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 spin_lock(&cgroup_sk_update_lock); 76 sock_cgroup_set_classid(&sock->sk->sk_cgrp_data, ctx->classid); 77 spin_unlock(&cgroup_sk_update_lock); 78 } 79 if (--ctx->batch == 0) { 80 ctx->batch = UPDATE_CLASSID_BATCH; 81 return n + 1; 82 } 83 return 0; 84 } 85 86 static void update_classid_task(struct task_struct *p, u32 classid) 87 { 88 struct update_classid_context ctx = { 89 .classid = classid, 90 .batch = UPDATE_CLASSID_BATCH 91 }; 92 unsigned int fd = 0; 93 94 do { 95 task_lock(p); 96 fd = iterate_fd(p->files, fd, update_classid_sock, &ctx); 97 task_unlock(p); 98 cond_resched(); 99 } while (fd); 100 } 101 102 static void cgrp_attach(struct cgroup_taskset *tset) 103 { 104 struct cgroup_subsys_state *css; 105 struct task_struct *p; 106 107 cgroup_taskset_for_each(p, css, tset) { 108 update_classid_task(p, css_cls_state(css)->classid); 109 } 110 } 111 112 static u64 read_classid(struct cgroup_subsys_state *css, struct cftype *cft) 113 { 114 return css_cls_state(css)->classid; 115 } 116 117 static int write_classid(struct cgroup_subsys_state *css, struct cftype *cft, 118 u64 value) 119 { 120 struct cgroup_cls_state *cs = css_cls_state(css); 121 struct css_task_iter it; 122 struct task_struct *p; 123 124 cgroup_sk_alloc_disable(); 125 126 cs->classid = (u32)value; 127 128 css_task_iter_start(css, 0, &it); 129 while ((p = css_task_iter_next(&it))) 130 update_classid_task(p, cs->classid); 131 css_task_iter_end(&it); 132 133 return 0; 134 } 135 136 static struct cftype ss_files[] = { 137 { 138 .name = "classid", 139 .read_u64 = read_classid, 140 .write_u64 = write_classid, 141 }, 142 { } /* terminate */ 143 }; 144 145 struct cgroup_subsys net_cls_cgrp_subsys = { 146 .css_alloc = cgrp_css_alloc, 147 .css_online = cgrp_css_online, 148 .css_free = cgrp_css_free, 149 .attach = cgrp_attach, 150 .legacy_cftypes = ss_files, 151 }; 152