From ee27ca4a781844ddbf556ec64daae24d748a7c5a Mon Sep 17 00:00:00 2001 From: Jeff King Date: Thu, 17 Nov 2011 18:04:22 -0500 Subject: [PATCH] archive: don't let remote clients get unreachable commits Usually git is careful not to allow clients to fetch arbitrary objects from the database; for example, objects received via upload-pack must be reachable from a ref. Upload-archive breaks this by feeding the client's tree-ish directly to get_sha1, which will accept arbitrary hex sha1s, reflogs, etc. This is not a problem if all of your objects are publicly reachable anyway (or at least public to anybody who can run upload-archive). Or if you are making the repo available by dumb protocols like http or rsync (in which case the client can read your whole object db directly). But for sites which allow access only through smart protocols, clients may be able to fetch trees from commits that exist in the server's object database but are not referenced (e.g., because history was rewound). This patch tightens upload-archive's lookup to use dwim_ref rather than get_sha1. This means a remote client can only fetch the tip of a named ref, not an arbitrary sha1 or reflog entry. This also restricts some legitimate requests, too: 1. Reachable non-tip commits, like: git archive --remote=$url v1.0~5 2. Sub-trees of reachable commits, like: git archive --remote=$url v1.7.7:Documentation Local requests continue to use get_sha1, and are not restricted at all. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- archive.c | 20 +++++++++++++++----- archive.h | 3 ++- builtin-archive.c | 2 +- builtin-upload-archive.c | 2 +- t/t5000-tar-tree.sh | 8 ++++++++ 5 files changed, 27 insertions(+), 8 deletions(-) diff --git a/archive.c b/archive.c index e6de0397c..251d69e15 100644 --- a/archive.c +++ b/archive.c @@ -196,7 +196,8 @@ static void parse_pathspec_arg(const char **pathspec, } static void parse_treeish_arg(const char **argv, - struct archiver_args *ar_args, const char *prefix) + struct archiver_args *ar_args, const char *prefix, + int remote) { const char *name = argv[0]; const unsigned char *commit_sha1; @@ -205,8 +206,17 @@ static void parse_treeish_arg(const char **argv, const struct commit *commit; unsigned char sha1[20]; - if (get_sha1(name, sha1)) - die("Not a valid object name"); + /* Remotes are only allowed to fetch actual refs */ + if (remote) { + char *ref = NULL; + if (!dwim_ref(name, strlen(name), sha1, &ref)) + die("no such ref: %s", name); + free(ref); + } + else { + if (get_sha1(name, sha1)) + die("Not a valid object name"); + } commit = lookup_commit_reference_gently(sha1, 1); if (commit) { @@ -324,7 +334,7 @@ static int parse_archive_args(int argc, const char **argv, } int write_archive(int argc, const char **argv, const char *prefix, - int setup_prefix) + int setup_prefix, int remote) { const struct archiver *ar = NULL; struct archiver_args args; @@ -333,7 +343,7 @@ int write_archive(int argc, const char **argv, const char *prefix, if (setup_prefix && prefix == NULL) prefix = setup_git_directory(); - parse_treeish_arg(argv, &args, prefix); + parse_treeish_arg(argv, &args, prefix, remote); parse_pathspec_arg(argv + 1, &args); git_config(git_default_config, NULL); diff --git a/archive.h b/archive.h index 0b15b3514..9375057d7 100644 --- a/archive.h +++ b/archive.h @@ -24,6 +24,7 @@ extern int write_tar_archive(struct archiver_args *); extern int write_zip_archive(struct archiver_args *); extern int write_archive_entries(struct archiver_args *args, write_archive_entry_fn_t write_entry); -extern int write_archive(int argc, const char **argv, const char *prefix, int setup_prefix); +extern int write_archive(int argc, const char **argv, const char *prefix, + int setup_prefix, int remote); #endif /* ARCHIVE_H */ diff --git a/builtin-archive.c b/builtin-archive.c index 5ceec433f..a081a6bf1 100644 --- a/builtin-archive.c +++ b/builtin-archive.c @@ -117,5 +117,5 @@ int cmd_archive(int argc, const char **argv, const char *prefix) setvbuf(stderr, NULL, _IOLBF, BUFSIZ); - return write_archive(argc, argv, prefix, 1); + return write_archive(argc, argv, prefix, 1, 0); } diff --git a/builtin-upload-archive.c b/builtin-upload-archive.c index a9b02fa32..47efadc46 100644 --- a/builtin-upload-archive.c +++ b/builtin-upload-archive.c @@ -64,7 +64,7 @@ static int run_upload_archive(int argc, const char **argv, const char *prefix) sent_argv[sent_argc] = NULL; /* parse all options sent by the client */ - return write_archive(sent_argc, sent_argv, prefix, 0); + return write_archive(sent_argc, sent_argv, prefix, 0, 1); } static void error_clnt(const char *fmt, ...) diff --git a/t/t5000-tar-tree.sh b/t/t5000-tar-tree.sh index c942c8be8..1a2ee105a 100755 --- a/t/t5000-tar-tree.sh +++ b/t/t5000-tar-tree.sh @@ -213,4 +213,12 @@ test_expect_success \ 'git archive --list outside of a git repo' \ 'GIT_DIR=some/non-existing/directory git archive --list' +test_expect_success 'clients cannot access unreachable commits' ' + test_commit unreachable && + sha1=`git rev-parse HEAD` && + git reset --hard HEAD^ && + git archive $sha1 >remote.tar && + test_must_fail git archive --remote=. $sha1 >remote.tar +' + test_done -- 2.26.2