Alright, I've implemented pretty much every single suggestion you
made :). Note that _php_array_to_envp() actually suffers the same
"modify in place" problem, but because it iterates the array twice (is
that REALLY so much better than allocating a few extra pointers or
calling perealloc() a few times?), the fix for it isn't trivial, so I
left it alone. The updated patch is (again) posted at:
http://darkrainfall.org/php-5.3-shellbypass.patch
On Jul 15, 2009, at 4:20 PM, Nuno Lopes wrote:
Hi,
So the patch looks generally good. Here are some minor comments
about it:
- I believe _php_array_to_argv() doesn't need TSRMLS_DC. If that's
the case, please remove it.
- in _php_array_to_argv() you modify the input array destructively
(when calling convert_to_string_ex). You should not modify the input.
- in _php_array_to_argv(), HASH_OF will never return NULL (because
we already know that it's an array).
- apparently the check 'if (cnt < 1) {' will never be true, as the
array will always have one element. please verify that this special
case does what you want (maybe change to 'cnt <= 1')
- argvs with length==0 are perfectly valid, and so you shouldn't
skip them.
- the api is a little inconsistent, as you use the idx 0 to retrieve
the command name, but then you use the array order to retrieve the
rest of the elements (and thus if the idx 0 doesn't appear in the
beginning your code will fail). I would just stick with the array
order. e.g. array(1=>'/usr/bin/echo', 0=>'foo') or similar should
print 'foo'.
- in exit_fail you can remove the check for bypass_shell, as
_php_free_argv() will check the argument against NULL.
- the line 'proc->argv = (bypass_shell ? child_argv : NULL);' can be
simplified to 'proc->argv = child_argv;' since child_argv is already
initialized to NULL
I think that's it :) It's only minor things, I guess.
As soon as you fix these things, please go ahead and commit the
patch, or mail it back to the ML in case you need me to do it.
Nuno
----- Original Message ----- From: "Gwynne Raskind" <gwy...@darkrainfall.org
>
To: "PHP internals" <internals@lists.php.net>
Sent: Friday, June 26, 2009 10:20 PM
Subject: [PHP-DEV] A patch for HEAD
I've just finished making this patch for my own use (diffed
against 5.3 CVS):
http://darkrainfall.org/php-5.3-shellbypass.patch
In short, what it does is make proc_open()'s shell_bypass option
available to UNIX systems. This is accomplished by allowing the
"command" parameter to proc_open() to be an array of arguments to
pass to execv[e](). I've included a few tests to check the
functionality.
(A few more tests could be devised to, for example, check that the
correct warning is issued if you pass an array without
bypass_shell set, or a string with it set, etc.)
The exact behavior of the argument array is:
1) The array must contain at least one element, at index 0.
2) The element at index 0 is always the exact command path passed
to execv[e]() (after being filtered through any safe_mode
restrictions, as with the normal behavior of proc_open()).
3) Any other elements form the argv array passed to execv[e](). By
convention the first of these arguments (argv[0] in the child
process) is the same as the command path, however my patch does
NOT enforce or assume this; it simply calls execv[e]
($argument_array[0], array_slice($argument_array, 1)).
This patch currently provides the only useful way to fork a process
without running a shell (pcntl_fork() + pcntl_exec() are useless
since there's no pcntl_dup2() to control the descriptors of the
child).
Why would you want to avoid the shell?
- Efficiency. The shell is an extra, often unnecessary process,
which must parse the commandline given to it into individual
arguments according to all its various rules. Not to mention the
overhead of setting up another entire process just to run a third
process.
- Resource control. The shell is an extra process. If you don't
need it, and your system is tight on process space, best to avoid
it.
- Sanity. Correctly quoting arguments to a shell command ranges
from mildly annoying (escapeshellarg() in simple cases) to
nightmarish (manual parsing of a string in some edge cases).
Passing arguments directly completely bypasses this, quite
possibly saving you quite a bit of string parsing time if you were
doing something like "$shell_args = implode(' ',
array_map('escapeshellarg', $raw_args));".
- Oddly enough, security. Since there's no shell, it's more
difficult to subvert the child process to do other things than the
coder intended (unless of course, said coder executes a shell this
way).
This patch does nothing on Windows, since the option was already
implemented there. It also does nothing on Netware, since from what
I could see in the code, Netware doesn't have a shell in the first
place.
I'm proposing the inclusion of this patch in HEAD (which I'll port
it to if I get a thumbs-up here), and possibly 5.3.2. Criticism
and angry flames welcome. Constructive critcism and good-natured
comments will be ignored ;) (just kidding... or am I?).
-- Gwynne
-- Gwynne
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