summaryrefslogtreecommitdiffstats
path: root/kernel
diff options
context:
space:
mode:
Diffstat (limited to 'kernel')
-rw-r--r--kernel/bpf/Makefile6
-rw-r--r--kernel/bpf/core.c29
-rw-r--r--kernel/bpf/syscall.c606
-rw-r--r--kernel/bpf/test_stub.c116
-rw-r--r--kernel/bpf/verifier.c1777
-rw-r--r--kernel/sys_ni.c3
6 files changed, 2522 insertions, 15 deletions
diff --git a/kernel/bpf/Makefile b/kernel/bpf/Makefile
index 6a71145e2769..45427239f375 100644
--- a/kernel/bpf/Makefile
+++ b/kernel/bpf/Makefile
@@ -1 +1,5 @@
-obj-y := core.o
+obj-y := core.o syscall.o verifier.o
+
+ifdef CONFIG_TEST_BPF
+obj-y += test_stub.o
+endif
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index 8b7002488251..f0c30c59b317 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -27,6 +27,7 @@
#include <linux/random.h>
#include <linux/moduleloader.h>
#include <asm/unaligned.h>
+#include <linux/bpf.h>
/* Registers */
#define BPF_R0 regs[BPF_REG_0]
@@ -71,7 +72,7 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
{
gfp_t gfp_flags = GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO |
gfp_extra_flags;
- struct bpf_work_struct *ws;
+ struct bpf_prog_aux *aux;
struct bpf_prog *fp;
size = round_up(size, PAGE_SIZE);
@@ -79,14 +80,14 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags)
if (fp == NULL)
return NULL;
- ws = kmalloc(sizeof(*ws), GFP_KERNEL | gfp_extra_flags);
- if (ws == NULL) {
+ aux = kzalloc(sizeof(*aux), GFP_KERNEL | gfp_extra_flags);
+ if (aux == NULL) {
vfree(fp);
return NULL;
}
fp->pages = size / PAGE_SIZE;
- fp->work = ws;
+ fp->aux = aux;
return fp;
}
@@ -110,10 +111,10 @@ struct bpf_prog *bpf_prog_realloc(struct bpf_prog *fp_old, unsigned int size,
memcpy(fp, fp_old, fp_old->pages * PAGE_SIZE);
fp->pages = size / PAGE_SIZE;
- /* We keep fp->work from fp_old around in the new
+ /* We keep fp->aux from fp_old around in the new
* reallocated structure.
*/
- fp_old->work = NULL;
+ fp_old->aux = NULL;
__bpf_prog_free(fp_old);
}
@@ -123,7 +124,7 @@ EXPORT_SYMBOL_GPL(bpf_prog_realloc);
void __bpf_prog_free(struct bpf_prog *fp)
{
- kfree(fp->work);
+ kfree(fp->aux);
vfree(fp);
}
EXPORT_SYMBOL_GPL(__bpf_prog_free);
@@ -638,19 +639,19 @@ EXPORT_SYMBOL_GPL(bpf_prog_select_runtime);
static void bpf_prog_free_deferred(struct work_struct *work)
{
- struct bpf_work_struct *ws;
+ struct bpf_prog_aux *aux;
- ws = container_of(work, struct bpf_work_struct, work);
- bpf_jit_free(ws->prog);
+ aux = container_of(work, struct bpf_prog_aux, work);
+ bpf_jit_free(aux->prog);
}
/* Free internal BPF program */
void bpf_prog_free(struct bpf_prog *fp)
{
- struct bpf_work_struct *ws = fp->work;
+ struct bpf_prog_aux *aux = fp->aux;
- INIT_WORK(&ws->work, bpf_prog_free_deferred);
- ws->prog = fp;
- schedule_work(&ws->work);
+ INIT_WORK(&aux->work, bpf_prog_free_deferred);
+ aux->prog = fp;
+ schedule_work(&aux->work);
}
EXPORT_SYMBOL_GPL(bpf_prog_free);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
new file mode 100644
index 000000000000..ba61c8c16032
--- /dev/null
+++ b/kernel/bpf/syscall.c
@@ -0,0 +1,606 @@
+/* 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>
+
+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);
+}
+
+/* called from workqueue */
+static void bpf_map_free_deferred(struct work_struct *work)
+{
+ struct bpf_map *map = container_of(work, struct bpf_map, work);
+
+ /* implementation dependent freeing */
+ map->ops->map_free(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);
+ }
+}
+
+static int bpf_map_release(struct inode *inode, struct file *filp)
+{
+ struct bpf_map *map = filp->private_data;
+
+ bpf_map_put(map);
+ return 0;
+}
+
+static const struct file_operations bpf_map_fops = {
+ .release = bpf_map_release,
+};
+
+/* 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);
+
+ err = anon_inode_getfd("bpf-map", &bpf_map_fops, map, O_RDWR | O_CLOEXEC);
+
+ if (err < 0)
+ /* failed to allocate fd */
+ goto free_map;
+
+ return err;
+
+free_map:
+ 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)
+{
+ struct bpf_map *map;
+
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ if (f.file->f_op != &bpf_map_fops) {
+ fdput(f);
+ return ERR_PTR(-EINVAL);
+ }
+
+ map = f.file->private_data;
+
+ 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 fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_LOOKUP_ELEM))
+ return -EINVAL;
+
+ 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 = -ESRCH;
+ rcu_read_lock();
+ value = map->ops->map_lookup_elem(map, key);
+ if (!value)
+ goto err_unlock;
+
+ err = -EFAULT;
+ if (copy_to_user(uvalue, value, map->value_size) != 0)
+ goto err_unlock;
+
+ err = 0;
+
+err_unlock:
+ rcu_read_unlock();
+free_key:
+ kfree(key);
+err_put:
+ fdput(f);
+ return err;
+}
+
+#define BPF_MAP_UPDATE_ELEM_LAST_FIELD value
+
+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 fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *value;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_UPDATE_ELEM))
+ return -EINVAL;
+
+ 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);
+ 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);
+ 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 fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_DELETE_ELEM))
+ return -EINVAL;
+
+ 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 fd f = fdget(ufd);
+ struct bpf_map *map;
+ void *key, *next_key;
+ int err;
+
+ if (CHECK_ATTR(BPF_MAP_GET_NEXT_KEY))
+ return -EINVAL;
+
+ 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;
+ 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->aux->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);
+}
+
+/* fixup insn->imm field of bpf_call instructions:
+ * if (insn->imm == BPF_FUNC_map_lookup_elem)
+ * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
+ * else if (insn->imm == BPF_FUNC_map_update_elem)
+ * insn->imm = bpf_map_update_elem - __bpf_call_base;
+ * else ...
+ *
+ * this function is called after eBPF program passed verification
+ */
+static void fixup_bpf_calls(struct bpf_prog *prog)
+{
+ const struct bpf_func_proto *fn;
+ int i;
+
+ for (i = 0; i < prog->len; i++) {
+ struct bpf_insn *insn = &prog->insnsi[i];
+
+ if (insn->code == (BPF_JMP | BPF_CALL)) {
+ /* we reach here when program has bpf_call instructions
+ * and it passed bpf_check(), means that
+ * ops->get_func_proto must have been supplied, check it
+ */
+ BUG_ON(!prog->aux->ops->get_func_proto);
+
+ fn = prog->aux->ops->get_func_proto(insn->imm);
+ /* all functions that have prototype and verifier allowed
+ * programs to call them, must be real in-kernel functions
+ */
+ BUG_ON(!fn->func);
+ insn->imm = fn->func - __bpf_call_base;
+ }
+ }
+}
+
+/* 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);
+}
+
+void bpf_prog_put(struct bpf_prog *prog)
+{
+ if (atomic_dec_and_test(&prog->aux->refcnt)) {
+ free_used_maps(prog->aux);
+ bpf_prog_free(prog);
+ }
+}
+
+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,
+};
+
+static struct bpf_prog *get_prog(struct fd f)
+{
+ struct bpf_prog *prog;
+
+ if (!f.file)
+ return ERR_PTR(-EBADF);
+
+ if (f.file->f_op != &bpf_prog_fops) {
+ fdput(f);
+ return ERR_PTR(-EINVAL);
+ }
+
+ prog = f.file->private_data;
+
+ 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 = get_prog(f);
+
+ if (IS_ERR(prog))
+ return prog;
+
+ atomic_inc(&prog->aux->refcnt);
+ fdput(f);
+ return prog;
+}
+
+/* last field in 'union bpf_attr' used by this command */
+#define BPF_PROG_LOAD_LAST_FIELD log_buf
+
+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;
+
+ /* plain bpf_prog allocation */
+ prog = bpf_prog_alloc(bpf_prog_size(attr->insn_cnt), GFP_USER);
+ if (!prog)
+ return -ENOMEM;
+
+ 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 = false;
+
+ atomic_set(&prog->aux->refcnt, 1);
+ prog->aux->is_gpl_compatible = is_gpl;
+
+ /* 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;
+
+ /* fixup BPF_CALL->imm field */
+ fixup_bpf_calls(prog);
+
+ /* eBPF program is ready to be JITed */
+ bpf_prog_select_runtime(prog);
+
+ err = anon_inode_getfd("bpf-prog", &bpf_prog_fops, prog, O_RDWR | O_CLOEXEC);
+
+ 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_free(prog);
+ return err;
+}
+
+SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
+{
+ union bpf_attr attr = {};
+ int err;
+
+ /* the syscall is limited to root temporarily. This restriction will be
+ * lifted when security audit is clean. Note that eBPF+tracing must have
+ * this restriction, since it may pass kernel data to user space
+ */
+ if (!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) */
+ 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;
+ default:
+ err = -EINVAL;
+ break;
+ }
+
+ return err;
+}
diff --git a/kernel/bpf/test_stub.c b/kernel/bpf/test_stub.c
new file mode 100644
index 000000000000..fcaddff4003e
--- /dev/null
+++ b/kernel/bpf/test_stub.c
@@ -0,0 +1,116 @@
+/* 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.
+ */
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/bpf.h>
+
+/* test stubs for BPF_MAP_TYPE_UNSPEC and for BPF_PROG_TYPE_UNSPEC
+ * to be used by user space verifier testsuite
+ */
+struct bpf_context {
+ u64 arg1;
+ u64 arg2;
+};
+
+static u64 test_func(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+{
+ return 0;
+}
+
+static struct bpf_func_proto test_funcs[] = {
+ [BPF_FUNC_unspec] = {
+ .func = test_func,
+ .gpl_only = true,
+ .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+ .arg1_type = ARG_CONST_MAP_PTR,
+ .arg2_type = ARG_PTR_TO_MAP_KEY,
+ },
+};
+
+static const struct bpf_func_proto *test_func_proto(enum bpf_func_id func_id)
+{
+ if (func_id < 0 || func_id >= ARRAY_SIZE(test_funcs))
+ return NULL;
+ return &test_funcs[func_id];
+}
+
+static const struct bpf_context_access {
+ int size;
+ enum bpf_access_type type;
+} test_ctx_access[] = {
+ [offsetof(struct bpf_context, arg1)] = {
+ FIELD_SIZEOF(struct bpf_context, arg1),
+ BPF_READ
+ },
+ [offsetof(struct bpf_context, arg2)] = {
+ FIELD_SIZEOF(struct bpf_context, arg2),
+ BPF_READ
+ },
+};
+
+static bool test_is_valid_access(int off, int size, enum bpf_access_type type)
+{
+ const struct bpf_context_access *access;
+
+ if (off < 0 || off >= ARRAY_SIZE(test_ctx_access))
+ return false;
+
+ access = &test_ctx_access[off];
+ if (access->size == size && (access->type & type))
+ return true;
+
+ return false;
+}
+
+static struct bpf_verifier_ops test_ops = {
+ .get_func_proto = test_func_proto,
+ .is_valid_access = test_is_valid_access,
+};
+
+static struct bpf_prog_type_list tl_prog = {
+ .ops = &test_ops,
+ .type = BPF_PROG_TYPE_UNSPEC,
+};
+
+static struct bpf_map *test_map_alloc(union bpf_attr *attr)
+{
+ struct bpf_map *map;
+
+ map = kzalloc(sizeof(*map), GFP_USER);
+ if (!map)
+ return ERR_PTR(-ENOMEM);
+
+ map->key_size = attr->key_size;
+ map->value_size = attr->value_size;
+ map->max_entries = attr->max_entries;
+ return map;
+}
+
+static void test_map_free(struct bpf_map *map)
+{
+ kfree(map);
+}
+
+static struct bpf_map_ops test_map_ops = {
+ .map_alloc = test_map_alloc,
+ .map_free = test_map_free,
+};
+
+static struct bpf_map_type_list tl_map = {
+ .ops = &test_map_ops,
+ .type = BPF_MAP_TYPE_UNSPEC,
+};
+
+static int __init register_test_ops(void)
+{
+ bpf_register_map_type(&tl_map);
+ bpf_register_prog_type(&tl_prog);
+ return 0;
+}
+late_initcall(register_test_ops);
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
new file mode 100644
index 000000000000..a086dd3210a8
--- /dev/null
+++ b/kernel/bpf/verifier.c
@@ -0,0 +1,1777 @@
+/* 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/kernel.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <net/netlink.h>
+#include <linux/file.h>
+#include <linux/vmalloc.h>
+
+/* bpf_check() is a static code analyzer that walks eBPF program
+ * instruction by instruction and updates register/stack state.
+ * All paths of conditional branches are analyzed until 'bpf_exit' insn.
+ *
+ * The first pass is depth-first-search to check that the program is a DAG.
+ * It rejects the following programs:
+ * - larger than BPF_MAXINSNS insns
+ * - if loop is present (detected via back-edge)
+ * - unreachable insns exist (shouldn't be a forest. program = one function)
+ * - out of bounds or malformed jumps
+ * The second pass is all possible path descent from the 1st insn.
+ * Since it's analyzing all pathes through the program, the length of the
+ * analysis is limited to 32k insn, which may be hit even if total number of
+ * insn is less then 4K, but there are too many branches that change stack/regs.
+ * Number of 'branches to be analyzed' is limited to 1k
+ *
+ * On entry to each instruction, each register has a type, and the instruction
+ * changes the types of the registers depending on instruction semantics.
+ * If instruction is BPF_MOV64_REG(BPF_REG_1, BPF_REG_5), then type of R5 is
+ * copied to R1.
+ *
+ * All registers are 64-bit.
+ * R0 - return register
+ * R1-R5 argument passing registers
+ * R6-R9 callee saved registers
+ * R10 - frame pointer read-only
+ *
+ * At the start of BPF program the register R1 contains a pointer to bpf_context
+ * and has type PTR_TO_CTX.
+ *
+ * Verifier tracks arithmetic operations on pointers in case:
+ * BPF_MOV64_REG(BPF_REG_1, BPF_REG_10),
+ * BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -20),
+ * 1st insn copies R10 (which has FRAME_PTR) type into R1
+ * and 2nd arithmetic instruction is pattern matched to recognize
+ * that it wants to construct a pointer to some element within stack.
+ * So after 2nd insn, the register R1 has type PTR_TO_STACK
+ * (and -20 constant is saved for further stack bounds checking).
+ * Meaning that this reg is a pointer to stack plus known immediate constant.
+ *
+ * Most of the time the registers have UNKNOWN_VALUE type, which
+ * means the register has some value, but it's not a valid pointer.
+ * (like pointer plus pointer becomes UNKNOWN_VALUE type)
+ *
+ * When verifier sees load or store instructions the type of base register
+ * can be: PTR_TO_MAP_VALUE, PTR_TO_CTX, FRAME_PTR. These are three pointer
+ * types recognized by check_mem_access() function.
+ *
+ * PTR_TO_MAP_VALUE means that this register is pointing to 'map element value'
+ * and the range of [ptr, ptr + map's value_size) is accessible.
+ *
+ * registers used to pass values to function calls are checked against
+ * function argument constraints.
+ *
+ * ARG_PTR_TO_MAP_KEY is one of such argument constraints.
+ * It means that the register type passed to this function must be
+ * PTR_TO_STACK and it will be used inside the function as
+ * 'pointer to map element key'
+ *
+ * For example the argument constraints for bpf_map_lookup_elem():
+ * .ret_type = RET_PTR_TO_MAP_VALUE_OR_NULL,
+ * .arg1_type = ARG_CONST_MAP_PTR,
+ * .arg2_type = ARG_PTR_TO_MAP_KEY,
+ *
+ * ret_type says that this function returns 'pointer to map elem value or null'
+ * function expects 1st argument to be a const pointer to 'struct bpf_map' and
+ * 2nd argument should be a pointer to stack, which will be used inside
+ * the helper function as a pointer to map element key.
+ *
+ * On the kernel side the helper function looks like:
+ * u64 bpf_map_lookup_elem(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5)
+ * {
+ * struct bpf_map *map = (struct bpf_map *) (unsigned long) r1;
+ * void *key = (void *) (unsigned long) r2;
+ * void *value;
+ *
+ * here kernel can access 'key' and 'map' pointers safely, knowing that
+ * [key, key + map->key_size) bytes are valid and were initialized on
+ * the stack of eBPF program.
+ * }
+ *
+ * Corresponding eBPF program may look like:
+ * BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), // after this insn R2 type is FRAME_PTR
+ * BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), // after this insn R2 type is PTR_TO_STACK
+ * BPF_LD_MAP_FD(BPF_REG_1, map_fd), // after this insn R1 type is CONST_PTR_TO_MAP
+ * BPF_RAW_INSN(BPF_JMP | BPF_CALL, 0, 0, 0, BPF_FUNC_map_lookup_elem),
+ * here verifier looks at prototype of map_lookup_elem() and sees:
+ * .arg1_type == ARG_CONST_MAP_PTR and R1->type == CONST_PTR_TO_MAP, which is ok,
+ * Now verifier knows that this map has key of R1->map_ptr->key_size bytes
+ *
+ * Then .arg2_type == ARG_PTR_TO_MAP_KEY and R2->type == PTR_TO_STACK, ok so far,
+ * Now verifier checks that [R2, R2 + map's key_size) are within stack limits
+ * and were initialized prior to this call.
+ * If it's ok, then verifier allows this BPF_CALL insn and looks at
+ * .ret_type which is RET_PTR_TO_MAP_VALUE_OR_NULL, so it sets
+ * R0->type = PTR_TO_MAP_VALUE_OR_NULL which means bpf_map_lookup_elem() function
+ * returns ether pointer to map value or NULL.
+ *
+ * When type PTR_TO_MAP_VALUE_OR_NULL passes through 'if (reg != 0) goto +off'
+ * insn, the register holding that pointer in the true branch changes state to
+ * PTR_TO_MAP_VALUE and the same register changes state to CONST_IMM in the false
+ * branch. See check_cond_jmp_op().
+ *
+ * After the call R0 is set to return type of the function and registers R1-R5
+ * are set to NOT_INIT to indicate that they are no longer readable.
+ */
+
+/* types of values stored in eBPF registers */
+enum bpf_reg_type {
+ NOT_INIT = 0, /* nothing was written into register */
+ UNKNOWN_VALUE, /* reg doesn't contain a valid pointer */
+ PTR_TO_CTX, /* reg points to bpf_context */
+ CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
+ PTR_TO_MAP_VALUE, /* reg points to map element value */
+ PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
+ FRAME_PTR, /* reg == frame_pointer */
+ PTR_TO_STACK, /* reg == frame_pointer + imm */
+ CONST_IMM, /* constant integer value */
+};
+
+struct reg_state {
+ enum bpf_reg_type type;
+ union {
+ /* valid when type == CONST_IMM | PTR_TO_STACK */
+ int imm;
+
+ /* valid when type == CONST_PTR_TO_MAP | PTR_TO_MAP_VALUE |
+ * PTR_TO_MAP_VALUE_OR_NULL
+ */
+ struct bpf_map *map_ptr;
+ };
+};
+
+enum bpf_stack_slot_type {
+ STACK_INVALID, /* nothing was stored in this stack slot */
+ STACK_SPILL, /* 1st byte of register spilled into stack */
+ STACK_SPILL_PART, /* other 7 bytes of register spill */
+ STACK_MISC /* BPF program wrote some data into this slot */
+};
+
+struct bpf_stack_slot {
+ enum bpf_stack_slot_type stype;
+ struct reg_state reg_st;
+};
+
+/* state of the program:
+ * type of all registers and stack info
+ */
+struct verifier_state {
+ struct reg_state regs[MAX_BPF_REG];
+ struct bpf_stack_slot stack[MAX_BPF_STACK];
+};
+
+/* linked list of verifier states used to prune search */
+struct verifier_state_list {
+ struct verifier_state state;
+ struct verifier_state_list *next;
+};
+
+/* verifier_state + insn_idx are pushed to stack when branch is encountered */
+struct verifier_stack_elem {
+ /* verifer state is 'st'
+ * before processing instruction 'insn_idx'
+ * and after processing instruction 'prev_insn_idx'
+ */
+ struct verifier_state st;
+ int insn_idx;
+ int prev_insn_idx;
+ struct verifier_stack_elem *next;
+};
+
+#define MAX_USED_MAPS 64 /* max number of maps accessed by one eBPF program */
+
+/* single container for all structs
+ * one verifier_env per bpf_check() call
+ */
+struct verifier_env {
+ struct bpf_prog *prog; /* eBPF program being verified */
+ struct verifier_stack_elem *head; /* stack of verifier states to be processed */
+ int stack_size; /* number of states to be processed */
+ struct verifier_state cur_state; /* current verifier state */
+ struct bpf_map *used_maps[MAX_USED_MAPS]; /* array of map's used by eBPF program */
+ u32 used_map_cnt; /* number of used maps */
+};
+
+/* verbose verifier prints what it's seeing
+ * bpf_check() is called under lock, so no race to access these global vars
+ */
+static u32 log_level, log_size, log_len;
+static char *log_buf;
+
+static DEFINE_MUTEX(bpf_verifier_lock);
+
+/* log_level controls verbosity level of eBPF verifier.
+ * verbose() is used to dump the verification trace to the log, so the user
+ * can figure out what's wrong with the program
+ */
+static void verbose(const char *fmt, ...)
+{
+ va_list args;
+
+ if (log_level == 0 || log_len >= log_size - 1)
+ return;
+
+ va_start(args, fmt);
+ log_len += vscnprintf(log_buf + log_len, log_size - log_len, fmt, args);
+ va_end(args);
+}
+
+/* string representation of 'enum bpf_reg_type' */
+static const char * const reg_type_str[] = {
+ [NOT_INIT] = "?",
+ [UNKNOWN_VALUE] = "inv",
+ [PTR_TO_CTX] = "ctx",
+ [CONST_PTR_TO_MAP] = "map_ptr",
+ [PTR_TO_MAP_VALUE] = "map_value",
+ [PTR_TO_MAP_VALUE_OR_NULL] = "map_value_or_null",
+ [FRAME_PTR] = "fp",
+ [PTR_TO_STACK] = "fp",
+ [CONST_IMM] = "imm",
+};
+
+static void print_verifier_state(struct verifier_env *env)
+{
+ enum bpf_reg_type t;
+ int i;
+
+ for (i = 0; i < MAX_BPF_REG; i++) {
+ t = env->cur_state.regs[i].type;
+ if (t == NOT_INIT)
+ continue;
+ verbose(" R%d=%s", i, reg_type_str[t]);
+ if (t == CONST_IMM || t == PTR_TO_STACK)
+ verbose("%d", env->cur_state.regs[i].imm);
+ else if (t == CONST_PTR_TO_MAP || t == PTR_TO_MAP_VALUE ||
+ t == PTR_TO_MAP_VALUE_OR_NULL)
+ verbose("(ks=%d,vs=%d)",
+ env->cur_state.regs[i].map_ptr->key_size,
+ env->cur_state.regs[i].map_ptr->value_size);
+ }
+ for (i = 0; i < MAX_BPF_STACK; i++) {
+ if (env->cur_state.stack[i].stype == STACK_SPILL)
+ verbose(" fp%d=%s", -MAX_BPF_STACK + i,
+ reg_type_str[env->cur_state.stack[i].reg_st.type]);
+ }
+ verbose("\n");
+}
+
+static const char *const bpf_class_string[] = {
+ [BPF_LD] = "ld",
+ [BPF_LDX] = "ldx",
+ [BPF_ST] = "st",
+ [BPF_STX] = "stx",
+ [BPF_ALU] = "alu",
+ [BPF_JMP] = "jmp",
+ [BPF_RET] = "BUG",
+ [BPF_ALU64] = "alu64",
+};
+
+static const char *const bpf_alu_string[] = {
+ [BPF_ADD >> 4] = "+=",
+ [BPF_SUB >> 4] = "-=",
+ [BPF_MUL >> 4] = "*=",
+ [BPF_DIV >> 4] = "/=",
+ [BPF_OR >> 4] = "|=",
+ [BPF_AND >> 4] = "&=",
+ [BPF_LSH >> 4] = "<<=",
+ [BPF_RSH >> 4] = ">>=",
+ [BPF_NEG >> 4] = "neg",
+ [BPF_MOD >> 4] = "%=",
+ [BPF_XOR >> 4] = "^=",
+ [BPF_MOV >> 4] = "=",
+ [BPF_ARSH >> 4] = "s>>=",
+ [BPF_END >> 4] = "endian",
+};
+
+static const char *const bpf_ldst_string[] = {
+ [BPF_W >> 3] = "u32",
+ [BPF_H >> 3] = "u16",
+ [BPF_B >> 3] = "u8",
+ [BPF_DW >> 3] = "u64",
+};
+
+static const char *const bpf_jmp_string[] = {
+ [BPF_JA >> 4] = "jmp",
+ [BPF_JEQ >> 4] = "==",
+ [BPF_JGT >> 4] = ">",
+ [BPF_JGE >> 4] = ">=",
+ [BPF_JSET >> 4] = "&",
+ [BPF_JNE >> 4] = "!=",
+ [BPF_JSGT >> 4] = "s>",
+ [BPF_JSGE >> 4] = "s>=",
+ [BPF_CALL >> 4] = "call",
+ [BPF_EXIT >> 4] = "exit",
+};
+
+static void print_bpf_insn(struct bpf_insn *insn)
+{
+ u8 class = BPF_CLASS(insn->code);
+
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ if (BPF_SRC(insn->code) == BPF_X)
+ verbose("(%02x) %sr%d %s %sr%d\n",
+ insn->code, class == BPF_ALU ? "(u32) " : "",
+ insn->dst_reg,
+ bpf_alu_string[BPF_OP(insn->code) >> 4],
+ class == BPF_ALU ? "(u32) " : "",
+ insn->src_reg);
+ else
+ verbose("(%02x) %sr%d %s %s%d\n",
+ insn->code, class == BPF_ALU ? "(u32) " : "",
+ insn->dst_reg,
+ bpf_alu_string[BPF_OP(insn->code) >> 4],
+ class == BPF_ALU ? "(u32) " : "",
+ insn->imm);
+ } else if (class == BPF_STX) {
+ if (BPF_MODE(insn->code) == BPF_MEM)
+ verbose("(%02x) *(%s *)(r%d %+d) = r%d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg,
+ insn->off, insn->src_reg);
+ else if (BPF_MODE(insn->code) == BPF_XADD)
+ verbose("(%02x) lock *(%s *)(r%d %+d) += r%d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg, insn->off,
+ insn->src_reg);
+ else
+ verbose("BUG_%02x\n", insn->code);
+ } else if (class == BPF_ST) {
+ if (BPF_MODE(insn->code) != BPF_MEM) {
+ verbose("BUG_st_%02x\n", insn->code);
+ return;
+ }
+ verbose("(%02x) *(%s *)(r%d %+d) = %d\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->dst_reg,
+ insn->off, insn->imm);
+ } else if (class == BPF_LDX) {
+ if (BPF_MODE(insn->code) != BPF_MEM) {
+ verbose("BUG_ldx_%02x\n", insn->code);
+ return;
+ }
+ verbose("(%02x) r%d = *(%s *)(r%d %+d)\n",
+ insn->code, insn->dst_reg,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->src_reg, insn->off);
+ } else if (class == BPF_LD) {
+ if (BPF_MODE(insn->code) == BPF_ABS) {
+ verbose("(%02x) r0 = *(%s *)skb[%d]\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->imm);
+ } else if (BPF_MODE(insn->code) == BPF_IND) {
+ verbose("(%02x) r0 = *(%s *)skb[r%d + %d]\n",
+ insn->code,
+ bpf_ldst_string[BPF_SIZE(insn->code) >> 3],
+ insn->src_reg, insn->imm);
+ } else if (BPF_MODE(insn->code) == BPF_IMM) {
+ verbose("(%02x) r%d = 0x%x\n",
+ insn->code, insn->dst_reg, insn->imm);
+ } else {
+ verbose("BUG_ld_%02x\n", insn->code);
+ return;
+ }
+ } else if (class == BPF_JMP) {
+ u8 opcode = BPF_OP(insn->code);
+
+ if (opcode == BPF_CALL) {
+ verbose("(%02x) call %d\n", insn->code, insn->imm);
+ } else if (insn->code == (BPF_JMP | BPF_JA)) {
+ verbose("(%02x) goto pc%+d\n",
+ insn->code, insn->off);
+ } else if (insn->code == (BPF_JMP | BPF_EXIT)) {
+ verbose("(%02x) exit\n", insn->code);
+ } else if (BPF_SRC(insn->code) == BPF_X) {
+ verbose("(%02x) if r%d %s r%d goto pc%+d\n",
+ insn->code, insn->dst_reg,
+ bpf_jmp_string[BPF_OP(insn->code) >> 4],
+ insn->src_reg, insn->off);
+ } else {
+ verbose("(%02x) if r%d %s 0x%x goto pc%+d\n",
+ insn->code, insn->dst_reg,
+ bpf_jmp_string[BPF_OP(insn->code) >> 4],
+ insn->imm, insn->off);
+ }
+ } else {
+ verbose("(%02x) %s\n", insn->code, bpf_class_string[class]);
+ }
+}
+
+static int pop_stack(struct verifier_env *env, int *prev_insn_idx)
+{
+ struct verifier_stack_elem *elem;
+ int insn_idx;
+
+ if (env->head == NULL)
+ return -1;
+
+ memcpy(&env->cur_state, &env->head->st, sizeof(env->cur_state));
+ insn_idx = env->head->insn_idx;
+ if (prev_insn_idx)
+ *prev_insn_idx = env->head->prev_insn_idx;
+ elem = env->head->next;
+ kfree(env->head);
+ env->head = elem;
+ env->stack_size--;
+ return insn_idx;
+}
+
+static struct verifier_state *push_stack(struct verifier_env *env, int insn_idx,
+ int prev_insn_idx)
+{
+ struct verifier_stack_elem *elem;
+
+ elem = kmalloc(sizeof(struct verifier_stack_elem), GFP_KERNEL);
+ if (!elem)
+ goto err;
+
+ memcpy(&elem->st, &env->cur_state, sizeof(env->cur_state));
+ elem->insn_idx = insn_idx;
+ elem->prev_insn_idx = prev_insn_idx;
+ elem->next = env->head;
+ env->head = elem;
+ env->stack_size++;
+ if (env->stack_size > 1024) {
+ verbose("BPF program is too complex\n");
+ goto err;
+ }
+ return &elem->st;
+err:
+ /* pop all elements and return */
+ while (pop_stack(env, NULL) >= 0);
+ return NULL;
+}
+
+#define CALLER_SAVED_REGS 6
+static const int caller_saved[CALLER_SAVED_REGS] = {
+ BPF_REG_0, BPF_REG_1, BPF_REG_2, BPF_REG_3, BPF_REG_4, BPF_REG_5
+};
+
+static void init_reg_state(struct reg_state *regs)
+{
+ int i;
+
+ for (i = 0; i < MAX_BPF_REG; i++) {
+ regs[i].type = NOT_INIT;
+ regs[i].imm = 0;
+ regs[i].map_ptr = NULL;
+ }
+
+ /* frame pointer */
+ regs[BPF_REG_FP].type = FRAME_PTR;
+
+ /* 1st arg to a function */
+ regs[BPF_REG_1].type = PTR_TO_CTX;
+}
+
+static void mark_reg_unknown_value(struct reg_state *regs, u32 regno)
+{
+ BUG_ON(regno >= MAX_BPF_REG);
+ regs[regno].type = UNKNOWN_VALUE;
+ regs[regno].imm = 0;
+ regs[regno].map_ptr = NULL;
+}
+
+enum reg_arg_type {
+ SRC_OP, /* register is used as source operand */
+ DST_OP, /* register is used as destination operand */
+ DST_OP_NO_MARK /* same as above, check only, don't mark */
+};
+
+static int check_reg_arg(struct reg_state *regs, u32 regno,
+ enum reg_arg_type t)
+{
+ if (regno >= MAX_BPF_REG) {
+ verbose("R%d is invalid\n", regno);
+ return -EINVAL;
+ }
+
+ if (t == SRC_OP) {
+ /* check whether register used as source operand can be read */
+ if (regs[regno].type == NOT_INIT) {
+ verbose("R%d !read_ok\n", regno);
+ return -EACCES;
+ }
+ } else {
+ /* check whether register used as dest operand can be written to */
+ if (regno == BPF_REG_FP) {
+ verbose("frame pointer is read only\n");
+ return -EACCES;
+ }
+ if (t == DST_OP)
+ mark_reg_unknown_value(regs, regno);
+ }
+ return 0;
+}
+
+static int bpf_size_to_bytes(int bpf_size)
+{
+ if (bpf_size == BPF_W)
+ return 4;
+ else if (bpf_size == BPF_H)
+ return 2;
+ else if (bpf_size == BPF_B)
+ return 1;
+ else if (bpf_size == BPF_DW)
+ return 8;
+ else
+ return -EINVAL;
+}
+
+/* check_stack_read/write functions track spill/fill of registers,
+ * stack boundary and alignment are checked in check_mem_access()
+ */
+static int check_stack_write(struct verifier_state *state, int off, int size,
+ int value_regno)
+{
+ struct bpf_stack_slot *slot;
+ int i;
+
+ if (value_regno >= 0 &&
+ (state->regs[value_regno].type == PTR_TO_MAP_VALUE ||
+ state->regs[value_regno].type == PTR_TO_STACK ||
+ state->regs[value_regno].type == PTR_TO_CTX)) {
+
+ /* register containing pointer is being spilled into stack */
+ if (size != 8) {
+ verbose("invalid size of register spill\n");
+ return -EACCES;
+ }
+
+ slot = &state->stack[MAX_BPF_STACK + off];
+ slot->stype = STACK_SPILL;
+ /* save register state */
+ slot->reg_st = state->regs[value_regno];
+ for (i = 1; i < 8; i++) {
+ slot = &state->stack[MAX_BPF_STACK + off + i];
+ slot->stype = STACK_SPILL_PART;
+ slot->reg_st.type = UNKNOWN_VALUE;
+ slot->reg_st.map_ptr = NULL;
+ }
+ } else {
+
+ /* regular write of data into stack */
+ for (i = 0; i < size; i++) {
+ slot = &state->stack[MAX_BPF_STACK + off + i];
+ slot->stype = STACK_MISC;
+ slot->reg_st.type = UNKNOWN_VALUE;
+ slot->reg_st.map_ptr = NULL;
+ }
+ }
+ return 0;
+}
+
+static int check_stack_read(struct verifier_state *state, int off, int size,
+ int value_regno)
+{
+ int i;
+ struct bpf_stack_slot *slot;
+
+ slot = &state->stack[MAX_BPF_STACK + off];
+
+ if (slot->stype == STACK_SPILL) {
+ if (size != 8) {
+ verbose("invalid size of register spill\n");
+ return -EACCES;
+ }
+ for (i = 1; i < 8; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype !=
+ STACK_SPILL_PART) {
+ verbose("corrupted spill memory\n");
+ return -EACCES;
+ }
+ }
+
+ if (value_regno >= 0)
+ /* restore register state from stack */
+ state->regs[value_regno] = slot->reg_st;
+ return 0;
+ } else {
+ for (i = 0; i < size; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype !=
+ STACK_MISC) {
+ verbose("invalid read from stack off %d+%d size %d\n",
+ off, i, size);
+ return -EACCES;
+ }
+ }
+ if (value_regno >= 0)
+ /* have read misc data from the stack */
+ mark_reg_unknown_value(state->regs, value_regno);
+ return 0;
+ }
+}
+
+/* check read/write into map element returned by bpf_map_lookup_elem() */
+static int check_map_access(struct verifier_env *env, u32 regno, int off,
+ int size)
+{
+ struct bpf_map *map = env->cur_state.regs[regno].map_ptr;
+
+ if (off < 0 || off + size > map->value_size) {
+ verbose("invalid access to map value, value_size=%d off=%d size=%d\n",
+ map->value_size, off, size);
+ return -EACCES;
+ }
+ return 0;
+}
+
+/* check access to 'struct bpf_context' fields */
+static int check_ctx_access(struct verifier_env *env, int off, int size,
+ enum bpf_access_type t)
+{
+ if (env->prog->aux->ops->is_valid_access &&
+ env->prog->aux->ops->is_valid_access(off, size, t))
+ return 0;
+
+ verbose("invalid bpf_context access off=%d size=%d\n", off, size);
+ return -EACCES;
+}
+
+/* check whether memory at (regno + off) is accessible for t = (read | write)
+ * if t==write, value_regno is a register which value is stored into memory
+ * if t==read, value_regno is a register which will receive the value from memory
+ * if t==write && value_regno==-1, some unknown value is stored into memory
+ * if t==read && value_regno==-1, don't care what we read from memory
+ */
+static int check_mem_access(struct verifier_env *env, u32 regno, int off,
+ int bpf_size, enum bpf_access_type t,
+ int value_regno)
+{
+ struct verifier_state *state = &env->cur_state;
+ int size, err = 0;
+
+ size = bpf_size_to_bytes(bpf_size);
+ if (size < 0)
+ return size;
+
+ if (off % size != 0) {
+ verbose("misaligned access off %d size %d\n", off, size);
+ return -EACCES;
+ }
+
+ if (state->regs[regno].type == PTR_TO_MAP_VALUE) {
+ err = check_map_access(env, regno, off, size);
+ if (!err && t == BPF_READ && value_regno >= 0)
+ mark_reg_unknown_value(state->regs, value_regno);
+
+ } else if (state->regs[regno].type == PTR_TO_CTX) {
+ err = check_ctx_access(env, off, size, t);
+ if (!err && t == BPF_READ && value_regno >= 0)
+ mark_reg_unknown_value(state->regs, value_regno);
+
+ } else if (state->regs[regno].type == FRAME_PTR) {
+ if (off >= 0 || off < -MAX_BPF_STACK) {
+ verbose("invalid stack off=%d size=%d\n", off, size);
+ return -EACCES;
+ }
+ if (t == BPF_WRITE)
+ err = check_stack_write(state, off, size, value_regno);
+ else
+ err = check_stack_read(state, off, size, value_regno);
+ } else {
+ verbose("R%d invalid mem access '%s'\n",
+ regno, reg_type_str[state->regs[regno].type]);
+ return -EACCES;
+ }
+ return err;
+}
+
+static int check_xadd(struct verifier_env *env, struct bpf_insn *insn)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ int err;
+
+ if ((BPF_SIZE(insn->code) != BPF_W && BPF_SIZE(insn->code) != BPF_DW) ||
+ insn->imm != 0) {
+ verbose("BPF_XADD uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check whether atomic_add can read the memory */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_READ, -1);
+ if (err)
+ return err;
+
+ /* check whether atomic_add can write into the same memory */
+ return check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE, -1);
+}
+
+/* when register 'regno' is passed into function that will read 'access_size'
+ * bytes from that pointer, make sure that it's within stack boundary
+ * and all elements of stack are initialized
+ */
+static int check_stack_boundary(struct verifier_env *env,
+ int regno, int access_size)
+{
+ struct verifier_state *state = &env->cur_state;
+ struct reg_state *regs = state->regs;
+ int off, i;
+
+ if (regs[regno].type != PTR_TO_STACK)
+ return -EACCES;
+
+ off = regs[regno].imm;
+ if (off >= 0 || off < -MAX_BPF_STACK || off + access_size > 0 ||
+ access_size <= 0) {
+ verbose("invalid stack type R%d off=%d access_size=%d\n",
+ regno, off, access_size);
+ return -EACCES;
+ }
+
+ for (i = 0; i < access_size; i++) {
+ if (state->stack[MAX_BPF_STACK + off + i].stype != STACK_MISC) {
+ verbose("invalid indirect read from stack off %d+%d size %d\n",
+ off, i, access_size);
+ return -EACCES;
+ }
+ }
+ return 0;
+}
+
+static int check_func_arg(struct verifier_env *env, u32 regno,
+ enum bpf_arg_type arg_type, struct bpf_map **mapp)
+{
+ struct reg_state *reg = env->cur_state.regs + regno;
+ enum bpf_reg_type expected_type;
+ int err = 0;
+
+ if (arg_type == ARG_ANYTHING)
+ return 0;
+
+ if (reg->type == NOT_INIT) {
+ verbose("R%d !read_ok\n", regno);
+ return -EACCES;
+ }
+
+ if (arg_type == ARG_PTR_TO_STACK || arg_type == ARG_PTR_TO_MAP_KEY ||
+ arg_type == ARG_PTR_TO_MAP_VALUE) {
+ expected_type = PTR_TO_STACK;
+ } else if (arg_type == ARG_CONST_STACK_SIZE) {
+ expected_type = CONST_IMM;
+ } else if (arg_type == ARG_CONST_MAP_PTR) {
+ expected_type = CONST_PTR_TO_MAP;
+ } else {
+ verbose("unsupported arg_type %d\n", arg_type);
+ return -EFAULT;
+ }
+
+ if (reg->type != expected_type) {
+ verbose("R%d type=%s expected=%s\n", regno,
+ reg_type_str[reg->type], reg_type_str[expected_type]);
+ return -EACCES;
+ }
+
+ if (arg_type == ARG_CONST_MAP_PTR) {
+ /* bpf_map_xxx(map_ptr) call: remember that map_ptr */
+ *mapp = reg->map_ptr;
+
+ } else if (arg_type == ARG_PTR_TO_MAP_KEY) {
+ /* bpf_map_xxx(..., map_ptr, ..., key) call:
+ * check that [key, key + map->key_size) are within
+ * stack limits and initialized
+ */
+ if (!*mapp) {
+ /* in function declaration map_ptr must come before
+ * map_key, so that it's verified and known before
+ * we have to check map_key here. Otherwise it means
+ * that kernel subsystem misconfigured verifier
+ */
+ verbose("invalid map_ptr to access map->key\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno, (*mapp)->key_size);
+
+ } else if (arg_type == ARG_PTR_TO_MAP_VALUE) {
+ /* bpf_map_xxx(..., map_ptr, ..., value) call:
+ * check [value, value + map->value_size) validity
+ */
+ if (!*mapp) {
+ /* kernel subsystem misconfigured verifier */
+ verbose("invalid map_ptr to access map->value\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno, (*mapp)->value_size);
+
+ } else if (arg_type == ARG_CONST_STACK_SIZE) {
+ /* bpf_xxx(..., buf, len) call will access 'len' bytes
+ * from stack pointer 'buf'. Check it
+ * note: regno == len, regno - 1 == buf
+ */
+ if (regno == 0) {
+ /* kernel subsystem misconfigured verifier */
+ verbose("ARG_CONST_STACK_SIZE cannot be first argument\n");
+ return -EACCES;
+ }
+ err = check_stack_boundary(env, regno - 1, reg->imm);
+ }
+
+ return err;
+}
+
+static int check_call(struct verifier_env *env, int func_id)
+{
+ struct verifier_state *state = &env->cur_state;
+ const struct bpf_func_proto *fn = NULL;
+ struct reg_state *regs = state->regs;
+ struct bpf_map *map = NULL;
+ struct reg_state *reg;
+ int i, err;
+
+ /* find function prototype */
+ if (func_id < 0 || func_id >= __BPF_FUNC_MAX_ID) {
+ verbose("invalid func %d\n", func_id);
+ return -EINVAL;
+ }
+
+ if (env->prog->aux->ops->get_func_proto)
+ fn = env->prog->aux->ops->get_func_proto(func_id);
+
+ if (!fn) {
+ verbose("unknown func %d\n", func_id);
+ return -EINVAL;
+ }
+
+ /* eBPF programs must be GPL compatible to use GPL-ed functions */
+ if (!env->prog->aux->is_gpl_compatible && fn->gpl_only) {
+ verbose("cannot call GPL only function from proprietary program\n");
+ return -EINVAL;
+ }
+
+ /* check args */
+ err = check_func_arg(env, BPF_REG_1, fn->arg1_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_2, fn->arg2_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_3, fn->arg3_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_4, fn->arg4_type, &map);
+ if (err)
+ return err;
+ err = check_func_arg(env, BPF_REG_5, fn->arg5_type, &map);
+ if (err)
+ return err;
+
+ /* reset caller saved regs */
+ for (i = 0; i < CALLER_SAVED_REGS; i++) {
+ reg = regs + caller_saved[i];
+ reg->type = NOT_INIT;
+ reg->imm = 0;
+ }
+
+ /* update return register */
+ if (fn->ret_type == RET_INTEGER) {
+ regs[BPF_REG_0].type = UNKNOWN_VALUE;
+ } else if (fn->ret_type == RET_VOID) {
+ regs[BPF_REG_0].type = NOT_INIT;
+ } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL) {
+ regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL;
+ /* remember map_ptr, so that check_map_access()
+ * can check 'value_size' boundary of memory access
+ * to map element returned from bpf_map_lookup_elem()
+ */
+ if (map == NULL) {
+ verbose("kernel subsystem misconfigured verifier\n");
+ return -EINVAL;
+ }
+ regs[BPF_REG_0].map_ptr = map;
+ } else {
+ verbose("unknown return type %d of func %d\n",
+ fn->ret_type, func_id);
+ return -EINVAL;
+ }
+ return 0;
+}
+
+/* check validity of 32-bit and 64-bit arithmetic operations */
+static int check_alu_op(struct reg_state *regs, struct bpf_insn *insn)
+{
+ u8 opcode = BPF_OP(insn->code);
+ int err;
+
+ if (opcode == BPF_END || opcode == BPF_NEG) {
+ if (opcode == BPF_NEG) {
+ if (BPF_SRC(insn->code) != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->off != 0 || insn->imm != 0) {
+ verbose("BPF_NEG uses reserved fields\n");
+ return -EINVAL;
+ }
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
+ (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
+ verbose("BPF_END uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ } else if (opcode == BPF_MOV) {
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0 || insn->off != 0) {
+ verbose("BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
+ verbose("BPF_MOV uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (BPF_CLASS(insn->code) == BPF_ALU64) {
+ /* case: R1 = R2
+ * copy register state to dest reg
+ */
+ regs[insn->dst_reg] = regs[insn->src_reg];
+ } else {
+ regs[insn->dst_reg].type = UNKNOWN_VALUE;
+ regs[insn->dst_reg].map_ptr = NULL;
+ }
+ } else {
+ /* case: R = imm
+ * remember the value we stored into this reg
+ */
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+
+ } else if (opcode > BPF_END) {
+ verbose("invalid BPF_ALU opcode %x\n", opcode);
+ return -EINVAL;
+
+ } else { /* all other ALU ops: and, sub, xor, add, ... */
+
+ bool stack_relative = false;
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0 || insn->off != 0) {
+ verbose("BPF_ALU uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0 || insn->off != 0) {
+ verbose("BPF_ALU uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ if ((opcode == BPF_MOD || opcode == BPF_DIV) &&
+ BPF_SRC(insn->code) == BPF_K && insn->imm == 0) {
+ verbose("div by zero\n");
+ return -EINVAL;
+ }
+
+ /* pattern match 'bpf_add Rx, imm' instruction */
+ if (opcode == BPF_ADD && BPF_CLASS(insn->code) == BPF_ALU64 &&
+ regs[insn->dst_reg].type == FRAME_PTR &&
+ BPF_SRC(insn->code) == BPF_K)
+ stack_relative = true;
+
+ /* check dest operand */
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (stack_relative) {
+ regs[insn->dst_reg].type = PTR_TO_STACK;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+ }
+
+ return 0;
+}
+
+static int check_cond_jmp_op(struct verifier_env *env,
+ struct bpf_insn *insn, int *insn_idx)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ struct verifier_state *other_branch;
+ u8 opcode = BPF_OP(insn->code);
+ int err;
+
+ if (opcode > BPF_EXIT) {
+ verbose("invalid BPF_JMP opcode %x\n", opcode);
+ return -EINVAL;
+ }
+
+ if (BPF_SRC(insn->code) == BPF_X) {
+ if (insn->imm != 0) {
+ verbose("BPF_JMP uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ } else {
+ if (insn->src_reg != BPF_REG_0) {
+ verbose("BPF_JMP uses reserved fields\n");
+ return -EINVAL;
+ }
+ }
+
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* detect if R == 0 where R was initialized to zero earlier */
+ if (BPF_SRC(insn->code) == BPF_K &&
+ (opcode == BPF_JEQ || opcode == BPF_JNE) &&
+ regs[insn->dst_reg].type == CONST_IMM &&
+ regs[insn->dst_reg].imm == insn->imm) {
+ if (opcode == BPF_JEQ) {
+ /* if (imm == imm) goto pc+off;
+ * only follow the goto, ignore fall-through
+ */
+ *insn_idx += insn->off;
+ return 0;
+ } else {
+ /* if (imm != imm) goto pc+off;
+ * only follow fall-through branch, since
+ * that's where the program will go
+ */
+ return 0;
+ }
+ }
+
+ other_branch = push_stack(env, *insn_idx + insn->off + 1, *insn_idx);
+ if (!other_branch)
+ return -EFAULT;
+
+ /* detect if R == 0 where R is returned value from bpf_map_lookup_elem() */
+ if (BPF_SRC(insn->code) == BPF_K &&
+ insn->imm == 0 && (opcode == BPF_JEQ ||
+ opcode == BPF_JNE) &&
+ regs[insn->dst_reg].type == PTR_TO_MAP_VALUE_OR_NULL) {
+ if (opcode == BPF_JEQ) {
+ /* next fallthrough insn can access memory via
+ * this register
+ */
+ regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
+ /* branch targer cannot access it, since reg == 0 */
+ other_branch->regs[insn->dst_reg].type = CONST_IMM;
+ other_branch->regs[insn->dst_reg].imm = 0;
+ } else {
+ other_branch->regs[insn->dst_reg].type = PTR_TO_MAP_VALUE;
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = 0;
+ }
+ } else if (BPF_SRC(insn->code) == BPF_K &&
+ (opcode == BPF_JEQ || opcode == BPF_JNE)) {
+
+ if (opcode == BPF_JEQ) {
+ /* detect if (R == imm) goto
+ * and in the target state recognize that R = imm
+ */
+ other_branch->regs[insn->dst_reg].type = CONST_IMM;
+ other_branch->regs[insn->dst_reg].imm = insn->imm;
+ } else {
+ /* detect if (R != imm) goto
+ * and in the fall-through state recognize that R = imm
+ */
+ regs[insn->dst_reg].type = CONST_IMM;
+ regs[insn->dst_reg].imm = insn->imm;
+ }
+ }
+ if (log_level)
+ print_verifier_state(env);
+ return 0;
+}
+
+/* return the map pointer stored inside BPF_LD_IMM64 instruction */
+static struct bpf_map *ld_imm64_to_map_ptr(struct bpf_insn *insn)
+{
+ u64 imm64 = ((u64) (u32) insn[0].imm) | ((u64) (u32) insn[1].imm) << 32;
+
+ return (struct bpf_map *) (unsigned long) imm64;
+}
+
+/* verify BPF_LD_IMM64 instruction */
+static int check_ld_imm(struct verifier_env *env, struct bpf_insn *insn)
+{
+ struct reg_state *regs = env->cur_state.regs;
+ int err;
+
+ if (BPF_SIZE(insn->code) != BPF_DW) {
+ verbose("invalid BPF_LD_IMM insn\n");
+ return -EINVAL;
+ }
+ if (insn->off != 0) {
+ verbose("BPF_LD_IMM64 uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP);
+ if (err)
+ return err;
+
+ if (insn->src_reg == 0)
+ /* generic move 64-bit immediate into a register */
+ return 0;
+
+ /* replace_map_fd_with_map_ptr() should have caught bad ld_imm64 */
+ BUG_ON(insn->src_reg != BPF_PSEUDO_MAP_FD);
+
+ regs[insn->dst_reg].type = CONST_PTR_TO_MAP;
+ regs[insn->dst_reg].map_ptr = ld_imm64_to_map_ptr(insn);
+ return 0;
+}
+
+/* non-recursive DFS pseudo code
+ * 1 procedure DFS-iterative(G,v):
+ * 2 label v as discovered
+ * 3 let S be a stack
+ * 4 S.push(v)
+ * 5 while S is not empty
+ * 6 t <- S.pop()
+ * 7 if t is what we're looking for:
+ * 8 return t
+ * 9 for all edges e in G.adjacentEdges(t) do
+ * 10 if edge e is already labelled
+ * 11 continue with the next edge
+ * 12 w <- G.adjacentVertex(t,e)
+ * 13 if vertex w is not discovered and not explored
+ * 14 label e as tree-edge
+ * 15 label w as discovered
+ * 16 S.push(w)
+ * 17 continue at 5
+ * 18 else if vertex w is discovered
+ * 19 label e as back-edge
+ * 20 else
+ * 21 // vertex w is explored
+ * 22 label e as forward- or cross-edge
+ * 23 label t as explored
+ * 24 S.pop()
+ *
+ * convention:
+ * 0x10 - discovered
+ * 0x11 - discovered and fall-through edge labelled
+ * 0x12 - discovered and fall-through and branch edges labelled
+ * 0x20 - explored
+ */
+
+enum {
+ DISCOVERED = 0x10,
+ EXPLORED = 0x20,
+ FALLTHROUGH = 1,
+ BRANCH = 2,
+};
+
+static int *insn_stack; /* stack of insns to process */
+static int cur_stack; /* current stack index */
+static int *insn_state;
+
+/* t, w, e - match pseudo-code above:
+ * t - index of current instruction
+ * w - next instruction
+ * e - edge
+ */
+static int push_insn(int t, int w, int e, struct verifier_env *env)
+{
+ if (e == FALLTHROUGH && insn_state[t] >= (DISCOVERED | FALLTHROUGH))
+ return 0;
+
+ if (e == BRANCH && insn_state[t] >= (DISCOVERED | BRANCH))
+ return 0;
+
+ if (w < 0 || w >= env->prog->len) {
+ verbose("jump out of range from insn %d to %d\n", t, w);
+ return -EINVAL;
+ }
+
+ if (insn_state[w] == 0) {
+ /* tree-edge */
+ insn_state[t] = DISCOVERED | e;
+ insn_state[w] = DISCOVERED;
+ if (cur_stack >= env->prog->len)
+ return -E2BIG;
+ insn_stack[cur_stack++] = w;
+ return 1;
+ } else if ((insn_state[w] & 0xF0) == DISCOVERED) {
+ verbose("back-edge from insn %d to %d\n", t, w);
+ return -EINVAL;
+ } else if (insn_state[w] == EXPLORED) {
+ /* forward- or cross-edge */
+ insn_state[t] = DISCOVERED | e;
+ } else {
+ verbose("insn state internal bug\n");
+ return -EFAULT;
+ }
+ return 0;
+}
+
+/* non-recursive depth-first-search to detect loops in BPF program
+ * loop == back-edge in directed graph
+ */
+static int check_cfg(struct verifier_env *env)
+{
+ struct bpf_insn *insns = env->prog->insnsi;
+ int insn_cnt = env->prog->len;
+ int ret = 0;
+ int i, t;
+
+ insn_state = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
+ if (!insn_state)
+ return -ENOMEM;
+
+ insn_stack = kcalloc(insn_cnt, sizeof(int), GFP_KERNEL);
+ if (!insn_stack) {
+ kfree(insn_state);
+ return -ENOMEM;
+ }
+
+ insn_state[0] = DISCOVERED; /* mark 1st insn as discovered */
+ insn_stack[0] = 0; /* 0 is the first instruction */
+ cur_stack = 1;
+
+peek_stack:
+ if (cur_stack == 0)
+ goto check_state;
+ t = insn_stack[cur_stack - 1];
+
+ if (BPF_CLASS(insns[t].code) == BPF_JMP) {
+ u8 opcode = BPF_OP(insns[t].code);
+
+ if (opcode == BPF_EXIT) {
+ goto mark_explored;
+ } else if (opcode == BPF_CALL) {
+ ret = push_insn(t, t + 1, FALLTHROUGH, env);
+ if (ret == 1)
+ goto peek_stack;
+ else if (ret < 0)
+ goto err_free;
+ } else if (opcode == BPF_JA) {
+ if (BPF_SRC(insns[t].code) != BPF_K) {
+ ret = -EINVAL;
+ goto err_free;
+ }
+ /* unconditional jump with single edge */
+ ret = push_insn(t, t + insns[t].off + 1,
+ FALLTHROUGH, env);
+ if (ret == 1)
+ goto peek_stack;
+ else if (ret < 0)
+ goto err_free;
+ } else {
+ /* conditional jump with two edges */
+ ret = push_insn(t, t + 1, FALLTHROUGH, env);
+ if (ret == 1)
+ goto peek_stack;
+ else if (ret < 0)
+ goto err_free;
+
+ ret = push_insn(t, t + insns[t].off + 1, BRANCH, env);
+ if (ret == 1)
+ goto peek_stack;
+ else if (ret < 0)
+ goto err_free;
+ }
+ } else {
+ /* all other non-branch instructions with single
+ * fall-through edge
+ */
+ ret = push_insn(t, t + 1, FALLTHROUGH, env);
+ if (ret == 1)
+ goto peek_stack;
+ else if (ret < 0)
+ goto err_free;
+ }
+
+mark_explored:
+ insn_state[t] = EXPLORED;
+ if (cur_stack-- <= 0) {
+ verbose("pop stack internal bug\n");
+ ret = -EFAULT;
+ goto err_free;
+ }
+ goto peek_stack;
+
+check_state:
+ for (i = 0; i < insn_cnt; i++) {
+ if (insn_state[i] != EXPLORED) {
+ verbose("unreachable insn %d\n", i);
+ ret = -EINVAL;
+ goto err_free;
+ }
+ }
+ ret = 0; /* cfg looks good */
+
+err_free:
+ kfree(insn_state);
+ kfree(insn_stack);
+ return ret;
+}
+
+static int do_check(struct verifier_env *env)
+{
+ struct verifier_state *state = &env->cur_state;
+ struct bpf_insn *insns = env->prog->insnsi;
+ struct reg_state *regs = state->regs;
+ int insn_cnt = env->prog->len;
+ int insn_idx, prev_insn_idx = 0;
+ int insn_processed = 0;
+ bool do_print_state = false;
+
+ init_reg_state(regs);
+ insn_idx = 0;
+ for (;;) {
+ struct bpf_insn *insn;
+ u8 class;
+ int err;
+
+ if (insn_idx >= insn_cnt) {
+ verbose("invalid insn idx %d insn_cnt %d\n",
+ insn_idx, insn_cnt);
+ return -EFAULT;
+ }
+
+ insn = &insns[insn_idx];
+ class = BPF_CLASS(insn->code);
+
+ if (++insn_processed > 32768) {
+ verbose("BPF program is too large. Proccessed %d insn\n",
+ insn_processed);
+ return -E2BIG;
+ }
+
+ if (log_level && do_print_state) {
+ verbose("\nfrom %d to %d:", prev_insn_idx, insn_idx);
+ print_verifier_state(env);
+ do_print_state = false;
+ }
+
+ if (log_level) {
+ verbose("%d: ", insn_idx);
+ print_bpf_insn(insn);
+ }
+
+ if (class == BPF_ALU || class == BPF_ALU64) {
+ err = check_alu_op(regs, insn);
+ if (err)
+ return err;
+
+ } else if (class == BPF_LDX) {
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->imm != 0) {
+ verbose("BPF_LDX uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+
+ err = check_reg_arg(regs, insn->dst_reg, DST_OP_NO_MARK);
+ if (err)
+ return err;
+
+ /* check that memory (src_reg + off) is readable,
+ * the state of dst_reg will be updated by this func
+ */
+ err = check_mem_access(env, insn->src_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_READ,
+ insn->dst_reg);
+ if (err)
+ return err;
+
+ } else if (class == BPF_STX) {
+ if (BPF_MODE(insn->code) == BPF_XADD) {
+ err = check_xadd(env, insn);
+ if (err)
+ return err;
+ insn_idx++;
+ continue;
+ }
+
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->imm != 0) {
+ verbose("BPF_STX uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src1 operand */
+ err = check_reg_arg(regs, insn->src_reg, SRC_OP);
+ if (err)
+ return err;
+ /* check src2 operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check that memory (dst_reg + off) is writeable */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE,
+ insn->src_reg);
+ if (err)
+ return err;
+
+ } else if (class == BPF_ST) {
+ if (BPF_MODE(insn->code) != BPF_MEM ||
+ insn->src_reg != BPF_REG_0) {
+ verbose("BPF_ST uses reserved fields\n");
+ return -EINVAL;
+ }
+ /* check src operand */
+ err = check_reg_arg(regs, insn->dst_reg, SRC_OP);
+ if (err)
+ return err;
+
+ /* check that memory (dst_reg + off) is writeable */
+ err = check_mem_access(env, insn->dst_reg, insn->off,
+ BPF_SIZE(insn->code), BPF_WRITE,
+ -1);
+ if (err)
+ return err;
+
+ } else if (class == BPF_JMP) {
+ u8 opcode = BPF_OP(insn->code);
+
+ if (opcode == BPF_CALL) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->off != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_CALL uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ err = check_call(env, insn->imm);
+ if (err)
+ return err;
+
+ } else if (opcode == BPF_JA) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->imm != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_JA uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ insn_idx += insn->off + 1;
+ continue;
+
+ } else if (opcode == BPF_EXIT) {
+ if (BPF_SRC(insn->code) != BPF_K ||
+ insn->imm != 0 ||
+ insn->src_reg != BPF_REG_0 ||
+ insn->dst_reg != BPF_REG_0) {
+ verbose("BPF_EXIT uses reserved fields\n");
+ return -EINVAL;
+ }
+
+ /* eBPF calling convetion is such that R0 is used
+ * to return the value from eBPF program.
+ * Make sure that it's readable at this time
+ * of bpf_exit, which means that program wrote
+ * something into it earlier
+ */
+ err = check_reg_arg(regs, BPF_REG_0, SRC_OP);
+ if (err)
+ return err;
+
+ insn_idx = pop_stack(env, &prev_insn_idx);
+ if (insn_idx < 0) {
+ break;
+ } else {
+ do_print_state = true;
+ continue;
+ }
+ } else {
+ err = check_cond_jmp_op(env, insn, &insn_idx);
+ if (err)
+ return err;
+ }
+ } else if (class == BPF_LD) {
+ u8 mode = BPF_MODE(insn->code);
+
+ if (mode == BPF_ABS || mode == BPF_IND) {
+ verbose("LD_ABS is not supported yet\n");
+ return -EINVAL;
+ } else if (mode == BPF_IMM) {
+ err = check_ld_imm(env, insn);
+ if (err)
+ return err;
+
+ insn_idx++;
+ } else {
+ verbose("invalid BPF_LD mode\n");
+ return -EINVAL;
+ }
+ } else {
+ verbose("unknown insn class %d\n", class);
+ return -EINVAL;
+ }
+
+ insn_idx++;
+ }
+
+ return 0;
+}
+
+/* look for pseudo eBPF instructions that access map FDs and
+ * replace them with actual map pointers
+ */
+static int replace_map_fd_with_map_ptr(struct verifier_env *env)
+{
+ struct bpf_insn *insn = env->prog->insnsi;
+ int insn_cnt = env->prog->len;
+ int i, j;
+
+ for (i = 0; i < insn_cnt; i++, insn++) {
+ if (insn[0].code == (BPF_LD | BPF_IMM | BPF_DW)) {
+ struct bpf_map *map;
+ struct fd f;
+
+ if (i == insn_cnt - 1 || insn[1].code != 0 ||
+ insn[1].dst_reg != 0 || insn[1].src_reg != 0 ||
+ insn[1].off != 0) {
+ verbose("invalid bpf_ld_imm64 insn\n");
+ return -EINVAL;
+ }
+
+ if (insn->src_reg == 0)
+ /* valid generic load 64-bit imm */
+ goto next_insn;
+
+ if (insn->src_reg != BPF_PSEUDO_MAP_FD) {
+ verbose("unrecognized bpf_ld_imm64 insn\n");
+ return -EINVAL;
+ }
+
+ f = fdget(insn->imm);
+
+ map = bpf_map_get(f);
+ if (IS_ERR(map)) {
+ verbose("fd %d is not pointing to valid bpf_map\n",
+ insn->imm);
+ fdput(f);
+ return PTR_ERR(map);
+ }
+
+ /* store map pointer inside BPF_LD_IMM64 instruction */
+ insn[0].imm = (u32) (unsigned long) map;
+ insn[1].imm = ((u64) (unsigned long) map) >> 32;
+
+ /* check whether we recorded this map already */
+ for (j = 0; j < env->used_map_cnt; j++)
+ if (env->used_maps[j] == map) {
+ fdput(f);
+ goto next_insn;
+ }
+
+ if (env->used_map_cnt >= MAX_USED_MAPS) {
+ fdput(f);
+ return -E2BIG;
+ }
+
+ /* remember this map */
+ env->used_maps[env->used_map_cnt++] = map;
+
+ /* hold the map. If the program is rejected by verifier,
+ * the map will be released by release_maps() or it
+ * will be used by the valid program until it's unloaded
+ * and all maps are released in free_bpf_prog_info()
+ */
+ atomic_inc(&map->refcnt);
+
+ fdput(f);
+next_insn:
+ insn++;
+ i++;
+ }
+ }
+
+ /* now all pseudo BPF_LD_IMM64 instructions load valid
+ * 'struct bpf_map *' into a register instead of user map_fd.
+ * These pointers will be used later by verifier to validate map access.
+ */
+ return 0;
+}
+
+/* drop refcnt of maps used by the rejected program */
+static void release_maps(struct verifier_env *env)
+{
+ int i;
+
+ for (i = 0; i < env->used_map_cnt; i++)
+ bpf_map_put(env->used_maps[i]);
+}
+
+/* convert pseudo BPF_LD_IMM64 into generic BPF_LD_IMM64 */
+static void convert_pseudo_ld_imm64(struct verifier_env *env)
+{
+ struct bpf_insn *insn = env->prog->insnsi;
+ int insn_cnt = env->prog->len;
+ int i;
+
+ for (i = 0; i < insn_cnt; i++, insn++)
+ if (insn->code == (BPF_LD | BPF_IMM | BPF_DW))
+ insn->src_reg = 0;
+}
+
+int bpf_check(struct bpf_prog *prog, union bpf_attr *attr)
+{
+ char __user *log_ubuf = NULL;
+ struct verifier_env *env;
+ int ret = -EINVAL;
+
+ if (prog->len <= 0 || prog->len > BPF_MAXINSNS)
+ return -E2BIG;
+
+ /* 'struct verifier_env' can be global, but since it's not small,
+ * allocate/free it every time bpf_check() is called
+ */
+ env = kzalloc(sizeof(struct verifier_env), GFP_KERNEL);
+ if (!env)
+ return -ENOMEM;
+
+ env->prog = prog;
+
+ /* grab the mutex to protect few globals used by verifier */
+ mutex_lock(&bpf_verifier_lock);
+
+ if (attr->log_level || attr->log_buf || attr->log_size) {
+ /* user requested verbose verifier output
+ * and supplied buffer to store the verification trace
+ */
+ log_level = attr->log_level;
+ log_ubuf = (char __user *) (unsigned long) attr->log_buf;
+ log_size = attr->log_size;
+ log_len = 0;
+
+ ret = -EINVAL;
+ /* log_* values have to be sane */
+ if (log_size < 128 || log_size > UINT_MAX >> 8 ||
+ log_level == 0 || log_ubuf == NULL)
+ goto free_env;
+
+ ret = -ENOMEM;
+ log_buf = vmalloc(log_size);
+ if (!log_buf)
+ goto free_env;
+ } else {
+ log_level = 0;
+ }
+
+ ret = replace_map_fd_with_map_ptr(env);
+ if (ret < 0)
+ goto skip_full_check;
+
+ ret = check_cfg(env);
+ if (ret < 0)
+ goto skip_full_check;
+
+ ret = do_check(env);
+
+skip_full_check:
+ while (pop_stack(env, NULL) >= 0);
+
+ if (log_level && log_len >= log_size - 1) {
+ BUG_ON(log_len >= log_size);
+ /* verifier log exceeded user supplied buffer */
+ ret = -ENOSPC;
+ /* fall through to return what was recorded */
+ }
+
+ /* copy verifier log back to user space including trailing zero */
+ if (log_level && copy_to_user(log_ubuf, log_buf, log_len + 1) != 0) {
+ ret = -EFAULT;
+ goto free_log_buf;
+ }
+
+ if (ret == 0 && env->used_map_cnt) {
+ /* if program passed verifier, update used_maps in bpf_prog_info */
+ prog->aux->used_maps = kmalloc_array(env->used_map_cnt,
+ sizeof(env->used_maps[0]),
+ GFP_KERNEL);
+
+ if (!prog->aux->used_maps) {
+ ret = -ENOMEM;
+ goto free_log_buf;
+ }
+
+ memcpy(prog->aux->used_maps, env->used_maps,
+ sizeof(env->used_maps[0]) * env->used_map_cnt);
+ prog->aux->used_map_cnt = env->used_map_cnt;
+
+ /* program is valid. Convert pseudo bpf_ld_imm64 into generic
+ * bpf_ld_imm64 instructions
+ */
+ convert_pseudo_ld_imm64(env);
+ }
+
+free_log_buf:
+ if (log_level)
+ vfree(log_buf);
+free_env:
+ if (!prog->aux->used_maps)
+ /* if we didn't copy map pointers into bpf_prog_info, release
+ * them now. Otherwise free_bpf_prog_info() will release them.
+ */
+ release_maps(env);
+ kfree(env);
+ mutex_unlock(&bpf_verifier_lock);
+ return ret;
+}
diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
index 391d4ddb6f4b..b4b5083f5f5e 100644
--- a/kernel/sys_ni.c
+++ b/kernel/sys_ni.c
@@ -218,3 +218,6 @@ cond_syscall(sys_kcmp);
/* operate on Secure Computing state */
cond_syscall(sys_seccomp);
+
+/* access BPF programs and maps */
+cond_syscall(sys_bpf);
generated by cgit v1.2.3 (git 2.25.1) at 2024-12-02 12:23:23 +0000