1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/core/netclassid_cgroup.c Classid Cgroupfs Handling 4 * 5 * Authors: Thomas Graf <tgraf@suug.ch> 6 */ 7 8 #include <linux/slab.h> 9 #include <linux/cgroup.h> 10 #include <linux/fdtable.h> 11 #include <linux/sched/task.h> 12 13 #include <net/cls_cgroup.h> 14 #include <net/sock.h> 15 16 static inline struct cgroup_cls_state *css_cls_state(struct cgroup_subsys_state *css) 17 { 18 return css ? container_of(css, struct cgroup_cls_state, css) : NULL; 19 } 20 21 struct cgroup_cls_state *task_cls_state(struct task_struct *p) 22 { 23 return css_cls_state(task_css_check(p, net_cls_cgrp_id, 24 rcu_read_lock_bh_held())); 25 } 26 EXPORT_SYMBOL_GPL(task_cls_state); 27 28 static struct cgroup_subsys_state * 29 cgrp_css_alloc(struct cgroup_subsys_state *parent_css) 30 { 31 struct cgroup_cls_state *cs; 32 33 cs = kzalloc(sizeof(*cs), GFP_KERNEL); 34 if (!cs) 35 return ERR_PTR(-ENOMEM); 36 37 return &cs->css; 38 } 39 40 static int cgrp_css_online(struct cgroup_subsys_state *css) 41 { 42 struct cgroup_cls_state *cs = css_cls_state(css); 43 struct cgroup_cls_state *parent = css_cls_state(css->parent); 44 45 if (parent) 46 cs->classid = parent->classid; 47 48 return 0; 49 } 50 51 static void cgrp_css_free(struct cgroup_subsys_state *css) 52 { 53 kfree(css_cls_state(css)); 54 } 55 56 /* 57 * To avoid freezing of sockets creation for tasks with big number of threads 58 * and opened sockets lets release file_lock every 1000 iterated descriptors. 59 * New sockets will already have been created with new classid. 60 */ 61 62 struct update_classid_context { 63 u32 classid; 64 unsigned int batch; 65 }; 66 67 #define UPDATE_CLASSID_BATCH 1000 68 69 static int update_classid_sock(const void *v, struct file *file, unsigned n) 70 { 71 struct update_classid_context *ctx = (void *)v; 72 struct socket *sock = sock_from_file(file); 73 74 if (sock) 75 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid); 76 if (--ctx->batch == 0) { 77 ctx->batch = UPDATE_CLASSID_BATCH; 78 return n + 1; 79 } 80 return 0; 81 } 82 83 static void update_classid_task(struct task_struct *p, u32 classid) 84 { 85 struct update_classid_context ctx = { 86 .classid = classid, 87 .batch = UPDATE_CLASSID_BATCH 88 }; 89 unsigned int fd = 0; 90 91 do { 92 task_lock(p); 93 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx); 94 task_unlock(p); 95 cond_resched(); 96 } while (fd); 97 } 98 99 static void cgrp_attach(struct cgroup_taskset *tset) 100 { 101 struct cgroup_subsys_state *css; 102 struct task_struct *p; 103 104 cgroup_taskset_for_each(p, css, tset) { 105 update_classid_task(p, css_cls_state(css)->classid); 106 } 107 } 108 109 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft) 110 { 111 return css_cls_state(css)->classid; 112 } 113 114 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft, 115 u64 value) 116 { 117 struct cgroup_cls_state *cs = css_cls_state(css); 118 struct css_task_iter it; 119 struct task_struct *p; 120 121 cs->classid = (u32)value; 122 123 css_task_iter_start(css, 0, &it); 124 while ((p = css_task_iter_next(&it))) 125 update_classid_task(p, cs->classid); 126 css_task_iter_end(&it); 127 128 return 0; 129 } 130 131 static struct cftype ss_files[] = { 132 { 133 .name = "classid", 134 .read_u64 = read_classid, 135 .write_u64 = write_classid, 136 }, 137 { } /* terminate */ 138 }; 139 140 struct cgroup_subsys net_cls_cgrp_subsys = { 141 .css_alloc = cgrp_css_alloc, 142 .css_online = cgrp_css_online, 143 .css_free = cgrp_css_free, 144 .attach = cgrp_attach, 145 .legacy_cftypes = ss_files, 146 }; 147