| Message ID | patch-v8-9.9-6fce633493b-20230328T140127Z-avarab@gmail.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 3611f7467fddcff6063ed2c99484047b410969fc |
| Headers | show |
| Series | config API: make "multi" safe, fix segfaults, propagate "ret" | expand |
On Tue, Mar 28, 2023 at 04:04:28PM +0200, Ævar Arnfjörð Bjarmason wrote: > Fix a logic error in 4950b2a2b5c (for-each-repo: run subcommands on > configured repos, 2020-09-11). Due to assuming that elements returned > from the repo_config_get_value_multi() call wouldn't be "NULL" we'd > conflate the <path> and <command> part of the argument list when > running commands. > > As noted in the preceding commit the fix is to move to a safer > "*_string_multi()" version of the *_multi() API. This change is > separated from the rest because those all segfaulted. In this change > we ended up with different behavior. > > When using the "--config=<config>" form we take each element of the > list as a path to a repository. E.g. with a configuration like: > > [repo] list = /some/repo > > We would, with this command: > > git for-each-repo --config=repo.list status builtin > > Run a "git status" in /some/repo, as: > > git -C /some/repo status builtin > > I.e. ask "status" to report on the "builtin" directory. But since a > configuration such as this would result in a "struct string_list *" > with one element, whose "string" member is "NULL": > > [repo] list > > We would, when constructing our command-line in > "builtin/for-each-repo.c"... > > strvec_pushl(&child.args, "-C", path, NULL); > for (i = 0; i < argc; i++) > strvec_push(&child.args, argv[i]); > > ...have that "path" be "NULL", and as strvec_pushl() stops when it > sees NULL we'd end with the first "argv" element as the argument to > the "-C" option, e.g.: > > git -C status builtin > > I.e. we'd run the command "builtin" in the "status" directory. > > In another context this might be an interesting security > vulnerability, but I think that this amounts to a nothingburger on > that front. > > A hypothetical attacker would need to be able to write config for the > victim to run, if they're able to do that there's more interesting > attack vectors. See the "safe.directory" facility added in > 8d1a7448206 (setup.c: create `safe.bareRepository`, 2022-07-14). > > An even more unlikely possibility would be an attacker able to > generate the config used for "for-each-repo --config=<key>", but > nothing else (e.g. an automated system producing that list). > > Even in that case the attack vector is limited to the user running > commands whose name matches a directory that's interesting to the > attacker (e.g. a "log" directory in a repository). The second > argument (if any) of the command is likely to make git die without > doing anything interesting (e.g. "-p" to "log", there being no "-p" > built-in command to run). > > Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> > --- > builtin/for-each-repo.c | 2 +- > t/t0068-for-each-repo.sh | 13 +++++++++++++ > 2 files changed, 14 insertions(+), 1 deletion(-) > > diff --git a/builtin/for-each-repo.c b/builtin/for-each-repo.c > index 224164addb3..ce8f7a99086 100644 > --- a/builtin/for-each-repo.c > +++ b/builtin/for-each-repo.c > @@ -46,7 +46,7 @@ int cmd_for_each_repo(int argc, const char **argv, const char *prefix) > if (!config_key) > die(_("missing --config=<config>")); > > - err = repo_config_get_value_multi(the_repository, config_key, &values); > + err = repo_config_get_string_multi(the_repository, config_key, &values); > if (err < 0) > usage_msg_optf(_("got bad config --config=%s"), > for_each_repo_usage, options, config_key); > diff --git a/t/t0068-for-each-repo.sh b/t/t0068-for-each-repo.sh > index 6b51e00da0e..4b90b74d5d5 100755 > --- a/t/t0068-for-each-repo.sh > +++ b/t/t0068-for-each-repo.sh > @@ -46,4 +46,17 @@ test_expect_success 'error on bad config keys' ' > test_expect_code 129 git for-each-repo --config="'\''.b" > ' > > +test_expect_success 'error on NULL value for config keys' ' > + cat >>.git/config <<-\EOF && > + [empty] > + key > + EOF > + cat >expect <<-\EOF && > + error: missing value for '\''empty.key'\'' > + EOF > + test_expect_code 129 git for-each-repo --config=empty.key 2>actual.raw && > + grep ^error actual.raw >actual && > + test_cmp expect actual > +' In this case the full error message looks like this: $ ./git -c empty.key for-each-repo --config=empty.key error: missing value for 'empty.key' fatal: got bad config --config=empty.key usage: git for-each-repo --config=<config> [--] <arguments> --config <config> config key storing a list of repository paths Having both an "error:" and a "fatal:" message seems redundant. On a related note, according to the usage shown above (and the synopsis in the man page), 'git for-each-repo' expects mandatory <arguments>, but this doesn't seem to be enforced, and invoking it without any arguments results in the usage of the main git command: $ ./git -c empty.key=. for-each-repo --config=empty.key usage: git [-v | --version] [-h | --help] [-C <path>] [-c <name>=<value>] [--exec-path[=<path>]] [--html-path] [--man-path] [--info-path] [-p | --paginate | -P | --no-pager] [--no-replace-objects] [--bare] [--git-dir=<path>] [--work-tree=<path>] [--namespace=<name>] [--config-env=<name>=<envvar>] <command> [<args>] These are common Git commands used in various situations: start a working area (see also: git help tutorial) [...] This is misleading, because without any hints as to what was wrong I thought that the problem is with the options of the main git command, not with the (lack of) arguments of the 'for-each-repo' command.
diff --git a/builtin/for-each-repo.c b/builtin/for-each-repo.c index 224164addb3..ce8f7a99086 100644 --- a/builtin/for-each-repo.c +++ b/builtin/for-each-repo.c @@ -46,7 +46,7 @@ int cmd_for_each_repo(int argc, const char **argv, const char *prefix) if (!config_key) die(_("missing --config=<config>")); - err = repo_config_get_value_multi(the_repository, config_key, &values); + err = repo_config_get_string_multi(the_repository, config_key, &values); if (err < 0) usage_msg_optf(_("got bad config --config=%s"), for_each_repo_usage, options, config_key); diff --git a/t/t0068-for-each-repo.sh b/t/t0068-for-each-repo.sh index 6b51e00da0e..4b90b74d5d5 100755 --- a/t/t0068-for-each-repo.sh +++ b/t/t0068-for-each-repo.sh @@ -46,4 +46,17 @@ test_expect_success 'error on bad config keys' ' test_expect_code 129 git for-each-repo --config="'\''.b" ' +test_expect_success 'error on NULL value for config keys' ' + cat >>.git/config <<-\EOF && + [empty] + key + EOF + cat >expect <<-\EOF && + error: missing value for '\''empty.key'\'' + EOF + test_expect_code 129 git for-each-repo --config=empty.key 2>actual.raw && + grep ^error actual.raw >actual && + test_cmp expect actual +' + test_done
Fix a logic error in 4950b2a2b5c (for-each-repo: run subcommands on configured repos, 2020-09-11). Due to assuming that elements returned from the repo_config_get_value_multi() call wouldn't be "NULL" we'd conflate the <path> and <command> part of the argument list when running commands. As noted in the preceding commit the fix is to move to a safer "*_string_multi()" version of the *_multi() API. This change is separated from the rest because those all segfaulted. In this change we ended up with different behavior. When using the "--config=<config>" form we take each element of the list as a path to a repository. E.g. with a configuration like: [repo] list = /some/repo We would, with this command: git for-each-repo --config=repo.list status builtin Run a "git status" in /some/repo, as: git -C /some/repo status builtin I.e. ask "status" to report on the "builtin" directory. But since a configuration such as this would result in a "struct string_list *" with one element, whose "string" member is "NULL": [repo] list We would, when constructing our command-line in "builtin/for-each-repo.c"... strvec_pushl(&child.args, "-C", path, NULL); for (i = 0; i < argc; i++) strvec_push(&child.args, argv[i]); ...have that "path" be "NULL", and as strvec_pushl() stops when it sees NULL we'd end with the first "argv" element as the argument to the "-C" option, e.g.: git -C status builtin I.e. we'd run the command "builtin" in the "status" directory. In another context this might be an interesting security vulnerability, but I think that this amounts to a nothingburger on that front. A hypothetical attacker would need to be able to write config for the victim to run, if they're able to do that there's more interesting attack vectors. See the "safe.directory" facility added in 8d1a7448206 (setup.c: create `safe.bareRepository`, 2022-07-14). An even more unlikely possibility would be an attacker able to generate the config used for "for-each-repo --config=<key>", but nothing else (e.g. an automated system producing that list). Even in that case the attack vector is limited to the user running commands whose name matches a directory that's interesting to the attacker (e.g. a "log" directory in a repository). The second argument (if any) of the command is likely to make git die without doing anything interesting (e.g. "-p" to "log", there being no "-p" built-in command to run). Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com> --- builtin/for-each-repo.c | 2 +- t/t0068-for-each-repo.sh | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-)