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From e08afc373611ba3e7f2f90bd8e7ce022a1bebed9 Mon Sep 17 00:00:00 2001
From: Jonathan Nieder <jrnieder@gmail.com>
Date: Mon, 26 Sep 2011 16:16:37 -0500
Subject: [PATCH 3/6] [BUILTIN] Fix "test -x" as root on platforms with
old-fashioned faccessat()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
When dash switched from its own emulation to the true faccessat in
v0.5.7~54 (2010-04-02), on some platforms (e.g., old versions of
glibc-bsd), "test -x <path>" started returning true on all files when
run as root. This violates POSIX.1-2008 ยง4.4 "File Access
Permission", which says:
If execute permission is requested, access shall be granted
if execute permission is granted to at least one user by the
file permission bits or by an alternate access control
mechanism; otherwise, access shall be denied.
Unfortunately, for historical reasons, access() and faccessat() are
allowed by POSIX to return success for X_OK when the current process
is privileged even when the above condition is not fulfilled and
actual execution would fail. Work around this by checking the
permissions bits when mode == X_OK and geteuid() == 0.
Reported-by: Christoph Egger <christoph@debian.org>
Analysis-by: Petr Salinger <Petr.Salinger@seznam.cz>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
---
src/bltin/test.c | 11 +++++++++++
1 file changed, 11 insertions(+)
diff --git a/src/bltin/test.c b/src/bltin/test.c
index baa91a5..ca29f40 100644
--- a/src/bltin/test.c
+++ b/src/bltin/test.c
@@ -489,8 +489,19 @@ equalf (const char *f1, const char *f2)
}
#ifdef HAVE_FACCESSAT
+static int has_exec_bit_set(const char *path)
+{
+ struct stat64 st;
+
+ if (stat64(path, &st))
+ return 0;
+ return st.st_mode & (S_IXUSR | S_IXGRP | S_IXOTH);
+}
+
static int test_file_access(const char *path, int mode)
{
+ if (mode == X_OK && geteuid() == 0 && !has_exec_bit_set(path))
+ return 0;
return !faccessat(AT_FDCWD, path, mode, AT_EACCESS);
}
#else /* HAVE_FACCESSAT */
--
2.1.0
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