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: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h
index 37836d598ff897cbf5711dd48c05677d58039f25..e627ff193dbac65bed953b2e997c80ed0279fb2e 100644 (file)
--- a/kernel/cgroup/cgroup-internal.h
+++ b/kernel/cgroup/cgroup-internal.h
@@ -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 */

diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c
index 7ae3810dcbdf8dd2b9ee5a534ccc8a9bfbd9041e..5c93643090e9f812e4b613596fbe9ce2fbef1b62 100644 (file)
--- a/kernel/cgroup/cgroup-v1.c
+++ b/kernel/cgroup/cgroup-v1.c
@@ -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;
+}
+
+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))
+                       enabled |= 1 << i;
+
+       ctx->subsys_mask &= enabled;
 
        /*
-        * 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'
+        * In absense of 'none', 'name=' or subsystem name options,
+        * let's default to 'all'.
         */
-       if (all_ss || (!one_ss && !opts->none && !opts->name))
-               for_each_subsys(ss, i)
-                       if (cgroup_ssid_enabled(i) && !cgroup1_ssid_disabled(i))
-                               opts->subsys_mask |= (1 << i);
+       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 @@ out_unlock:
        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;
 

diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 0652f74064a20ca72708dbd605b72fef1b2b2e34..33da9eef3ef4f1678c4b9577e9aeaa469036f18c 100644 (file)
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -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);