ovl: move all parameter handling into params.{c,h} (7fb7998b) · Commits · EulixOS / Software / Kernel

fs/overlayfs/overlayfs.h

+9 −32

Original line number	Diff line number	Diff line
		@@ -70,14 +70,6 @@ enum {
		OVL_XINO_ON,
		};

		/* The set of options that user requested explicitly via mount options */
		struct ovl_opt_set {
		bool metacopy;
		bool redirect;
		bool nfs_export;
		bool index;
		};

		/*
		* The tuple (fh,uuid) is a universal unique identifier for a copy up origin,
		* where:
		@@ -368,30 +360,6 @@ static inline bool ovl_open_flags_need_copy_up(int flags)
		return ((OPEN_FMODE(flags) & FMODE_WRITE) \|\| (flags & O_TRUNC));
		}


		/* params.c */
		#define OVL_MAX_STACK 500

		struct ovl_fs_context_layer {
		char *name;
		struct path path;
		};

		struct ovl_fs_context {
		struct path upper;
		struct path work;
		size_t capacity;
		size_t nr; /* includes nr_data */
		size_t nr_data;
		struct ovl_opt_set set;
		struct ovl_fs_context_layer *lower;
		};

		int ovl_parse_param_upperdir(const char name, struct fs_context fc,
		bool workdir);
		int ovl_parse_param_lowerdir(const char name, struct fs_context fc);
		void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx);

		/* util.c */
		int ovl_want_write(struct dentry *dentry);
		void ovl_drop_write(struct dentry *dentry);
		@@ -791,3 +759,12 @@ int ovl_set_origin(struct ovl_fs ofs, struct dentry lower,

		/* export.c */
		extern const struct export_operations ovl_export_operations;

		/* super.c */
		int ovl_fill_super(struct super_block sb, struct fs_context fc);

		/* Will this overlay be forced to mount/remount ro? */
		static inline bool ovl_force_readonly(struct ovl_fs *ofs)
		{
		return (!ovl_upper_mnt(ofs) \|\| !ofs->workdir);
		}

fs/overlayfs/params.c

+528 −4

Original line number	Diff line number	Diff line
		// SPDX-License-Identifier: GPL-2.0-only

		#include <linux/fs.h>
		#include <linux/module.h>
		#include <linux/namei.h>
		#include <linux/fs_context.h>
		#include <linux/fs_parser.h>
		#include <linux/posix_acl_xattr.h>
		#include <linux/seq_file.h>
		#include <linux/xattr.h>
		#include "overlayfs.h"
		#include "params.h"

		static bool ovl_redirect_dir_def = IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_DIR);
		module_param_named(redirect_dir, ovl_redirect_dir_def, bool, 0644);
		MODULE_PARM_DESC(redirect_dir,
		"Default to on or off for the redirect_dir feature");

		static bool ovl_redirect_always_follow =
		IS_ENABLED(CONFIG_OVERLAY_FS_REDIRECT_ALWAYS_FOLLOW);
		module_param_named(redirect_always_follow, ovl_redirect_always_follow,
		bool, 0644);
		MODULE_PARM_DESC(redirect_always_follow,
		"Follow redirects even if redirect_dir feature is turned off");

		static bool ovl_xino_auto_def = IS_ENABLED(CONFIG_OVERLAY_FS_XINO_AUTO);
		module_param_named(xino_auto, ovl_xino_auto_def, bool, 0644);
		MODULE_PARM_DESC(xino_auto,
		"Auto enable xino feature");

		static bool ovl_index_def = IS_ENABLED(CONFIG_OVERLAY_FS_INDEX);
		module_param_named(index, ovl_index_def, bool, 0644);
		MODULE_PARM_DESC(index,
		"Default to on or off for the inodes index feature");

		static bool ovl_nfs_export_def = IS_ENABLED(CONFIG_OVERLAY_FS_NFS_EXPORT);
		module_param_named(nfs_export, ovl_nfs_export_def, bool, 0644);
		MODULE_PARM_DESC(nfs_export,
		"Default to on or off for the NFS export feature");

		static bool ovl_metacopy_def = IS_ENABLED(CONFIG_OVERLAY_FS_METACOPY);
		module_param_named(metacopy, ovl_metacopy_def, bool, 0644);
		MODULE_PARM_DESC(metacopy,
		"Default to on or off for the metadata only copy up feature");

		enum {
		Opt_lowerdir,
		Opt_upperdir,
		Opt_workdir,
		Opt_default_permissions,
		Opt_redirect_dir,
		Opt_index,
		Opt_uuid,
		Opt_nfs_export,
		Opt_userxattr,
		Opt_xino,
		Opt_metacopy,
		Opt_volatile,
		};

		static const struct constant_table ovl_parameter_bool[] = {
		{ "on", true },
		{ "off", false },
		{}
		};

		static const struct constant_table ovl_parameter_xino[] = {
		{ "off", OVL_XINO_OFF },
		{ "auto", OVL_XINO_AUTO },
		{ "on", OVL_XINO_ON },
		{}
		};

		const char ovl_xino_mode(struct ovl_config config)
		{
		return ovl_parameter_xino[config->xino].name;
		}

		static int ovl_xino_def(void)
		{
		return ovl_xino_auto_def ? OVL_XINO_AUTO : OVL_XINO_OFF;
		}

		const struct constant_table ovl_parameter_redirect_dir[] = {
		{ "off", OVL_REDIRECT_OFF },
		{ "follow", OVL_REDIRECT_FOLLOW },
		{ "nofollow", OVL_REDIRECT_NOFOLLOW },
		{ "on", OVL_REDIRECT_ON },
		{}
		};

		static const char ovl_redirect_mode(struct ovl_config config)
		{
		return ovl_parameter_redirect_dir[config->redirect_mode].name;
		}

		static int ovl_redirect_mode_def(void)
		{
		return ovl_redirect_dir_def ? OVL_REDIRECT_ON :
		ovl_redirect_always_follow ? OVL_REDIRECT_FOLLOW :
		OVL_REDIRECT_NOFOLLOW;
		}

		#define fsparam_string_empty(NAME, OPT) \
		__fsparam(fs_param_is_string, NAME, OPT, fs_param_can_be_empty, NULL)

		const struct fs_parameter_spec ovl_parameter_spec[] = {
		fsparam_string_empty("lowerdir", Opt_lowerdir),
		fsparam_string("upperdir", Opt_upperdir),
		fsparam_string("workdir", Opt_workdir),
		fsparam_flag("default_permissions", Opt_default_permissions),
		fsparam_enum("redirect_dir", Opt_redirect_dir, ovl_parameter_redirect_dir),
		fsparam_enum("index", Opt_index, ovl_parameter_bool),
		fsparam_enum("uuid", Opt_uuid, ovl_parameter_bool),
		fsparam_enum("nfs_export", Opt_nfs_export, ovl_parameter_bool),
		fsparam_flag("userxattr", Opt_userxattr),
		fsparam_enum("xino", Opt_xino, ovl_parameter_xino),
		fsparam_enum("metacopy", Opt_metacopy, ovl_parameter_bool),
		fsparam_flag("volatile", Opt_volatile),
		{}
		};

		static ssize_t ovl_parse_param_split_lowerdirs(char *str)
		{
		@@ -110,7 +222,7 @@ static int ovl_mount_dir(const char name, struct path path)
		return err;
		}

		int ovl_parse_param_upperdir(const char name, struct fs_context fc,
		static int ovl_parse_param_upperdir(const char name, struct fs_context fc,
		bool workdir)
		{
		int err;
		@@ -154,7 +266,7 @@ int ovl_parse_param_upperdir(const char name, struct fs_context fc,
		return 0;
		}

		void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx)
		static void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx)
		{
		for (size_t nr = 0; nr < ctx->nr; nr++) {
		path_put(&ctx->lower[nr].path);
		@@ -179,7 +291,7 @@ void ovl_parse_param_drop_lowerdir(struct ovl_fs_context *ctx)
		* Append data "/lower5" as data lower layer. This requires that
		* there's at least one regular lower layer present.
		*/
		int ovl_parse_param_lowerdir(const char name, struct fs_context fc)
		static int ovl_parse_param_lowerdir(const char name, struct fs_context fc)
		{
		int err;
		struct ovl_fs_context *ctx = fc->fs_private;
		@@ -387,3 +499,415 @@ int ovl_parse_param_lowerdir(const char name, struct fs_context fc)
		/* Intentionally don't realloc to a smaller size. */
		return err;
		}

		static int ovl_parse_param(struct fs_context fc, struct fs_parameter param)
		{
		int err = 0;
		struct fs_parse_result result;
		struct ovl_fs *ofs = fc->s_fs_info;
		struct ovl_config *config = &ofs->config;
		struct ovl_fs_context *ctx = fc->fs_private;
		int opt;

		if (fc->purpose == FS_CONTEXT_FOR_RECONFIGURE) {
		/*
		* On remount overlayfs has always ignored all mount
		* options no matter if malformed or not so for
		* backwards compatibility we do the same here.
		*/
		if (fc->oldapi)
		return 0;

		/*
		* Give us the freedom to allow changing mount options
		* with the new mount api in the future. So instead of
		* silently ignoring everything we report a proper
		* error. This is only visible for users of the new
		* mount api.
		*/
		return invalfc(fc, "No changes allowed in reconfigure");
		}

		opt = fs_parse(fc, ovl_parameter_spec, param, &result);
		if (opt < 0)
		return opt;

		switch (opt) {
		case Opt_lowerdir:
		err = ovl_parse_param_lowerdir(param->string, fc);
		break;
		case Opt_upperdir:
		fallthrough;
		case Opt_workdir:
		err = ovl_parse_param_upperdir(param->string, fc,
		(Opt_workdir == opt));
		break;
		case Opt_default_permissions:
		config->default_permissions = true;
		break;
		case Opt_redirect_dir:
		config->redirect_mode = result.uint_32;
		if (config->redirect_mode == OVL_REDIRECT_OFF) {
		config->redirect_mode = ovl_redirect_always_follow ?
		OVL_REDIRECT_FOLLOW :
		OVL_REDIRECT_NOFOLLOW;
		}
		ctx->set.redirect = true;
		break;
		case Opt_index:
		config->index = result.uint_32;
		ctx->set.index = true;
		break;
		case Opt_uuid:
		config->uuid = result.uint_32;
		break;
		case Opt_nfs_export:
		config->nfs_export = result.uint_32;
		ctx->set.nfs_export = true;
		break;
		case Opt_xino:
		config->xino = result.uint_32;
		break;
		case Opt_metacopy:
		config->metacopy = result.uint_32;
		ctx->set.metacopy = true;
		break;
		case Opt_volatile:
		config->ovl_volatile = true;
		break;
		case Opt_userxattr:
		config->userxattr = true;
		break;
		default:
		pr_err("unrecognized mount option \"%s\" or missing value\n",
		param->key);
		return -EINVAL;
		}

		return err;
		}

		static int ovl_get_tree(struct fs_context *fc)
		{
		return get_tree_nodev(fc, ovl_fill_super);
		}

		static inline void ovl_fs_context_free(struct ovl_fs_context *ctx)
		{
		ovl_parse_param_drop_lowerdir(ctx);
		path_put(&ctx->upper);
		path_put(&ctx->work);
		kfree(ctx->lower);
		kfree(ctx);
		}

		static void ovl_free(struct fs_context *fc)
		{
		struct ovl_fs *ofs = fc->s_fs_info;
		struct ovl_fs_context *ctx = fc->fs_private;

		/*
		* ofs is stored in the fs_context when it is initialized.
		* ofs is transferred to the superblock on a successful mount,
		* but if an error occurs before the transfer we have to free
		* it here.
		*/
		if (ofs)
		ovl_free_fs(ofs);

		if (ctx)
		ovl_fs_context_free(ctx);
		}

		static int ovl_reconfigure(struct fs_context *fc)
		{
		struct super_block *sb = fc->root->d_sb;
		struct ovl_fs *ofs = sb->s_fs_info;
		struct super_block *upper_sb;
		int ret = 0;

		if (!(fc->sb_flags & SB_RDONLY) && ovl_force_readonly(ofs))
		return -EROFS;

		if (fc->sb_flags & SB_RDONLY && !sb_rdonly(sb)) {
		upper_sb = ovl_upper_mnt(ofs)->mnt_sb;
		if (ovl_should_sync(ofs)) {
		down_read(&upper_sb->s_umount);
		ret = sync_filesystem(upper_sb);
		up_read(&upper_sb->s_umount);
		}
		}

		return ret;
		}

		static const struct fs_context_operations ovl_context_ops = {
		.parse_param = ovl_parse_param,
		.get_tree = ovl_get_tree,
		.reconfigure = ovl_reconfigure,
		.free = ovl_free,
		};

		/*
		* This is called during fsopen() and will record the user namespace of
		* the caller in fc->user_ns since we've raised FS_USERNS_MOUNT. We'll
		* need it when we actually create the superblock to verify that the
		* process creating the superblock is in the same user namespace as
		* process that called fsopen().
		*/
		int ovl_init_fs_context(struct fs_context *fc)
		{
		struct ovl_fs_context *ctx;
		struct ovl_fs *ofs;

		ctx = kzalloc(sizeof(*ctx), GFP_KERNEL_ACCOUNT);
		if (!ctx)
		return -ENOMEM;

		/*
		* By default we allocate for three lower layers. It's likely
		* that it'll cover most users.
		*/
		ctx->lower = kmalloc_array(3, sizeof(*ctx->lower), GFP_KERNEL_ACCOUNT);
		if (!ctx->lower)
		goto out_err;
		ctx->capacity = 3;

		ofs = kzalloc(sizeof(struct ovl_fs), GFP_KERNEL);
		if (!ofs)
		goto out_err;

		ofs->config.redirect_mode = ovl_redirect_mode_def();
		ofs->config.index = ovl_index_def;
		ofs->config.uuid = true;
		ofs->config.nfs_export = ovl_nfs_export_def;
		ofs->config.xino = ovl_xino_def();
		ofs->config.metacopy = ovl_metacopy_def;

		fc->s_fs_info = ofs;
		fc->fs_private = ctx;
		fc->ops = &ovl_context_ops;
		return 0;

		out_err:
		ovl_fs_context_free(ctx);
		return -ENOMEM;

		}

		void ovl_free_fs(struct ovl_fs *ofs)
		{
		struct vfsmount **mounts;
		unsigned i;

		iput(ofs->workbasedir_trap);
		iput(ofs->indexdir_trap);
		iput(ofs->workdir_trap);
		dput(ofs->whiteout);
		dput(ofs->indexdir);
		dput(ofs->workdir);
		if (ofs->workdir_locked)
		ovl_inuse_unlock(ofs->workbasedir);
		dput(ofs->workbasedir);
		if (ofs->upperdir_locked)
		ovl_inuse_unlock(ovl_upper_mnt(ofs)->mnt_root);

		/* Hack! Reuse ofs->layers as a vfsmount array before freeing it */
		mounts = (struct vfsmount **) ofs->layers;
		for (i = 0; i < ofs->numlayer; i++) {
		iput(ofs->layers[i].trap);
		mounts[i] = ofs->layers[i].mnt;
		kfree(ofs->layers[i].name);
		}
		kern_unmount_array(mounts, ofs->numlayer);
		kfree(ofs->layers);
		for (i = 0; i < ofs->numfs; i++)
		free_anon_bdev(ofs->fs[i].pseudo_dev);
		kfree(ofs->fs);

		kfree(ofs->config.upperdir);
		kfree(ofs->config.workdir);
		if (ofs->creator_cred)
		put_cred(ofs->creator_cred);
		kfree(ofs);
		}

		int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
		struct ovl_config *config)
		{
		struct ovl_opt_set set = ctx->set;

		if (ctx->nr_data > 0 && !config->metacopy) {
		pr_err("lower data-only dirs require metacopy support.\n");
		return -EINVAL;
		}

		/* Workdir/index are useless in non-upper mount */
		if (!config->upperdir) {
		if (config->workdir) {
		pr_info("option \"workdir=%s\" is useless in a non-upper mount, ignore\n",
		config->workdir);
		kfree(config->workdir);
		config->workdir = NULL;
		}
		if (config->index && set.index) {
		pr_info("option \"index=on\" is useless in a non-upper mount, ignore\n");
		set.index = false;
		}
		config->index = false;
		}

		if (!config->upperdir && config->ovl_volatile) {
		pr_info("option \"volatile\" is meaningless in a non-upper mount, ignoring it.\n");
		config->ovl_volatile = false;
		}

		/*
		* This is to make the logic below simpler. It doesn't make any other
		* difference, since redirect_dir=on is only used for upper.
		*/
		if (!config->upperdir && config->redirect_mode == OVL_REDIRECT_FOLLOW)
		config->redirect_mode = OVL_REDIRECT_ON;

		/* Resolve metacopy -> redirect_dir dependency */
		if (config->metacopy && config->redirect_mode != OVL_REDIRECT_ON) {
		if (set.metacopy && set.redirect) {
		pr_err("conflicting options: metacopy=on,redirect_dir=%s\n",
		ovl_redirect_mode(config));
		return -EINVAL;
		}
		if (set.redirect) {
		/*
		* There was an explicit redirect_dir=... that resulted
		* in this conflict.
		*/
		pr_info("disabling metacopy due to redirect_dir=%s\n",
		ovl_redirect_mode(config));
		config->metacopy = false;
		} else {
		/* Automatically enable redirect otherwise. */
		config->redirect_mode = OVL_REDIRECT_ON;
		}
		}

		/* Resolve nfs_export -> index dependency */
		if (config->nfs_export && !config->index) {
		if (!config->upperdir &&
		config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
		pr_info("NFS export requires \"redirect_dir=nofollow\" on non-upper mount, falling back to nfs_export=off.\n");
		config->nfs_export = false;
		} else if (set.nfs_export && set.index) {
		pr_err("conflicting options: nfs_export=on,index=off\n");
		return -EINVAL;
		} else if (set.index) {
		/*
		* There was an explicit index=off that resulted
		* in this conflict.
		*/
		pr_info("disabling nfs_export due to index=off\n");
		config->nfs_export = false;
		} else {
		/* Automatically enable index otherwise. */
		config->index = true;
		}
		}

		/* Resolve nfs_export -> !metacopy dependency */
		if (config->nfs_export && config->metacopy) {
		if (set.nfs_export && set.metacopy) {
		pr_err("conflicting options: nfs_export=on,metacopy=on\n");
		return -EINVAL;
		}
		if (set.metacopy) {
		/*
		* There was an explicit metacopy=on that resulted
		* in this conflict.
		*/
		pr_info("disabling nfs_export due to metacopy=on\n");
		config->nfs_export = false;
		} else {
		/*
		* There was an explicit nfs_export=on that resulted
		* in this conflict.
		*/
		pr_info("disabling metacopy due to nfs_export=on\n");
		config->metacopy = false;
		}
		}


		/* Resolve userxattr -> !redirect && !metacopy dependency */
		if (config->userxattr) {
		if (set.redirect &&
		config->redirect_mode != OVL_REDIRECT_NOFOLLOW) {
		pr_err("conflicting options: userxattr,redirect_dir=%s\n",
		ovl_redirect_mode(config));
		return -EINVAL;
		}
		if (config->metacopy && set.metacopy) {
		pr_err("conflicting options: userxattr,metacopy=on\n");
		return -EINVAL;
		}
		/*
		* Silently disable default setting of redirect and metacopy.
		* This shall be the default in the future as well: these
		* options must be explicitly enabled if used together with
		* userxattr.
		*/
		config->redirect_mode = OVL_REDIRECT_NOFOLLOW;
		config->metacopy = false;
		}

		return 0;
		}

		/**
		* ovl_show_options
		* @m: the seq_file handle
		* @dentry: The dentry to query
		*
		* Prints the mount options for a given superblock.
		* Returns zero; does not fail.
		*/
		int ovl_show_options(struct seq_file m, struct dentry dentry)
		{
		struct super_block *sb = dentry->d_sb;
		struct ovl_fs *ofs = sb->s_fs_info;
		size_t nr, nr_merged_lower = ofs->numlayer - ofs->numdatalayer;
		const struct ovl_layer *data_layers = &ofs->layers[nr_merged_lower];

		/* ofs->layers[0] is the upper layer */
		seq_printf(m, ",lowerdir=%s", ofs->layers[1].name);
		/* dump regular lower layers */
		for (nr = 2; nr < nr_merged_lower; nr++)
		seq_printf(m, ":%s", ofs->layers[nr].name);
		/* dump data lower layers */
		for (nr = 0; nr < ofs->numdatalayer; nr++)
		seq_printf(m, "::%s", data_layers[nr].name);
		if (ofs->config.upperdir) {
		seq_show_option(m, "upperdir", ofs->config.upperdir);
		seq_show_option(m, "workdir", ofs->config.workdir);
		}
		if (ofs->config.default_permissions)
		seq_puts(m, ",default_permissions");
		if (ofs->config.redirect_mode != ovl_redirect_mode_def())
		seq_printf(m, ",redirect_dir=%s",
		ovl_redirect_mode(&ofs->config));
		if (ofs->config.index != ovl_index_def)
		seq_printf(m, ",index=%s", ofs->config.index ? "on" : "off");
		if (!ofs->config.uuid)
		seq_puts(m, ",uuid=off");
		if (ofs->config.nfs_export != ovl_nfs_export_def)
		seq_printf(m, ",nfs_export=%s", ofs->config.nfs_export ?
		"on" : "off");
		if (ofs->config.xino != ovl_xino_def() && !ovl_same_fs(ofs))
		seq_printf(m, ",xino=%s", ovl_xino_mode(&ofs->config));
		if (ofs->config.metacopy != ovl_metacopy_def)
		seq_printf(m, ",metacopy=%s",
		ofs->config.metacopy ? "on" : "off");
		if (ofs->config.ovl_volatile)
		seq_puts(m, ",volatile");
		if (ofs->config.userxattr)
		seq_puts(m, ",userxattr");
		return 0;
		}

fs/overlayfs/params.h

0 → 100644

+42 −0

Original line number	Diff line number	Diff line
		/* SPDX-License-Identifier: GPL-2.0-only */

		#include <linux/fs_context.h>
		#include <linux/fs_parser.h>

		struct ovl_fs;
		struct ovl_config;

		extern const struct fs_parameter_spec ovl_parameter_spec[];
		extern const struct constant_table ovl_parameter_redirect_dir[];

		/* The set of options that user requested explicitly via mount options */
		struct ovl_opt_set {
		bool metacopy;
		bool redirect;
		bool nfs_export;
		bool index;
		};

		#define OVL_MAX_STACK 500

		struct ovl_fs_context_layer {
		char *name;
		struct path path;
		};

		struct ovl_fs_context {
		struct path upper;
		struct path work;
		size_t capacity;
		size_t nr; /* includes nr_data */
		size_t nr_data;
		struct ovl_opt_set set;
		struct ovl_fs_context_layer *lower;
		};

		int ovl_init_fs_context(struct fs_context *fc);
		void ovl_free_fs(struct ovl_fs *ofs);
		int ovl_fs_params_verify(const struct ovl_fs_context *ctx,
		struct ovl_config *config);
		int ovl_show_options(struct seq_file m, struct dentry dentry);
		const char ovl_xino_mode(struct ovl_config config);

fs/overlayfs/super.c

+2 −528

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