diff options
Diffstat (limited to 'kernel/bpf/trampoline.c')
| -rw-r--r-- | kernel/bpf/trampoline.c | 198 |
1 files changed, 198 insertions, 0 deletions
diff --git a/kernel/bpf/trampoline.c b/kernel/bpf/trampoline.c index 5466e15be61f..d7c251d7fbcd 100644 --- a/kernel/bpf/trampoline.c +++ b/kernel/bpf/trampoline.c @@ -11,6 +11,8 @@ #include <linux/rcupdate_wait.h> #include <linux/module.h> #include <linux/static_call.h> +#include <linux/bpf_verifier.h> +#include <linux/bpf_lsm.h> /* dummy _ops. The verifier will operate on target program's ops. */ const struct bpf_verifier_ops bpf_extension_verifier_ops = { @@ -496,6 +498,177 @@ int bpf_trampoline_unlink_prog(struct bpf_tramp_link *link, struct bpf_trampolin return err; } +#if defined(CONFIG_BPF_JIT) && defined(CONFIG_BPF_SYSCALL) +static void bpf_shim_tramp_link_release(struct bpf_link *link) +{ + struct bpf_shim_tramp_link *shim_link = + container_of(link, struct bpf_shim_tramp_link, link.link); + + /* paired with 'shim_link->trampoline = tr' in bpf_trampoline_link_cgroup_shim */ + if (!shim_link->trampoline) + return; + + WARN_ON_ONCE(bpf_trampoline_unlink_prog(&shim_link->link, shim_link->trampoline)); + bpf_trampoline_put(shim_link->trampoline); +} + +static void bpf_shim_tramp_link_dealloc(struct bpf_link *link) +{ + struct bpf_shim_tramp_link *shim_link = + container_of(link, struct bpf_shim_tramp_link, link.link); + + kfree(shim_link); +} + +static const struct bpf_link_ops bpf_shim_tramp_link_lops = { + .release = bpf_shim_tramp_link_release, + .dealloc = bpf_shim_tramp_link_dealloc, +}; + +static struct bpf_shim_tramp_link *cgroup_shim_alloc(const struct bpf_prog *prog, + bpf_func_t bpf_func, + int cgroup_atype) +{ + struct bpf_shim_tramp_link *shim_link = NULL; + struct bpf_prog *p; + + shim_link = kzalloc(sizeof(*shim_link), GFP_USER); + if (!shim_link) + return NULL; + + p = bpf_prog_alloc(1, 0); + if (!p) { + kfree(shim_link); + return NULL; + } + + p->jited = false; + p->bpf_func = bpf_func; + + p->aux->cgroup_atype = cgroup_atype; + p->aux->attach_func_proto = prog->aux->attach_func_proto; + p->aux->attach_btf_id = prog->aux->attach_btf_id; + p->aux->attach_btf = prog->aux->attach_btf; + btf_get(p->aux->attach_btf); + p->type = BPF_PROG_TYPE_LSM; + p->expected_attach_type = BPF_LSM_MAC; + bpf_prog_inc(p); + bpf_link_init(&shim_link->link.link, BPF_LINK_TYPE_UNSPEC, + &bpf_shim_tramp_link_lops, p); + + return shim_link; +} + +static struct bpf_shim_tramp_link *cgroup_shim_find(struct bpf_trampoline *tr, + bpf_func_t bpf_func) +{ + struct bpf_tramp_link *link; + int kind; + + for (kind = 0; kind < BPF_TRAMP_MAX; kind++) { + hlist_for_each_entry(link, &tr->progs_hlist[kind], tramp_hlist) { + struct bpf_prog *p = link->link.prog; + + if (p->bpf_func == bpf_func) + return container_of(link, struct bpf_shim_tramp_link, link); + } + } + + return NULL; +} + +int bpf_trampoline_link_cgroup_shim(struct bpf_prog *prog, + int cgroup_atype) +{ + struct bpf_shim_tramp_link *shim_link = NULL; + struct bpf_attach_target_info tgt_info = {}; + struct bpf_trampoline *tr; + bpf_func_t bpf_func; + u64 key; + int err; + + err = bpf_check_attach_target(NULL, prog, NULL, + prog->aux->attach_btf_id, + &tgt_info); + if (err) + return err; + + key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, + prog->aux->attach_btf_id); + + bpf_lsm_find_cgroup_shim(prog, &bpf_func); + tr = bpf_trampoline_get(key, &tgt_info); + if (!tr) + return -ENOMEM; + + mutex_lock(&tr->mutex); + + shim_link = cgroup_shim_find(tr, bpf_func); + if (shim_link) { + /* Reusing existing shim attached by the other program. */ + bpf_link_inc(&shim_link->link.link); + + mutex_unlock(&tr->mutex); + bpf_trampoline_put(tr); /* bpf_trampoline_get above */ + return 0; + } + + /* Allocate and install new shim. */ + + shim_link = cgroup_shim_alloc(prog, bpf_func, cgroup_atype); + if (!shim_link) { + err = -ENOMEM; + goto err; + } + + err = __bpf_trampoline_link_prog(&shim_link->link, tr); + if (err) + goto err; + + shim_link->trampoline = tr; + /* note, we're still holding tr refcnt from above */ + + mutex_unlock(&tr->mutex); + + return 0; +err: + mutex_unlock(&tr->mutex); + + if (shim_link) + bpf_link_put(&shim_link->link.link); + + /* have to release tr while _not_ holding its mutex */ + bpf_trampoline_put(tr); /* bpf_trampoline_get above */ + + return err; +} + +void bpf_trampoline_unlink_cgroup_shim(struct bpf_prog *prog) +{ + struct bpf_shim_tramp_link *shim_link = NULL; + struct bpf_trampoline *tr; + bpf_func_t bpf_func; + u64 key; + + key = bpf_trampoline_compute_key(NULL, prog->aux->attach_btf, + prog->aux->attach_btf_id); + + bpf_lsm_find_cgroup_shim(prog, &bpf_func); + tr = bpf_trampoline_lookup(key); + if (WARN_ON_ONCE(!tr)) + return; + + mutex_lock(&tr->mutex); + shim_link = cgroup_shim_find(tr, bpf_func); + mutex_unlock(&tr->mutex); + + if (shim_link) + bpf_link_put(&shim_link->link.link); + + bpf_trampoline_put(tr); /* bpf_trampoline_lookup above */ +} +#endif + struct bpf_trampoline *bpf_trampoline_get(u64 key, struct bpf_attach_target_info *tgt_info) { @@ -628,6 +801,31 @@ void notrace __bpf_prog_exit(struct bpf_prog *prog, u64 start, struct bpf_tramp_ rcu_read_unlock(); } +u64 notrace __bpf_prog_enter_lsm_cgroup(struct bpf_prog *prog, + struct bpf_tramp_run_ctx *run_ctx) + __acquires(RCU) +{ + /* Runtime stats are exported via actual BPF_LSM_CGROUP + * programs, not the shims. + */ + rcu_read_lock(); + migrate_disable(); + + run_ctx->saved_run_ctx = bpf_set_run_ctx(&run_ctx->run_ctx); + + return NO_START_TIME; +} + +void notrace __bpf_prog_exit_lsm_cgroup(struct bpf_prog *prog, u64 start, + struct bpf_tramp_run_ctx *run_ctx) + __releases(RCU) +{ + bpf_reset_run_ctx(run_ctx->saved_run_ctx); + + migrate_enable(); + rcu_read_unlock(); +} + u64 notrace __bpf_prog_enter_sleepable(struct bpf_prog *prog, struct bpf_tramp_run_ctx *run_ctx) { rcu_read_lock_trace(); |