From: Tian Yuchen Date: Tue, 17 Feb 2026 08:41:24 GMT Subject: [PATCH v4] setup: allow cwd/.git to be a symlink to a directory Message-ID: <20260217084124.150366-1-a3205153416@gmail.com> In-Reply-To: <5b29218a-8d18-41f0-8a03-eac707151945@gmail.com> Strictly enforcing 'lstat()' and 'S_ISREG()' on '.git' prevents valid workflows where '.git' is a symbolic link pointing to a real git directory (e.g. created via 'ln -s'). Refactor 'setup_git_directory_gently_1()' to use 'stat()' instead of 'lstat()'. This allows the filesystem to automatically resolve symbolic links. To ensure safety and correctness, the logic flow is updated to: 1. Ignore 'ENOENT' (file missing). 2. Check 'IS_A_DIR' cases via 'is_git_directory()'. 3. Explicitly reject 'NOT_A_FILE' cases (FIFOs or sockets). Add a new test script t/t0009-setup-security.sh which verifies: - Valid .git symlinks to real directories are accepted. - .git as a named pipe (FIFO) is rejected. - .git as a symlink to a named pipe is rejected. - .git with garbage content is rejected. - Empty .git directories are ignored. Signed-off-by: Tian Yuchen --- setup.c | 39 ++++++++++++++------- setup.h | 2 ++ t/t0009-setup-security.sh | 72 +++++++++++++++++++++++++++++++++++++++ 3 files changed, 101 insertions(+), 12 deletions(-) create mode 100755 t/t0009-setup-security.sh diff --git a/setup.c b/setup.c index 3a6a048620..269aa9faaa 100644 --- a/setup.c +++ b/setup.c @@ -939,8 +939,14 @@ const char *read_gitfile_gently(const char *path, int *return_error_code) static struct strbuf realpath = STRBUF_INIT; if (stat(path, &st)) { - /* NEEDSWORK: discern between ENOENT vs other errors */ - error_code = READ_GITFILE_ERR_STAT_FAILED; + if (errno == ENOENT) + error_code = READ_GITFILE_ERR_STAT_ENOENT; + else + error_code = READ_GITFILE_ERR_STAT_FAILED; + goto cleanup_return; + } + if (S_ISDIR(st.st_mode)) { + error_code = READ_GITFILE_ERR_IS_A_DIR; goto cleanup_return; } if (!S_ISREG(st.st_mode)) { @@ -994,7 +1000,9 @@ const char *read_gitfile_gently(const char *path, int *return_error_code) cleanup_return: if (return_error_code) *return_error_code = error_code; - else if (error_code) + else if (error_code && + error_code != READ_GITFILE_ERR_STAT_ENOENT && + error_code != READ_GITFILE_ERR_IS_A_DIR) read_gitfile_error_die(error_code, path, dir); free(buf); @@ -1576,20 +1584,27 @@ static enum discovery_result setup_git_directory_gently_1(struct strbuf *dir, if (offset > min_offset) strbuf_addch(dir, '/'); strbuf_addstr(dir, DEFAULT_GIT_DIR_ENVIRONMENT); - gitdirenv = read_gitfile_gently(dir->buf, die_on_error ? - NULL : &error_code); + gitdirenv = read_gitfile_gently(dir->buf, &error_code); if (!gitdirenv) { - if (die_on_error || - error_code == READ_GITFILE_ERR_NOT_A_FILE) { - /* NEEDSWORK: fail if .git is not file nor dir */ + if (error_code == READ_GITFILE_ERR_STAT_ENOENT) { + ; + } else if (error_code == READ_GITFILE_ERR_IS_A_DIR) { if (is_git_directory(dir->buf)) { gitdirenv = DEFAULT_GIT_DIR_ENVIRONMENT; gitdir_path = xstrdup(dir->buf); } - } else if (error_code != READ_GITFILE_ERR_STAT_FAILED) - return GIT_DIR_INVALID_GITFILE; - } else - gitfile = xstrdup(dir->buf); + } else if (error_code == READ_GITFILE_ERR_NOT_A_FILE) { + if (die_on_error) + die(_("Invalid %s: not a regular file or directory"), dir->buf); + else + return GIT_DIR_INVALID_GITFILE; + } else if (error_code != READ_GITFILE_ERR_STAT_FAILED) { + if (die_on_error) + read_gitfile_error_die(error_code, dir->buf, NULL); + else + return GIT_DIR_INVALID_GITFILE; + } + } /* * Earlier, we tentatively added DEFAULT_GIT_DIR_ENVIRONMENT * to check that directory for a repository. diff --git a/setup.h b/setup.h index d55dcc6608..c23629cb4f 100644 --- a/setup.h +++ b/setup.h @@ -36,6 +36,8 @@ int is_nonbare_repository_dir(struct strbuf *path); #define READ_GITFILE_ERR_NO_PATH 6 #define READ_GITFILE_ERR_NOT_A_REPO 7 #define READ_GITFILE_ERR_TOO_LARGE 8 +#define READ_GITFILE_ERR_STAT_ENOENT 9 +#define READ_GITFILE_ERR_IS_A_DIR 10 void read_gitfile_error_die(int error_code, const char *path, const char *dir); const char *read_gitfile_gently(const char *path, int *return_error_code); #define read_gitfile(path) read_gitfile_gently((path), NULL) diff --git a/t/t0009-setup-security.sh b/t/t0009-setup-security.sh new file mode 100755 index 0000000000..72c5232147 --- /dev/null +++ b/t/t0009-setup-security.sh @@ -0,0 +1,72 @@ +#!/bin/sh + +test_description='setup: validation of .git file/directory types + +Verify that setup_git_directory() correctly handles: +1. Valid .git directories (including symlinks to them). +2. Invalid .git files (FIFOs, sockets) by erroring out. +3. Invalid .git files (garbage) by erroring out. +' + +. ./test-lib.sh + +test_expect_success 'setup: create parent git repository' ' + git init parent && + test_commit -C parent "root-commit" +' + +test_expect_success SYMLINKS 'setup: .git as a symlink to a directory is valid' ' + mkdir -p parent/link-to-dir && + ( + cd parent/link-to-dir && + git init real-repo && + ln -s real-repo/.git .git && + git rev-parse --git-dir >actual && + echo .git >expect && + test_cmp expect actual + ) +' + +test_expect_success PIPE 'setup: .git as a FIFO (named pipe) is rejected' ' + mkdir -p parent/fifo && + ( + cd parent/fifo && + mkfifo .git && + test_must_fail git rev-parse --git-dir 2>stderr && + grep "not a regular file" stderr + ) +' + +test_expect_success SYMLINKS,PIPE 'setup: .git as a symlink to a FIFO is rejected' ' + mkdir -p parent/symlink-fifo && + ( + cd parent/symlink-fifo && + mkfifo target-fifo && + ln -s target-fifo .git && + test_must_fail git rev-parse --git-dir 2>stderr && + grep "not a regular file" stderr + ) +' + +test_expect_success 'setup: .git with garbage content is rejected' ' + mkdir -p parent/garbage && + ( + cd parent/garbage && + echo "garbage" >.git && + test_must_fail git rev-parse --git-dir 2>stderr && + grep "invalid gitfile format" stderr + ) +' + +test_expect_success 'setup: .git as an empty directory is ignored' ' + mkdir -p parent/empty-dir && + ( + cd parent/empty-dir && + mkdir .git && + git rev-parse --git-dir >actual && + echo "$TRASH_DIRECTORY/parent/.git" >expect && + test_cmp expect actual + ) +' + +test_done -- 2.43.0