From patchwork Tue May 12 15:44:50 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Stefan Berger X-Patchwork-Id: 1288568 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 49M2Fh5jNtz9sSr for ; Wed, 13 May 2020 01:45:44 +1000 (AEST) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from bilbo.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 49M2Fh14lgzDqjb for ; Wed, 13 May 2020 01:45:44 +1000 (AEST) X-Original-To: slof@lists.ozlabs.org Delivered-To: slof@lists.ozlabs.org Authentication-Results: lists.ozlabs.org; spf=none (no SPF record) smtp.mailfrom=linux.vnet.ibm.com (client-ip=148.163.158.5; helo=mx0a-001b2d01.pphosted.com; envelope-from=stefanb@linux.vnet.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=linux.vnet.ibm.com Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 49M2F11BSVzDqX7 for ; Wed, 13 May 2020 01:45:02 +1000 (AEST) Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 04CFZJ1v006559; Tue, 12 May 2020 11:44:59 -0400 Received: from ppma02wdc.us.ibm.com (aa.5b.37a9.ip4.static.sl-reverse.com [169.55.91.170]) by mx0b-001b2d01.pphosted.com with ESMTP id 30yv20wmm8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 May 2020 11:44:59 -0400 Received: from pps.filterd (ppma02wdc.us.ibm.com [127.0.0.1]) by ppma02wdc.us.ibm.com (8.16.0.27/8.16.0.27) with SMTP id 04CFfpBH027368; Tue, 12 May 2020 15:44:59 GMT Received: from b03cxnp07028.gho.boulder.ibm.com (b03cxnp07028.gho.boulder.ibm.com [9.17.130.15]) by ppma02wdc.us.ibm.com with ESMTP id 30wm56jefm-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 12 May 2020 15:44:58 +0000 Received: from b03ledav006.gho.boulder.ibm.com (b03ledav006.gho.boulder.ibm.com [9.17.130.237]) by b03cxnp07028.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 04CFivXR52887934 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Tue, 12 May 2020 15:44:57 GMT Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 650A4C6059; Tue, 12 May 2020 15:44:57 +0000 (GMT) Received: from b03ledav006.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id F3D71C6055; Tue, 12 May 2020 15:44:56 +0000 (GMT) Received: from sbct-3.pok.ibm.com (unknown [9.47.158.153]) by b03ledav006.gho.boulder.ibm.com (Postfix) with ESMTP; Tue, 12 May 2020 15:44:56 +0000 (GMT) From: Stefan Berger To: aik@ozlabs.ru, slof@lists.ozlabs.org Date: Tue, 12 May 2020 11:44:50 -0400 Message-Id: <20200512154452.1702985-2-stefanb@linux.vnet.ibm.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200512154452.1702985-1-stefanb@linux.vnet.ibm.com> References: <20200512154452.1702985-1-stefanb@linux.vnet.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216, 18.0.676 definitions=2020-05-12_04:2020-05-11, 2020-05-12 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 mlxscore=0 suspectscore=0 bulkscore=0 clxscore=1015 spamscore=0 phishscore=0 priorityscore=1501 mlxlogscore=999 adultscore=0 impostorscore=0 malwarescore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005120115 Subject: [SLOF] [PATCH 1/3] elf: Implement elf_get_file_size to determine size of an ELF image X-BeenThere: slof@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: "Patches for https://github.com/aik/SLOF" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Stefan Berger Errors-To: slof-bounces+incoming=patchwork.ozlabs.org@lists.ozlabs.org Sender: "SLOF" From: Stefan Berger Implement elf_get_file_size to determine the size of an ELF image that has been loaded into a buffer much larger than the actual size of the original file. We determine the size by searching for the farthest offset declared by the ELF headers. Signed-off-by: Stefan Berger --- include/helpers.h | 2 ++ include/libelf.h | 14 ++++++++++ lib/libelf/elf.c | 26 +++++++++++++++++ lib/libelf/elf32.c | 69 ++++++++++++++++++++++++++++++++++++++++++++++ lib/libelf/elf64.c | 57 ++++++++++++++++++++++++++++++++++++++ 5 files changed, 168 insertions(+) diff --git a/include/helpers.h b/include/helpers.h index 47b2674..112184f 100644 --- a/include/helpers.h +++ b/include/helpers.h @@ -51,5 +51,7 @@ extern unsigned long SLOF_get_vtpm_unit(void); const typeof(((type *)0)->member)* struct_ptr = (ptr); \ (type *)((char *)struct_ptr - offset_of(type, member)); }) #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0])) +#define ROUNDUP(x,v) ((((x) + ((v) - 1)) / (v)) * (v)) +#define MAX(x,y) ((x) > (y) ? (x) : (y)) #endif diff --git a/include/libelf.h b/include/libelf.h index 5fbf279..48ff4d7 100644 --- a/include/libelf.h +++ b/include/libelf.h @@ -96,4 +96,18 @@ void elf_relocate64(void *file_addr, signed long offset); int elf_forth_claim(void *addr, long size); +long elf_get_file_size(const void *buffer, const long buffer_size); +long elf_get_file_size32(const void *buffer, const long buffer_size); +long elf_get_file_size64(const void *buffer, const long buffer_size); + +#ifdef __BIG_ENDIAN__ +#define elf64_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2MSB ? (x) : bswap_64(x)) +#define elf32_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2MSB ? (x) : bswap_32(x)) +#define elf16_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2MSB ? (x) : bswap_16(x)) +#else +#define elf64_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2LSB ? (x) : bswap_64(x)) +#define elf32_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2LSB ? (x) : bswap_32(x)) +#define elf16_to_cpu(x, ehdr) ((ehdr)->ei_data == ELFDATA2LSB ? (x) : bswap_16(x)) +#endif + #endif /* __LIBELF_H */ diff --git a/lib/libelf/elf.c b/lib/libelf/elf.c index 5204bc3..d368454 100644 --- a/lib/libelf/elf.c +++ b/lib/libelf/elf.c @@ -196,3 +196,29 @@ elf_get_base_addr(void *file_addr) return -1; } + +/** + * Get the file size of the ELF image that has been loaded into a + * buffer larger than the size of the file + * @return The size of the ELF image or < 0 for error + */ +long elf_get_file_size(const void *buffer, const long buffer_size) +{ + const struct ehdr *ehdr = (const struct ehdr *)buffer; + + if (buffer_size < sizeof(struct ehdr)) + return -1; + + /* check if it is an ELF image at all */ + if (cpu_to_be32(ehdr->ei_ident) != 0x7f454c46) + return -1; + + switch (ehdr->ei_class) { + case 1: + return elf_get_file_size32(buffer, buffer_size); + case 2: + return elf_get_file_size64(buffer, buffer_size); + } + + return -1; +} diff --git a/lib/libelf/elf32.c b/lib/libelf/elf32.c index fea5cf4..64ea386 100644 --- a/lib/libelf/elf32.c +++ b/lib/libelf/elf32.c @@ -17,6 +17,7 @@ #include #include #include +#include struct ehdr32 { uint32_t ei_ident; @@ -50,6 +51,18 @@ struct phdr32 { uint32_t p_align; }; +struct shdr32 { + uint32_t sh_name; + uint32_t sh_type; + uint32_t sh_flags; + uint32_t sh_addr; + uint32_t sh_offset; + uint32_t sh_size; + uint32_t sh_link; + uint32_t sh_info; + uint32_t sh_addralign; + uint32_t sh_entsize; +}; static struct phdr32* get_phdr32(void *file_addr) @@ -191,3 +204,59 @@ elf_byteswap_header32(void *file_addr) phdr = (struct phdr32 *)(((uint8_t *)phdr) + ehdr->e_phentsize); } } + +/* + * Determine the size of an ELF image that has been loaded into + * a buffer larger than its size. We search all program headers + * and sections for the one that shows the farthest extent of the + * file. + * @return Return -1 on error, size of file otherwise. + */ +long elf_get_file_size32(const void *buffer, const long buffer_size) +{ + const struct ehdr32 *ehdr = (const struct ehdr32 *) buffer; + const uint8_t *buffer_end = buffer + buffer_size; + const struct phdr32 *phdr; + const struct shdr32 *shdr; + long elf_size = -1; + uint16_t entsize; + unsigned i; + + if (buffer_size < sizeof(struct ehdr) || + ehdr->e_ehsize != sizeof(struct ehdr32)) + return -1; + + phdr = buffer + elf32_to_cpu(ehdr->e_phoff, ehdr); + entsize = elf16_to_cpu(ehdr->e_phentsize, ehdr); + for (i = 0; i < elf16_to_cpu(ehdr->e_phnum, ehdr); i++) { + if (((uint8_t *)phdr) + entsize > buffer_end) + return -1; + + elf_size = MAX(elf32_to_cpu(phdr->p_offset, ehdr) + + elf32_to_cpu(phdr->p_filesz, ehdr), + elf_size); + + /* step to next header */ + phdr = (struct phdr32 *)(((uint8_t *)phdr) + entsize); + } + + shdr = buffer + elf32_to_cpu(ehdr->e_shoff, ehdr); + entsize = elf16_to_cpu(ehdr->e_shentsize, ehdr); + for (i = 0; i < elf16_to_cpu(ehdr->e_shnum, ehdr); i++) { + if (((uint8_t *)shdr) + entsize > buffer_end) + return -1; + + elf_size = MAX(elf32_to_cpu(shdr->sh_offset, ehdr) + + elf32_to_cpu(shdr->sh_size, ehdr), + elf_size); + + /* step to next header */ + shdr = (struct shdr32 *)(((uint8_t *)shdr) + entsize); + } + + elf_size = ROUNDUP(elf_size, 4); + if (elf_size > buffer_size) + return -1; + + return elf_size; +} diff --git a/lib/libelf/elf64.c b/lib/libelf/elf64.c index 775cdee..0f30267 100644 --- a/lib/libelf/elf64.c +++ b/lib/libelf/elf64.c @@ -20,6 +20,7 @@ #include #include #include +#include struct ehdr64 { @@ -472,3 +473,59 @@ uint32_t elf_get_eflags_64(void *file_addr) return ehdr->e_flags; } + +/* + * Determine the size of an ELF image that has been loaded into + * a buffer larger than its size. We search all program headers + * and sections for the one that shows the farthest extent of the + * file. + * @return Return -1 on error, size of file otherwise. + */ +long elf_get_file_size64(const void *buffer, const long buffer_size) +{ + const struct ehdr64 *ehdr = (const struct ehdr64 *) buffer; + const uint8_t *buffer_end = buffer + buffer_size; + const struct phdr64 *phdr; + const struct shdr64 *shdr; + long elf_size = -1; + uint16_t entsize; + unsigned i; + + if (buffer_size < sizeof(struct ehdr) || + ehdr->e_ehsize != sizeof(struct ehdr64)) + return -1; + + phdr = buffer + elf64_to_cpu(ehdr->e_phoff, ehdr); + entsize = elf16_to_cpu(ehdr->e_phentsize, ehdr); + for (i = 0; i < elf16_to_cpu(ehdr->e_phnum, ehdr); i++) { + if (((uint8_t *)phdr) + entsize > buffer_end) + return -1; + + elf_size = MAX(elf64_to_cpu(phdr->p_offset, ehdr) + + elf64_to_cpu(phdr->p_filesz, ehdr), + elf_size); + + /* step to next header */ + phdr = (struct phdr64 *)(((uint8_t *)phdr) + entsize); + } + + shdr = buffer + elf64_to_cpu(ehdr->e_shoff, ehdr); + entsize = elf16_to_cpu(ehdr->e_shentsize, ehdr); + for (i = 0; i < elf16_to_cpu(ehdr->e_shnum, ehdr); i++) { + if (((uint8_t *)shdr) + entsize > buffer_end) + return -1; + + elf_size = MAX(elf64_to_cpu(shdr->sh_offset, ehdr) + + elf64_to_cpu(shdr->sh_size, ehdr), + elf_size); + + /* step to next header */ + shdr = (struct shdr64 *)(((uint8_t *)shdr) + entsize); + } + + elf_size = ROUNDUP(elf_size, 4); + if (elf_size > buffer_size) + return -1; + + return elf_size; +}