tag *)obj, data, options);
default:
error("Unknown object type for %s",
fsck_describe_object(options, &obj->oid));
return -1;
}
}
struct name_stack {
const char **names;
size_t nr, alloc;
};
static void name_stack_push(struct name_stack *stack, const char *name)
{
ALLOC_GROW(stack->names, stack->nr + 1, stack->alloc);
stack->names[stack->nr++] = name;
}
static const char *name_stack_pop(struct name_stack *stack)
{
return stack->nr ? stack->names[--stack->nr] : NULL;
}
static void name_stack_clear(struct name_stack *stack)
{
FREE_AND_NULL(stack->names);
stack->nr = stack->alloc = 0;
}
/*
* The entries in a tree are ordered in the _path_ order,
* which means that a directory entry is ordered by adding
* a slash to the end of it.
*
* So a directory called "a" is ordered _after_ a file
* called "a.c", because "a/" sorts after "a.c".
*/
#define TREE_UNORDERED (-1)
#define TREE_HAS_DUPS (-2)
static int is_less_than_slash(unsigned char c)
{
return '\0' < c && c < '/';
}
static int verify_ordered(unsigned mode1, const char *name1,
unsigned mode2, const char *name2,
struct name_stack *candidates)
{
int len1 = strlen(name1);
int len2 = strlen(name2);
int len = len1 < len2 ? len1 : len2;
unsigned char c1, c2;
int cmp;
cmp = memcmp(name1, name2, len);
if (cmp < 0)
return 0;
if (cmp > 0)
return TREE_UNORDERED;
/*
* Ok, the first <len> characters are the same.
* Now we need to order the next one, but turn
* a '\0' into a '/' for a directory entry.
*/
c1 = name1[len];
c2 = name2[len];
if (!c1 && !c2)
/*
* git-write-tree used to write out a nonsense tree that has
* entries with the same name, one blob and one tree. Make
* sure we do not have duplicate entries.
*/
return TREE_HAS_DUPS;
if (!c1 && S_ISDIR(mode1))
c1 = '/';
if (!c2 && S_ISDIR(mode2))
c2 = '/';
/*
* There can be non-consecutive duplicates due to the implicitly
* added slash, e.g.:
*
* foo
* foo.bar
* foo.bar.baz
* foo.bar/
* foo/
*
* Record non-directory candidates (like "foo" and "foo.bar" in
* the example) on a stack and check directory candidates (like
* foo/" and "foo.bar/") against that stack.
*/
if (!c1 && is_less_than_slash(c2)) {
name_stack_push(candidates, name1);
} else if (c2 == '/' && is_less_than_slash(c1)) {
for (;;) {
const char *p;
const char *f_name = name_stack_pop(candidates);
if (!f_name)
break;
if (!skip_prefix(name2, f_name, &p))
continue;
if (!*p)
return TREE_HAS_DUPS;
if (is_less_than_slash(*p)) {
name_stack_push(candidates, f_name);
break;
}
}
}
return c1 < c2 ? 0 : TREE_UNORDERED;
}
static int fsck_tree(const struct object_id *tree_oid,
const char *buffer, unsigned long size,
struct fsck_options *options)
{
int retval = 0;
int has_null_sha1 = 0;
int has_full_path = 0;
int has_empty_name = 0;
int has_dot = 0;
int has_dotdot = 0;
int has_dotgit = 0;
int has_zero_pad = 0;
int has_bad_modes = 0;
int has_dup_entries = 0;
int not_properly_sorted = 0;
struct tree_desc desc;
unsigned o_mode;
const char *o_name;
struct name_stack df_dup_candidates = { NULL };
if (init_tree_desc_gently(&desc, buffer, size, TREE_DESC_RAW_MODES)) {
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_BAD_TREE,
"cannot be parsed as a tree");
return retval;
}
o_mode = 0;
o_name = NULL;
while (desc.size) {
unsigned short mode;
const char *name, *backslash;
const struct object_id *entry_oid;
entry_oid = tree_entry_extract(&desc, &name, &mode);
has_null_sha1 |= is_null_oid(entry_oid);
has_full_path |= !!strchr(name, '/');
has_empty_name |= !*name;
has_dot |= !strcmp(name, ".");
has_dotdot |= !strcmp(name, "..");
has_dotgit |= is_hfs_dotgit(name) || is_ntfs_dotgit(name);
has_zero_pad |= *(char *)desc.buffer == '0';
if (is_hfs_dotgitmodules(name) || is_ntfs_dotgitmodules(name)) {
if (!S_ISLNK(mode))
oidset_insert(&options->gitmodules_found,
entry_oid);
else
retval += report(options,
tree_oid, OBJ_TREE,
FSCK_MSG_GITMODULES_SYMLINK,
".gitmodules is a symbolic link");
}
if (is_hfs_dotgitattributes(name) || is_ntfs_dotgitattributes(name)) {
if (!S_ISLNK(mode))
oidset_insert(&options->gitattributes_found,
entry_oid);
else
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_GITATTRIBUTES_SYMLINK,
".gitattributes is a symlink");
}
if (S_ISLNK(mode)) {
if (is_hfs_dotgitignore(name) ||
is_ntfs_dotgitignore(name))
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_GITIGNORE_SYMLINK,
".gitignore is a symlink");
if (is_hfs_dotmailmap(name) ||
is_ntfs_dotmailmap(name))
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_MAILMAP_SYMLINK,
".mailmap is a symlink");
}
if ((backslash = strchr(name, '\\'))) {
while (backslash) {
backslash++;
has_dotgit |= is_ntfs_dotgit(backslash);
if (is_ntfs_dotgitmodules(backslash)) {
if (!S_ISLNK(mode))
oidset_insert(&options->gitmodules_found,
entry_oid);
else
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_GITMODULES_SYMLINK,
".gitmodules is a symbolic link");
}
backslash = strchr(backslash, '\\');
}
}
if (update_tree_entry_gently(&desc)) {
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_BAD_TREE,
"cannot be parsed as a tree");
break;
}
switch (mode) {
/*
* Standard modes..
*/
case S_IFREG | 0755:
case S_IFREG | 0644:
case S_IFLNK:
case S_IFDIR:
case S_IFGITLINK:
break;
/*
* This is nonstandard, but we had a few of these
* early on when we honored the full set of mode
* bits..
*/
case S_IFREG | 0664:
if (!options->strict)
break;
/* fallthrough */
default:
has_bad_modes = 1;
}
if (o_name) {
switch (verify_ordered(o_mode, o_name, mode, name,
&df_dup_candidates)) {
case TREE_UNORDERED:
not_properly_sorted = 1;
break;
case TREE_HAS_DUPS:
has_dup_entries = 1;
break;
default:
break;
}
}
o_mode = mode;
o_name = name;
}
name_stack_clear(&df_dup_candidates);
if (has_null_sha1)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_NULL_SHA1,
"contains entries pointing to null sha1");
if (has_full_path)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_FULL_PATHNAME,
"contains full pathnames");
if (has_empty_name)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_EMPTY_NAME,
"contains empty pathname");
if (has_dot)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_HAS_DOT,
"contains '.'");
if (has_dotdot)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_HAS_DOTDOT,
"contains '..'");
if (has_dotgit)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_HAS_DOTGIT,
"contains '.git'");
if (has_zero_pad)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_ZERO_PADDED_FILEMODE,
"contains zero-padded file modes");
if (has_bad_modes)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_BAD_FILEMODE,
"contains bad file modes");
if (has_dup_entries)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_DUPLICATE_ENTRIES,
"contains duplicate file entries");
if (not_properly_sorted)
retval += report(options, tree_oid, OBJ_TREE,
FSCK_MSG_TREE_NOT_SORTED,
"not properly sorted");
return retval;
}
/*
* Confirm that the headers of a commit or tag object end in a reasonable way,
* either with the usual "\n\n" separator, or at least with a trailing newline
* on the final header line.
*
* This property is important for the memory safety of our callers. It allows
* them to scan the buffer linewise without constantly checking the remaining
* size as long as:
*
* - they check that there are bytes left in the buffer at the start of any
* line (i.e., that the last newline they saw was not the final one we
* found here)
*
* - any intra-line scanning they do will stop at a newline, which will worst
* case hit the newline we found here as the end-of-header. This makes it
* OK for them to use helpers like parse_oid_hex(), or even skip_prefix().
*/
static int verify_headers(const void *data, unsigned long size,
const struct object_id *oid, enum object_type type,
struct fsck_options *options)
{
const char *buffer = (const char *)data;
unsigned long i;
for (i = 0; i < size; i++) {
switch (buffer[i]) {
case '\0':
return report(options, oid, type,
FSCK_MSG_NUL_IN_HEADER,
"unterminated header: NUL at offset %ld", i);
case '\n':
if (i + 1 < size && buffer[i + 1] == '\n')
return 0;
}
}
/*
* We did not find double-LF that separates the header
* and the body. Not having a body is not a crime but
* we do want to see the terminating LF for the last header
* line.
*/
if (size && buffer[size - 1] == '\n')
return 0;
return report(options, oid, type,
FSCK_MSG_UNTERMINATED_HEADER, "unterminated header");
}
static int fsck_ident(const char **ident,
const struct object_id *oid, enum object_type type,
struct fsck_options *options)
{
const char *p = *ident;
char *end;
*ident = strchrnul(*ident, '\n');
if (**ident == '\n')
(*ident)++;
if (*p == '<')
return report(options, oid, type, FSCK_MSG_MISSING_NAME_BEFORE_EMAIL, "invalid author/committer line - missing space before email");
p += strcspn(p, "<>\n");
if (*p == '>')
return report(options, oid, type, FSCK_MSG_BAD_NAME, "invalid author/committer line - bad name");
if (*p != '<')
return report(options, oid, type, FSCK_MSG_MISSING_EMAIL, "invalid author/committer line - missing email");
if (p[-1] != ' ')
return report(options, oid, type, FSCK_MSG_MISSING_SPACE_BEFORE_EMAIL, "invalid author/committer line - missing space before email");
p++;
p += strcspn(p, "<>\n");
if (*p != '>')
return report(options, oid, type, FSCK_MSG_BAD_EMAIL, "invalid author/committer line - bad email");
p++;
if (*p != ' ')
return report(options, oid, type, FSCK_MSG_MISSING_SPACE_BEFORE_DATE, "invalid author/committer line - missing space before date");
p++;
/*
* Our timestamp parser is based on the C strto*() functions, which
* will happily eat whitespace, including the newline that is supposed
* to prevent us walking past the end of the buffer. So do our own
* scan, skipping linear whitespace but not newlines, and then
* confirming we found a digit. We _could_ be even more strict here,
* as we really expect only a single space, but since we have
* traditionally allowed extra whitespace, we'll continue to do so.
*/
while (*p == ' ' || *p == '\t')
p++;
if (!isdigit(*p))
return report(options, oid, type, FSCK_MSG_BAD_DATE,
"invalid author/committer line - bad date");
if (*p == '0' && p[1] != ' ')
return report(options, oid, type, FSCK_MSG_ZERO_PADDED_DATE, "invalid author/committer line - zero-padded date");
if (date_overflows(parse_timestamp(p, &end, 10)))
return report(options, oid, type, FSCK_MSG_BAD_DATE_OVERFLOW, "invalid author/committer line - date causes integer overflow");
if ((end == p || *end != ' '))
return report(options, oid, type, FSCK_MSG_BAD_DATE, "invalid author/committer line - bad date");
p = end + 1;
if ((*p != '+' && *p != '-') ||
!isdigit(p[1]) ||
!isdigit(p[2]) ||
!isdigit(p[3]) ||
!isdigit(p[4]) ||
(p[5] != '\n'))
return report(options, oid, type, FSCK_MSG_BAD_TIMEZONE, "invalid author/committer line - bad time zone");
p += 6;
return 0;
}
static int fsck_commit(const struct object_id *oid,
const char *buffer, unsigned long size,
struct fsck_options *options)
{
struct object_id tree_oid, parent_oid;
unsigned author_count;
int err;
const char *buffer_begin = buffer;
const char *buffer_end = buffer + size;
const char *p;
/*
* We _must_ stop parsing immediately if this reports failure, as the
* memory safety of the rest of the function depends on it. See the
* comment above the definition of verify_headers() for more details.
*/
if (verify_headers(buffer, size, oid, OBJ_COMMIT, options))
return -1;
if (buffer >= buffer_end || !skip_prefix(buffer, "tree ", &buffer))
return report(options, oid, OBJ_COMMIT, FSCK_MSG_MISSING_TREE, "invalid format - expected 'tree' line");
if (parse_oid_hex(buffer, &tree_oid, &p) || *p != '\n') {
err = report(options, oid, OBJ_COMMIT, FSCK_MSG_BAD_TREE_SHA1, "invalid 'tree' line format - bad sha1");
if (err)
return err;
}
buffer = p + 1;
while (buffer < buffer_end && skip_prefix(buffer, "parent ", &buffer)) {
if (parse_oid_hex(buffer, &parent_oid, &p) || *p != '\n') {
err = report(options, oid, OBJ_COMMIT, FSCK_MSG_BAD_PARENT_SHA1, "invalid 'parent' line format - bad sha1");
if (err)
return err;
}
buffer = p + 1;
}
author_count = 0;
while (buffer < buffer_end && skip_prefix(buffer, "author ", &buffer)) {
author_count++;
err = fsck_ident(&buffer, oid, OBJ_COMMIT, options);
if (err)
return err;
}
if (author_count < 1)
err = report(options, oid, OBJ_COMMIT, FSCK_MSG_MISSING_AUTHOR, "invalid format - expected 'author' line");
else if (author_count > 1)
err = report(options, oid, OBJ_COMMIT, FSCK_MSG_MULTIPLE_AUTHORS, "invalid format - multiple 'author' lines");
if (err)
return err;
if (buffer >= buffer_end || !skip_prefix(buffer, "committer ", &buffer))
return report(options, oid, OBJ_COMMIT, FSCK_MSG_MISSING_COMMITTER, "invalid format - expected 'committer' line");
err = fsck_ident(&buffer, oid, OBJ_COMMIT, options);
if (err)
return err;
if (memchr(buffer_begin, '\0', size)) {
err = report(options, oid, OBJ_COMMIT, FSCK_MSG_NUL_IN_COMMIT,
"NUL byte in the commit object body");
if (err)
return err;
}
return 0;
}
static int fsck_tag(const struct object_id *oid, const char *buffer,
unsigned long size, struct fsck_options *options)
{
struct object_id tagged_oid;
int tagged_type;
return fsck_tag_standalone(oid, buffer, size, options, &tagged_oid,
&tagged_type);
}
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 *tagged_type)
{
int ret = 0;
char *eol;
struct strbuf sb = STRBUF_INIT;
const char *buffer_end = buffer + size;
const char *p;
/*
* We _must_ stop parsing immediately if this reports failure, as the
* memory safety of the rest of the function depends on it. See the
* comment above the definition of verify_headers() for more details.
*/
ret = verify_headers(buffer, size, oid, OBJ_TAG, options);
if (ret)
goto done;
if (buffer >= buffer_end || !skip_prefix(buffer, "object ", &buffer)) {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_OBJECT, "invalid format - expected 'object' line");
goto done;
}
if (parse_oid_hex(buffer, tagged_oid, &p) || *p != '\n') {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_BAD_OBJECT_SHA1, "invalid 'object' line format - bad sha1");
if (ret)
goto done;
}
buffer = p + 1;
if (buffer >= buffer_end || !skip_prefix(buffer, "type ", &buffer)) {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_TYPE_ENTRY, "invalid format - expected 'type' line");
goto done;
}
eol = memchr(buffer, '\n', buffer_end - buffer);
if (!eol) {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_TYPE, "invalid format - unexpected end after 'type' line");
goto done;
}
*tagged_type = type_from_string_gently(buffer, eol - buffer, 1);
if (*tagged_type < 0)
ret = report(options, oid, OBJ_TAG, FSCK_MSG_BAD_TYPE, "invalid 'type' value");
if (ret)
goto done;
buffer = eol + 1;
if (buffer >= buffer_end || !skip_prefix(buffer, "tag ", &buffer)) {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_TAG_ENTRY, "invalid format - expected 'tag' line");
goto done;
}
eol = memchr(buffer, '\n', buffer_end - buffer);
if (!eol) {
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_TAG, "invalid format - unexpected end after 'type' line");
goto done;
}
strbuf_addf(&sb, "refs/tags/%.*s", (int)(eol - buffer), buffer);
if (check_refname_format(sb.buf, 0)) {
ret = report(options, oid, OBJ_TAG,
FSCK_MSG_BAD_TAG_NAME,
"invalid 'tag' name: %.*s",
(int)(eol - buffer), buffer);
if (ret)
goto done;
}
buffer = eol + 1;
if (buffer >= buffer_end || !skip_prefix(buffer, "tagger ", &buffer)) {
/* early tags do not contain 'tagger' lines; warn only */
ret = report(options, oid, OBJ_TAG, FSCK_MSG_MISSING_TAGGER_ENTRY, "invalid format - expected 'tagger' line");
if (ret)
goto done;
}
else
ret = fsck_ident(&buffer, oid, OBJ_TAG, options);
if (buffer < buffer_end && !starts_with(buffer, "\n")) {
/*
* The verify_headers() check will allow
* e.g. "[...]tagger <tagger>\nsome
* garbage\n\nmessage" to pass, thinking "some
* garbage" could be a custom header. E.g. "mktag"
* doesn't want any unknown headers.
*/
ret = report(options, oid, OBJ_TAG, FSCK_MSG_EXTRA_HEADER_ENTRY, "invalid format - extra header(s) after 'tagger'");
if (ret)
goto done;
}
done:
strbuf_release(&sb);
return ret;
}
static int starts_with_dot_slash(const char *const path)
{
return path_match_flags(path, PATH_MATCH_STARTS_WITH_DOT_SLASH |
PATH_MATCH_XPLATFORM);
}
static int starts_with_dot_dot_slash(const char *const path)
{
return path_match_flags(path, PATH_MATCH_STARTS_WITH_DOT_DOT_SLASH |
PATH_MATCH_XPLATFORM);
}
static int submodule_url_is_relative(const char *url)
{
return starts_with_dot_slash(url) || starts_with_dot_dot_slash(url);
}
/*
* Count directory components that a relative submodule URL should chop
* from the remote_url it is to be resolved against.
*
* In other words, this counts "../" components at the start of a
* submodule URL.
*
* Returns the number of directory components to chop and writes a
* pointer to the next character of url after all leading "./" and
* "../" components to out.
*/
static int count_leading_dotdots(const char *url, const char **out)
{
int result = 0;
while (1) {
if (starts_with_dot_dot_slash(url)) {
result++;
url += strlen("../");
continue;
}
if (starts_with_dot_slash(url)) {
url += strlen("./");
continue;
}
*out = url;
return result;
}
}
/*
* Check whether a transport is implemented by git-remote-curl.
*
* If it is, returns 1 and writes the URL that would be passed to
* git-remote-curl to the "out" parameter.
*
* Otherwise, returns 0 and leaves "out" untouched.
*
* Examples:
* http::https://example.com/repo.git -> 1, https://example.com/repo.git
* https://example.com/repo.git -> 1, https://example.com/repo.git
* git://example.com/repo.git -> 0
*
* This is for use in checking for previously exploitable bugs that
* required a submodule URL to be passed to git-remote-curl.
*/
static int url_to_curl_url(const char *url, const char **out)
{
/*
* We don't need to check for case-aliases, "http.exe", and so
* on because in the default configuration, is_transport_allowed
* prevents URLs with those schemes from being cloned
* automatically.
*/
if (skip_prefix(url, "http::", out) ||
skip_prefix(url, "https::", out) ||
skip_prefix(url, "ftp::", out) ||
skip_prefix(url, "ftps::", out))
return 1;
if (starts_with(url, "http://") ||
starts_with(url, "https://") ||
starts_with(url, "ftp://") ||
starts_with(url, "ftps://")) {
*out = url;
return 1;
}
return 0;
}
static int check_submodule_url(const char *url)
{
const char *curl_url;
if (looks_like_command_line_option(url))
return -1;
if (submodule_url_is_relative(url) || starts_with(url, "git://")) {
char *decoded;
const char *next;
int has_nl;
/*
* This could be appended to an http URL and url-decoded;
* check for malicious characters.
*/
decoded = url_decode(url);
has_nl = !!strchr(decoded, '\n');
free(decoded);
if (has_nl)
return -1;
/*
* URLs which escape their root via "../" can overwrite
* the host field and previous components, resolving to
* URLs like https::example.com/submodule.git and
* https:///example.com/submodule.git that were
* susceptible to CVE-2020-11008.
*/
if (count_leading_dotdots(url, &next) > 0 &&
(*next == ':' || *next == '/'))
return -1;
}
else if (url_to_curl_url(url, &curl_url)) {
struct credential c = CREDENTIAL_INIT;
int ret = 0;
if (credential_from_url_gently(&c, curl_url, 1) ||
!*c.host)
ret = -1;
credential_clear(&c);
return ret;
}
return 0;
}
struct fsck_gitmodules_data {
const struct object_id *oid;
struct fsck_options *options;
int ret;
};
static int fsck_gitmodules_fn(const char *var, const char *value, void *vdata)
{
struct fsck_gitmodules_data *data = vdata;
const char *subsection, *key;
size_t subsection_len;
char *name;
if (parse_config_key(var, "submodule", &subsection, &subsection_len, &key) < 0 ||
!subsection)
return 0;
name = xmemdupz(subsection, subsection_len);
if (check_submodule_name(name) < 0)
data->ret |= report(data->options,
data->oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_NAME,
"disallowed submodule name: %s",
name);
if (!strcmp(key, "url") && value &&
check_submodule_url(value) < 0)
data->ret |= report(data->options,
data->oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_URL,
"disallowed submodule url: %s",
value);
if (!strcmp(key, "path") && value &&
looks_like_command_line_option(value))
data->ret |= report(data->options,
data->oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_PATH,
"disallowed submodule path: %s",
value);
if (!strcmp(key, "update") && value &&
parse_submodule_update_type(value) == SM_UPDATE_COMMAND)
data->ret |= report(data->options, data->oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_UPDATE,
"disallowed submodule update setting: %s",
value);
free(name);
return 0;
}
static int fsck_blob(const struct object_id *oid, const char *buf,
unsigned long size, struct fsck_options *options)
{
int ret = 0;
if (object_on_skiplist(options, oid))
return 0;
if (oidset_contains(&options->gitmodules_found, oid)) {
struct config_options config_opts = { 0 };
struct fsck_gitmodules_data data;
oidset_insert(&options->gitmodules_done, oid);
if (!buf) {
/*
* A missing buffer here is a sign that the caller found the
* blob too gigantic to load into memory. Let's just consider
* that an error.
*/
return report(options, oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_LARGE,
".gitmodules too large to parse");
}
data.oid = oid;
data.options = options;
data.ret = 0;
config_opts.error_action = CONFIG_ERROR_SILENT;
if (git_config_from_mem(fsck_gitmodules_fn, CONFIG_ORIGIN_BLOB,
".gitmodules", buf, size, &data, &config_opts))
data.ret |= report(options, oid, OBJ_BLOB,
FSCK_MSG_GITMODULES_PARSE,
"could not parse gitmodules blob");
ret |= data.ret;
}
if (oidset_contains(&options->gitattributes_found, oid)) {
const char *ptr;
oidset_insert(&options->gitattributes_done, oid);
if (!buf || size > ATTR_MAX_FILE_SIZE) {
/*
* A missing buffer here is a sign that the caller found the
* blob too gigantic to load into memory. Let's just consider
* that an error.
*/
return report(options, oid, OBJ_BLOB,
FSCK_MSG_GITATTRIBUTES_LARGE,
".gitattributes too large to parse");
}
for (ptr = buf; *ptr; ) {
const char *eol = strchrnul(ptr, '\n');
if (eol - ptr >= ATTR_MAX_LINE_LENGTH) {
ret |= report(options, oid, OBJ_BLOB,
FSCK_MSG_GITATTRIBUTES_LINE_LENGTH,
".gitattributes has too long lines to parse");
break;
}
ptr = *eol ? eol + 1 : eol;
}
}
return ret;
}
int fsck_object(struct object *obj, void *data, unsigned long size,
struct fsck_options *options)
{
if (!obj)
return report(options, NULL, OBJ_NONE, FSCK_MSG_BAD_OBJECT_SHA1, "no valid object to fsck");
return fsck_buffer(&obj->oid, obj->type, data, size, options);
}
int fsck_buffer(const struct object_id *oid, enum object_type type,
void *data, unsigned long size,
struct fsck_options *options)
{
if (type == OBJ_BLOB)
return fsck_blob(oid, data, size, options);
if (type == OBJ_TREE)
return fsck_tree(oid, data, size, options);
if (type == OBJ_COMMIT)
return fsck_commit(oid, data, size, options);
if (type == OBJ_TAG)
return fsck_tag(oid, data, size, options);
return report(options, oid, type,
FSCK_MSG_UNKNOWN_TYPE,
"unknown type '%d' (internal fsck error)",
type);
}
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)
{
if (msg_type == FSCK_WARN) {
warning("object %s: %s", fsck_describe_object(o, oid), message);
return 0;
}
error("object %s: %s", fsck_describe_object(o, oid), message);
return 1;
}
static int fsck_blobs(struct oidset *blobs_found, struct oidset *blobs_done,
enum fsck_msg_id msg_missing, enum fsck_msg_id msg_type,
struct fsck_options *options, const char *blob_type)
{
int ret = 0;
struct oidset_iter iter;
const struct object_id *oid;
oidset_iter_init(blobs_found, &iter);
while ((oid = oidset_iter_next(&iter))) {
enum object_type type;
unsigned long size;
char *buf;
if (oidset_contains(blobs_done, oid))
continue;
buf = read_object_file(oid, &type, &size);
if (!buf) {
if (is_promisor_object(oid))
continue;
ret |= report(options,
oid, OBJ_BLOB, msg_missing,
"unable to read %s blob", blob_type);
continue;
}
if (type == OBJ_BLOB)
ret |= fsck_blob(oid, buf, size, options);
else
ret |= report(options, oid, type, msg_type,
"non-blob found at %s", blob_type);
free(buf);
}
oidset_clear(blobs_found);
oidset_clear(blobs_done);
return ret;
}
int fsck_finish(struct fsck_options *options)
{
int ret = 0;
ret |= fsck_blobs(&options->gitmodules_found, &options->gitmodules_done,
FSCK_MSG_GITMODULES_MISSING, FSCK_MSG_GITMODULES_BLOB,
options, ".gitmodules");
ret |= fsck_blobs(&options->gitattributes_found, &options->gitattributes_done,
FSCK_MSG_GITATTRIBUTES_MISSING, FSCK_MSG_GITATTRIBUTES_BLOB,
options, ".gitattributes");
return ret;
}
int git_fsck_config(const char *var, const char *value, void *cb)
{
struct fsck_options *options = cb;
if (strcmp(var, "fsck.skiplist") == 0) {
const char *path;
struct strbuf sb = STRBUF_INIT;
if (git_config_pathname(&path, var, value))
return 1;
strbuf_addf(&sb, "skiplist=%s", path);
free((char *)path);
fsck_set_msg_types(options, sb.buf);
strbuf_release(&sb);
return 0;
}
if (skip_prefix(var, "fsck.", &var)) {
fsck_set_msg_type(options, var, value);
return 0;
}
return git_default_config(var, value, cb);
}
/*
* Custom error callbacks that are used in more than one place.
*/
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)
{
if (msg_id == FSCK_MSG_GITMODULES_MISSING) {
puts(oid_to_hex(oid));
return 0;
}
return fsck_error_function(o, oid, object_type, msg_type, msg_id, message);
}