From 2d7b5bfa9bd0b8096bf1ec5069fb6638d538a028 Mon Sep 17 00:00:00 2001 From: Denys Vlasenko Date: Sun, 5 Jul 2009 12:49:29 +0200 Subject: [PATCH] cp: by popular demand, make it POSIX compliant (but less safe) Signed-off-by: Denys Vlasenko --- libbb/Config.in | 10 ++++++++++ libbb/copy_file.c | 18 +++++++++--------- 2 files changed, 19 insertions(+), 9 deletions(-) diff --git a/libbb/Config.in b/libbb/Config.in index a572775c9..9b616d1af 100644 --- a/libbb/Config.in +++ b/libbb/Config.in @@ -114,6 +114,16 @@ config FEATURE_EDITING_ASK_TERMINAL correctly, or want to save on code size (about 300 bytes), then do not turn this option on. +config FEATURE_NON_POSIX_CP + bool "Non-POSIX, but safer, copying to special nodes" + default y + help + With this option, "cp file symlink" will delete symlink + and create a regular file. This does not conform to POSIX, + but prevents a symlink attack. + Similarly, "cp file device" will not send file's data + to the device. + config FEATURE_VERBOSE_CP_MESSAGE bool "Give more precise messages when copy fails (cp, mv etc)" default n diff --git a/libbb/copy_file.c b/libbb/copy_file.c index d804eccfa..4d2f17aa5 100644 --- a/libbb/copy_file.c +++ b/libbb/copy_file.c @@ -8,9 +8,10 @@ * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. * */ - #include "libbb.h" +// FEATURE_NON_POSIX_CP: +// // POSIX: if exists and -i, ask (w/o -i assume yes). // Then open w/o EXCL (yes, not unlink!). // If open still fails and -f, try unlink, then try open again. @@ -23,22 +24,21 @@ // NB: we have special code which still allows for "cp file /dev/node" // to work POSIX-ly (the only realistic case where it makes sense) -#define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */ - // errno must be set to relevant value ("why we cannot create dest?") // for POSIX mode to give reasonable error message static int ask_and_unlink(const char *dest, int flags) { int e = errno; -#if DO_POSIX_CP +#if !ENABLE_FEATURE_NON_POSIX_CP if (!(flags & (FILEUTILS_FORCE|FILEUTILS_INTERACTIVE))) { // Either it exists, or the *path* doesnt exist bb_perror_msg("cannot create '%s'", dest); return -1; } #endif - // If !DO_POSIX_CP, act as if -f is always in effect - we don't want - // "cannot create" msg, we want unlink to be done (silently unless -i). + // If ENABLE_FEATURE_NON_POSIX_CP, act as if -f is always in effect + // - we don't want "cannot create" msg, we want unlink to be done + // (silently unless -i). // TODO: maybe we should do it only if ctty is present? if (flags & FILEUTILS_INTERACTIVE) { @@ -279,10 +279,10 @@ int FAST_FUNC copy_file(const char *source, const char *dest, int flags) * 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 + if (!ENABLE_FEATURE_NON_POSIX_CP || (dest_exists - && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE)) - && !S_ISLNK(dest_stat.st_mode)) + && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE)) + && !S_ISLNK(dest_stat.st_mode)) ) { dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, new_mode); } else /* safe way: */ -- 2.25.1