/* $OpenBSD: readelf.c,v 1.8 2004/05/19 02:32:35 tedu Exp $ */ /* * Copyright (c) Christos Zoulas 2003. * All Rights Reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice immediately at the beginning of the file, without modification, * this list of conditions, and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include "file.h" #ifdef BUILTIN_ELF #include <string.h> #include <ctype.h> #include <stdlib.h> #ifdef HAVE_UNISTD_H #include <unistd.h> #endif #include "readelf.h" #ifndef lint FILE_RCSID("@(#)$Id: readelf.c,v 1.8 2004/05/19 02:32:35 tedu Exp $") #endif #ifdef ELFCORE private int dophn_core(struct magic_set *, int, int, int, off_t, int, size_t); #endif private int dophn_exec(struct magic_set *, int, int, int, off_t, int, size_t); private int doshn(struct magic_set *, int, int, int, off_t, int, size_t); private size_t donote(struct magic_set *, unsigned char *, size_t, size_t, int, int, size_t); #define ELF_ALIGN(a) ((((a) + align - 1) / align) * align) private uint16_t getu16(int, uint16_t); private uint32_t getu32(int, uint32_t); private uint64_t getu64(int, uint64_t); private uint16_t getu16(int swap, uint16_t value) { union { uint16_t ui; char c[2]; } retval, tmpval; if (swap) { tmpval.ui = value; retval.c[0] = tmpval.c[1]; retval.c[1] = tmpval.c[0]; return retval.ui; } else return value; } private uint32_t getu32(int swap, uint32_t value) { union { uint32_t ui; char c[4]; } retval, tmpval; if (swap) { tmpval.ui = value; retval.c[0] = tmpval.c[3]; retval.c[1] = tmpval.c[2]; retval.c[2] = tmpval.c[1]; retval.c[3] = tmpval.c[0]; return retval.ui; } else return value; } private uint64_t getu64(int swap, uint64_t value) { union { uint64_t ui; char c[8]; } retval, tmpval; if (swap) { tmpval.ui = value; retval.c[0] = tmpval.c[7]; retval.c[1] = tmpval.c[6]; retval.c[2] = tmpval.c[5]; retval.c[3] = tmpval.c[4]; retval.c[4] = tmpval.c[3]; retval.c[5] = tmpval.c[2]; retval.c[6] = tmpval.c[1]; retval.c[7] = tmpval.c[0]; return retval.ui; } else return value; } #define sh_addr (class == ELFCLASS32 \ ? (void *) &sh32 \ : (void *) &sh64) #define sh_size (class == ELFCLASS32 \ ? sizeof sh32 \ : sizeof sh64) #define shs_type (class == ELFCLASS32 \ ? getu32(swap, sh32.sh_type) \ : getu32(swap, sh64.sh_type)) #define ph_addr (class == ELFCLASS32 \ ? (void *) &ph32 \ : (void *) &ph64) #define ph_size (class == ELFCLASS32 \ ? sizeof ph32 \ : sizeof ph64) #define ph_type (class == ELFCLASS32 \ ? getu32(swap, ph32.p_type) \ : getu32(swap, ph64.p_type)) #define ph_offset (class == ELFCLASS32 \ ? getu32(swap, ph32.p_offset) \ : getu64(swap, ph64.p_offset)) #define ph_align (size_t)((class == ELFCLASS32 \ ? (off_t) (ph32.p_align ? \ getu32(swap, ph32.p_align) : 4) \ : (off_t) (ph64.p_align ? \ getu64(swap, ph64.p_align) : 4))) #define nh_size (class == ELFCLASS32 \ ? sizeof nh32 \ : sizeof nh64) #define nh_type (class == ELFCLASS32 \ ? getu32(swap, nh32.n_type) \ : getu32(swap, nh64.n_type)) #define nh_namesz (class == ELFCLASS32 \ ? getu32(swap, nh32.n_namesz) \ : getu32(swap, nh64.n_namesz)) #define nh_descsz (class == ELFCLASS32 \ ? getu32(swap, nh32.n_descsz) \ : getu32(swap, nh64.n_descsz)) #define prpsoffsets(i) (class == ELFCLASS32 \ ? prpsoffsets32[i] \ : prpsoffsets64[i]) #ifdef ELFCORE size_t prpsoffsets32[] = { 8, /* FreeBSD */ 28, /* Linux 2.0.36 */ 32, /* Linux (I forget which kernel version) */ 84, /* SunOS 5.x */ }; size_t prpsoffsets64[] = { 120, /* SunOS 5.x, 64-bit */ }; #define NOFFSETS32 (sizeof prpsoffsets32 / sizeof prpsoffsets32[0]) #define NOFFSETS64 (sizeof prpsoffsets64 / sizeof prpsoffsets64[0]) #define NOFFSETS (class == ELFCLASS32 ? NOFFSETS32 : NOFFSETS64) /* * Look through the program headers of an executable image, searching * for a PT_NOTE section of type NT_PRPSINFO, with a name "CORE" or * "FreeBSD"; if one is found, try looking in various places in its * contents for a 16-character string containing only printable * characters - if found, that string should be the name of the program * that dropped core. Note: right after that 16-character string is, * at least in SunOS 5.x (and possibly other SVR4-flavored systems) and * Linux, a longer string (80 characters, in 5.x, probably other * SVR4-flavored systems, and Linux) containing the start of the * command line for that program. * * The signal number probably appears in a section of type NT_PRSTATUS, * but that's also rather OS-dependent, in ways that are harder to * dissect with heuristics, so I'm not bothering with the signal number. * (I suppose the signal number could be of interest in situations where * you don't have the binary of the program that dropped core; if you * *do* have that binary, the debugger will probably tell you what * signal it was.) */ #define OS_STYLE_SVR4 0 #define OS_STYLE_FREEBSD 1 #define OS_STYLE_NETBSD 2 private const char *os_style_names[] = { "SVR4", "FreeBSD", "NetBSD", }; private int dophn_core(struct magic_set *ms, int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Phdr ph32; Elf64_Phdr ph64; size_t offset; unsigned char nbuf[BUFSIZ]; ssize_t bufsize; if (size != ph_size) { if (file_printf(ms, ", corrupted program header size") == -1) return -1; return 0; } /* * Loop through all the program headers. */ for ( ; num; num--) { if (lseek(fd, off, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } if (read(fd, ph_addr, ph_size) == -1) { file_badread(ms); return -1; } off += size; if (ph_type != PT_NOTE) continue; /* * This is a PT_NOTE section; loop through all the notes * in the section. */ if (lseek(fd, (off_t) ph_offset, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } bufsize = read(fd, nbuf, BUFSIZ); if (bufsize == -1) { file_badread(ms); return -1; } offset = 0; for (;;) { if (offset >= (size_t)bufsize) break; offset = donote(ms, nbuf, offset, (size_t)bufsize, class, swap, 4); if (offset == 0) break; } } return 0; } #endif private size_t donote(struct magic_set *ms, unsigned char *nbuf, size_t offset, size_t size, int class, int swap, size_t align) { Elf32_Nhdr nh32; Elf64_Nhdr nh64; size_t noff, doff; #ifdef ELFCORE int os_style = -1; #endif uint32_t namesz, descsz; if (class == ELFCLASS32) memcpy(&nh32, &nbuf[offset], sizeof(nh32)); else memcpy(&nh64, &nbuf[offset], sizeof(nh64)); offset += nh_size; namesz = nh_namesz; descsz = nh_descsz; if ((namesz == 0) && (descsz == 0)) { /* * We're out of note headers. */ return offset; } if (namesz & 0x80000000) { (void)file_printf(ms, ", bad note name size 0x%lx", (unsigned long)namesz); return offset; } if (descsz & 0x80000000) { (void)file_printf(ms, ", bad note description size 0x%lx", (unsigned long)descsz); return offset; } noff = offset; doff = ELF_ALIGN(offset + namesz); if (offset + namesz >= size) { /* * We're past the end of the buffer. */ return doff; } offset = ELF_ALIGN(doff + descsz); if (offset + descsz >= size) { return offset; } if (namesz == 4 && strcmp((char *)&nbuf[noff], "GNU") == 0 && nh_type == NT_GNU_VERSION && descsz == 16) { uint32_t desc[4]; (void)memcpy(desc, &nbuf[doff], sizeof(desc)); if (file_printf(ms, ", for GNU/") == -1) return size; switch (getu32(swap, desc[0])) { case GNU_OS_LINUX: if (file_printf(ms, "Linux") == -1) return size; break; case GNU_OS_HURD: if (file_printf(ms, "Hurd") == -1) return size; break; case GNU_OS_SOLARIS: if (file_printf(ms, "Solaris") == -1) return size; break; default: if (file_printf(ms, "<unknown>") == -1) return size; } if (file_printf(ms, " %d.%d.%d", getu32(swap, desc[1]), getu32(swap, desc[2]), getu32(swap, desc[3])) == -1) return size; return size; } if (namesz == 7 && strcmp((char *)&nbuf[noff], "NetBSD") == 0 && nh_type == NT_NETBSD_VERSION && descsz == 4) { uint32_t desc; (void)memcpy(&desc, &nbuf[doff], sizeof(desc)); desc = getu32(swap, desc); if (file_printf(ms, ", for NetBSD") == -1) return size; /* * The version number used to be stuck as 199905, and was thus * basically content-free. Newer versions of NetBSD have fixed * this and now use the encoding of __NetBSD_Version__: * * MMmmrrpp00 * * M = major version * m = minor version * r = release ["",A-Z,Z[A-Z] but numeric] * p = patchlevel */ if (desc > 100000000U) { u_int ver_patch = (desc / 100) % 100; u_int ver_rel = (desc / 10000) % 100; u_int ver_min = (desc / 1000000) % 100; u_int ver_maj = desc / 100000000; if (file_printf(ms, " %u.%u", ver_maj, ver_min) == -1) return size; if (ver_rel == 0 && ver_patch != 0) { if (file_printf(ms, ".%u", ver_patch) == -1) return size; } else if (ver_rel != 0) { while (ver_rel > 26) { file_printf(ms, "Z"); ver_rel -= 26; } file_printf(ms, "%c", 'A' + ver_rel - 1); } } return size; } if (namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0 && nh_type == NT_FREEBSD_VERSION && descsz == 4) { uint32_t desc; (void)memcpy(&desc, &nbuf[doff], sizeof(desc)); desc = getu32(swap, desc); if (file_printf(ms, ", for FreeBSD") == -1) return size; /* * Contents is __FreeBSD_version, whose relation to OS * versions is defined by a huge table in the Porters' * Handbook. For up to 5.x, the first three digits are * the version number. For 5.x and higher, the scheme * is: <major><two digit minor> <0 if release branch, * otherwise 1>xx */ if (desc / 100000 < 5) { if (file_printf(ms, " %d.%d", desc / 100000, desc / 10000 % 10) == -1) return size; if (desc / 1000 % 10 > 0) if (file_printf(ms, ".%d", desc / 1000 % 10) == -1) return size; } else { if (file_printf(ms, " %d.%d", desc / 100000, desc / 1000 % 100) == -1) return size; desc %= 1000; if (desc > 100) { if (file_printf(ms, "-CURRENT (rev %d)", desc % 100) == -1) return size; } else if (desc != 0) { if (file_printf(ms, ".%d", desc / 10) == -1) return size; } } return size; } if (namesz == 8 && strcmp((char *)&nbuf[noff], "OpenBSD") == 0 && nh_type == NT_OPENBSD_VERSION && descsz == 4) { if (file_printf(ms, ", for OpenBSD") == -1) return size; /* Content of note is always 0 */ return size; } /* * Sigh. The 2.0.36 kernel in Debian 2.1, at * least, doesn't correctly implement name * sections, in core dumps, as specified by * the "Program Linking" section of "UNIX(R) System * V Release 4 Programmer's Guide: ANSI C and * Programming Support Tools", because my copy * clearly says "The first 'namesz' bytes in 'name' * contain a *null-terminated* [emphasis mine] * character representation of the entry's owner * or originator", but the 2.0.36 kernel code * doesn't include the terminating null in the * name.... */ if ((namesz == 4 && strncmp((char *)&nbuf[noff], "CORE", 4) == 0) || (namesz == 5 && strcmp((char *)&nbuf[noff], "CORE") == 0)) { os_style = OS_STYLE_SVR4; } if ((namesz == 8 && strcmp((char *)&nbuf[noff], "FreeBSD") == 0)) { os_style = OS_STYLE_FREEBSD; } if ((namesz >= 11 && strncmp((char *)&nbuf[noff], "NetBSD-CORE", 11) == 0)) { os_style = OS_STYLE_NETBSD; } #ifdef ELFCORE if (os_style != -1) if (file_printf(ms, ", %s-style", os_style_names[os_style]) == -1) return size; if (os_style == OS_STYLE_NETBSD && nh_type == NT_NETBSD_CORE_PROCINFO) { uint32_t signo; /* * Extract the program name. It is at * offset 0x7c, and is up to 32-bytes, * including the terminating NUL. */ if (file_printf(ms, ", from '%.31s'", &nbuf[doff + 0x7c]) == -1) return size; /* * Extract the signal number. It is at * offset 0x08. */ memcpy(&signo, &nbuf[doff + 0x08], sizeof(signo)); if (file_printf(ms, " (signal %u)", getu32(swap, signo)) == -1) return size; return size; } else if (os_style != OS_STYLE_NETBSD && nh_type == NT_PRPSINFO) { size_t i, j; unsigned char c; /* * Extract the program name. We assume * it to be 16 characters (that's what it * is in SunOS 5.x and Linux). * * Unfortunately, it's at a different offset * in varous OSes, so try multiple offsets. * If the characters aren't all printable, * reject it. */ for (i = 0; i < NOFFSETS; i++) { size_t reloffset = prpsoffsets(i); size_t noffset = doff + reloffset; for (j = 0; j < 16; j++, noffset++, reloffset++) { /* * Make sure we're not past * the end of the buffer; if * we are, just give up. */ if (noffset >= size) goto tryanother; /* * Make sure we're not past * the end of the contents; * if we are, this obviously * isn't the right offset. */ if (reloffset >= descsz) goto tryanother; c = nbuf[noffset]; if (c == '\0') { /* * A '\0' at the * beginning is * obviously wrong. * Any other '\0' * means we're done. */ if (j == 0) goto tryanother; else break; } else { /* * A nonprintable * character is also * wrong. */ #define isquote(c) (strchr("'\"`", (c)) != NULL) if (!isprint(c) || isquote(c)) goto tryanother; } } /* * Well, that worked. */ if (file_printf(ms, ", from '%.16s'", &nbuf[doff + prpsoffsets(i)]) == -1) return size; return size; tryanother: ; } return offset; } #endif return offset; } private int doshn(struct magic_set *ms, int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Shdr sh32; Elf64_Shdr sh64; if (size != sh_size) { if (file_printf(ms, ", corrupted section header size") == -1) return -1; return 0; } if (lseek(fd, off, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } for ( ; num; num--) { if (read(fd, sh_addr, sh_size) == -1) { file_badread(ms); return -1; } if (shs_type == SHT_SYMTAB /* || shs_type == SHT_DYNSYM */) { if (file_printf(ms, ", not stripped") == -1) return -1; return 0; } } if (file_printf(ms, ", stripped") == -1) return -1; return 0; } /* * Look through the program headers of an executable image, searching * for a PT_INTERP section; if one is found, it's dynamically linked, * otherwise it's statically linked. */ private int dophn_exec(struct magic_set *ms, int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Phdr ph32; Elf64_Phdr ph64; const char *linking_style = "statically"; const char *shared_libraries = ""; unsigned char nbuf[BUFSIZ]; int bufsize; size_t offset, align; off_t savedoffset; if (size != ph_size) { if (file_printf(ms, ", corrupted program header size") == -1) return -1; return 0; } if (lseek(fd, off, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } for ( ; num; num--) { if (read(fd, ph_addr, ph_size) == -1) { file_badread(ms); return -1; } if ((savedoffset = lseek(fd, (off_t)0, SEEK_CUR)) == (off_t)-1) { file_badseek(ms); return -1; } switch (ph_type) { case PT_DYNAMIC: linking_style = "dynamically"; break; case PT_INTERP: shared_libraries = " (uses shared libs)"; break; case PT_NOTE: if ((align = ph_align) & 0x80000000) { if (file_printf(ms, ", invalid note alignment 0x%lx", (unsigned long)align) == -1) return -1; align = 4; } /* * This is a PT_NOTE section; loop through all the notes * in the section. */ if (lseek(fd, (off_t) ph_offset, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } bufsize = read(fd, nbuf, sizeof(nbuf)); if (bufsize == -1) { file_badread(ms); return -1; } offset = 0; for (;;) { if (offset >= (size_t)bufsize) break; offset = donote(ms, nbuf, offset, (size_t)bufsize, class, swap, align); if (offset == 0) break; } if (lseek(fd, savedoffset + offset, SEEK_SET) == (off_t)-1) { file_badseek(ms); return -1; } break; } } if (file_printf(ms, ", %s linked%s", linking_style, shared_libraries) == -1) return -1; return 0; } protected int file_tryelf(struct magic_set *ms, int fd, const unsigned char *buf, size_t nbytes) { union { int32_t l; char c[sizeof (int32_t)]; } u; int class; int swap; /* * If we cannot seek, it must be a pipe, socket or fifo. */ if((lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) && (errno == ESPIPE)) fd = file_pipe2file(ms, fd, buf, nbytes); /* * ELF executables have multiple section headers in arbitrary * file locations and thus file(1) cannot determine it from easily. * Instead we traverse thru all section headers until a symbol table * one is found or else the binary is stripped. */ if (buf[EI_MAG0] != ELFMAG0 || (buf[EI_MAG1] != ELFMAG1 && buf[EI_MAG1] != OLFMAG1) || buf[EI_MAG2] != ELFMAG2 || buf[EI_MAG3] != ELFMAG3) return 0; class = buf[4]; if (class == ELFCLASS32) { Elf32_Ehdr elfhdr; if (nbytes <= sizeof (Elf32_Ehdr)) return 0; u.l = 1; (void) memcpy(&elfhdr, buf, sizeof elfhdr); swap = (u.c[sizeof(int32_t) - 1] + 1) != elfhdr.e_ident[5]; if (getu16(swap, elfhdr.e_type) == ET_CORE) { #ifdef ELFCORE if (dophn_core(ms, class, swap, fd, (off_t)getu32(swap, elfhdr.e_phoff), getu16(swap, elfhdr.e_phnum), (size_t)getu16(swap, elfhdr.e_phentsize)) == -1) return -1; #else ; #endif } else { if (getu16(swap, elfhdr.e_type) == ET_EXEC) { if (dophn_exec(ms, class, swap, fd, (off_t)getu32(swap, elfhdr.e_phoff), getu16(swap, elfhdr.e_phnum), (size_t)getu16(swap, elfhdr.e_phentsize)) == -1) return -1; } if (doshn(ms, class, swap, fd, (off_t)getu32(swap, elfhdr.e_shoff), getu16(swap, elfhdr.e_shnum), (size_t)getu16(swap, elfhdr.e_shentsize)) == -1) return -1; } return 1; } if (class == ELFCLASS64) { Elf64_Ehdr elfhdr; if (nbytes <= sizeof (Elf64_Ehdr)) return 0; u.l = 1; (void) memcpy(&elfhdr, buf, sizeof elfhdr); swap = (u.c[sizeof(int32_t) - 1] + 1) != elfhdr.e_ident[5]; if (getu16(swap, elfhdr.e_type) == ET_CORE) { #ifdef ELFCORE if (dophn_core(ms, class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES (off_t)getu32(swap, elfhdr.e_phoff[1]), #else (off_t)getu64(swap, elfhdr.e_phoff), #endif getu16(swap, elfhdr.e_phnum), (size_t)getu16(swap, elfhdr.e_phentsize)) == -1) return -1; #else ; #endif } else { if (getu16(swap, elfhdr.e_type) == ET_EXEC) { if (dophn_exec(ms, class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES (off_t)getu32(swap, elfhdr.e_phoff[1]), #else (off_t)getu64(swap, elfhdr.e_phoff), #endif getu16(swap, elfhdr.e_phnum), (size_t)getu16(swap, elfhdr.e_phentsize)) == -1) return -1; } if (doshn(ms, class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES (off_t)getu32(swap, elfhdr.e_shoff[1]), #else (off_t)getu64(swap, elfhdr.e_shoff), #endif getu16(swap, elfhdr.e_shnum), (size_t)getu16(swap, elfhdr.e_shentsize)) == -1) return -1; } return 1; } return 0; } #endif