From patchwork Fri Jul 17 16:59:59 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: 11670827 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 5E6F56C1 for ; Fri, 17 Jul 2020 17:00:58 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 9A92F20737 for ; Fri, 17 Jul 2020 17:00:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9A92F20737 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-19377-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 5686 invoked by uid 550); 17 Jul 2020 17:00:39 -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 5447 invoked from network); 17 Jul 2020 17:00:38 -0000 IronPort-SDR: 8++28qQ0xLZy7mQz2Rqx6fiRHRCelk6pQzRrlHWX2LP5NGE8RHHnBVFwsQY3JsQKjl0wOjYUWa OsbSKWpuj+zQ== X-IronPort-AV: E=McAfee;i="6000,8403,9685"; a="167773819" X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="167773819" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False IronPort-SDR: 6GDDFSl4WIUvFvoQr4cvKSMzFPsgPABxdzkAMlVZvTV632NuRIDCcfOX9A9KJMeuIY6djN2iS/ yDiBEKa/JZ3A== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.75,362,1589266800"; d="scan'208";a="270861907" 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 v4 02/10] x86: tools/relocs: Support >64K section headers Date: Fri, 17 Jul 2020 09:59:59 -0700 Message-Id: <20200717170008.5949-3-kristen@linux.intel.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20200717170008.5949-1-kristen@linux.intel.com> References: <20200717170008.5949-1-kristen@linux.intel.com> MIME-Version: 1.0 While the relocs tool already supports finding the total number of section headers if vmlinux exceeds 64K sections, it fails to read the extended symbol table to get section header indexes for symbols, causing incorrect symbol table indexes to be used when there are > 64K symbols. Parse the elf file to read the extended symbol table info, and then replace all direct references to st_shndx with calls to sym_index(), which will determine whether the value can be read directly or whether the value should be pulled out of the extended table. Signed-off-by: Kristen Carlson Accardi Reviewed-by: Kees Cook Reviewed-by: Tony Luck Tested-by: Tony Luck --- arch/x86/tools/relocs.c | 104 ++++++++++++++++++++++++++++++---------- 1 file changed, 78 insertions(+), 26 deletions(-) diff --git a/arch/x86/tools/relocs.c b/arch/x86/tools/relocs.c index ce7188cbdae5..31b2d151aa63 100644 --- a/arch/x86/tools/relocs.c +++ b/arch/x86/tools/relocs.c @@ -14,6 +14,10 @@ static Elf_Ehdr ehdr; static unsigned long shnum; static unsigned int shstrndx; +static unsigned int shsymtabndx; +static unsigned int shxsymtabndx; + +static int sym_index(Elf_Sym *sym); struct relocs { uint32_t *offset; @@ -32,6 +36,7 @@ struct section { Elf_Shdr shdr; struct section *link; Elf_Sym *symtab; + Elf32_Word *xsymtab; Elf_Rel *reltab; char *strtab; }; @@ -265,7 +270,7 @@ static const char *sym_name(const char *sym_strtab, Elf_Sym *sym) name = sym_strtab + sym->st_name; } else { - name = sec_name(sym->st_shndx); + name = sec_name(sym_index(sym)); } return name; } @@ -335,6 +340,23 @@ static uint64_t elf64_to_cpu(uint64_t val) #define elf_xword_to_cpu(x) elf32_to_cpu(x) #endif +static int sym_index(Elf_Sym *sym) +{ + Elf_Sym *symtab = secs[shsymtabndx].symtab; + Elf32_Word *xsymtab = secs[shxsymtabndx].xsymtab; + unsigned long offset; + int index; + + if (sym->st_shndx != SHN_XINDEX) + return sym->st_shndx; + + /* calculate offset of sym from head of table. */ + offset = (unsigned long)sym - (unsigned long)symtab; + index = offset / sizeof(*sym); + + return elf32_to_cpu(xsymtab[index]); +} + static void read_ehdr(FILE *fp) { if (fread(&ehdr, sizeof(ehdr), 1, fp) != 1) { @@ -468,31 +490,60 @@ static void read_strtabs(FILE *fp) static void read_symtabs(FILE *fp) { int i,j; + for (i = 0; i < shnum; i++) { struct section *sec = &secs[i]; - if (sec->shdr.sh_type != SHT_SYMTAB) { + int num_syms; + + switch (sec->shdr.sh_type) { + case SHT_SYMTAB_SHNDX: + sec->xsymtab = malloc(sec->shdr.sh_size); + if (!sec->xsymtab) { + die("malloc of %d bytes for xsymtab failed\n", + 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)); + } + if (fread(sec->xsymtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read extended symbol table: %s\n", + strerror(errno)); + } + shxsymtabndx = i; + continue; + + case SHT_SYMTAB: + num_syms = sec->shdr.sh_size / sizeof(Elf_Sym); + + sec->symtab = malloc(sec->shdr.sh_size); + if (!sec->symtab) { + die("malloc of %d bytes for symtab failed\n", + 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)); + } + if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) + != sec->shdr.sh_size) { + die("Cannot read symbol table: %s\n", + strerror(errno)); + } + for (j = 0; j < num_syms; j++) { + Elf_Sym *sym = &sec->symtab[j]; + + sym->st_name = elf_word_to_cpu(sym->st_name); + sym->st_value = elf_addr_to_cpu(sym->st_value); + sym->st_size = elf_xword_to_cpu(sym->st_size); + sym->st_shndx = elf_half_to_cpu(sym->st_shndx); + } + shsymtabndx = i; + continue; + + default: continue; - } - sec->symtab = malloc(sec->shdr.sh_size); - if (!sec->symtab) { - die("malloc of %d bytes for symtab failed\n", - 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)); - } - if (fread(sec->symtab, 1, sec->shdr.sh_size, fp) - != sec->shdr.sh_size) { - die("Cannot read symbol table: %s\n", - strerror(errno)); - } - for (j = 0; j < sec->shdr.sh_size/sizeof(Elf_Sym); j++) { - Elf_Sym *sym = &sec->symtab[j]; - sym->st_name = elf_word_to_cpu(sym->st_name); - sym->st_value = elf_addr_to_cpu(sym->st_value); - sym->st_size = elf_xword_to_cpu(sym->st_size); - sym->st_shndx = elf_half_to_cpu(sym->st_shndx); } } } @@ -759,13 +810,14 @@ static void percpu_init(void) */ static int is_percpu_sym(ElfW(Sym) *sym, const char *symname) { - return (sym->st_shndx == per_cpu_shndx) && + int shndx = sym_index(sym); + + return (shndx == per_cpu_shndx) && strcmp(symname, "__init_begin") && strcmp(symname, "__per_cpu_load") && strncmp(symname, "init_per_cpu_", 13); } - static int do_reloc64(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, const char *symname) { @@ -1088,7 +1140,7 @@ static int do_reloc_info(struct section *sec, Elf_Rel *rel, ElfW(Sym) *sym, sec_name(sec->shdr.sh_info), rel_type(ELF_R_TYPE(rel->r_info)), symname, - sec_name(sym->st_shndx)); + sec_name(sym_index(sym))); return 0; }