diff options
Diffstat (limited to 'kernel/bpf/syscall.c')
| -rw-r--r-- | kernel/bpf/syscall.c | 743 |
1 files changed, 743 insertions, 0 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c new file mode 100644 index 000000000000..01431ef8cf07 --- /dev/null +++ b/kernel/bpf/syscall.c @@ -0,0 +1,743 @@ +/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of version 2 of the GNU General Public + * License as published by the Free Software Foundation. + * + * This program is distributed in the hope that it will be useful, but + * WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * General Public License for more details. + */ +#include <linux/bpf.h> +#include <linux/syscalls.h> +#include <linux/slab.h> +#include <linux/anon_inodes.h> +#include <linux/file.h> +#include <linux/license.h> +#include <linux/filter.h> +#include <linux/version.h> + +int sysctl_unprivileged_bpf_disabled __read_mostly; + +static LIST_HEAD(bpf_map_types); + +static struct bpf_map *find_and_alloc_map(union bpf_attr *attr) +{ + struct bpf_map_type_list *tl; + struct bpf_map *map; + + list_for_each_entry(tl, &bpf_map_types, list_node) { + if (tl->type == attr->map_type) { + map = tl->ops->map_alloc(attr); + if (IS_ERR(map)) + return map; + map->ops = tl->ops; + map->map_type = attr->map_type; + return map; + } + } + return ERR_PTR(-EINVAL); +} + +/* boot time registration of different map implementations */ +void bpf_register_map_type(struct bpf_map_type_list *tl) +{ + list_add(&tl->list_node, &bpf_map_types); +} + +static int bpf_map_charge_memlock(struct bpf_map *map) +{ + struct user_struct *user = get_current_user(); + unsigned long memlock_limit; + + memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + + atomic_long_add(map->pages, &user->locked_vm); + + if (atomic_long_read(&user->locked_vm) > memlock_limit) { + atomic_long_sub(map->pages, &user->locked_vm); + free_uid(user); + return -EPERM; + } + map->user = user; + return 0; +} + +static void bpf_map_uncharge_memlock(struct bpf_map *map) +{ + struct user_struct *user = map->user; + + atomic_long_sub(map->pages, &user->locked_vm); + free_uid(user); +} + +/* called from workqueue */ +static void bpf_map_free_deferred(struct work_struct *work) +{ + struct bpf_map *map = container_of(work, struct bpf_map, work); + + bpf_map_uncharge_memlock(map); + /* implementation dependent freeing */ + map->ops->map_free(map); +} + +static void bpf_map_put_uref(struct bpf_map *map) +{ + if (atomic_dec_and_test(&map->usercnt)) { + if (map->map_type == BPF_MAP_TYPE_PROG_ARRAY) + bpf_fd_array_map_clear(map); + } +} + +/* decrement map refcnt and schedule it for freeing via workqueue + * (unrelying map implementation ops->map_free() might sleep) + */ +void bpf_map_put(struct bpf_map *map) +{ + if (atomic_dec_and_test(&map->refcnt)) { + INIT_WORK(&map->work, bpf_map_free_deferred); + schedule_work(&map->work); + } +} + +void bpf_map_put_with_uref(struct bpf_map *map) +{ + bpf_map_put_uref(map); + bpf_map_put(map); +} + +static int bpf_map_release(struct inode *inode, struct file *filp) +{ + bpf_map_put_with_uref(filp->private_data); + return 0; +} + +static const struct file_operations bpf_map_fops = { + .release = bpf_map_release, +}; + +int bpf_map_new_fd(struct bpf_map *map) +{ + return anon_inode_getfd("bpf-map", &bpf_map_fops, map, + O_RDWR | O_CLOEXEC); +} + +/* helper macro to check that unused fields 'union bpf_attr' are zero */ +#define CHECK_ATTR(CMD) \ + memchr_inv((void *) &attr->CMD##_LAST_FIELD + \ + sizeof(attr->CMD##_LAST_FIELD), 0, \ + sizeof(*attr) - \ + offsetof(union bpf_attr, CMD##_LAST_FIELD) - \ + sizeof(attr->CMD##_LAST_FIELD)) != NULL + +#define BPF_MAP_CREATE_LAST_FIELD max_entries +/* called via syscall */ +static int map_create(union bpf_attr *attr) +{ + struct bpf_map *map; + int err; + + err = CHECK_ATTR(BPF_MAP_CREATE); + if (err) + return -EINVAL; + + /* find map type and init map: hashtable vs rbtree vs bloom vs ... */ + map = find_and_alloc_map(attr); + if (IS_ERR(map)) + return PTR_ERR(map); + + atomic_set(&map->refcnt, 1); + atomic_set(&map->usercnt, 1); + + err = bpf_map_charge_memlock(map); + if (err) + goto free_map_nouncharge; + + err = bpf_map_new_fd(map); + if (err < 0) + /* failed to allocate fd */ + goto free_map; + + return err; + +free_map: + bpf_map_uncharge_memlock(map); +free_map_nouncharge: + map->ops->map_free(map); + return err; +} + +/* if error is returned, fd is released. + * On success caller should complete fd access with matching fdput() + */ +struct bpf_map *__bpf_map_get(struct fd f) +{ + if (!f.file) + return ERR_PTR(-EBADF); + if (f.file->f_op != &bpf_map_fops) { + fdput(f); + return ERR_PTR(-EINVAL); + } + + return f.file->private_data; +} + +/* prog's and map's refcnt limit */ +#define BPF_MAX_REFCNT 32768 + +struct bpf_map *bpf_map_inc(struct bpf_map *map, bool uref) +{ + if (atomic_inc_return(&map->refcnt) > BPF_MAX_REFCNT) { + atomic_dec(&map->refcnt); + return ERR_PTR(-EBUSY); + } + if (uref) + atomic_inc(&map->usercnt); + return map; +} + +struct bpf_map *bpf_map_get_with_uref(u32 ufd) +{ + struct fd f = fdget(ufd); + struct bpf_map *map; + + map = __bpf_map_get(f); + if (IS_ERR(map)) + return map; + + map = bpf_map_inc(map, true); + fdput(f); + + return map; +} + +/* helper to convert user pointers passed inside __aligned_u64 fields */ +static void __user *u64_to_ptr(__u64 val) +{ + return (void __user *) (unsigned long) val; +} + +/* last field in 'union bpf_attr' used by this command */ +#define BPF_MAP_LOOKUP_ELEM_LAST_FIELD value + +static int map_lookup_elem(union bpf_attr *attr) +{ + void __user *ukey = u64_to_ptr(attr->key); + void __user *uvalue = u64_to_ptr(attr->value); + int ufd = attr->map_fd; + struct bpf_map *map; + void *key, *value, *ptr; + struct fd f; + int err; + + if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM)) + return -EINVAL; + + f = fdget(ufd); + map = __bpf_map_get(f); + if (IS_ERR(map)) + return PTR_ERR(map); + + err = -ENOMEM; + key = kmalloc(map->key_size, GFP_USER); + if (!key) + goto err_put; + + err = -EFAULT; + if (copy_from_user(key, ukey, map->key_size) != 0) + goto free_key; + + err = -ENOMEM; + value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN); + if (!value) + goto free_key; + + rcu_read_lock(); + ptr = map->ops->map_lookup_elem(map, key); + if (ptr) + memcpy(value, ptr, map->value_size); + rcu_read_unlock(); + + err = -ENOENT; + if (!ptr) + goto free_value; + + err = -EFAULT; + if (copy_to_user(uvalue, value, map->value_size) != 0) + goto free_value; + + err = 0; + +free_value: + kfree(value); +free_key: + kfree(key); +err_put: + fdput(f); + return err; +} + +#define BPF_MAP_UPDATE_ELEM_LAST_FIELD flags + +static int map_update_elem(union bpf_attr *attr) +{ + void __user *ukey = u64_to_ptr(attr->key); + void __user *uvalue = u64_to_ptr(attr->value); + int ufd = attr->map_fd; + struct bpf_map *map; + void *key, *value; + struct fd f; + int err; + + if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM)) + return -EINVAL; + + f = fdget(ufd); + map = __bpf_map_get(f); + if (IS_ERR(map)) + return PTR_ERR(map); + + err = -ENOMEM; + key = kmalloc(map->key_size, GFP_USER); + if (!key) + goto err_put; + + err = -EFAULT; + if (copy_from_user(key, ukey, map->key_size) != 0) + goto free_key; + + err = -ENOMEM; + value = kmalloc(map->value_size, GFP_USER | __GFP_NOWARN); + if (!value) + goto free_key; + + err = -EFAULT; + if (copy_from_user(value, uvalue, map->value_size) != 0) + goto free_value; + + /* eBPF program that use maps are running under rcu_read_lock(), + * therefore all map accessors rely on this fact, so do the same here + */ + rcu_read_lock(); + err = map->ops->map_update_elem(map, key, value, attr->flags); + rcu_read_unlock(); + +free_value: + kfree(value); +free_key: + kfree(key); +err_put: + fdput(f); + return err; +} + +#define BPF_MAP_DELETE_ELEM_LAST_FIELD key + +static int map_delete_elem(union bpf_attr *attr) +{ + void __user *ukey = u64_to_ptr(attr->key); + int ufd = attr->map_fd; + struct bpf_map *map; + struct fd f; + void *key; + int err; + + if (CHECK_ATTR(BPF_MAP_DELETE_ELEM)) + return -EINVAL; + + f = fdget(ufd); + map = __bpf_map_get(f); + if (IS_ERR(map)) + return PTR_ERR(map); + + err = -ENOMEM; + key = kmalloc(map->key_size, GFP_USER); + if (!key) + goto err_put; + + err = -EFAULT; + if (copy_from_user(key, ukey, map->key_size) != 0) + goto free_key; + + rcu_read_lock(); + err = map->ops->map_delete_elem(map, key); + rcu_read_unlock(); + +free_key: + kfree(key); +err_put: + fdput(f); + return err; +} + +/* last field in 'union bpf_attr' used by this command */ +#define BPF_MAP_GET_NEXT_KEY_LAST_FIELD next_key + +static int map_get_next_key(union bpf_attr *attr) +{ + void __user *ukey = u64_to_ptr(attr->key); + void __user *unext_key = u64_to_ptr(attr->next_key); + int ufd = attr->map_fd; + struct bpf_map *map; + void *key, *next_key; + struct fd f; + int err; + + if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY)) + return -EINVAL; + + f = fdget(ufd); + map = __bpf_map_get(f); + if (IS_ERR(map)) + return PTR_ERR(map); + + if (ukey) { + err = -ENOMEM; + key = kmalloc(map->key_size, GFP_USER); + if (!key) + goto err_put; + + err = -EFAULT; + if (copy_from_user(key, ukey, map->key_size) != 0) + goto free_key; + } else { + key = NULL; + } + + err = -ENOMEM; + next_key = kmalloc(map->key_size, GFP_USER); + if (!next_key) + goto free_key; + + rcu_read_lock(); + err = map->ops->map_get_next_key(map, key, next_key); + rcu_read_unlock(); + if (err) + goto free_next_key; + + err = -EFAULT; + if (copy_to_user(unext_key, next_key, map->key_size) != 0) + goto free_next_key; + + err = 0; + +free_next_key: + kfree(next_key); +free_key: + kfree(key); +err_put: + fdput(f); + return err; +} + +static LIST_HEAD(bpf_prog_types); + +static int find_prog_type(enum bpf_prog_type type, struct bpf_prog *prog) +{ + struct bpf_prog_type_list *tl; + + list_for_each_entry(tl, &bpf_prog_types, list_node) { + if (tl->type == type) { + prog->aux->ops = tl->ops; + prog->type = type; + return 0; + } + } + + return -EINVAL; +} + +void bpf_register_prog_type(struct bpf_prog_type_list *tl) +{ + list_add(&tl->list_node, &bpf_prog_types); +} + +/* drop refcnt on maps used by eBPF program and free auxilary data */ +static void free_used_maps(struct bpf_prog_aux *aux) +{ + int i; + + for (i = 0; i < aux->used_map_cnt; i++) + bpf_map_put(aux->used_maps[i]); + + kfree(aux->used_maps); +} + +static int bpf_prog_charge_memlock(struct bpf_prog *prog) +{ + struct user_struct *user = get_current_user(); + unsigned long memlock_limit; + + memlock_limit = rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT; + + atomic_long_add(prog->pages, &user->locked_vm); + if (atomic_long_read(&user->locked_vm) > memlock_limit) { + atomic_long_sub(prog->pages, &user->locked_vm); + free_uid(user); + return -EPERM; + } + prog->aux->user = user; + return 0; +} + +static void bpf_prog_uncharge_memlock(struct bpf_prog *prog) +{ + struct user_struct *user = prog->aux->user; + + atomic_long_sub(prog->pages, &user->locked_vm); + free_uid(user); +} + +static void __bpf_prog_put_rcu(struct rcu_head *rcu) +{ + struct bpf_prog_aux *aux = container_of(rcu, struct bpf_prog_aux, rcu); + + free_used_maps(aux); + bpf_prog_uncharge_memlock(aux->prog); + bpf_prog_free(aux->prog); +} + +void bpf_prog_put(struct bpf_prog *prog) +{ + if (atomic_dec_and_test(&prog->aux->refcnt)) + call_rcu(&prog->aux->rcu, __bpf_prog_put_rcu); +} +EXPORT_SYMBOL_GPL(bpf_prog_put); + +static int bpf_prog_release(struct inode *inode, struct file *filp) +{ + struct bpf_prog *prog = filp->private_data; + + bpf_prog_put(prog); + return 0; +} + +static const struct file_operations bpf_prog_fops = { + .release = bpf_prog_release, +}; + +int bpf_prog_new_fd(struct bpf_prog *prog) +{ + return anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog, + O_RDWR | O_CLOEXEC); +} + +static struct bpf_prog *__bpf_prog_get(struct fd f) +{ + if (!f.file) + return ERR_PTR(-EBADF); + if (f.file->f_op != &bpf_prog_fops) { + fdput(f); + return ERR_PTR(-EINVAL); + } + + return f.file->private_data; +} + +struct bpf_prog *bpf_prog_inc(struct bpf_prog *prog) +{ + if (atomic_inc_return(&prog->aux->refcnt) > BPF_MAX_REFCNT) { + atomic_dec(&prog->aux->refcnt); + return ERR_PTR(-EBUSY); + } + return prog; +} + +/* called by sockets/tracing/seccomp before attaching program to an event + * pairs with bpf_prog_put() + */ +struct bpf_prog *bpf_prog_get(u32 ufd) +{ + struct fd f = fdget(ufd); + struct bpf_prog *prog; + + prog = __bpf_prog_get(f); + if (IS_ERR(prog)) + return prog; + + prog = bpf_prog_inc(prog); + fdput(f); + + return prog; +} +EXPORT_SYMBOL_GPL(bpf_prog_get); + +/* last field in 'union bpf_attr' used by this command */ +#define BPF_PROG_LOAD_LAST_FIELD kern_version + +static int bpf_prog_load(union bpf_attr *attr) +{ + enum bpf_prog_type type = attr->prog_type; + struct bpf_prog *prog; + int err; + char license[128]; + bool is_gpl; + + if (CHECK_ATTR(BPF_PROG_LOAD)) + return -EINVAL; + + /* copy eBPF program license from user space */ + if (strncpy_from_user(license, u64_to_ptr(attr->license), + sizeof(license) - 1) < 0) + return -EFAULT; + license[sizeof(license) - 1] = 0; + + /* eBPF programs must be GPL compatible to use GPL-ed functions */ + is_gpl = license_is_gpl_compatible(license); + + if (attr->insn_cnt >= BPF_MAXINSNS) + return -EINVAL; + + if (type == BPF_PROG_TYPE_KPROBE && + attr->kern_version != LINUX_VERSION_CODE) + return -EINVAL; + + if (type != BPF_PROG_TYPE_SOCKET_FILTER && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* plain bpf_prog allocation */ + prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER); + if (!prog) + return -ENOMEM; + + err = bpf_prog_charge_memlock(prog); + if (err) + goto free_prog_nouncharge; + + prog->len = attr->insn_cnt; + + err = -EFAULT; + if (copy_from_user(prog->insns, u64_to_ptr(attr->insns), + prog->len * sizeof(struct bpf_insn)) != 0) + goto free_prog; + + prog->orig_prog = NULL; + prog->jited = 0; + + atomic_set(&prog->aux->refcnt, 1); + prog->gpl_compatible = is_gpl ? 1 : 0; + + /* find program type: socket_filter vs tracing_filter */ + err = find_prog_type(type, prog); + if (err < 0) + goto free_prog; + + /* run eBPF verifier */ + err = bpf_check(&prog, attr); + if (err < 0) + goto free_used_maps; + + /* eBPF program is ready to be JITed */ + err = bpf_prog_select_runtime(prog); + if (err < 0) + goto free_used_maps; + + err = bpf_prog_new_fd(prog); + if (err < 0) + /* failed to allocate fd */ + goto free_used_maps; + + return err; + +free_used_maps: + free_used_maps(prog->aux); +free_prog: + bpf_prog_uncharge_memlock(prog); +free_prog_nouncharge: + bpf_prog_free(prog); + return err; +} + +#define BPF_OBJ_LAST_FIELD bpf_fd + +static int bpf_obj_pin(const union bpf_attr *attr) +{ + if (CHECK_ATTR(BPF_OBJ)) + return -EINVAL; + + return bpf_obj_pin_user(attr->bpf_fd, u64_to_ptr(attr->pathname)); +} + +static int bpf_obj_get(const union bpf_attr *attr) +{ + if (CHECK_ATTR(BPF_OBJ) || attr->bpf_fd != 0) + return -EINVAL; + + return bpf_obj_get_user(u64_to_ptr(attr->pathname)); +} + +SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size) +{ + union bpf_attr attr; + int err; + + if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) + return -EPERM; + + if (!access_ok(VERIFY_READ, uattr, 1)) + return -EFAULT; + + if (size > PAGE_SIZE) /* silly large */ + return -E2BIG; + + /* If we're handed a bigger struct than we know of, + * ensure all the unknown bits are 0 - i.e. new + * user-space does not rely on any kernel feature + * extensions we dont know about yet. + */ + if (size > sizeof(attr)) { + unsigned char __user *addr; + unsigned char __user *end; + unsigned char val; + + addr = (void __user *)uattr + sizeof(attr); + end = (void __user *)uattr + size; + + for (; addr < end; addr++) { + err = get_user(val, addr); + if (err) + return err; + if (val) + return -E2BIG; + } + size = sizeof(attr); + } + + /* copy attributes from user space, may be less than sizeof(bpf_attr) */ + memset(&attr, 0, sizeof(attr)); + if (copy_from_user(&attr, uattr, size) != 0) + return -EFAULT; + + switch (cmd) { + case BPF_MAP_CREATE: + err = map_create(&attr); + break; + case BPF_MAP_LOOKUP_ELEM: + err = map_lookup_elem(&attr); + break; + case BPF_MAP_UPDATE_ELEM: + err = map_update_elem(&attr); + break; + case BPF_MAP_DELETE_ELEM: + err = map_delete_elem(&attr); + break; + case BPF_MAP_GET_NEXT_KEY: + err = map_get_next_key(&attr); + break; + case BPF_PROG_LOAD: + err = bpf_prog_load(&attr); + break; + case BPF_OBJ_PIN: + err = bpf_obj_pin(&attr); + break; + case BPF_OBJ_GET: + err = bpf_obj_get(&attr); + break; + default: + err = -EINVAL; + break; + } + + return err; +} |