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![Shmulik Ladkani](/assets/img/avatar_default.png)
Commit 2c16d60332
("netfilter: xt_bpf: support ebpf") introduced
support for attaching an eBPF object by an fd, with the
'bpf_mt_check_v1' ABI expecting the '.fd' to be specified upon each
IPT_SO_SET_REPLACE call.
However this breaks subsequent iptables calls:
# iptables -A INPUT -m bpf --object-pinned /sys/fs/bpf/xxx -j ACCEPT
# iptables -A INPUT -s 5.6.7.8 -j ACCEPT
iptables: Invalid argument. Run `dmesg' for more information.
That's because iptables works by loading existing rules using
IPT_SO_GET_ENTRIES to userspace, then issuing IPT_SO_SET_REPLACE with
the replacement set.
However, the loaded 'xt_bpf_info_v1' has an arbitrary '.fd' number
(from the initial "iptables -m bpf" invocation) - so when 2nd invocation
occurs, userspace passes a bogus fd number, which leads to
'bpf_mt_check_v1' to fail.
One suggested solution [1] was to hack iptables userspace, to perform a
"entries fixup" immediatley after IPT_SO_GET_ENTRIES, by opening a new,
process-local fd per every 'xt_bpf_info_v1' entry seen.
However, in [2] both Pablo Neira Ayuso and Willem de Bruijn suggested to
depricate the xt_bpf_info_v1 ABI dealing with pinned ebpf objects.
This fix changes the XT_BPF_MODE_FD_PINNED behavior to ignore the given
'.fd' and instead perform an in-kernel lookup for the bpf object given
the provided '.path'.
It also defines an alias for the XT_BPF_MODE_FD_PINNED mode, named
XT_BPF_MODE_PATH_PINNED, to better reflect the fact that the user is
expected to provide the path of the pinned object.
Existing XT_BPF_MODE_FD_ELF behavior (non-pinned fd mode) is preserved.
References: [1] https://marc.info/?l=netfilter-devel&m=150564724607440&w=2
[2] https://marc.info/?l=netfilter-devel&m=150575727129880&w=2
Reported-by: Rafael Buchbinder <rafi@rbk.ms>
Signed-off-by: Shmulik Ladkani <shmulik.ladkani@gmail.com>
Acked-by: Willem de Bruijn <willemb@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
430 lines
13 KiB
C
430 lines
13 KiB
C
/* Copyright (c) 2011-2014 PLUMgrid, http://plumgrid.com
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of version 2 of the GNU General Public
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* License as published by the Free Software Foundation.
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*/
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#ifndef _LINUX_BPF_H
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#define _LINUX_BPF_H 1
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#include <uapi/linux/bpf.h>
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#include <linux/workqueue.h>
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#include <linux/file.h>
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#include <linux/percpu.h>
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#include <linux/err.h>
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#include <linux/rbtree_latch.h>
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#include <linux/numa.h>
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struct perf_event;
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struct bpf_prog;
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struct bpf_map;
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/* map is generic key/value storage optionally accesible by eBPF programs */
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struct bpf_map_ops {
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/* funcs callable from userspace (via syscall) */
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struct bpf_map *(*map_alloc)(union bpf_attr *attr);
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void (*map_release)(struct bpf_map *map, struct file *map_file);
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void (*map_free)(struct bpf_map *map);
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int (*map_get_next_key)(struct bpf_map *map, void *key, void *next_key);
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/* funcs callable from userspace and from eBPF programs */
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void *(*map_lookup_elem)(struct bpf_map *map, void *key);
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int (*map_update_elem)(struct bpf_map *map, void *key, void *value, u64 flags);
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int (*map_delete_elem)(struct bpf_map *map, void *key);
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/* funcs called by prog_array and perf_event_array map */
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void *(*map_fd_get_ptr)(struct bpf_map *map, struct file *map_file,
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int fd);
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void (*map_fd_put_ptr)(void *ptr);
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u32 (*map_gen_lookup)(struct bpf_map *map, struct bpf_insn *insn_buf);
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u32 (*map_fd_sys_lookup_elem)(void *ptr);
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};
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struct bpf_map {
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atomic_t refcnt;
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enum bpf_map_type map_type;
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u32 key_size;
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u32 value_size;
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u32 max_entries;
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u32 map_flags;
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u32 pages;
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u32 id;
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int numa_node;
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struct user_struct *user;
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const struct bpf_map_ops *ops;
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struct work_struct work;
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atomic_t usercnt;
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struct bpf_map *inner_map_meta;
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};
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/* function argument constraints */
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enum bpf_arg_type {
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ARG_DONTCARE = 0, /* unused argument in helper function */
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/* the following constraints used to prototype
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* bpf_map_lookup/update/delete_elem() functions
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*/
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ARG_CONST_MAP_PTR, /* const argument used as pointer to bpf_map */
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ARG_PTR_TO_MAP_KEY, /* pointer to stack used as map key */
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ARG_PTR_TO_MAP_VALUE, /* pointer to stack used as map value */
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/* the following constraints used to prototype bpf_memcmp() and other
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* functions that access data on eBPF program stack
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*/
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ARG_PTR_TO_MEM, /* pointer to valid memory (stack, packet, map value) */
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ARG_PTR_TO_UNINIT_MEM, /* pointer to memory does not need to be initialized,
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* helper function must fill all bytes or clear
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* them in error case.
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*/
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ARG_CONST_SIZE, /* number of bytes accessed from memory */
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ARG_CONST_SIZE_OR_ZERO, /* number of bytes accessed from memory or 0 */
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ARG_PTR_TO_CTX, /* pointer to context */
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ARG_ANYTHING, /* any (initialized) argument is ok */
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};
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/* type of values returned from helper functions */
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enum bpf_return_type {
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RET_INTEGER, /* function returns integer */
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RET_VOID, /* function doesn't return anything */
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RET_PTR_TO_MAP_VALUE_OR_NULL, /* returns a pointer to map elem value or NULL */
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};
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/* eBPF function prototype used by verifier to allow BPF_CALLs from eBPF programs
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* to in-kernel helper functions and for adjusting imm32 field in BPF_CALL
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* instructions after verifying
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*/
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struct bpf_func_proto {
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u64 (*func)(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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bool gpl_only;
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bool pkt_access;
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enum bpf_return_type ret_type;
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enum bpf_arg_type arg1_type;
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enum bpf_arg_type arg2_type;
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enum bpf_arg_type arg3_type;
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enum bpf_arg_type arg4_type;
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enum bpf_arg_type arg5_type;
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};
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/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
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* the first argument to eBPF programs.
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* For socket filters: 'struct bpf_context *' == 'struct sk_buff *'
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*/
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struct bpf_context;
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enum bpf_access_type {
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BPF_READ = 1,
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BPF_WRITE = 2
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};
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/* types of values stored in eBPF registers */
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/* Pointer types represent:
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* pointer
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* pointer + imm
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* pointer + (u16) var
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* pointer + (u16) var + imm
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* if (range > 0) then [ptr, ptr + range - off) is safe to access
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* if (id > 0) means that some 'var' was added
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* if (off > 0) means that 'imm' was added
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*/
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enum bpf_reg_type {
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NOT_INIT = 0, /* nothing was written into register */
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SCALAR_VALUE, /* reg doesn't contain a valid pointer */
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PTR_TO_CTX, /* reg points to bpf_context */
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CONST_PTR_TO_MAP, /* reg points to struct bpf_map */
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PTR_TO_MAP_VALUE, /* reg points to map element value */
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PTR_TO_MAP_VALUE_OR_NULL,/* points to map elem value or NULL */
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PTR_TO_STACK, /* reg == frame_pointer + offset */
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PTR_TO_PACKET, /* reg points to skb->data */
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PTR_TO_PACKET_END, /* skb->data + headlen */
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};
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/* The information passed from prog-specific *_is_valid_access
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* back to the verifier.
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*/
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struct bpf_insn_access_aux {
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enum bpf_reg_type reg_type;
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int ctx_field_size;
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};
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static inline void
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bpf_ctx_record_field_size(struct bpf_insn_access_aux *aux, u32 size)
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{
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aux->ctx_field_size = size;
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}
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struct bpf_verifier_ops {
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/* return eBPF function prototype for verification */
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const struct bpf_func_proto *(*get_func_proto)(enum bpf_func_id func_id);
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/* return true if 'size' wide access at offset 'off' within bpf_context
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* with 'type' (read or write) is allowed
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*/
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bool (*is_valid_access)(int off, int size, enum bpf_access_type type,
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struct bpf_insn_access_aux *info);
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int (*gen_prologue)(struct bpf_insn *insn, bool direct_write,
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const struct bpf_prog *prog);
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u32 (*convert_ctx_access)(enum bpf_access_type type,
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const struct bpf_insn *src,
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struct bpf_insn *dst,
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struct bpf_prog *prog, u32 *target_size);
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int (*test_run)(struct bpf_prog *prog, const union bpf_attr *kattr,
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union bpf_attr __user *uattr);
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};
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struct bpf_prog_aux {
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atomic_t refcnt;
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u32 used_map_cnt;
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u32 max_ctx_offset;
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u32 stack_depth;
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u32 id;
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struct latch_tree_node ksym_tnode;
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struct list_head ksym_lnode;
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const struct bpf_verifier_ops *ops;
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struct bpf_map **used_maps;
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struct bpf_prog *prog;
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struct user_struct *user;
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union {
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struct work_struct work;
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struct rcu_head rcu;
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};
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};
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struct bpf_array {
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struct bpf_map map;
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u32 elem_size;
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/* 'ownership' of prog_array is claimed by the first program that
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* is going to use this map or by the first program which FD is stored
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* in the map to make sure that all callers and callees have the same
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* prog_type and JITed flag
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*/
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enum bpf_prog_type owner_prog_type;
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bool owner_jited;
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union {
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char value[0] __aligned(8);
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void *ptrs[0] __aligned(8);
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void __percpu *pptrs[0] __aligned(8);
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};
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};
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#define MAX_TAIL_CALL_CNT 32
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struct bpf_event_entry {
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struct perf_event *event;
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struct file *perf_file;
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struct file *map_file;
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struct rcu_head rcu;
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};
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u64 bpf_tail_call(u64 ctx, u64 r2, u64 index, u64 r4, u64 r5);
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u64 bpf_get_stackid(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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bool bpf_prog_array_compatible(struct bpf_array *array, const struct bpf_prog *fp);
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int bpf_prog_calc_tag(struct bpf_prog *fp);
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const struct bpf_func_proto *bpf_get_trace_printk_proto(void);
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typedef unsigned long (*bpf_ctx_copy_t)(void *dst, const void *src,
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unsigned long off, unsigned long len);
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u64 bpf_event_output(struct bpf_map *map, u64 flags, void *meta, u64 meta_size,
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void *ctx, u64 ctx_size, bpf_ctx_copy_t ctx_copy);
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int bpf_prog_test_run_xdp(struct bpf_prog *prog, const union bpf_attr *kattr,
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union bpf_attr __user *uattr);
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int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
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union bpf_attr __user *uattr);
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#ifdef CONFIG_BPF_SYSCALL
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DECLARE_PER_CPU(int, bpf_prog_active);
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#define BPF_PROG_TYPE(_id, _ops) \
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extern const struct bpf_verifier_ops _ops;
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#define BPF_MAP_TYPE(_id, _ops) \
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extern const struct bpf_map_ops _ops;
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#include <linux/bpf_types.h>
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#undef BPF_PROG_TYPE
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#undef BPF_MAP_TYPE
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struct bpf_prog *bpf_prog_get(u32 ufd);
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struct bpf_prog *bpf_prog_get_type(u32 ufd, enum bpf_prog_type type);
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struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog, int i);
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void bpf_prog_sub(struct bpf_prog *prog, int i);
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struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog);
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struct bpf_prog * __must_check bpf_prog_inc_not_zero(struct bpf_prog *prog);
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void bpf_prog_put(struct bpf_prog *prog);
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int __bpf_prog_charge(struct user_struct *user, u32 pages);
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void __bpf_prog_uncharge(struct user_struct *user, u32 pages);
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struct bpf_map *bpf_map_get_with_uref(u32 ufd);
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struct bpf_map *__bpf_map_get(struct fd f);
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struct bpf_map * __must_check bpf_map_inc(struct bpf_map *map, bool uref);
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void bpf_map_put_with_uref(struct bpf_map *map);
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void bpf_map_put(struct bpf_map *map);
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int bpf_map_precharge_memlock(u32 pages);
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void *bpf_map_area_alloc(size_t size, int numa_node);
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void bpf_map_area_free(void *base);
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extern int sysctl_unprivileged_bpf_disabled;
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int bpf_map_new_fd(struct bpf_map *map);
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int bpf_prog_new_fd(struct bpf_prog *prog);
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int bpf_obj_pin_user(u32 ufd, const char __user *pathname);
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int bpf_obj_get_user(const char __user *pathname);
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int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value);
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int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value);
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int bpf_percpu_hash_update(struct bpf_map *map, void *key, void *value,
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u64 flags);
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int bpf_percpu_array_update(struct bpf_map *map, void *key, void *value,
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u64 flags);
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int bpf_stackmap_copy(struct bpf_map *map, void *key, void *value);
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int bpf_fd_array_map_update_elem(struct bpf_map *map, struct file *map_file,
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void *key, void *value, u64 map_flags);
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int bpf_fd_array_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
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void bpf_fd_array_map_clear(struct bpf_map *map);
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int bpf_fd_htab_map_update_elem(struct bpf_map *map, struct file *map_file,
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void *key, void *value, u64 map_flags);
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int bpf_fd_htab_map_lookup_elem(struct bpf_map *map, void *key, u32 *value);
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/* memcpy that is used with 8-byte aligned pointers, power-of-8 size and
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* forced to use 'long' read/writes to try to atomically copy long counters.
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* Best-effort only. No barriers here, since it _will_ race with concurrent
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* updates from BPF programs. Called from bpf syscall and mostly used with
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* size 8 or 16 bytes, so ask compiler to inline it.
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*/
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static inline void bpf_long_memcpy(void *dst, const void *src, u32 size)
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{
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const long *lsrc = src;
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long *ldst = dst;
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size /= sizeof(long);
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while (size--)
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*ldst++ = *lsrc++;
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}
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/* verify correctness of eBPF program */
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int bpf_check(struct bpf_prog **fp, union bpf_attr *attr);
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/* Map specifics */
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struct net_device *__dev_map_lookup_elem(struct bpf_map *map, u32 key);
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void __dev_map_insert_ctx(struct bpf_map *map, u32 index);
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void __dev_map_flush(struct bpf_map *map);
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/* Return map's numa specified by userspace */
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static inline int bpf_map_attr_numa_node(const union bpf_attr *attr)
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{
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return (attr->map_flags & BPF_F_NUMA_NODE) ?
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attr->numa_node : NUMA_NO_NODE;
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}
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#else
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static inline struct bpf_prog *bpf_prog_get(u32 ufd)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline struct bpf_prog *bpf_prog_get_type(u32 ufd,
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enum bpf_prog_type type)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline struct bpf_prog * __must_check bpf_prog_add(struct bpf_prog *prog,
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int i)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline void bpf_prog_sub(struct bpf_prog *prog, int i)
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{
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}
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static inline void bpf_prog_put(struct bpf_prog *prog)
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{
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}
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static inline struct bpf_prog * __must_check bpf_prog_inc(struct bpf_prog *prog)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline struct bpf_prog *__must_check
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bpf_prog_inc_not_zero(struct bpf_prog *prog)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline int __bpf_prog_charge(struct user_struct *user, u32 pages)
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{
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return 0;
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}
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static inline void __bpf_prog_uncharge(struct user_struct *user, u32 pages)
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{
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}
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static inline int bpf_obj_get_user(const char __user *pathname)
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{
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return -EOPNOTSUPP;
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}
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static inline struct net_device *__dev_map_lookup_elem(struct bpf_map *map,
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u32 key)
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{
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return NULL;
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}
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static inline void __dev_map_insert_ctx(struct bpf_map *map, u32 index)
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{
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}
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static inline void __dev_map_flush(struct bpf_map *map)
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{
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}
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#endif /* CONFIG_BPF_SYSCALL */
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#if defined(CONFIG_STREAM_PARSER) && defined(CONFIG_BPF_SYSCALL)
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struct sock *__sock_map_lookup_elem(struct bpf_map *map, u32 key);
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int sock_map_prog(struct bpf_map *map, struct bpf_prog *prog, u32 type);
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#else
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static inline struct sock *__sock_map_lookup_elem(struct bpf_map *map, u32 key)
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{
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return NULL;
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}
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static inline int sock_map_prog(struct bpf_map *map,
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struct bpf_prog *prog,
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u32 type)
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{
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return -EOPNOTSUPP;
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}
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#endif
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/* verifier prototypes for helper functions called from eBPF programs */
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extern const struct bpf_func_proto bpf_map_lookup_elem_proto;
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extern const struct bpf_func_proto bpf_map_update_elem_proto;
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extern const struct bpf_func_proto bpf_map_delete_elem_proto;
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extern const struct bpf_func_proto bpf_get_prandom_u32_proto;
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extern const struct bpf_func_proto bpf_get_smp_processor_id_proto;
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extern const struct bpf_func_proto bpf_get_numa_node_id_proto;
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extern const struct bpf_func_proto bpf_tail_call_proto;
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extern const struct bpf_func_proto bpf_ktime_get_ns_proto;
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extern const struct bpf_func_proto bpf_get_current_pid_tgid_proto;
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extern const struct bpf_func_proto bpf_get_current_uid_gid_proto;
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extern const struct bpf_func_proto bpf_get_current_comm_proto;
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extern const struct bpf_func_proto bpf_skb_vlan_push_proto;
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extern const struct bpf_func_proto bpf_skb_vlan_pop_proto;
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extern const struct bpf_func_proto bpf_get_stackid_proto;
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extern const struct bpf_func_proto bpf_sock_map_update_proto;
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/* Shared helpers among cBPF and eBPF. */
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void bpf_user_rnd_init_once(void);
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u64 bpf_user_rnd_u32(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5);
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#endif /* _LINUX_BPF_H */
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