Commit | Line | Data |
---|---|---|
249b812d AS |
1 | #include <stdio.h> |
2 | #include <sys/types.h> | |
3 | #include <sys/stat.h> | |
4 | #include <fcntl.h> | |
5 | #include <libelf.h> | |
6 | #include <gelf.h> | |
7 | #include <errno.h> | |
8 | #include <unistd.h> | |
9 | #include <string.h> | |
10 | #include <stdbool.h> | |
11 | #include <linux/bpf.h> | |
12 | #include <linux/filter.h> | |
13 | #include "libbpf.h" | |
14 | #include "bpf_helpers.h" | |
15 | #include "bpf_load.h" | |
16 | ||
17 | static char license[128]; | |
18 | static bool processed_sec[128]; | |
19 | int map_fd[MAX_MAPS]; | |
20 | int prog_fd[MAX_PROGS]; | |
21 | int prog_cnt; | |
22 | ||
23 | static int load_and_attach(const char *event, struct bpf_insn *prog, int size) | |
24 | { | |
25 | int fd; | |
26 | bool is_socket = strncmp(event, "socket", 6) == 0; | |
27 | ||
28 | if (!is_socket) | |
29 | /* tracing events tbd */ | |
30 | return -1; | |
31 | ||
32 | fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, | |
33 | prog, size, license); | |
34 | ||
35 | if (fd < 0) { | |
36 | printf("bpf_prog_load() err=%d\n%s", errno, bpf_log_buf); | |
37 | return -1; | |
38 | } | |
39 | ||
40 | prog_fd[prog_cnt++] = fd; | |
41 | ||
42 | return 0; | |
43 | } | |
44 | ||
45 | static int load_maps(struct bpf_map_def *maps, int len) | |
46 | { | |
47 | int i; | |
48 | ||
49 | for (i = 0; i < len / sizeof(struct bpf_map_def); i++) { | |
50 | ||
51 | map_fd[i] = bpf_create_map(maps[i].type, | |
52 | maps[i].key_size, | |
53 | maps[i].value_size, | |
54 | maps[i].max_entries); | |
55 | if (map_fd[i] < 0) | |
56 | return 1; | |
57 | } | |
58 | return 0; | |
59 | } | |
60 | ||
61 | static int get_sec(Elf *elf, int i, GElf_Ehdr *ehdr, char **shname, | |
62 | GElf_Shdr *shdr, Elf_Data **data) | |
63 | { | |
64 | Elf_Scn *scn; | |
65 | ||
66 | scn = elf_getscn(elf, i); | |
67 | if (!scn) | |
68 | return 1; | |
69 | ||
70 | if (gelf_getshdr(scn, shdr) != shdr) | |
71 | return 2; | |
72 | ||
73 | *shname = elf_strptr(elf, ehdr->e_shstrndx, shdr->sh_name); | |
74 | if (!*shname || !shdr->sh_size) | |
75 | return 3; | |
76 | ||
77 | *data = elf_getdata(scn, 0); | |
78 | if (!*data || elf_getdata(scn, *data) != NULL) | |
79 | return 4; | |
80 | ||
81 | return 0; | |
82 | } | |
83 | ||
84 | static int parse_relo_and_apply(Elf_Data *data, Elf_Data *symbols, | |
85 | GElf_Shdr *shdr, struct bpf_insn *insn) | |
86 | { | |
87 | int i, nrels; | |
88 | ||
89 | nrels = shdr->sh_size / shdr->sh_entsize; | |
90 | ||
91 | for (i = 0; i < nrels; i++) { | |
92 | GElf_Sym sym; | |
93 | GElf_Rel rel; | |
94 | unsigned int insn_idx; | |
95 | ||
96 | gelf_getrel(data, i, &rel); | |
97 | ||
98 | insn_idx = rel.r_offset / sizeof(struct bpf_insn); | |
99 | ||
100 | gelf_getsym(symbols, GELF_R_SYM(rel.r_info), &sym); | |
101 | ||
102 | if (insn[insn_idx].code != (BPF_LD | BPF_IMM | BPF_DW)) { | |
103 | printf("invalid relo for insn[%d].code 0x%x\n", | |
104 | insn_idx, insn[insn_idx].code); | |
105 | return 1; | |
106 | } | |
107 | insn[insn_idx].src_reg = BPF_PSEUDO_MAP_FD; | |
108 | insn[insn_idx].imm = map_fd[sym.st_value / sizeof(struct bpf_map_def)]; | |
109 | } | |
110 | ||
111 | return 0; | |
112 | } | |
113 | ||
114 | int load_bpf_file(char *path) | |
115 | { | |
116 | int fd, i; | |
117 | Elf *elf; | |
118 | GElf_Ehdr ehdr; | |
119 | GElf_Shdr shdr, shdr_prog; | |
120 | Elf_Data *data, *data_prog, *symbols = NULL; | |
121 | char *shname, *shname_prog; | |
122 | ||
123 | if (elf_version(EV_CURRENT) == EV_NONE) | |
124 | return 1; | |
125 | ||
126 | fd = open(path, O_RDONLY, 0); | |
127 | if (fd < 0) | |
128 | return 1; | |
129 | ||
130 | elf = elf_begin(fd, ELF_C_READ, NULL); | |
131 | ||
132 | if (!elf) | |
133 | return 1; | |
134 | ||
135 | if (gelf_getehdr(elf, &ehdr) != &ehdr) | |
136 | return 1; | |
137 | ||
138 | /* scan over all elf sections to get license and map info */ | |
139 | for (i = 1; i < ehdr.e_shnum; i++) { | |
140 | ||
141 | if (get_sec(elf, i, &ehdr, &shname, &shdr, &data)) | |
142 | continue; | |
143 | ||
144 | if (0) /* helpful for llvm debugging */ | |
145 | printf("section %d:%s data %p size %zd link %d flags %d\n", | |
146 | i, shname, data->d_buf, data->d_size, | |
147 | shdr.sh_link, (int) shdr.sh_flags); | |
148 | ||
149 | if (strcmp(shname, "license") == 0) { | |
150 | processed_sec[i] = true; | |
151 | memcpy(license, data->d_buf, data->d_size); | |
152 | } else if (strcmp(shname, "maps") == 0) { | |
153 | processed_sec[i] = true; | |
154 | if (load_maps(data->d_buf, data->d_size)) | |
155 | return 1; | |
156 | } else if (shdr.sh_type == SHT_SYMTAB) { | |
157 | symbols = data; | |
158 | } | |
159 | } | |
160 | ||
161 | /* load programs that need map fixup (relocations) */ | |
162 | for (i = 1; i < ehdr.e_shnum; i++) { | |
163 | ||
164 | if (get_sec(elf, i, &ehdr, &shname, &shdr, &data)) | |
165 | continue; | |
166 | if (shdr.sh_type == SHT_REL) { | |
167 | struct bpf_insn *insns; | |
168 | ||
169 | if (get_sec(elf, shdr.sh_info, &ehdr, &shname_prog, | |
170 | &shdr_prog, &data_prog)) | |
171 | continue; | |
172 | ||
173 | insns = (struct bpf_insn *) data_prog->d_buf; | |
174 | ||
175 | processed_sec[shdr.sh_info] = true; | |
176 | processed_sec[i] = true; | |
177 | ||
178 | if (parse_relo_and_apply(data, symbols, &shdr, insns)) | |
179 | continue; | |
180 | ||
181 | if (memcmp(shname_prog, "events/", 7) == 0 || | |
182 | memcmp(shname_prog, "socket", 6) == 0) | |
183 | load_and_attach(shname_prog, insns, data_prog->d_size); | |
184 | } | |
185 | } | |
186 | ||
187 | /* load programs that don't use maps */ | |
188 | for (i = 1; i < ehdr.e_shnum; i++) { | |
189 | ||
190 | if (processed_sec[i]) | |
191 | continue; | |
192 | ||
193 | if (get_sec(elf, i, &ehdr, &shname, &shdr, &data)) | |
194 | continue; | |
195 | ||
196 | if (memcmp(shname, "events/", 7) == 0 || | |
197 | memcmp(shname, "socket", 6) == 0) | |
198 | load_and_attach(shname, data->d_buf, data->d_size); | |
199 | } | |
200 | ||
201 | close(fd); | |
202 | return 0; | |
203 | } |