iproute2/bpf-data-section-support-poc.patch

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From: Daniel Borkmann <daniel@iogearbox.net>
Subject: bpf: data section support poc
Patch-mainline: No, status unknown, seems to be implemented in libbpf instead
References: none
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
lib/bpf.c | 40 ++++++++++++++++++++++++++++++++++++++--
1 file changed, 38 insertions(+), 2 deletions(-)
--- a/lib/bpf.c
+++ b/lib/bpf.c
@@ -1147,6 +1147,7 @@ struct bpf_elf_ctx {
Elf_Data *sym_tab;
Elf_Data *str_tab;
Elf_Data *btf_data;
+ Elf_Data *glo_data;
char obj_uid[64];
int obj_fd;
int btf_fd;
@@ -1162,6 +1163,7 @@ struct bpf_elf_ctx {
int sec_maps;
int sec_text;
int sec_btf;
+ int sec_data;
char license[ELF_MAX_LICENSE_LEN];
enum bpf_prog_type type;
__u32 ifindex;
@@ -2057,6 +2059,15 @@ static int bpf_fetch_text(struct bpf_elf_ctx *ctx, int section,
return 0;
}
+static int bpf_fetch_data(struct bpf_elf_ctx *ctx, int section,
+ struct bpf_elf_sec_data *data)
+{
+ ctx->sec_data = section;
+ ctx->glo_data = data->sec_data;
+ ctx->sec_done[section] = true;
+ return 0;
+}
+
static void bpf_btf_report(int fd, struct bpf_elf_ctx *ctx)
{
fprintf(stderr, "\nBTF debug data section \'.BTF\' %s%s (%d)!\n",
@@ -2270,6 +2281,11 @@ static bool bpf_has_call_data(const struct bpf_elf_ctx *ctx)
return ctx->sec_text;
}
+static bool bpf_has_glob_data(const struct bpf_elf_ctx *ctx)
+{
+ return ctx->sec_data;
+}
+
static int bpf_fetch_ancillary(struct bpf_elf_ctx *ctx, bool check_text_sec)
{
struct bpf_elf_sec_data data;
@@ -2291,6 +2307,9 @@ static int bpf_fetch_ancillary(struct bpf_elf_ctx *ctx, bool check_text_sec)
!strcmp(data.sec_name, ".text") &&
check_text_sec)
ret = bpf_fetch_text(ctx, i, &data);
+ else if (data.sec_hdr.sh_type == SHT_PROGBITS &&
+ !strcmp(data.sec_name, ".data"))
+ ret = bpf_fetch_data(ctx, i, &data);
else if (data.sec_hdr.sh_type == SHT_SYMTAB &&
!strcmp(data.sec_name, ".symtab"))
ret = bpf_fetch_symtab(ctx, i, &data);
@@ -2404,6 +2423,21 @@ static int bpf_apply_relo_map(struct bpf_elf_ctx *ctx, struct bpf_elf_prog *prog
return 0;
}
+static int bpf_apply_relo_glob(struct bpf_elf_ctx *ctx, struct bpf_elf_prog *prog,
+ GElf_Rel *relo, GElf_Sym *sym,
+ struct bpf_relo_props *props)
+{
+ unsigned int insn_off = relo->r_offset / sizeof(struct bpf_insn);
+ int *data;
+
+ if (insn_off >= prog->insns_num)
+ return -EINVAL;
+
+ data = ctx->glo_data->d_buf + sym->st_value;
+ prog->insns[insn_off].imm = *data;
+ return 0;
+}
+
static int bpf_apply_relo_call(struct bpf_elf_ctx *ctx, struct bpf_elf_prog *prog,
GElf_Rel *relo, GElf_Sym *sym,
struct bpf_relo_props *props)
@@ -2458,10 +2492,12 @@ static int bpf_apply_relo_data(struct bpf_elf_ctx *ctx,
if (sym.st_shndx == ctx->sec_maps)
ret = bpf_apply_relo_map(ctx, prog, &relo, &sym, props);
+ else if (sym.st_shndx == ctx->sec_data)
+ ret = bpf_apply_relo_glob(ctx, prog, &relo, &sym, props);
else if (sym.st_shndx == ctx->sec_text)
ret = bpf_apply_relo_call(ctx, prog, &relo, &sym, props);
else
- fprintf(stderr, "ELF contains non-{map,call} related relo data in entry %u pointing to section %u! Compiler bug?!\n",
+ fprintf(stderr, "ELF contains non-{map,data,call} related relo data in entry %u pointing to section %u! Compiler bug?!\n",
relo_ent, sym.st_shndx);
if (ret < 0)
return ret;
@@ -2557,7 +2593,7 @@ static int bpf_fetch_prog_sec(struct bpf_elf_ctx *ctx, const char *section)
return ret;
}
- if (bpf_has_map_data(ctx) || bpf_has_call_data(ctx))
+ if (bpf_has_map_data(ctx) || bpf_has_call_data(ctx) || bpf_has_glob_data(ctx))
ret = bpf_fetch_prog_relo(ctx, section, &lderr, &sseen, &prog);
if (ret < 0 && !lderr)
ret = bpf_fetch_prog(ctx, section, &sseen);