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authorRob Landley <rlandley@parallels.com>2011-01-22 16:44:05 -0500
committerSteve French <sfrench@us.ibm.com>2011-01-23 23:28:51 -0500
commitf1d0c998653f1eeec60ee6420e550135b62dbab4 (patch)
tree1db07e198f4c0a86bca7160f9a6a3255f4b4f4a9 /kernel/rtmutex.c
parent3f391c79b0686ce183668c6e2b7d02f3e716766c (diff)
Make CIFS mount work in a container.
Teach cifs about network namespaces, so mounting uses adresses/routing visible from the container rather than from init context. A container is a chroot on steroids that changes more than just the root filesystem the new processes see. One thing containers can isolate is "network namespaces", meaning each container can have its own set of ethernet interfaces, each with its own own IP address and routing to the outside world. And if you open a socket in _userspace_ from processes within such a container, this works fine. But sockets opened from within the kernel still use a single global networking context in a lot of places, meaning the new socket's address and routing are correct for PID 1 on the host, but are _not_ what userspace processes in the container get to use. So when you mount a network filesystem from within in a container, the mount code in the CIFS driver uses the host's networking context and not the container's networking context, so it gets the wrong address, uses the wrong routing, and may even try to go out an interface that the container can't even access... Bad stuff. This patch copies the mount process's network context into the CIFS structure that stores the rest of the server information for that mount point, and changes the socket open code to use the saved network context instead of the global network context. I.E. "when you attempt to use these addresses, do so relative to THIS set of network interfaces and routing rules, not the old global context from back before we supported containers". The big long HOWTO sets up a test environment on the assumption you've never used ocntainers before. It basically says: 1) configure and build a new kernel that has container support 2) build a new root filesystem that includes the userspace container control package (LXC) 3) package/run them under KVM (so you don't have to mess up your host system in order to play with containers). 4) set up some containers under the KVM system 5) set up contradictory routing in the KVM system and the container so that the host and the container see different things for the same address 6) try to mount a CIFS share from both contexts so you can both force it to work and force it to fail. For a long drawn out test reproduction sequence, see: http://landley.livejournal.com/47024.html http://landley.livejournal.com/47205.html http://landley.livejournal.com/47476.html Signed-off-by: Rob Landley <rlandley@parallels.com> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Steve French <sfrench@us.ibm.com>
Diffstat (limited to 'kernel/rtmutex.c')
0 files changed, 0 insertions, 0 deletions
generated by cgit v1.2.2 (git 2.25.0) at 2025-11-10 09:31:52 -0500
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/*
 * Copyright (C) 2013 STMicroelectronics Limited
 * Author: Stephen Gallimore <stephen.gallimore@st.com>
 *
 * Inspired by mach-imx/src.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 */
#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/module.h>
#include <linux/err.h>
#include <linux/types.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
#include <linux/mfd/syscon.h>

#include "reset-syscfg.h"

/**
 * Reset channel regmap configuration
 *
 * @reset: regmap field for the channel's reset bit.
 * @ack: regmap field for the channel's ack bit (optional).
 */
struct syscfg_reset_channel {
	struct regmap_field *reset;
	struct regmap_field *ack;
};

/**
 * A reset controller which groups together a set of related reset bits, which
 * may be located in different system configuration registers.
 *
 * @rst: base reset controller structure.
 * @active_low: are the resets in this controller active low, i.e. clearing
 *              the reset bit puts the hardware into reset.
 * @channels: An array of reset channels for this controller.
 */
struct syscfg_reset_controller {
	struct reset_controller_dev rst;
	bool active_low;
	struct syscfg_reset_channel *channels;
};

#define to_syscfg_reset_controller(_rst) \
	container_of(_rst, struct syscfg_reset_controller, rst)

static int syscfg_reset_program_hw(struct reset_controller_dev *rcdev,
				   unsigned long idx, int assert)
{
	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
	const struct syscfg_reset_channel *ch;
	u32 ctrl_val = rst->active_low ? !assert : !!assert;
	int err;

	if (idx >= rcdev->nr_resets)
		return -EINVAL;

	ch = &rst->channels[idx];

	err = regmap_field_write(ch->reset, ctrl_val);
	if (err)
		return err;

	if (ch->ack) {
		unsigned long timeout = jiffies + msecs_to_jiffies(1000);
		u32 ack_val;

		while (true) {
			err = regmap_field_read(ch->ack, &ack_val);
			if (err)
				return err;

			if (ack_val == ctrl_val)
				break;

			if (time_after(jiffies, timeout))
				return -ETIME;

			cpu_relax();
		}
	}

	return 0;
}

static int syscfg_reset_assert(struct reset_controller_dev *rcdev,
			       unsigned long idx)
{
	return syscfg_reset_program_hw(rcdev, idx, true);
}

static int syscfg_reset_deassert(struct reset_controller_dev *rcdev,
				 unsigned long idx)
{
	return syscfg_reset_program_hw(rcdev, idx, false);
}

static int syscfg_reset_dev(struct reset_controller_dev *rcdev,
			    unsigned long idx)
{
	int err;

	err = syscfg_reset_assert(rcdev, idx);
	if (err)
		return err;

	return syscfg_reset_deassert(rcdev, idx);
}

static int syscfg_reset_status(struct reset_controller_dev *rcdev,
			       unsigned long idx)
{
	struct syscfg_reset_controller *rst = to_syscfg_reset_controller(rcdev);
	const struct syscfg_reset_channel *ch;
	u32 ret_val = 0;
	int err;

	if (idx >= rcdev->nr_resets)
		return -EINVAL;

	ch = &rst->channels[idx];
	if (ch->ack)
		err = regmap_field_read(ch->ack, &ret_val);
	else
		err = regmap_field_read(ch->reset, &ret_val);
	if (err)
		return err;

	return rst->active_low ? !ret_val : !!ret_val;
}

static const struct reset_control_ops syscfg_reset_ops = {
	.reset    = syscfg_reset_dev,
	.assert   = syscfg_reset_assert,
	.deassert = syscfg_reset_deassert,
	.status   = syscfg_reset_status,
};

static int syscfg_reset_controller_register(struct device *dev,
				const struct syscfg_reset_controller_data *data)
{
	struct syscfg_reset_controller *rc;
	size_t size;
	int i, err;

	rc = devm_kzalloc(dev, sizeof(*rc), GFP_KERNEL);
	if (!rc)
		return -ENOMEM;

	size = sizeof(struct syscfg_reset_channel) * data->nr_channels;

	rc->channels = devm_kzalloc(dev, size, GFP_KERNEL);
	if (!rc->channels)
		return -ENOMEM;

	rc->rst.ops = &syscfg_reset_ops,
	rc->rst.of_node = dev->of_node;
	rc->rst.nr_resets = data->nr_channels;
	rc->active_low = data->active_low;

	for (i = 0; i < data->nr_channels; i++) {
		struct regmap *map;
		struct regmap_field *f;
		const char *compatible = data->channels[i].compatible;

		map = syscon_regmap_lookup_by_compatible(compatible);
		if (IS_ERR(map))
			return PTR_ERR(map);

		f = devm_regmap_field_alloc(dev, map, data->channels[i].reset);
		if (IS_ERR(f))
			return PTR_ERR(f);

		rc->channels[i].reset = f;

		if (!data->wait_for_ack)
			continue;

		f = devm_regmap_field_alloc(dev, map, data->channels[i].ack);
		if (IS_ERR(f))
			return PTR_ERR(f);

		rc->channels[i].ack = f;
	}

	err = reset_controller_register(&rc->rst);
	if (!err)
		dev_info(dev, "registered\n");

	return err;
}

int syscfg_reset_probe(struct platform_device *pdev)
{
	struct device *dev = pdev ? &pdev->dev : NULL;
	const struct of_device_id *match;

	if (!dev || !dev->driver)
		return -ENODEV;

	match = of_match_device(dev->driver->of_match_table, dev);
	if (!match || !match->data)
		return -EINVAL;

	return syscfg_reset_controller_register(dev, match->data);
}
generated by cgit v1.2.2 (git 2.25.0) at 2025-11-10 09:31:52 -0500