From: Kees Cook <keescook@chromium.org>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>,
Ingo Molnar <mingo@redhat.com>,
Frank Rowand <frowand.list@gmail.com>,
Randy Dunlap <rdunlap@infradead.org>,
Namhyung Kim <namhyung@kernel.org>, Tim Bird <Tim.Bird@sony.com>,
Jiri Olsa <jolsa@redhat.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Tom Zanussi <tom.zanussi@linux.intel.com>,
Rob Herring <robh+dt@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
Jonathan Corbet <corbet@lwn.net>,
Linus Torvalds <torvalds@linux-foundation.org>,
linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig for init command line
Date: Fri, 7 Feb 2020 16:44:49 -0800 [thread overview]
Message-ID: <202002071640.49BFDA2D1A@keescook> (raw)
In-Reply-To: <20200207144603.30688b94@oasis.local.home>
On Fri, Feb 07, 2020 at 02:46:03PM -0500, Steven Rostedt wrote:
> On Fri, 7 Feb 2020 10:03:16 -0800
> Kees Cook <keescook@chromium.org> wrote:
> > > + len = strlen(saved_command_line);
> > > + if (!strstr(boot_command_line, " -- ")) {
> > > + strcpy(saved_command_line + len, " -- ");
> > > + len += 4;
> > > + } else
> > > + saved_command_line[len++] = ' ';
> > > +
> > > + strcpy(saved_command_line + len, extra_init_args);
> > > + }
> >
> > This isn't safe because it will destroy any argument with " -- " in
> > quotes and anything after it. For example, booting with:
> >
> > thing=on acpi_osi="! -- " other=setting
> >
> > will wreck acpi_osi's value and potentially overwrite "other=settings",
> > etc.
> >
> > (Yes, this seems very unlikely, but you can't treat " -- " as special,
> > the command line string must be correct parsed for double quotes, as
> > parse_args() does.)
> >
>
> This is not the args you are looking for. ;-)
>
> There is a slight bug, but not as bad as you may think it is.
> bootconfig (when added to the command line) will look for a json like
> file appended to the initrd, and it will parse that. That's what all the
> xbc_*() functions do (extended boot commandline). If one of the options
> in that json like file is "init", then it will create the
> extra_init_args, which will make ilen greater than zero.
>
> The above if statement looks for that ' -- ', and if it doesn't find it
> (strcmp() returns NULL when not found) it will than append " -- " to
> the boot_command_line. If it is found, then the " -- " is not added. In
> either case, the init args found in the json like file in the initrd is
> appended to the saved_command_line.
>
> I did say there's a slight bug here. If you have your condition, and
> you add init arguments to that json file, it wont properly add the " --
> ", and the init arguments in that file will be ignored.
Ah, right, it's even more slight, sorry, I had the strstr() in my head
still. So, yes, with an "init" section and a very goofy " -- " present
in a kernel bootparam string value, the appended init args will be
parsed as kernel options.
--
Kees Cook
next prev parent reply other threads:[~2020-02-08 0:44 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-10 16:03 [PATCH v6 00/22] tracing: bootconfig: Boot-time tracing and Extra boot config Masami Hiramatsu
2020-01-10 16:03 ` [PATCH v6 01/22] bootconfig: Add Extra Boot Config support Masami Hiramatsu
2020-01-18 18:33 ` Randy Dunlap
2020-01-19 12:23 ` Masami Hiramatsu
2020-01-10 16:03 ` [PATCH v6 02/22] bootconfig: Load boot config from the tail of initrd Masami Hiramatsu
2020-01-10 16:03 ` [PATCH v6 03/22] tools: bootconfig: Add bootconfig command Masami Hiramatsu
2020-01-10 16:04 ` [PATCH v6 04/22] tools: bootconfig: Add bootconfig test script Masami Hiramatsu
2020-01-10 16:04 ` [PATCH v6 05/22] proc: bootconfig: Add /proc/bootconfig to show boot config list Masami Hiramatsu
2020-01-10 16:04 ` [PATCH v6 06/22] init/main.c: Alloc initcall_command_line in do_initcall() and free it Masami Hiramatsu
2020-01-10 16:04 ` [PATCH v6 07/22] bootconfig: init: Allow admin to use bootconfig for kernel command line Masami Hiramatsu
2020-01-10 16:04 ` [PATCH v6 08/22] bootconfig: init: Allow admin to use bootconfig for init " Masami Hiramatsu
2020-02-07 18:03 ` Kees Cook
2020-02-07 19:31 ` Arvind Sankar
2020-02-07 19:46 ` Steven Rostedt
2020-02-08 0:44 ` Kees Cook [this message]
2020-08-02 2:33 ` Arvind Sankar
2020-08-03 15:03 ` Masami Hiramatsu
2020-08-03 15:29 ` Arvind Sankar
2020-08-03 17:22 ` Steven Rostedt
2020-08-04 0:29 ` Masami Hiramatsu
2020-01-10 16:05 ` [PATCH v6 09/22] Documentation: bootconfig: Add a doc for extended boot config Masami Hiramatsu
2020-01-18 18:28 ` Randy Dunlap
2020-01-19 13:36 ` Masami Hiramatsu
2020-01-10 16:05 ` [PATCH v6 10/22] tracing: Apply soft-disabled and filter to tracepoints printk Masami Hiramatsu
2020-01-10 16:05 ` [PATCH v6 11/22] tracing: kprobes: Output kprobe event to printk buffer Masami Hiramatsu
2020-01-10 16:05 ` [PATCH v6 12/22] tracing: kprobes: Register to dynevent earlier stage Masami Hiramatsu
2020-01-10 16:05 ` [PATCH v6 13/22] tracing: Accept different type for synthetic event fields Masami Hiramatsu
2020-01-10 16:06 ` [PATCH v6 14/22] tracing: Add NULL trace-array check in print_synth_event() Masami Hiramatsu
2020-01-10 16:06 ` [PATCH v6 15/22] tracing/boot: Add boot-time tracing Masami Hiramatsu
2020-01-10 16:06 ` [PATCH v6 16/22] tracing/boot: Add per-event settings Masami Hiramatsu
2020-01-10 16:06 ` [PATCH v6 17/22] tracing/boot Add kprobe event support Masami Hiramatsu
2020-01-10 16:06 ` [PATCH v6 18/22] tracing/boot: Add synthetic " Masami Hiramatsu
2020-01-10 16:07 ` [PATCH v6 19/22] tracing/boot: Add instance node support Masami Hiramatsu
2020-01-10 16:07 ` [PATCH v6 20/22] tracing/boot: Add cpu_mask option support Masami Hiramatsu
2020-01-10 16:07 ` [PATCH v6 21/22] tracing/boot: Add function tracer filter options Masami Hiramatsu
2020-01-10 16:07 ` [PATCH v6 22/22] Documentation: tracing: Add boot-time tracing document Masami Hiramatsu
2020-01-18 18:14 ` Randy Dunlap
2020-01-19 14:15 ` Masami Hiramatsu
2020-01-19 14:20 ` [PATCH v6 00/22] tracing: bootconfig: Boot-time tracing and Extra boot config Masami Hiramatsu
2020-01-19 14:59 ` Steven Rostedt
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