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| author | Peter Zijlstra <peterz@infradead.org> | 2022-10-27 11:28:13 +0200 |
|---|---|---|
| committer | Peter Zijlstra <peterz@infradead.org> | 2022-11-01 13:44:10 +0100 |
| commit | 9a479f766be1dd777e12e3e57b6ee4c3028a40a5 (patch) | |
| tree | 5906547109c045bc9b590755b9c1ecd1218769e2 | |
| parent | x86: Add prefix symbols for function padding (diff) | |
| download | linux-9a479f766be1dd777e12e3e57b6ee4c3028a40a5.tar.xz linux-9a479f766be1dd777e12e3e57b6ee4c3028a40a5.zip | |
objtool: Add --cfi to generate the .cfi_sites section
Add the location of all __cfi_##name symbols (as generated by kCFI) to
a section such that we might re-write things at kernel boot.
Notably; boot time re-hashing and FineIBT are the intended use of
this.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221027092842.568039454@infradead.org
| -rw-r--r-- | tools/objtool/builtin-check.c | 1 | ||||
| -rw-r--r-- | tools/objtool/check.c | 69 | ||||
| -rw-r--r-- | tools/objtool/include/objtool/builtin.h | 1 |
3 files changed, 71 insertions, 0 deletions
diff --git a/tools/objtool/builtin-check.c b/tools/objtool/builtin-check.c index 95fcecee60ce..868e3e363786 100644 --- a/tools/objtool/builtin-check.c +++ b/tools/objtool/builtin-check.c @@ -80,6 +80,7 @@ const struct option check_options[] = { OPT_BOOLEAN('s', "stackval", &opts.stackval, "validate frame pointer rules"), OPT_BOOLEAN('t', "static-call", &opts.static_call, "annotate static calls"), OPT_BOOLEAN('u', "uaccess", &opts.uaccess, "validate uaccess rules for SMAP"), + OPT_BOOLEAN(0 , "cfi", &opts.cfi, "annotate kernel control flow integrity (kCFI) function preambles"), OPT_CALLBACK_OPTARG(0, "dump", NULL, NULL, "orc", "dump metadata", parse_dump), OPT_GROUP("Options:"), diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 27f35f5f831a..55066c493570 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -861,6 +861,68 @@ static int create_ibt_endbr_seal_sections(struct objtool_file *file) return 0; } +static int create_cfi_sections(struct objtool_file *file) +{ + struct section *sec, *s; + struct symbol *sym; + unsigned int *loc; + int idx; + + sec = find_section_by_name(file->elf, ".cfi_sites"); + if (sec) { + INIT_LIST_HEAD(&file->call_list); + WARN("file already has .cfi_sites section, skipping"); + return 0; + } + + idx = 0; + for_each_sec(file, s) { + if (!s->text) + continue; + + list_for_each_entry(sym, &s->symbol_list, list) { + if (sym->type != STT_FUNC) + continue; + + if (strncmp(sym->name, "__cfi_", 6)) + continue; + + idx++; + } + } + + sec = elf_create_section(file->elf, ".cfi_sites", 0, sizeof(unsigned int), idx); + if (!sec) + return -1; + + idx = 0; + for_each_sec(file, s) { + if (!s->text) + continue; + + list_for_each_entry(sym, &s->symbol_list, list) { + if (sym->type != STT_FUNC) + continue; + + if (strncmp(sym->name, "__cfi_", 6)) + continue; + + loc = (unsigned int *)sec->data->d_buf + idx; + memset(loc, 0, sizeof(unsigned int)); + + if (elf_add_reloc_to_insn(file->elf, sec, + idx * sizeof(unsigned int), + R_X86_64_PC32, + s, sym->offset)) + return -1; + + idx++; + } + } + + return 0; +} + static int create_mcount_loc_sections(struct objtool_file *file) { struct section *sec; @@ -4430,6 +4492,13 @@ int check(struct objtool_file *file) warnings += ret; } + if (opts.cfi) { + ret = create_cfi_sections(file); + if (ret < 0) + goto out; + warnings += ret; + } + if (opts.rethunk) { ret = create_return_sites_sections(file); if (ret < 0) diff --git a/tools/objtool/include/objtool/builtin.h b/tools/objtool/include/objtool/builtin.h index f341b620dead..c44ff39df80c 100644 --- a/tools/objtool/include/objtool/builtin.h +++ b/tools/objtool/include/objtool/builtin.h @@ -27,6 +27,7 @@ struct opts { bool static_call; bool uaccess; int prefix; + bool cfi; /* options: */ bool backtrace; |