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hush (a Bourne-style shell) for the GNO multitasking environment on the Apple IIgs
5797c7f0ef
While the permissions on the temp file are correct to prevent it from being maliciously mangled by passing strangers, (created with 600, opened O_EXCL, etc), the permissions on the _directory_ might not be, and we re-open the file to convert the filehandle to a FILE * (and automatically get an error message and exit if the directory's read-only or out of space or some such). This opens a potential race condition if somebody's using dnotify on the directory, deletes/renames the tempfile, and drops a symlink or something there. Somebody running sed -i as root in a world writeable directory could do damage. I dug up notes on an earlier discussion where we looked at the security implications of this (unfortunately on the #uclibc channel rather than email; I don't have a transcript, just notes-to-self) which pointed out that if the permissions on the directory allow other people's files to be deleted/renamed then the original file is vulnerable to sabotage anyway. However, there are two cases that discussion apparently didn't take into account: 1) Using another user's permissions to damage files in other directories you can't access (standard symlink attack). 2) Reading data another user couldn't otherwise access by having the new file belong to that other user. This patch uses fdopen to convert the filehandle into a FILE *, rather than reopening the file. |
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| TODO | ||
Please see the LICENSE file for details on copying and usage.
BusyBox combines tiny versions of many common UNIX utilities into a single
small executable. It provides minimalist replacements for most of the utilities
you usually find in GNU coreutils, util-linux, etc. The utilities in BusyBox
generally have fewer options than their full-featured GNU cousins; however, the
options that are included provide the expected functionality and behave very
much like their GNU counterparts.
BusyBox has been written with size-optimization and limited resources in mind.
It is also extremely modular so you can easily include or exclude commands (or
features) at compile time. This makes it easy to customize your embedded
systems. To create a working system, just add /dev, /etc, and a Linux kernel.
BusyBox provides a fairly complete POSIX environment for any small or embedded
system.
BusyBox is extremely configurable. This allows you to include only the
components you need, thereby reducing binary size. Run 'make config' or
'make menuconfig' to select the functionality that you wish to enable.
After the build is complete, a busybox.links file is generated. This is
used by 'make install' to create symlinks to the BusyBox binary for all
compiled in functions. By default, 'make install' will place the symlink
forest into `pwd`/_install unless you have defined the PREFIX environment
variable (i.e., 'make PREFIX=/tmp/foo install')
If you wish to install hard links, rather than symlinks, you can use
'make PREFIX=/tmp/foo install-hardlinks' instead.
----------------
Supported architectures:
BusyBox in general will build on any architecture supported by gcc.
Kernel module loading for 2.2 and 2.4 Linux kernels is currently
limited to ARM, CRIS, H8/300, x86, ia64, x86_64, m68k, MIPS, PowerPC,
S390, SH3/4/5, Sparc, v850e, and x86_64 for 2.4.x kernels. For 2.6.x
kernels, kernel module loading support should work on all architectures.
Supported C Libraries:
uClibc and glibc are supported. People have been looking at newlib and
dietlibc, but they are currently considered unsupported, untested, or
worse. Linux-libc5 is no longer supported -- you should probably use uClibc
instead if you want a small C library.
Supported kernels:
Full functionality requires Linux 2.2.x or better. A large fraction of the
code should run on just about anything. While the current code is fairly
Linux specific, it should be fairly easy to port the majority of the code
to support, say, FreeBSD or Solaris, or Mac OS X, or even Windows (if you
are into that sort of thing).
----------------
Getting help:
When you find you need help, you can check out the BusyBox mailing list
archives at http://busybox.net/lists/busybox/ or even join
the mailing list if you are interested.
----------------
Bugs:
If you find bugs, please submit a detailed bug report to the BusyBox mailing
list at busybox@mail.busybox.net. A well-written bug report should include a
transcript of a shell session that demonstrates the bad behavior and enables
anyone else to duplicate the bug on their own machine. The following is such
an example:
To: busybox@mail.busybox.net
From: diligent@testing.linux.org
Subject: /bin/date doesn't work
Package: BusyBox
Version: 1.00
When I execute BusyBox 'date' it produces unexpected results.
With GNU date I get the following output:
$ date
Fri Oct 8 14:19:41 MDT 2004
But when I use BusyBox date I get this instead:
$ date
illegal instruction
I am using Debian unstable, kernel version 2.4.25-vrs2 on a Netwinder,
and the latest uClibc from CVS. Thanks for the wonderful program!
-Diligent
Note the careful description and use of examples showing not only what BusyBox
does, but also a counter example showing what an equivalent GNU app does. Bug
reports lacking such detail may never be fixed... Thanks for understanding.
----------------
Downloads:
Source for the latest released version, as well as daily snapshots, can always
be downloaded from
http://busybox.net/downloads/
----------------
CVS:
BusyBox now has its own publicly browsable CVS tree at:
http://busybox.net/cgi-bin/cvsweb/busybox/
Anonymous CVS access is available. For instructions, check out:
http://busybox.net/cvs_anon.html
For those that are actively contributing there is even CVS write access:
http://busybox.net/cvs_write.html
----------------
Please feed suggestions, bug reports, insults, and bribes back to:
Erik Andersen
<andersen@codepoet.org>