From: Jonathan Nieder <jrnieder@gmail.com>
To: dash@vger.kernel.org
Cc: Christoph Egger <christoph@debian.org>,
Petr Salinger <Petr.Salinger@seznam.cz>,
Herbert Xu <herbert@gondor.apana.org.au>
Subject: [PATCH] [BUILTIN] Make "test -x" sane again when run as root
Date: Mon, 26 Sep 2011 16:16:37 -0500 [thread overview]
Message-ID: <20110926211636.GA6645@elie> (raw)
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 §4.4 "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>
---
Thanks, all, and sorry to take so long in sending this patch out.
Thoughts?
src/bltin/test.c | 11 +++++++++++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/src/bltin/test.c b/src/bltin/test.c
index 90135e14..1093b59f 100644
--- a/src/bltin/test.c
+++ b/src/bltin/test.c
@@ -485,8 +485,19 @@ 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 */
--
1.7.7.rc1
next reply other threads:[~2011-09-26 21:16 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-26 21:16 Jonathan Nieder [this message]
2011-09-26 22:16 ` [PATCH] [BUILTIN] Make "test -x" sane again when run as root Jonathan Nieder
2011-09-27 13:45 ` Herbert Xu
2011-09-27 23:19 ` [PATCH v2] [BUILTIN] Fix "test -x" as root on FreeBSD 8 Jonathan Nieder
2014-11-17 14:49 ` Herbert Xu
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