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-rw-r--r--tools/bpf/bpftool/prog.c181
1 files changed, 172 insertions, 9 deletions
diff --git a/tools/bpf/bpftool/prog.c b/tools/bpf/bpftool/prog.c
index 037484ceaeaf..42ee8892549c 100644
--- a/tools/bpf/bpftool/prog.c
+++ b/tools/bpf/bpftool/prog.c
@@ -401,6 +401,88 @@ static int do_show(int argc, char **argv)
return err;
}
+#define SYM_MAX_NAME 256
+
+struct kernel_sym {
+ unsigned long address;
+ char name[SYM_MAX_NAME];
+};
+
+struct dump_data {
+ unsigned long address_call_base;
+ struct kernel_sym *sym_mapping;
+ __u32 sym_count;
+ char scratch_buff[SYM_MAX_NAME];
+};
+
+static int kernel_syms_cmp(const void *sym_a, const void *sym_b)
+{
+ return ((struct kernel_sym *)sym_a)->address -
+ ((struct kernel_sym *)sym_b)->address;
+}
+
+static void kernel_syms_load(struct dump_data *dd)
+{
+ struct kernel_sym *sym;
+ char buff[256];
+ void *tmp, *address;
+ FILE *fp;
+
+ fp = fopen("/proc/kallsyms", "r");
+ if (!fp)
+ return;
+
+ while (!feof(fp)) {
+ if (!fgets(buff, sizeof(buff), fp))
+ break;
+ tmp = realloc(dd->sym_mapping,
+ (dd->sym_count + 1) *
+ sizeof(*dd->sym_mapping));
+ if (!tmp) {
+out:
+ free(dd->sym_mapping);
+ dd->sym_mapping = NULL;
+ fclose(fp);
+ return;
+ }
+ dd->sym_mapping = tmp;
+ sym = &dd->sym_mapping[dd->sym_count];
+ if (sscanf(buff, "%p %*c %s", &address, sym->name) != 2)
+ continue;
+ sym->address = (unsigned long)address;
+ if (!strcmp(sym->name, "__bpf_call_base")) {
+ dd->address_call_base = sym->address;
+ /* sysctl kernel.kptr_restrict was set */
+ if (!sym->address)
+ goto out;
+ }
+ if (sym->address)
+ dd->sym_count++;
+ }
+
+ fclose(fp);
+
+ qsort(dd->sym_mapping, dd->sym_count,
+ sizeof(*dd->sym_mapping), kernel_syms_cmp);
+}
+
+static void kernel_syms_destroy(struct dump_data *dd)
+{
+ free(dd->sym_mapping);
+}
+
+static struct kernel_sym *kernel_syms_search(struct dump_data *dd,
+ unsigned long key)
+{
+ struct kernel_sym sym = {
+ .address = key,
+ };
+
+ return dd->sym_mapping ?
+ bsearch(&sym, dd->sym_mapping, dd->sym_count,
+ sizeof(*dd->sym_mapping), kernel_syms_cmp) : NULL;
+}
+
static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...)
{
va_list args;
@@ -410,8 +492,71 @@ static void print_insn(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args);
}
-static void dump_xlated_plain(void *buf, unsigned int len, bool opcodes)
+static const char *print_call_pcrel(struct dump_data *dd,
+ struct kernel_sym *sym,
+ unsigned long address,
+ const struct bpf_insn *insn)
{
+ if (sym)
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "%+d#%s", insn->off, sym->name);
+ else
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "%+d#0x%lx", insn->off, address);
+ return dd->scratch_buff;
+}
+
+static const char *print_call_helper(struct dump_data *dd,
+ struct kernel_sym *sym,
+ unsigned long address)
+{
+ if (sym)
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "%s", sym->name);
+ else
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "0x%lx", address);
+ return dd->scratch_buff;
+}
+
+static const char *print_call(void *private_data,
+ const struct bpf_insn *insn)
+{
+ struct dump_data *dd = private_data;
+ unsigned long address = dd->address_call_base + insn->imm;
+ struct kernel_sym *sym;
+
+ sym = kernel_syms_search(dd, address);
+ if (insn->src_reg == BPF_PSEUDO_CALL)
+ return print_call_pcrel(dd, sym, address, insn);
+ else
+ return print_call_helper(dd, sym, address);
+}
+
+static const char *print_imm(void *private_data,
+ const struct bpf_insn *insn,
+ __u64 full_imm)
+{
+ struct dump_data *dd = private_data;
+
+ if (insn->src_reg == BPF_PSEUDO_MAP_FD)
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "map[id:%u]", insn->imm);
+ else
+ snprintf(dd->scratch_buff, sizeof(dd->scratch_buff),
+ "0x%llx", (unsigned long long)full_imm);
+ return dd->scratch_buff;
+}
+
+static void dump_xlated_plain(struct dump_data *dd, void *buf,
+ unsigned int len, bool opcodes)
+{
+ const struct bpf_insn_cbs cbs = {
+ .cb_print = print_insn,
+ .cb_call = print_call,
+ .cb_imm = print_imm,
+ .private_data = dd,
+ };
struct bpf_insn *insn = buf;
bool double_insn = false;
unsigned int i;
@@ -425,7 +570,7 @@ static void dump_xlated_plain(void *buf, unsigned int len, bool opcodes)
double_insn = insn[i].code == (BPF_LD | BPF_IMM | BPF_DW);
printf("% 4d: ", i);
- print_bpf_insn(print_insn, NULL, insn + i, true);
+ print_bpf_insn(&cbs, NULL, insn + i, true);
if (opcodes) {
printf(" ");
@@ -454,8 +599,15 @@ static void print_insn_json(struct bpf_verifier_env *env, const char *fmt, ...)
va_end(args);
}
-static void dump_xlated_json(void *buf, unsigned int len, bool opcodes)
+static void dump_xlated_json(struct dump_data *dd, void *buf,
+ unsigned int len, bool opcodes)
{
+ const struct bpf_insn_cbs cbs = {
+ .cb_print = print_insn_json,
+ .cb_call = print_call,
+ .cb_imm = print_imm,
+ .private_data = dd,
+ };
struct bpf_insn *insn = buf;
bool double_insn = false;
unsigned int i;
@@ -470,7 +622,7 @@ static void dump_xlated_json(void *buf, unsigned int len, bool opcodes)
jsonw_start_object(json_wtr);
jsonw_name(json_wtr, "disasm");
- print_bpf_insn(print_insn_json, NULL, insn + i, true);
+ print_bpf_insn(&cbs, NULL, insn + i, true);
if (opcodes) {
jsonw_name(json_wtr, "opcodes");
@@ -505,6 +657,7 @@ static void dump_xlated_json(void *buf, unsigned int len, bool opcodes)
static int do_dump(int argc, char **argv)
{
struct bpf_prog_info info = {};
+ struct dump_data dd = {};
__u32 len = sizeof(info);
unsigned int buf_size;
char *filepath = NULL;
@@ -592,6 +745,14 @@ static int do_dump(int argc, char **argv)
goto err_free;
}
+ if ((member_len == &info.jited_prog_len &&
+ info.jited_prog_insns == 0) ||
+ (member_len == &info.xlated_prog_len &&
+ info.xlated_prog_insns == 0)) {
+ p_err("error retrieving insn dump: kernel.kptr_restrict set?");
+ goto err_free;
+ }
+
if (filepath) {
fd = open(filepath, O_WRONLY | O_CREAT | O_TRUNC, 0600);
if (fd < 0) {
@@ -608,17 +769,19 @@ static int do_dump(int argc, char **argv)
goto err_free;
}
} else {
- if (member_len == &info.jited_prog_len)
+ if (member_len == &info.jited_prog_len) {
disasm_print_insn(buf, *member_len, opcodes);
- else
+ } else {
+ kernel_syms_load(&dd);
if (json_output)
- dump_xlated_json(buf, *member_len, opcodes);
+ dump_xlated_json(&dd, buf, *member_len, opcodes);
else
- dump_xlated_plain(buf, *member_len, opcodes);
+ dump_xlated_plain(&dd, buf, *member_len, opcodes);
+ kernel_syms_destroy(&dd);
+ }
}
free(buf);
-
return 0;
err_free:
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.