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From 3f668dc6ba1910085e61b3a24167ab1352c60d92 Mon Sep 17 00:00:00 2001
From: Mart Raudsepp <leio@gentoo.org>
Date: Fri, 11 Nov 2016 12:34:48 +0200
Subject: [PATCH] libsandbox: do not abort with a long name to opendir
Add a pre-check for opendir that catches too long name arguments
given to opendir, as it would get messed up and abort before it
even gets to the open*() syscall (which would handle it correctly),
due to opendir going through before_syscall/check_syscall, even
though it isn't a true syscall and it getting cut to SB_PATH_MAX
inbetween and getting confused somewhere.
URL: https://bugs.gentoo.org/553092
Signed-off-by: Mart Raudsepp <leio@gentoo.org>
---
libsandbox/wrapper-funcs/opendir.c | 2 ++
libsandbox/wrapper-funcs/opendir_pre_check.c | 26 ++++++++++++++++++++++++++
libsandbox/wrappers.h | 1 +
3 files changed, 29 insertions(+)
create mode 100644 libsandbox/wrapper-funcs/opendir_pre_check.c
diff --git a/libsandbox/wrapper-funcs/opendir.c b/libsandbox/wrapper-funcs/opendir.c
index 7670775..70c2692 100644
--- a/libsandbox/wrapper-funcs/opendir.c
+++ b/libsandbox/wrapper-funcs/opendir.c
@@ -10,4 +10,6 @@
#define WRAPPER_SAFE() SB_SAFE(name)
#define WRAPPER_RET_TYPE DIR *
#define WRAPPER_RET_DEFAULT NULL
+#define WRAPPER_PRE_CHECKS() sb_opendir_pre_check(STRING_NAME, name)
+
#include "__wrapper_simple.c"
diff --git a/libsandbox/wrapper-funcs/opendir_pre_check.c b/libsandbox/wrapper-funcs/opendir_pre_check.c
new file mode 100644
index 0000000..60c869f
--- /dev/null
+++ b/libsandbox/wrapper-funcs/opendir_pre_check.c
@@ -0,0 +1,26 @@
+/*
+ * opendir() pre-check.
+ *
+ * Copyright 1999-2016 Gentoo Foundation
+ * Licensed under the GPL-2
+ */
+
+bool sb_opendir_pre_check(const char *func, const char *name)
+{
+ /* If length of name is larger than PATH_MAX, we would mess it up
+ * before it reaches the open syscall, which would cleanly error out
+ * via sandbox as well (actually with much smaller lengths than even
+ * PATH_MAX).
+ * So error out early in this case, in order to avoid an abort in
+ * check_syscall later on, which gets ran for opendir, despite it not
+ * being a syscall.
+ */
+ if (strnlen(name, PATH_MAX) == PATH_MAX) {
+ errno = ENAMETOOLONG;
+ sb_debug_dyn("EARLY FAIL: %s(%s): %s\n",
+ func, name, strerror(errno));
+ return false;
+ }
+
+ return true;
+}
diff --git a/libsandbox/wrappers.h b/libsandbox/wrappers.h
index 0aa58bb..bf5bf64 100644
--- a/libsandbox/wrappers.h
+++ b/libsandbox/wrappers.h
@@ -27,6 +27,7 @@ attribute_hidden bool sb_fopen64_pre_check (const char *func, const char *pathn
attribute_hidden bool sb_mkdirat_pre_check (const char *func, const char *pathname, int dirfd);
attribute_hidden bool sb_openat_pre_check (const char *func, const char *pathname, int dirfd, int flags);
attribute_hidden bool sb_openat64_pre_check (const char *func, const char *pathname, int dirfd, int flags);
+attribute_hidden bool sb_opendir_pre_check (const char *func, const char *name);
attribute_hidden bool sb_unlinkat_pre_check (const char *func, const char *pathname, int dirfd);
attribute_hidden bool sb_common_at_pre_check(const char *func, const char **pathname, int dirfd,
char *dirfd_path, size_t dirfd_path_len);
--
2.9.0
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