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cp: make "cp file /dev/node" special case; explained in comments

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function                                             old     new   delta
copy_file                                           1487    1538     +51
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(add/remove: 0/0 grow/shrink: 1/0 up/down: 51/0)               Total: 51 bytes
   text    data     bss     dec     hex filename
 772502    1051   10724  784277   bf795 busybox_old
 772554    1051   10724  784329   bf7c9 busybox_unstripped
This commit is contained in:
Denis Vlasenko 2007-09-11 10:39:13 +00:00
parent 976690afe0
commit fa05074eee
1 changed files with 15 additions and 7 deletions
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20
libbb/copy_file.c
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@ -19,6 +19,9 @@
// (or fail, if it points to dir/nonexistent location/etc). // (or fail, if it points to dir/nonexistent location/etc).
// This is strange, but POSIX-correct. // This is strange, but POSIX-correct.
// coreutils cp has --remove-destination to override this... // coreutils cp has --remove-destination to override this...
//
// 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 */ #define DO_POSIX_CP 0 /* 1 - POSIX behavior, 0 - safe behavior */
@ -243,13 +246,18 @@ int copy_file(const char *source, const char *dest, int flags)
if (src_fd < 0) if (src_fd < 0)
return -1; return -1;
#if DO_POSIX_CP /* POSIX way (a security problem versus symlink attacks!): */ /* POSIX way is a security problem versus symlink attacks,
dst_fd = open(dest, (flags & FILEUTILS_INTERACTIVE) * we do it only for dest's which are device nodes,
? O_WRONLY|O_CREAT|O_EXCL * and only for non-recursive, non-interactive cp. NB: it is still racy
: O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode); * for "cp file /home/bad_user/device_node" case
#else /* safe way: */ * (user can rm device_node and create 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)))
) {
dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
} else /* safe way: */
dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode); dst_fd = open(dest, O_WRONLY|O_CREAT|O_EXCL, source_stat.st_mode);
#endif
if (dst_fd == -1) { if (dst_fd == -1) {
ovr = ask_and_unlink(dest, flags); ovr = ask_and_unlink(dest, flags);
if (ovr <= 0) { if (ovr <= 0) {