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Commit f5dfb531 authored by Al Viro's avatar Al Viro
Browse files

cgroup: take options parsing into ->parse_monolithic() 



Store the results in cgroup_fs_context.  There's a nasty twist caused
by the enabling/disabling subsystems - we can't do the checks sensitive
to that until cgroup_mutex gets grabbed.  Frankly, these checks are
complete bullshit (e.g. all,none combination is accepted if all subsystems
are disabled; so's cpusets,none and all,cpusets when cpusets is disabled,
etc.), but touching that would be a userland-visible behaviour change ;-/

So we do parsing in ->parse_monolithic() and have the consistency checks
done in check_cgroupfs_options(), with the latter called (on already parsed
options) from cgroup1_get_tree() and cgroup1_reconfigure().

Freeing the strdup'ed strings is done from fs_context destructor, which
somewhat simplifies the life for cgroup1_{get_tree,reconfigure}().

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 7feeef58

kernel/cgroup/cgroup-internal.h

+11 −12
Original line number Diff line number Diff line
@@ -41,7 +41,15 @@ extern void __init enable_debug_cgroup(void); 
 * The cgroup filesystem superblock creation/mount context.

 */

struct cgroup_fs_context {

	char *data;

	unsigned int	flags;			/* CGRP_ROOT_* flags */



	/* cgroup1 bits */

	bool		cpuset_clone_children;

	bool		none;			/* User explicitly requested empty subsystem */

	bool		all_ss;			/* Seen 'all' option */

	u16		subsys_mask;		/* Selected subsystems */

	char		*name;			/* Hierarchy name */

	char		*release_agent;		/* Path for release notifications */

};



static inline struct cgroup_fs_context *cgroup_fc2context(struct fs_context *fc)
@@ -130,16 +138,6 @@ struct cgroup_mgctx { 
#define DEFINE_CGROUP_MGCTX(name)						\

	struct cgroup_mgctx name = CGROUP_MGCTX_INIT(name)



struct cgroup_sb_opts {

	u16 subsys_mask;

	unsigned int flags;

	char *release_agent;

	bool cpuset_clone_children;

	char *name;

	/* User explicitly requested empty subsystem */

	bool none;

};



extern struct mutex cgroup_mutex;

extern spinlock_t css_set_lock;

extern struct cgroup_subsys *cgroup_subsys[];
@@ -210,7 +208,7 @@ int cgroup_path_ns_locked(struct cgroup *cgrp, char *buf, size_t buflen, 
			  struct cgroup_namespace *ns);



void cgroup_free_root(struct cgroup_root *root);

void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts);

void init_cgroup_root(struct cgroup_root *root, struct cgroup_fs_context *ctx);

int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask);

int rebind_subsystems(struct cgroup_root *dst_root, u16 ss_mask);

struct dentry *cgroup_do_mount(struct file_system_type *fs_type, int flags,
@@ -266,6 +264,7 @@ void cgroup1_pidlist_destroy_all(struct cgroup *cgrp); 
void cgroup1_release_agent(struct work_struct *work);

void cgroup1_check_for_release(struct cgroup *cgrp);

int cgroup1_get_tree(struct fs_context *fc);

int parse_cgroup1_options(char *data, struct cgroup_fs_context *ctx);

int cgroup1_reconfigure(struct fs_context *ctx);



#endif /* __CGROUP_INTERNAL_H */

kernel/cgroup/cgroup-v1.c

+67 −76
Original line number Diff line number Diff line
@@ -906,61 +906,47 @@ static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_roo 
	return 0;

}



static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts)

int parse_cgroup1_options(char *data, struct cgroup_fs_context *ctx)

{

	char *token, *o = data;

	bool all_ss = false, one_ss = false;

	u16 mask = U16_MAX;

	struct cgroup_subsys *ss;

	int nr_opts = 0;

	int i;



#ifdef CONFIG_CPUSETS

	mask = ~((u16)1 << cpuset_cgrp_id);

#endif



	memset(opts, 0, sizeof(*opts));



	while ((token = strsep(&o, ",")) != NULL) {

		nr_opts++;



		if (!*token)

			return -EINVAL;

		if (!strcmp(token, "none")) {

			/* Explicitly have no subsystems */

			opts->none = true;

			ctx->none = true;

			continue;

		}

		if (!strcmp(token, "all")) {

			/* Mutually exclusive option 'all' + subsystem name */

			if (one_ss)

				return -EINVAL;

			all_ss = true;

			ctx->all_ss = true;

			continue;

		}

		if (!strcmp(token, "noprefix")) {

			opts->flags |= CGRP_ROOT_NOPREFIX;

			ctx->flags |= CGRP_ROOT_NOPREFIX;

			continue;

		}

		if (!strcmp(token, "clone_children")) {

			opts->cpuset_clone_children = true;

			ctx->cpuset_clone_children = true;

			continue;

		}

		if (!strcmp(token, "cpuset_v2_mode")) {

			opts->flags |= CGRP_ROOT_CPUSET_V2_MODE;

			ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;

			continue;

		}

		if (!strcmp(token, "xattr")) {

			opts->flags |= CGRP_ROOT_XATTR;

			ctx->flags |= CGRP_ROOT_XATTR;

			continue;

		}

		if (!strncmp(token, "release_agent=", 14)) {

			/* Specifying two release agents is forbidden */

			if (opts->release_agent)

			if (ctx->release_agent)

				return -EINVAL;

			opts->release_agent =

			ctx->release_agent =

				kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);

			if (!opts->release_agent)

			if (!ctx->release_agent)

				return -ENOMEM;

			continue;

		}
@@ -983,12 +969,12 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
				return -EINVAL;

			}

			/* Specifying two names is forbidden */

			if (opts->name)

			if (ctx->name)

				return -EINVAL;

			opts->name = kstrndup(name,

			ctx->name = kstrndup(name,

					      MAX_CGROUP_ROOT_NAMELEN - 1,

					      GFP_KERNEL);

			if (!opts->name)

			if (!ctx->name)

				return -ENOMEM;



			continue;
@@ -997,38 +983,51 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
		for_each_subsys(ss, i) {

			if (strcmp(token, ss->legacy_name))

				continue;

			if (!cgroup_ssid_enabled(i))

				continue;

			if (cgroup1_ssid_disabled(i))

				continue;



			/* Mutually exclusive option 'all' + subsystem name */

			if (all_ss)

				return -EINVAL;

			opts->subsys_mask |= (1 << i);

			one_ss = true;



			ctx->subsys_mask |= (1 << i);

			break;

		}

		if (i == CGROUP_SUBSYS_COUNT)

			return -ENOENT;

	}

	return 0;

}



	/*

	 * If the 'all' option was specified select all the subsystems,

	 * otherwise if 'none', 'name=' and a subsystem name options were

	 * not specified, let's default to 'all'

	 */

	if (all_ss || (!one_ss && !opts->none && !opts->name))

static int check_cgroupfs_options(struct cgroup_fs_context *ctx)

{

	u16 mask = U16_MAX;

	u16 enabled = 0;

	struct cgroup_subsys *ss;

	int i;



#ifdef CONFIG_CPUSETS

	mask = ~((u16)1 << cpuset_cgrp_id);

#endif

	for_each_subsys(ss, i)

		if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))

				opts->subsys_mask |= (1 << i);

			enabled |= 1 << i;



	ctx->subsys_mask &= enabled;



	/*

	 * In absense of 'none', 'name=' or subsystem name options,

	 * let's default to 'all'.

	 */

	if (!ctx->subsys_mask && !ctx->none && !ctx->name)

		ctx->all_ss = true;



	if (ctx->all_ss) {

		/* Mutually exclusive option 'all' + subsystem name */

		if (ctx->subsys_mask)

			return -EINVAL;

		/* 'all' => select all the subsystems */

		ctx->subsys_mask = enabled;

	}



	/*

	 * We either have to specify by name or by subsystems. (So all

	 * empty hierarchies must have a name).

	 */

	if (!opts->subsys_mask && !opts->name)

	if (!ctx->subsys_mask && !ctx->name)

		return -EINVAL;



	/*
@@ -1036,11 +1035,11 @@ static int parse_cgroupfs_options(char *data, struct cgroup_sb_opts *opts) 
	 * with the old cpuset, so we allow noprefix only if mounting just

	 * the cpuset subsystem.

	 */

	if ((opts->flags & CGRP_ROOT_NOPREFIX) && (opts->subsys_mask & mask))

	if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))

		return -EINVAL;



	/* Can't specify "none" and some subsystems */

	if (opts->subsys_mask && opts->none)

	if (ctx->subsys_mask && ctx->none)

		return -EINVAL;



	return 0;
@@ -1052,28 +1051,27 @@ int cgroup1_reconfigure(struct fs_context *fc) 
	struct kernfs_root *kf_root = kernfs_root_from_sb(fc->root->d_sb);

	struct cgroup_root *root = cgroup_root_from_kf(kf_root);

	int ret = 0;

	struct cgroup_sb_opts opts;

	u16 added_mask, removed_mask;



	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);



	/* See what subsystems are wanted */

	ret = parse_cgroupfs_options(ctx->data, &opts);

	ret = check_cgroupfs_options(ctx);

	if (ret)

		goto out_unlock;



	if (opts.subsys_mask != root->subsys_mask || opts.release_agent)

	if (ctx->subsys_mask != root->subsys_mask || ctx->release_agent)

		pr_warn("option changes via remount are deprecated (pid=%d comm=%s)\n",

			task_tgid_nr(current), current->comm);



	added_mask = opts.subsys_mask & ~root->subsys_mask;

	removed_mask = root->subsys_mask & ~opts.subsys_mask;

	added_mask = ctx->subsys_mask & ~root->subsys_mask;

	removed_mask = root->subsys_mask & ~ctx->subsys_mask;



	/* Don't allow flags or name to change at remount */

	if ((opts.flags ^ root->flags) ||

	    (opts.name && strcmp(opts.name, root->name))) {

	if ((ctx->flags ^ root->flags) ||

	    (ctx->name && strcmp(ctx->name, root->name))) {

		pr_err("option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"\n",

		       opts.flags, opts.name ?: "", root->flags, root->name);

		       ctx->flags, ctx->name ?: "", root->flags, root->name);

		ret = -EINVAL;

		goto out_unlock;

	}
@@ -1090,17 +1088,15 @@ int cgroup1_reconfigure(struct fs_context *fc) 


	WARN_ON(rebind_subsystems(&cgrp_dfl_root, removed_mask));



	if (opts.release_agent) {

	if (ctx->release_agent) {

		spin_lock(&release_agent_path_lock);

		strcpy(root->release_agent_path, opts.release_agent);

		strcpy(root->release_agent_path, ctx->release_agent);

		spin_unlock(&release_agent_path_lock);

	}



	trace_cgroup_remount(root);



 out_unlock:

	kfree(opts.release_agent);

	kfree(opts.name);

	mutex_unlock(&cgroup_mutex);

	return ret;

}
@@ -1117,7 +1113,6 @@ int cgroup1_get_tree(struct fs_context *fc) 
{

	struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);

	struct cgroup_sb_opts opts;

	struct cgroup_root *root;

	struct cgroup_subsys *ss;

	struct dentry *dentry;
@@ -1130,7 +1125,7 @@ int cgroup1_get_tree(struct fs_context *fc) 
	cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);



	/* First find the desired set of subsystems */

	ret = parse_cgroupfs_options(ctx->data, &opts);

	ret = check_cgroupfs_options(ctx);

	if (ret)

		goto out_unlock;
@@ -1142,7 +1137,7 @@ int cgroup1_get_tree(struct fs_context *fc) 
	 * starting.  Testing ref liveliness is good enough.

	 */

	for_each_subsys(ss, i) {

		if (!(opts.subsys_mask & (1 << i)) ||

		if (!(ctx->subsys_mask & (1 << i)) ||

		    ss->root == &cgrp_dfl_root)

			continue;
@@ -1166,8 +1161,8 @@ int cgroup1_get_tree(struct fs_context *fc) 
		 * name matches but sybsys_mask doesn't, we should fail.

		 * Remember whether name matched.

		 */

		if (opts.name) {

			if (strcmp(opts.name, root->name))

		if (ctx->name) {

			if (strcmp(ctx->name, root->name))

				continue;

			name_match = true;

		}
@@ -1176,15 +1171,15 @@ int cgroup1_get_tree(struct fs_context *fc) 
		 * If we asked for subsystems (or explicitly for no

		 * subsystems) then they must match.

		 */

		if ((opts.subsys_mask || opts.none) &&

		    (opts.subsys_mask != root->subsys_mask)) {

		if ((ctx->subsys_mask || ctx->none) &&

		    (ctx->subsys_mask != root->subsys_mask)) {

			if (!name_match)

				continue;

			ret = -EBUSY;

			goto out_unlock;

		}



		if (root->flags ^ opts.flags)

		if (root->flags ^ ctx->flags)

			pr_warn("new mount options do not match the existing superblock, will be ignored\n");



		ret = 0;
@@ -1196,7 +1191,7 @@ int cgroup1_get_tree(struct fs_context *fc) 
	 * specification is allowed for already existing hierarchies but we

	 * can't create new one without subsys specification.

	 */

	if (!opts.subsys_mask && !opts.none) {

	if (!ctx->subsys_mask && !ctx->none) {

		ret = -EINVAL;

		goto out_unlock;

	}
@@ -1213,9 +1208,9 @@ int cgroup1_get_tree(struct fs_context *fc) 
		goto out_unlock;

	}



	init_cgroup_root(root, &opts);

	init_cgroup_root(root, ctx);



	ret = cgroup_setup_root(root, opts.subsys_mask);

	ret = cgroup_setup_root(root, ctx->subsys_mask);

	if (ret)

		cgroup_free_root(root);
@@ -1223,14 +1218,10 @@ int cgroup1_get_tree(struct fs_context *fc) 
	if (!ret && !percpu_ref_tryget_live(&root->cgrp.self.refcnt)) {

		mutex_unlock(&cgroup_mutex);

		msleep(10);

		ret = restart_syscall();

		goto out_free;

		return restart_syscall();

	}

	mutex_unlock(&cgroup_mutex);

out_free:

	kfree(opts.release_agent);

	kfree(opts.name);



	if (ret)

		return ret;

kernel/cgroup/cgroup.c

+26 −28
Original line number Diff line number Diff line
@@ -1814,14 +1814,8 @@ static int cgroup_show_options(struct seq_file *seq, struct kernfs_root *kf_root 
static int cgroup_reconfigure(struct fs_context *fc)

{

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);

	unsigned int root_flags;

	int ret;



	ret = parse_cgroup_root_flags(ctx->data, &root_flags);

	if (ret)

		return ret;



	apply_cgroup_root_flags(root_flags);

	apply_cgroup_root_flags(ctx->flags);

	return 0;

}
@@ -1909,7 +1903,7 @@ static void init_cgroup_housekeeping(struct cgroup *cgrp) 
	INIT_WORK(&cgrp->release_agent_work, cgroup1_release_agent);

}



void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts)

void init_cgroup_root(struct cgroup_root *root, struct cgroup_fs_context *ctx)

{

	struct cgroup *cgrp = &root->cgrp;
@@ -1919,12 +1913,12 @@ void init_cgroup_root(struct cgroup_root *root, struct cgroup_sb_opts *opts) 
	init_cgroup_housekeeping(cgrp);

	idr_init(&root->cgroup_idr);



	root->flags = opts->flags;

	if (opts->release_agent)

		strscpy(root->release_agent_path, opts->release_agent, PATH_MAX);

	if (opts->name)

		strscpy(root->name, opts->name, MAX_CGROUP_ROOT_NAMELEN);

	if (opts->cpuset_clone_children)

	root->flags = ctx->flags;

	if (ctx->release_agent)

		strscpy(root->release_agent_path, ctx->release_agent, PATH_MAX);

	if (ctx->name)

		strscpy(root->name, ctx->name, MAX_CGROUP_ROOT_NAMELEN);

	if (ctx->cpuset_clone_children)

		set_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags);

}
@@ -2075,6 +2069,8 @@ static void cgroup_fs_context_free(struct fs_context *fc) 
{

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);



	kfree(ctx->name);

	kfree(ctx->release_agent);

	kfree(ctx);

}
@@ -2082,28 +2078,30 @@ static int cgroup_parse_monolithic(struct fs_context *fc, void *data) 
{

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);



	ctx->data = data;

	if (ctx->data)

		security_sb_eat_lsm_opts(ctx->data, &fc->security);

	return 0;

	if (data)

		security_sb_eat_lsm_opts(data, &fc->security);

	return parse_cgroup_root_flags(data, &ctx->flags);

}



static int cgroup1_parse_monolithic(struct fs_context *fc, void *data)

{

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);



	if (data)

		security_sb_eat_lsm_opts(data, &fc->security);

	return parse_cgroup1_options(data, ctx);

}



static int cgroup_get_tree(struct fs_context *fc)

{

	struct cgroup_namespace *ns = current->nsproxy->cgroup_ns;

	struct cgroup_fs_context *ctx = cgroup_fc2context(fc);

	unsigned int root_flags;

	struct dentry *root;

	int ret;



	/* Check if the caller has permission to mount. */

	if (!ns_capable(ns->user_ns, CAP_SYS_ADMIN))

		return -EPERM;



	ret = parse_cgroup_root_flags(ctx->data, &root_flags);

	if (ret)

		return ret;



	cgrp_dfl_visible = true;

	cgroup_get_live(&cgrp_dfl_root.cgrp);
@@ -2112,7 +2110,7 @@ static int cgroup_get_tree(struct fs_context *fc) 
	if (IS_ERR(root))

		return PTR_ERR(root);



	apply_cgroup_root_flags(root_flags);

	apply_cgroup_root_flags(ctx->flags);

	fc->root = root;

	return 0;

}
@@ -2126,7 +2124,7 @@ static const struct fs_context_operations cgroup_fs_context_ops = { 


static const struct fs_context_operations cgroup1_fs_context_ops = {

	.free		= cgroup_fs_context_free,

	.parse_monolithic = cgroup_parse_monolithic,

	.parse_monolithic = cgroup1_parse_monolithic,

	.get_tree	= cgroup1_get_tree,

	.reconfigure	= cgroup1_reconfigure,

};
@@ -5376,11 +5374,11 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) 
 */

int __init cgroup_init_early(void)

{

	static struct cgroup_sb_opts __initdata opts;

	static struct cgroup_fs_context __initdata ctx;

	struct cgroup_subsys *ss;

	int i;



	init_cgroup_root(&cgrp_dfl_root, &opts);

	init_cgroup_root(&cgrp_dfl_root, &ctx);

	cgrp_dfl_root.cgrp.self.flags |= CSS_NO_REF;



	RCU_INIT_POINTER(init_task.cgroups, &init_css_set);