1 /*
2 * Copyright (C) 2016 Netronome Systems, Inc.
3 *
4 * This software is dual licensed under the GNU General License Version 2,
5 * June 1991 as shown in the file COPYING in the top-level directory of this
6 * source tree or the BSD 2-Clause License provided below. You have the
7 * option to license this software under the complete terms of either license.
8 *
9 * The BSD 2-Clause License:
10 *
11 * Redistribution and use in source and binary forms, with or
12 * without modification, are permitted provided that the following
13 * conditions are met:
14 *
15 * 1. Redistributions of source code must retain the above
16 * copyright notice, this list of conditions and the following
17 * disclaimer.
18 *
19 * 2. Redistributions in binary form must reproduce the above
20 * copyright notice, this list of conditions and the following
21 * disclaimer in the documentation and/or other materials
22 * provided with the distribution.
23 *
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
28 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
29 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
30 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
31 * SOFTWARE.
32 */
33
34 #define pr_fmt(fmt) "NFP net bpf: " fmt
35
36 #include <linux/bpf.h>
37 #include <linux/bpf_verifier.h>
38 #include <linux/kernel.h>
39 #include <linux/pkt_cls.h>
40
41 #include "nfp_bpf.h"
42
43 /* Analyzer/verifier definitions */
44 struct nfp_bpf_analyzer_priv {
45 struct nfp_prog *prog;
46 struct nfp_insn_meta *meta;
47 };
48
49 static struct nfp_insn_meta *
nfp_bpf_goto_meta(struct nfp_prog * nfp_prog,struct nfp_insn_meta * meta,unsigned int insn_idx,unsigned int n_insns)50 nfp_bpf_goto_meta(struct nfp_prog *nfp_prog, struct nfp_insn_meta *meta,
51 unsigned int insn_idx, unsigned int n_insns)
52 {
53 unsigned int forward, backward, i;
54
55 backward = meta->n - insn_idx;
56 forward = insn_idx - meta->n;
57
58 if (min(forward, backward) > n_insns - insn_idx - 1) {
59 backward = n_insns - insn_idx - 1;
60 meta = nfp_prog_last_meta(nfp_prog);
61 }
62 if (min(forward, backward) > insn_idx && backward > insn_idx) {
63 forward = insn_idx;
64 meta = nfp_prog_first_meta(nfp_prog);
65 }
66
67 if (forward < backward)
68 for (i = 0; i < forward; i++)
69 meta = nfp_meta_next(meta);
70 else
71 for (i = 0; i < backward; i++)
72 meta = nfp_meta_prev(meta);
73
74 return meta;
75 }
76
77 static int
nfp_bpf_check_exit(struct nfp_prog * nfp_prog,const struct bpf_verifier_env * env)78 nfp_bpf_check_exit(struct nfp_prog *nfp_prog,
79 const struct bpf_verifier_env *env)
80 {
81 const struct bpf_reg_state *reg0 = &env->cur_state.regs[0];
82
83 if (reg0->type != CONST_IMM) {
84 pr_info("unsupported exit state: %d, imm: %llx\n",
85 reg0->type, reg0->imm);
86 return -EINVAL;
87 }
88
89 if (nfp_prog->act != NN_ACT_DIRECT &&
90 reg0->imm != 0 && (reg0->imm & ~0U) != ~0U) {
91 pr_info("unsupported exit state: %d, imm: %llx\n",
92 reg0->type, reg0->imm);
93 return -EINVAL;
94 }
95
96 if (nfp_prog->act == NN_ACT_DIRECT && reg0->imm <= TC_ACT_REDIRECT &&
97 reg0->imm != TC_ACT_SHOT && reg0->imm != TC_ACT_STOLEN &&
98 reg0->imm != TC_ACT_QUEUED) {
99 pr_info("unsupported exit state: %d, imm: %llx\n",
100 reg0->type, reg0->imm);
101 return -EINVAL;
102 }
103
104 return 0;
105 }
106
107 static int
nfp_bpf_check_ctx_ptr(struct nfp_prog * nfp_prog,const struct bpf_verifier_env * env,u8 reg)108 nfp_bpf_check_ctx_ptr(struct nfp_prog *nfp_prog,
109 const struct bpf_verifier_env *env, u8 reg)
110 {
111 if (env->cur_state.regs[reg].type != PTR_TO_CTX)
112 return -EINVAL;
113
114 return 0;
115 }
116
117 static int
nfp_verify_insn(struct bpf_verifier_env * env,int insn_idx,int prev_insn_idx)118 nfp_verify_insn(struct bpf_verifier_env *env, int insn_idx, int prev_insn_idx)
119 {
120 struct nfp_bpf_analyzer_priv *priv = env->analyzer_priv;
121 struct nfp_insn_meta *meta = priv->meta;
122
123 meta = nfp_bpf_goto_meta(priv->prog, meta, insn_idx, env->prog->len);
124 priv->meta = meta;
125
126 if (meta->insn.src_reg == BPF_REG_10 ||
127 meta->insn.dst_reg == BPF_REG_10) {
128 pr_err("stack not yet supported\n");
129 return -EINVAL;
130 }
131 if (meta->insn.src_reg >= MAX_BPF_REG ||
132 meta->insn.dst_reg >= MAX_BPF_REG) {
133 pr_err("program uses extended registers - jit hardening?\n");
134 return -EINVAL;
135 }
136
137 if (meta->insn.code == (BPF_JMP | BPF_EXIT))
138 return nfp_bpf_check_exit(priv->prog, env);
139
140 if ((meta->insn.code & ~BPF_SIZE_MASK) == (BPF_LDX | BPF_MEM))
141 return nfp_bpf_check_ctx_ptr(priv->prog, env,
142 meta->insn.src_reg);
143 if ((meta->insn.code & ~BPF_SIZE_MASK) == (BPF_STX | BPF_MEM))
144 return nfp_bpf_check_ctx_ptr(priv->prog, env,
145 meta->insn.dst_reg);
146
147 return 0;
148 }
149
150 static const struct bpf_ext_analyzer_ops nfp_bpf_analyzer_ops = {
151 .insn_hook = nfp_verify_insn,
152 };
153
nfp_prog_verify(struct nfp_prog * nfp_prog,struct bpf_prog * prog)154 int nfp_prog_verify(struct nfp_prog *nfp_prog, struct bpf_prog *prog)
155 {
156 struct nfp_bpf_analyzer_priv *priv;
157 int ret;
158
159 priv = kzalloc(sizeof(*priv), GFP_KERNEL);
160 if (!priv)
161 return -ENOMEM;
162
163 priv->prog = nfp_prog;
164 priv->meta = nfp_prog_first_meta(nfp_prog);
165
166 ret = bpf_analyzer(prog, &nfp_bpf_analyzer_ops, priv);
167
168 kfree(priv);
169
170 return ret;
171 }
172