kernel/bpf/tcx.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Copyright (c) 2023 Isovalent */
   3
   4 #include <linux/bpf.h>
   5 #include <linux/bpf_mprog.h>
   6 #include <linux/netdevice.h>
   7
   8 #include <net/tcx.h>
   9
  10 int tcx_prog_attach(const union bpf_attr *attr, struct bpf_prog *prog)
  11 {
  12         bool created, ingress = attr->attach_type == BPF_TCX_INGRESS;
  13         struct net *net = current->nsproxy->net_ns;
  14         struct bpf_mprog_entry *entry, *entry_new;
  15         struct bpf_prog *replace_prog = NULL;
  16         struct net_device *dev;
  17         int ret;
  18
  19         rtnl_lock();
  20         dev = __dev_get_by_index(net, attr->target_ifindex);
  21         if (!dev) {
  22                 ret = -ENODEV;
  23                 goto out;
  24         }
  25         if (attr->attach_flags & BPF_F_REPLACE) {
  26                 replace_prog = bpf_prog_get_type(attr->replace_bpf_fd,
  27                                                  prog->type);
  28                 if (IS_ERR(replace_prog)) {
  29                         ret = PTR_ERR(replace_prog);
  30                         replace_prog = NULL;
  31                         goto out;
  32                 }
  33         }
  34         entry = tcx_entry_fetch_or_create(dev, ingress, &created);
  35         if (!entry) {
  36                 ret = -ENOMEM;
  37                 goto out;
  38         }
  39         ret = bpf_mprog_attach(entry, &entry_new, prog, NULL, replace_prog,
  40                                attr->attach_flags, attr->relative_fd,
  41                                attr->expected_revision);
  42         if (!ret) {
  43                 if (entry != entry_new) {
  44                         tcx_entry_update(dev, entry_new, ingress);
  45                         tcx_entry_sync();
  46                         tcx_skeys_inc(ingress);
  47                 }
  48                 bpf_mprog_commit(entry);
  49         } else if (created) {
  50                 tcx_entry_free(entry);
  51         }
  52 out:
  53         if (replace_prog)
  54                 bpf_prog_put(replace_prog);
  55         rtnl_unlock();
  56         return ret;
  57 }
  58
  59 int tcx_prog_detach(const union bpf_attr *attr, struct bpf_prog *prog)
  60 {
  61         bool ingress = attr->attach_type == BPF_TCX_INGRESS;
  62         struct net *net = current->nsproxy->net_ns;
  63         struct bpf_mprog_entry *entry, *entry_new;
  64         struct net_device *dev;
  65         int ret;
  66
  67         rtnl_lock();
  68         dev = __dev_get_by_index(net, attr->target_ifindex);
  69         if (!dev) {
  70                 ret = -ENODEV;
  71                 goto out;
  72         }
  73         entry = tcx_entry_fetch(dev, ingress);
  74         if (!entry) {
  75                 ret = -ENOENT;
  76                 goto out;
  77         }
  78         ret = bpf_mprog_detach(entry, &entry_new, prog, NULL, attr->attach_flags,
  79                                attr->relative_fd, attr->expected_revision);
  80         if (!ret) {
  81                 if (!tcx_entry_is_active(entry_new))
  82                         entry_new = NULL;
  83                 tcx_entry_update(dev, entry_new, ingress);
  84                 tcx_entry_sync();
  85                 tcx_skeys_dec(ingress);
  86                 bpf_mprog_commit(entry);
  87                 if (!entry_new)
  88                         tcx_entry_free(entry);
  89         }
  90 out:
  91         rtnl_unlock();
  92         return ret;
  93 }
  94
  95 void tcx_uninstall(struct net_device *dev, bool ingress)
  96 {
  97         struct bpf_mprog_entry *entry, *entry_new = NULL;
  98         struct bpf_tuple tuple = {};
  99         struct bpf_mprog_fp *fp;
 100         struct bpf_mprog_cp *cp;
 101         bool active;
 102
 103         entry = tcx_entry_fetch(dev, ingress);
 104         if (!entry)
 105                 return;
 106         active = tcx_entry(entry)->miniq_active;
 107         if (active)
 108                 bpf_mprog_clear_all(entry, &entry_new);
 109         tcx_entry_update(dev, entry_new, ingress);
 110         tcx_entry_sync();
 111         bpf_mprog_foreach_tuple(entry, fp, cp, tuple) {
 112                 if (tuple.link)
 113                         tcx_link(tuple.link)->dev = NULL;
 114                 else
 115                         bpf_prog_put(tuple.prog);
 116                 tcx_skeys_dec(ingress);
 117         }
 118         if (!active)
 119                 tcx_entry_free(entry);
 120 }
 121
 122 int tcx_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr)
 123 {
 124         bool ingress = attr->query.attach_type == BPF_TCX_INGRESS;
 125         struct net *net = current->nsproxy->net_ns;
 126         struct net_device *dev;
 127         int ret;
 128
 129         rtnl_lock();
 130         dev = __dev_get_by_index(net, attr->query.target_ifindex);
 131         if (!dev) {
 132                 ret = -ENODEV;
 133                 goto out;
 134         }
 135         ret = bpf_mprog_query(attr, uattr, tcx_entry_fetch(dev, ingress));
 136 out:
 137         rtnl_unlock();
 138         return ret;
 139 }
 140
 141 static int tcx_link_prog_attach(struct bpf_link *link, u32 flags, u32 id_or_fd,
 142                                 u64 revision)
 143 {
 144         struct tcx_link *tcx = tcx_link(link);
 145         bool created, ingress = tcx->location == BPF_TCX_INGRESS;
 146         struct bpf_mprog_entry *entry, *entry_new;
 147         struct net_device *dev = tcx->dev;
 148         int ret;
 149
 150         ASSERT_RTNL();
 151         entry = tcx_entry_fetch_or_create(dev, ingress, &created);
 152         if (!entry)
 153                 return -ENOMEM;
 154         ret = bpf_mprog_attach(entry, &entry_new, link->prog, link, NULL, flags,
 155                                id_or_fd, revision);
 156         if (!ret) {
 157                 if (entry != entry_new) {
 158                         tcx_entry_update(dev, entry_new, ingress);
 159                         tcx_entry_sync();
 160                         tcx_skeys_inc(ingress);
 161                 }
 162                 bpf_mprog_commit(entry);
 163         } else if (created) {
 164                 tcx_entry_free(entry);
 165         }
 166         return ret;
 167 }
 168
 169 static void tcx_link_release(struct bpf_link *link)
 170 {
 171         struct tcx_link *tcx = tcx_link(link);
 172         bool ingress = tcx->location == BPF_TCX_INGRESS;
 173         struct bpf_mprog_entry *entry, *entry_new;
 174         struct net_device *dev;
 175         int ret = 0;
 176
 177         rtnl_lock();
 178         dev = tcx->dev;
 179         if (!dev)
 180                 goto out;
 181         entry = tcx_entry_fetch(dev, ingress);
 182         if (!entry) {
 183                 ret = -ENOENT;
 184                 goto out;
 185         }
 186         ret = bpf_mprog_detach(entry, &entry_new, link->prog, link, 0, 0, 0);
 187         if (!ret) {
 188                 if (!tcx_entry_is_active(entry_new))
 189                         entry_new = NULL;
 190                 tcx_entry_update(dev, entry_new, ingress);
 191                 tcx_entry_sync();
 192                 tcx_skeys_dec(ingress);
 193                 bpf_mprog_commit(entry);
 194                 if (!entry_new)
 195                         tcx_entry_free(entry);
 196                 tcx->dev = NULL;
 197         }
 198 out:
 199         WARN_ON_ONCE(ret);
 200         rtnl_unlock();
 201 }
 202
 203 static int tcx_link_update(struct bpf_link *link, struct bpf_prog *nprog,
 204                            struct bpf_prog *oprog)
 205 {
 206         struct tcx_link *tcx = tcx_link(link);
 207         bool ingress = tcx->location == BPF_TCX_INGRESS;
 208         struct bpf_mprog_entry *entry, *entry_new;
 209         struct net_device *dev;
 210         int ret = 0;
 211
 212         rtnl_lock();
 213         dev = tcx->dev;
 214         if (!dev) {
 215                 ret = -ENOLINK;
 216                 goto out;
 217         }
 218         if (oprog && link->prog != oprog) {
 219                 ret = -EPERM;
 220                 goto out;
 221         }
 222         oprog = link->prog;
 223         if (oprog == nprog) {
 224                 bpf_prog_put(nprog);
 225                 goto out;
 226         }
 227         entry = tcx_entry_fetch(dev, ingress);
 228         if (!entry) {
 229                 ret = -ENOENT;
 230                 goto out;
 231         }
 232         ret = bpf_mprog_attach(entry, &entry_new, nprog, link, oprog,
 233                                BPF_F_REPLACE | BPF_F_ID,
 234                                link->prog->aux->id, 0);
 235         if (!ret) {
 236                 WARN_ON_ONCE(entry != entry_new);
 237                 oprog = xchg(&link->prog, nprog);
 238                 bpf_prog_put(oprog);
 239                 bpf_mprog_commit(entry);
 240         }
 241 out:
 242         rtnl_unlock();
 243         return ret;
 244 }
 245
 246 static void tcx_link_dealloc(struct bpf_link *link)
 247 {
 248         kfree(tcx_link(link));
 249 }
 250
 251 static void tcx_link_fdinfo(const struct bpf_link *link, struct seq_file *seq)
 252 {
 253         const struct tcx_link *tcx = tcx_link(link);
 254         u32 ifindex = 0;
 255
 256         rtnl_lock();
 257         if (tcx->dev)
 258                 ifindex = tcx->dev->ifindex;
 259         rtnl_unlock();
 260
 261         seq_printf(seq, "ifindex:\t%u\n", ifindex);
 262         seq_printf(seq, "attach_type:\t%u (%s)\n",
 263                    tcx->location,
 264                    tcx->location == BPF_TCX_INGRESS ? "ingress" : "egress");
 265 }
 266
 267 static int tcx_link_fill_info(const struct bpf_link *link,
 268                               struct bpf_link_info *info)
 269 {
 270         const struct tcx_link *tcx = tcx_link(link);
 271         u32 ifindex = 0;
 272
 273         rtnl_lock();
 274         if (tcx->dev)
 275                 ifindex = tcx->dev->ifindex;
 276         rtnl_unlock();
 277
 278         info->tcx.ifindex = ifindex;
 279         info->tcx.attach_type = tcx->location;
 280         return 0;
 281 }
 282
 283 static int tcx_link_detach(struct bpf_link *link)
 284 {
 285         tcx_link_release(link);
 286         return 0;
 287 }
 288
 289 static const struct bpf_link_ops tcx_link_lops = {
 290         .release        = tcx_link_release,
 291         .detach         = tcx_link_detach,
 292         .dealloc        = tcx_link_dealloc,
 293         .update_prog    = tcx_link_update,
 294         .show_fdinfo    = tcx_link_fdinfo,
 295         .fill_link_info = tcx_link_fill_info,
 296 };
 297
 298 static int tcx_link_init(struct tcx_link *tcx,
 299                          struct bpf_link_primer *link_primer,
 300                          const union bpf_attr *attr,
 301                          struct net_device *dev,
 302                          struct bpf_prog *prog)
 303 {
 304         bpf_link_init(&tcx->link, BPF_LINK_TYPE_TCX, &tcx_link_lops, prog);
 305         tcx->location = attr->link_create.attach_type;
 306         tcx->dev = dev;
 307         return bpf_link_prime(&tcx->link, link_primer);
 308 }
 309
 310 int tcx_link_attach(const union bpf_attr *attr, struct bpf_prog *prog)
 311 {
 312         struct net *net = current->nsproxy->net_ns;
 313         struct bpf_link_primer link_primer;
 314         struct net_device *dev;
 315         struct tcx_link *tcx;
 316         int ret;
 317
 318         rtnl_lock();
 319         dev = __dev_get_by_index(net, attr->link_create.target_ifindex);
 320         if (!dev) {
 321                 ret = -ENODEV;
 322                 goto out;
 323         }
 324         tcx = kzalloc(sizeof(*tcx), GFP_USER);
 325         if (!tcx) {
 326                 ret = -ENOMEM;
 327                 goto out;
 328         }
 329         ret = tcx_link_init(tcx, &link_primer, attr, dev, prog);
 330         if (ret) {
 331                 kfree(tcx);
 332                 goto out;
 333         }
 334         ret = tcx_link_prog_attach(&tcx->link, attr->link_create.flags,
 335                                    attr->link_create.tcx.relative_fd,
 336                                    attr->link_create.tcx.expected_revision);
 337         if (ret) {
 338                 tcx->dev = NULL;
 339                 bpf_link_cleanup(&link_primer);
 340                 goto out;
 341         }
 342         ret = bpf_link_settle(&link_primer);
 343 out:
 344         rtnl_unlock();
 345         return ret;
 346 }