cgroup1: switch to option-by-option parsing
authorAl Viro <viro@zeniv.linux.org.uk>
Thu, 17 Jan 2019 05:15:11 +0000 (00:15 -0500)
committerAl Viro <viro@zeniv.linux.org.uk>
Thu, 28 Feb 2019 08:29:31 +0000 (03:29 -0500)
[dhowells should be the author - it's carved out of his patch]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
kernel/cgroup/cgroup-internal.h
kernel/cgroup/cgroup-v1.c
kernel/cgroup/cgroup.c

index e627ff1..a7b5a41 100644 (file)
@@ -257,14 +257,15 @@ extern const struct proc_ns_operations cgroupns_operations;
  */
 extern struct cftype cgroup1_base_files[];
 extern struct kernfs_syscall_ops cgroup1_kf_syscall_ops;
+extern const struct fs_parameter_description cgroup1_fs_parameters;
 
 int proc_cgroupstats_show(struct seq_file *m, void *v);
 bool cgroup1_ssid_disabled(int ssid);
 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_parse_param(struct fs_context *fc, struct fs_parameter *param);
 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 */
index 5c93643..725e9f6 100644 (file)
 #include <linux/delayacct.h>
 #include <linux/pid_namespace.h>
 #include <linux/cgroupstats.h>
+#include <linux/fs_parser.h>
 
 #include <trace/events/cgroup.h>
 
+#define cg_invalf(fc, fmt, ...) ({ pr_err(fmt, ## __VA_ARGS__); -EINVAL; })
+
 /*
  * pidlists linger the following amount before being destroyed.  The goal
  * is avoiding frequent destruction in the middle of consecutive read calls
@@ -906,94 +909,117 @@ static int cgroup1_show_options(struct seq_file *seq, struct kernfs_root *kf_roo
        return 0;
 }
 
-int parse_cgroup1_options(char *data, struct cgroup_fs_context *ctx)
-{
-       char *token, *o = data;
-       struct cgroup_subsys *ss;
-       int i;
+enum cgroup1_param {
+       Opt_all,
+       Opt_clone_children,
+       Opt_cpuset_v2_mode,
+       Opt_name,
+       Opt_none,
+       Opt_noprefix,
+       Opt_release_agent,
+       Opt_xattr,
+};
 
-       while ((token = strsep(&o, ",")) != NULL) {
-               if (!*token)
-                       return -EINVAL;
-               if (!strcmp(token, "none")) {
-                       /* Explicitly have no subsystems */
-                       ctx->none = true;
-                       continue;
-               }
-               if (!strcmp(token, "all")) {
-                       ctx->all_ss = true;
-                       continue;
-               }
-               if (!strcmp(token, "noprefix")) {
-                       ctx->flags |= CGRP_ROOT_NOPREFIX;
-                       continue;
-               }
-               if (!strcmp(token, "clone_children")) {
-                       ctx->cpuset_clone_children = true;
-                       continue;
-               }
-               if (!strcmp(token, "cpuset_v2_mode")) {
-                       ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
-                       continue;
-               }
-               if (!strcmp(token, "xattr")) {
-                       ctx->flags |= CGRP_ROOT_XATTR;
-                       continue;
-               }
-               if (!strncmp(token, "release_agent=", 14)) {
-                       /* Specifying two release agents is forbidden */
-                       if (ctx->release_agent)
-                               return -EINVAL;
-                       ctx->release_agent =
-                               kstrndup(token + 14, PATH_MAX - 1, GFP_KERNEL);
-                       if (!ctx->release_agent)
-                               return -ENOMEM;
-                       continue;
-               }
-               if (!strncmp(token, "name=", 5)) {
-                       const char *name = token + 5;
-
-                       /* blocked by boot param? */
-                       if (cgroup_no_v1_named)
-                               return -ENOENT;
-                       /* Can't specify an empty name */
-                       if (!strlen(name))
-                               return -EINVAL;
-                       /* Must match [\w.-]+ */
-                       for (i = 0; i < strlen(name); i++) {
-                               char c = name[i];
-                               if (isalnum(c))
-                                       continue;
-                               if ((c == '.') || (c == '-') || (c == '_'))
-                                       continue;
-                               return -EINVAL;
-                       }
-                       /* Specifying two names is forbidden */
-                       if (ctx->name)
-                               return -EINVAL;
-                       ctx->name = kstrndup(name,
-                                             MAX_CGROUP_ROOT_NAMELEN - 1,
-                                             GFP_KERNEL);
-                       if (!ctx->name)
-                               return -ENOMEM;
+static const struct fs_parameter_spec cgroup1_param_specs[] = {
+       fsparam_flag  ("all",           Opt_all),
+       fsparam_flag  ("clone_children", Opt_clone_children),
+       fsparam_flag  ("cpuset_v2_mode", Opt_cpuset_v2_mode),
+       fsparam_string("name",          Opt_name),
+       fsparam_flag  ("none",          Opt_none),
+       fsparam_flag  ("noprefix",      Opt_noprefix),
+       fsparam_string("release_agent", Opt_release_agent),
+       fsparam_flag  ("xattr",         Opt_xattr),
+       {}
+};
 
-                       continue;
-               }
+const struct fs_parameter_description cgroup1_fs_parameters = {
+       .name           = "cgroup1",
+       .specs          = cgroup1_param_specs,
+};
 
+int cgroup1_parse_param(struct fs_context *fc, struct fs_parameter *param)
+{
+       struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
+       struct cgroup_subsys *ss;
+       struct fs_parse_result result;
+       int opt, i;
+
+       opt = fs_parse(fc, &cgroup1_fs_parameters, param, &result);
+       if (opt == -ENOPARAM) {
+               if (strcmp(param->key, "source") == 0) {
+                       fc->source = param->string;
+                       param->string = NULL;
+                       return 0;
+               }
                for_each_subsys(ss, i) {
-                       if (strcmp(token, ss->legacy_name))
+                       if (strcmp(param->key, ss->legacy_name))
                                continue;
                        ctx->subsys_mask |= (1 << i);
-                       break;
+                       return 0;
                }
-               if (i == CGROUP_SUBSYS_COUNT)
+               return cg_invalf(fc, "cgroup1: Unknown subsys name '%s'", param->key);
+       }
+       if (opt < 0)
+               return opt;
+
+       switch (opt) {
+       case Opt_none:
+               /* Explicitly have no subsystems */
+               ctx->none = true;
+               break;
+       case Opt_all:
+               ctx->all_ss = true;
+               break;
+       case Opt_noprefix:
+               ctx->flags |= CGRP_ROOT_NOPREFIX;
+               break;
+       case Opt_clone_children:
+               ctx->cpuset_clone_children = true;
+               break;
+       case Opt_cpuset_v2_mode:
+               ctx->flags |= CGRP_ROOT_CPUSET_V2_MODE;
+               break;
+       case Opt_xattr:
+               ctx->flags |= CGRP_ROOT_XATTR;
+               break;
+       case Opt_release_agent:
+               /* Specifying two release agents is forbidden */
+               if (ctx->release_agent)
+                       return cg_invalf(fc, "cgroup1: release_agent respecified");
+               ctx->release_agent = param->string;
+               param->string = NULL;
+               break;
+       case Opt_name:
+               /* blocked by boot param? */
+               if (cgroup_no_v1_named)
                        return -ENOENT;
+               /* Can't specify an empty name */
+               if (!param->size)
+                       return cg_invalf(fc, "cgroup1: Empty name");
+               if (param->size > MAX_CGROUP_ROOT_NAMELEN - 1)
+                       return cg_invalf(fc, "cgroup1: Name too long");
+               /* Must match [\w.-]+ */
+               for (i = 0; i < param->size; i++) {
+                       char c = param->string[i];
+                       if (isalnum(c))
+                               continue;
+                       if ((c == '.') || (c == '-') || (c == '_'))
+                               continue;
+                       return cg_invalf(fc, "cgroup1: Invalid name");
+               }
+               /* Specifying two names is forbidden */
+               if (ctx->name)
+                       return cg_invalf(fc, "cgroup1: name respecified");
+               ctx->name = param->string;
+               param->string = NULL;
+               break;
        }
        return 0;
 }
 
-static int check_cgroupfs_options(struct cgroup_fs_context *ctx)
+static int check_cgroupfs_options(struct fs_context *fc)
 {
+       struct cgroup_fs_context *ctx = cgroup_fc2context(fc);
        u16 mask = U16_MAX;
        u16 enabled = 0;
        struct cgroup_subsys *ss;
@@ -1018,7 +1044,7 @@ static int check_cgroupfs_options(struct cgroup_fs_context *ctx)
        if (ctx->all_ss) {
                /* Mutually exclusive option 'all' + subsystem name */
                if (ctx->subsys_mask)
-                       return -EINVAL;
+                       return cg_invalf(fc, "cgroup1: subsys name conflicts with all");
                /* 'all' => select all the subsystems */
                ctx->subsys_mask = enabled;
        }
@@ -1028,7 +1054,7 @@ static int check_cgroupfs_options(struct cgroup_fs_context *ctx)
         * empty hierarchies must have a name).
         */
        if (!ctx->subsys_mask && !ctx->name)
-               return -EINVAL;
+               return cg_invalf(fc, "cgroup1: Need name or subsystem set");
 
        /*
         * Option noprefix was introduced just for backward compatibility
@@ -1036,11 +1062,11 @@ static int check_cgroupfs_options(struct cgroup_fs_context *ctx)
         * the cpuset subsystem.
         */
        if ((ctx->flags & CGRP_ROOT_NOPREFIX) && (ctx->subsys_mask & mask))
-               return -EINVAL;
+               return cg_invalf(fc, "cgroup1: noprefix used incorrectly");
 
        /* Can't specify "none" and some subsystems */
        if (ctx->subsys_mask && ctx->none)
-               return -EINVAL;
+               return cg_invalf(fc, "cgroup1: none used incorrectly");
 
        return 0;
 }
@@ -1056,7 +1082,7 @@ int cgroup1_reconfigure(struct fs_context *fc)
        cgroup_lock_and_drain_offline(&cgrp_dfl_root.cgrp);
 
        /* See what subsystems are wanted */
-       ret = check_cgroupfs_options(ctx);
+       ret = check_cgroupfs_options(fc);
        if (ret)
                goto out_unlock;
 
@@ -1070,7 +1096,7 @@ int cgroup1_reconfigure(struct fs_context *fc)
        /* Don't allow flags or name to change at remount */
        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",
+               cg_invalf(fc, "option or name mismatch, new: 0x%x \"%s\", old: 0x%x \"%s\"",
                       ctx->flags, ctx->name ?: "", root->flags, root->name);
                ret = -EINVAL;
                goto out_unlock;
@@ -1125,7 +1151,7 @@ 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 = check_cgroupfs_options(ctx);
+       ret = check_cgroupfs_options(fc);
        if (ret)
                goto out_unlock;
 
@@ -1192,7 +1218,7 @@ int cgroup1_get_tree(struct fs_context *fc)
         * can't create new one without subsys specification.
         */
        if (!ctx->subsys_mask && !ctx->none) {
-               ret = -EINVAL;
+               ret = cg_invalf(fc, "cgroup1: No subsys list or none specified");
                goto out_unlock;
        }
 
index 33da9ee..faba00c 100644 (file)
@@ -2083,15 +2083,6 @@ static int cgroup_parse_monolithic(struct fs_context *fc, void *data)
        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;
@@ -2124,7 +2115,7 @@ 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 = cgroup1_parse_monolithic,
+       .parse_param    = cgroup1_parse_param,
        .get_tree       = cgroup1_get_tree,
        .reconfigure    = cgroup1_reconfigure,
 };
@@ -2175,10 +2166,11 @@ static void cgroup_kill_sb(struct super_block *sb)
 }
 
 struct file_system_type cgroup_fs_type = {
-       .name = "cgroup",
-       .init_fs_context = cgroup_init_fs_context,
-       .kill_sb = cgroup_kill_sb,
-       .fs_flags = FS_USERNS_MOUNT,
+       .name                   = "cgroup",
+       .init_fs_context        = cgroup_init_fs_context,
+       .parameters             = &cgroup1_fs_parameters,
+       .kill_sb                = cgroup_kill_sb,
+       .fs_flags               = FS_USERNS_MOUNT,
 };
 
 static struct file_system_type cgroup2_fs_type = {