From a9335eafcf113969e807d2aa4381cdd31051099f Mon Sep 17 00:00:00 2001
From: Denis Vlasenko <vda.linux@googlemail.com>
Date: Tue, 11 Sep 2007 16:28:14 +0000
Subject: cp: make it a bit closer to POSIX, but still refuse to open and write
to dest which is a symlink.
---
libbb/copy_file.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/libbb/copy_file.c b/libbb/copy_file.c
index 86449f27c..3da8a3531 100644
--- a/libbb/copy_file.c
+++ b/libbb/copy_file.c
@@ -141,6 +141,8 @@ int copy_file(const char *source, const char *dest, int flags)
bb_error_msg("target '%s' is not a directory", dest);
return -1;
}
+ /* race here: user can substitute a symlink between
+ * this check and actual creation of files inside dest */
} else {
mode_t mode;
saved_umask = umask(0);
@@ -247,13 +249,13 @@ int copy_file(const char *source, const char *dest, int flags)
return -1;
/* POSIX way is a security problem versus symlink attacks,
- * we do it only for dest's which are device nodes,
- * and only for non-recursive, non-interactive cp. NB: it is still racy
- * for "cp file /home/bad_user/device_node" case
- * (user can rm device_node and create link to /etc/passwd) */
+ * we do it only for non-symlinks, and only for non-recursive,
+ * non-interactive cp. NB: it is still racy
+ * for "cp file /home/bad_user/file" case
+ * (user can rm file and create a link to /etc/passwd) */
if (DO_POSIX_CP
|| (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE))
- && (S_ISBLK(dest_stat.st_mode) || S_ISCHR(dest_stat.st_mode)))
+ && !S_ISLNK(dest_stat.st_mode))
) {
dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
} else /* safe way: */
--
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