From patchwork Thu May 21 16:56:37 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kristen Carlson Accardi X-Patchwork-Id: 11563503 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7728C739 for ; Thu, 21 May 2020 16:58:27 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id B3400207F7 for ; Thu, 21 May 2020 16:58:26 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B3400207F7 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18841-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 32121 invoked by uid 550); 21 May 2020 16:57:27 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 31949 invoked from network); 21 May 2020 16:57:25 -0000 IronPort-SDR: x2F5Ib1W1YzJy6ozXXOgdwjes1+IZeZXV+517Lpouk7sP6SEuDHIlWopFIZCpY+kpA8KzU9XVe yyqbHGNRmyUQ== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False IronPort-SDR: njCmB4gTQK2dXMgbbspYYmVit8ug7SUj50qxN2fydRgyxBuD1iCtuub5OK15JFfabU7bfQ1djv BPXbA74Drzfg== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.73,418,1583222400"; d="scan'208";a="309094746" From: Kristen Carlson Accardi To: keescook@chromium.org, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, "H. Peter Anvin" Cc: arjan@linux.intel.com, linux-kernel@vger.kernel.org, kernel-hardening@lists.openwall.com, rick.p.edgecombe@intel.com, Kristen Carlson Accardi , Tony Luck Subject: [PATCH v2 6/9] x86/tools: Add relative relocs for randomized functions Date: Thu, 21 May 2020 09:56:37 -0700 Message-Id: <20200521165641.15940-7-kristen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200521165641.15940-1-kristen@linux.intel.com> References: <20200521165641.15940-1-kristen@linux.intel.com> MIME-Version: 1.0 When reordering functions, the relative offsets for relocs that are either in the randomized sections, or refer to the randomized sections will need to be adjusted. Add code to detect whether a reloc satisifies these cases, and if so, add them to the appropriate reloc list. Signed-off-by: Kristen Carlson Accardi Reviewed-by: Tony Luck Tested-by: Tony Luck Reviewed-by: Kees Cook --- arch/x86/boot/compressed/Makefile | 7 +++- arch/x86/tools/relocs.c | 55 ++++++++++++++++++++++++------- arch/x86/tools/relocs.h | 4 +-- arch/x86/tools/relocs_common.c | 15 ++++++--- 4 files changed, 62 insertions(+), 19 deletions(-) diff --git a/arch/x86/boot/compressed/Makefile b/arch/x86/boot/compressed/Makefile index 5f7c262bcc99..3a5a004498de 100644 --- a/arch/x86/boot/compressed/Makefile +++ b/arch/x86/boot/compressed/Makefile @@ -117,6 +117,11 @@ $(obj)/vmlinux: $(vmlinux-objs-y) FORCE $(call if_changed,check-and-link-vmlinux) OBJCOPYFLAGS_vmlinux.bin := -R .comment -S + +ifdef CONFIG_FG_KASLR + RELOCS_ARGS += --fg-kaslr +endif + $(obj)/vmlinux.bin: vmlinux FORCE $(call if_changed,objcopy) @@ -124,7 +129,7 @@ targets += $(patsubst $(obj)/%,%,$(vmlinux-objs-y)) vmlinux.bin.all vmlinux.relo CMD_RELOCS = arch/x86/tools/relocs quiet_cmd_relocs = RELOCS $@ - cmd_relocs = $(CMD_RELOCS) $< > $@;$(CMD_RELOCS) --abs-relocs $< + cmd_relocs = $(CMD_RELOCS) $(RELOCS_ARGS) $< > $@;$(CMD_RELOCS) $(RELOCS_ARGS) --abs-relocs $< $(obj)/vmlinux.relocs: vmlinux FORCE $(call if_changed,relocs) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index a00dc133f109..bf51ff1854ff 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -42,6 +42,8 @@ struct section { }; static struct section *secs; +static int fg_kaslr; + static const char * const sym_regex_kernel[S_NSYMTYPES] = { /* * Following symbols have been audited. There values are constant and do @@ -351,8 +353,8 @@ static int sym_index(Elf_Sym *sym) return sym->st_shndx; /* calculate offset of sym from head of table. */ - offset = (unsigned long) sym - (unsigned long) symtab; - index = offset/sizeof(*sym); + offset = (unsigned long)sym - (unsigned long)symtab; + index = offset / sizeof(*sym); return elf32_to_cpu(xsymtab[index]); } @@ -500,22 +502,22 @@ static void read_symtabs(FILE *fp) sec->xsymtab = malloc(sec->shdr.sh_size); if (!sec->xsymtab) { die("malloc of %d bytes for xsymtab failed\n", - sec->shdr.sh_size); + sec->shdr.sh_size); } if (fseek(fp, sec->shdr.sh_offset, SEEK_SET) < 0) { die("Seek to %d failed: %s\n", - sec->shdr.sh_offset, strerror(errno)); + sec->shdr.sh_offset, strerror(errno)); } if (fread(sec->xsymtab, 1, sec->shdr.sh_size, fp) - != sec->shdr.sh_size) { + != sec->shdr.sh_size) { die("Cannot read extended symbol table: %s\n", - strerror(errno)); + strerror(errno)); } shxsymtabndx = i; continue; case SHT_SYMTAB: - num_syms = sec->shdr.sh_size/sizeof(Elf_Sym); + num_syms = sec->shdr.sh_size / sizeof(Elf_Sym); sec->symtab = malloc(sec->shdr.sh_size); if (!sec->symtab) { @@ -818,6 +820,32 @@ static int is_percpu_sym(ElfW(Sym) *sym, const char *symname) strncmp(symname, "init_per_cpu_", 13); } +static int is_function_section(struct section *sec) +{ + const char *name; + + if (!fg_kaslr) + return 0; + + name = sec_name(sec->shdr.sh_info); + + return(!strncmp(name, ".text.", 6)); +} + +static int is_randomized_sym(ElfW(Sym) *sym) +{ + const char *name; + + if (!fg_kaslr) + return 0; + + if (sym->st_shndx > shnum) + return 0; + + name = sec_name(sym_index(sym)); + return(!strncmp(name, ".text.", 6)); +} + static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, const char *symname) { @@ -842,13 +870,17 @@ static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, case R_X86_64_PC32: case R_X86_64_PLT32: /* - * PC relative relocations don't need to be adjusted unless - * referencing a percpu symbol. + * we need to keep pc relative relocations for sections which + * might be randomized, and for the percpu section. + * We also need to keep relocations for any offset which might + * reference an address in a section which has been randomized. * * NB: R_X86_64_PLT32 can be treated as R_X86_64_PC32. */ - if (is_percpu_sym(sym, symname)) + if (is_function_section(sec) || is_randomized_sym(sym) || + is_percpu_sym(sym, symname)) add_reloc(&relocs32neg, offset); + break; case R_X86_64_PC64: @@ -1158,8 +1190,9 @@ static void print_reloc_info(void) void process(FILE *fp, int use_real_mode, int as_text, int show_absolute_syms, int show_absolute_relocs, - int show_reloc_info) + int show_reloc_info, int fgkaslr) { + fg_kaslr = fgkaslr; regex_init(use_real_mode); read_ehdr(fp); read_shdrs(fp); diff --git a/arch/x86/tools/relocs.h b/arch/x86/tools/relocs.h index 43c83c0fd22c..05504052c846 100644 --- a/arch/x86/tools/relocs.h +++ b/arch/x86/tools/relocs.h @@ -31,8 +31,8 @@ enum symtype { void process_32(FILE *fp, int use_real_mode, int as_text, int show_absolute_syms, int show_absolute_relocs, - int show_reloc_info); + int show_reloc_info, int fg_kaslr); void process_64(FILE *fp, int use_real_mode, int as_text, int show_absolute_syms, int show_absolute_relocs, - int show_reloc_info); + int show_reloc_info, int fg_kaslr); #endif /* RELOCS_H */ diff --git a/arch/x86/tools/relocs_common.c b/arch/x86/tools/relocs_common.c index 6634352a20bc..1407db72367a 100644 --- a/arch/x86/tools/relocs_common.c +++ b/arch/x86/tools/relocs_common.c @@ -12,14 +12,14 @@ void die(char *fmt, ...) static void usage(void) { - die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode]" \ - " vmlinux\n"); + die("relocs [--abs-syms|--abs-relocs|--reloc-info|--text|--realmode|" \ + "--fg-kaslr] vmlinux\n"); } int main(int argc, char **argv) { int show_absolute_syms, show_absolute_relocs, show_reloc_info; - int as_text, use_real_mode; + int as_text, use_real_mode, fg_kaslr; const char *fname; FILE *fp; int i; @@ -30,6 +30,7 @@ int main(int argc, char **argv) show_reloc_info = 0; as_text = 0; use_real_mode = 0; + fg_kaslr = 0; fname = NULL; for (i = 1; i < argc; i++) { char *arg = argv[i]; @@ -54,6 +55,10 @@ int main(int argc, char **argv) use_real_mode = 1; continue; } + if (strcmp(arg, "--fg-kaslr") == 0) { + fg_kaslr = 1; + continue; + } } else if (!fname) { fname = arg; @@ -75,11 +80,11 @@ int main(int argc, char **argv) if (e_ident[EI_CLASS] == ELFCLASS64) process_64(fp, use_real_mode, as_text, show_absolute_syms, show_absolute_relocs, - show_reloc_info); + show_reloc_info, fg_kaslr); else process_32(fp, use_real_mode, as_text, show_absolute_syms, show_absolute_relocs, - show_reloc_info); + show_reloc_info, fg_kaslr); fclose(fp); return 0; }