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cp: make it a bit closer to POSIX, but still refuse to open and

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write to dest which is a symlink.
This commit is contained in:
Denis Vlasenko 2007-09-11 16:28:14 +00:00
parent fa05074eee
commit a9335eafcf
1 changed files with 7 additions and 5 deletions
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12
libbb/copy_file.c
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@ -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); bb_error_msg("target '%s' is not a directory", dest);
return -1; return -1;
} }
/* race here: user can substitute a symlink between
* this check and actual creation of files inside dest */
} else { } else {
mode_t mode; mode_t mode;
saved_umask = umask(0); saved_umask = umask(0);
@ -247,13 +249,13 @@ int copy_file(const char *source, const char *dest, int flags)
return -1; return -1;
/* POSIX way is a security problem versus symlink attacks, /* POSIX way is a security problem versus symlink attacks,
* we do it only for dest's which are device nodes, * we do it only for non-symlinks, and only for non-recursive,
* and only for non-recursive, non-interactive cp. NB: it is still racy * non-interactive cp. NB: it is still racy
* for "cp file /home/bad_user/device_node" case * for "cp file /home/bad_user/file" case
* (user can rm device_node and create link to /etc/passwd) */ * (user can rm file and create a link to /etc/passwd) */
if (DO_POSIX_CP if (DO_POSIX_CP
|| (dest_exists && !(flags & (FILEUTILS_RECUR|FILEUTILS_INTERACTIVE)) || (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); dst_fd = open(dest, O_WRONLY|O_CREAT|O_TRUNC, source_stat.st_mode);
} else /* safe way: */ } else /* safe way: */