#include "file.h" #ifdef BUILTIN_ELF #include #include #include #ifdef HAVE_UNISTD_H #include #endif #include "readelf.h" #ifndef lint FILE_RCSID("@(#)$Id: readelf.c,v 1.26 2003/02/25 15:30:00 christos Exp $") #endif #ifdef ELFCORE static void dophn_core(int, int, int, off_t, int, size_t); #endif static void dophn_exec(int, int, int, off_t, int, size_t); static void doshn(int, int, int, off_t, int, size_t); static uint16_t getu16(int, uint16_t); static uint32_t getu32(int, uint32_t); static uint64_t getu64(int, uint64_t); static 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; } static 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; } static 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 (class == ELFCLASS32 \ ? (ph32.p_align ? getu32(swap, ph32.p_align) : 4) \ : (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]) static void doshn(int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Shdr sh32; Elf64_Shdr sh64; if (size != sh_size) error("corrupted section header size.\n"); if (lseek(fd, off, SEEK_SET) == -1) error("lseek failed (%s).\n", strerror(errno)); for ( ; num; num--) { if (read(fd, sh_addr, sh_size) == -1) error("read failed (%s).\n", strerror(errno)); if (shs_type == SHT_SYMTAB /* || shs_type == SHT_DYNSYM */) { (void) printf (", not stripped"); return; } } (void) printf (", stripped"); } /* * 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. */ static void dophn_exec(int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Phdr ph32; Elf32_Nhdr *nh32 = NULL; Elf64_Phdr ph64; Elf64_Nhdr *nh64 = NULL; char *linking_style = "statically"; char *shared_libraries = ""; char nbuf[BUFSIZ]; int bufsize; size_t offset, nameoffset; off_t savedoffset; if (size != ph_size) error("corrupted program header size.\n"); if (lseek(fd, off, SEEK_SET) == -1) error("lseek failed (%s).\n", strerror(errno)); for ( ; num; num--) { if (read(fd, ph_addr, ph_size) == -1) error("read failed (%s).\n", strerror(errno)); if ((savedoffset = lseek(fd, 0, SEEK_CUR)) == -1) error("lseek failed (%s).\n", strerror(errno)); switch (ph_type) { case PT_DYNAMIC: linking_style = "dynamically"; break; case PT_INTERP: shared_libraries = " (uses shared libs)"; break; case PT_NOTE: /* * This is a PT_NOTE section; loop through all the notes * in the section. */ if (lseek(fd, (off_t) ph_offset, SEEK_SET) == -1) error("lseek failed (%s).\n", strerror(errno)); bufsize = read(fd, nbuf, sizeof(nbuf)); if (bufsize == -1) error(": " "read failed (%s).\n", strerror(errno)); offset = 0; for (;;) { if (offset >= bufsize) break; if (class == ELFCLASS32) nh32 = (Elf32_Nhdr *)&nbuf[offset]; else nh64 = (Elf64_Nhdr *)&nbuf[offset]; offset += nh_size; if (offset + nh_namesz >= bufsize) { /* * We're past the end of the buffer. */ break; } nameoffset = offset; offset += nh_namesz; offset = ((offset+ph_align-1)/ph_align)*ph_align; if ((nh_namesz == 0) && (nh_descsz == 0)) { /* * We're out of note headers. */ break; } if (offset + nh_descsz >= bufsize) break; if (nh_namesz == 4 && strcmp(&nbuf[nameoffset], "GNU") == 0 && nh_type == NT_GNU_VERSION && nh_descsz == 16) { uint32_t *desc = (uint32_t *)&nbuf[offset]; printf(", for GNU/"); switch (getu32(swap, desc[0])) { case GNU_OS_LINUX: printf("Linux"); break; case GNU_OS_HURD: printf("Hurd"); break; case GNU_OS_SOLARIS: printf("Solaris"); break; default: printf(""); } printf(" %d.%d.%d", getu32(swap, desc[1]), getu32(swap, desc[2]), getu32(swap, desc[3])); } if (nh_namesz == 7 && strcmp(&nbuf[nameoffset], "NetBSD") == 0 && nh_type == NT_NETBSD_VERSION && nh_descsz == 4) { printf(", for NetBSD"); /* * Version number is stuck at 199905, * and hence is basically content-free. */ } if (nh_namesz == 8 && strcmp(&nbuf[nameoffset], "FreeBSD") == 0 && nh_type == NT_FREEBSD_VERSION && nh_descsz == 4) { uint32_t desc = getu32(swap, *(uint32_t *)&nbuf[offset]); printf(", for FreeBSD"); /* * Contents is __FreeBSD_version, * whose relation to OS versions is * defined by a huge table in the * Porters' Handbook. Happily, the * first three digits are the version * number, at least in versions of * FreeBSD that use this note. */ printf(" %d.%d", desc / 100000, desc / 10000 % 10); if (desc / 1000 % 10 > 0) printf(".%d", desc / 1000 % 10); } if (nh_namesz == 8 && strcmp(&nbuf[nameoffset], "OpenBSD") == 0 && nh_type == NT_OPENBSD_VERSION && nh_descsz == 4) { printf(", for OpenBSD"); /* Content of note is always 0 */ } } if ((lseek(fd, savedoffset + offset, SEEK_SET)) == -1) error("lseek failed (%s).\n", strerror(errno)); break; } } printf(", %s linked%s", linking_style, shared_libraries); } #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 static const char *os_style_names[] = { "SVR4", "FreeBSD", "NetBSD", }; static void dophn_core(int class, int swap, int fd, off_t off, int num, size_t size) { Elf32_Phdr ph32; Elf32_Nhdr *nh32 = NULL; Elf64_Phdr ph64; Elf64_Nhdr *nh64 = NULL; size_t offset, nameoffset, noffset, reloffset; unsigned char c; int i, j; char nbuf[BUFSIZ]; int bufsize; int os_style = -1; if (size != ph_size) error("corrupted program header size.\n"); /* * Loop through all the program headers. */ for ( ; num; num--) { if (lseek(fd, off, SEEK_SET) == -1) error("lseek failed (%s).\n", strerror(errno)); if (read(fd, ph_addr, ph_size) == -1) error("read failed (%s).\n", strerror(errno)); 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) == -1) error("lseek failed (%s).\n", strerror(errno)); bufsize = read(fd, nbuf, BUFSIZ); if (bufsize == -1) error(": " "read failed (%s).\n", strerror(errno)); offset = 0; for (;;) { if (offset >= bufsize) break; if (class == ELFCLASS32) nh32 = (Elf32_Nhdr *)&nbuf[offset]; else nh64 = (Elf64_Nhdr *)&nbuf[offset]; offset += nh_size; /* * Check whether this note has the name "CORE" or * "FreeBSD", or "NetBSD-CORE". */ if (offset + nh_namesz >= bufsize) { /* * We're past the end of the buffer. */ break; } nameoffset = offset; offset += nh_namesz; offset = ((offset + 3)/4)*4; /* * 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 (os_style == -1) { if ((nh_namesz == 4 && strncmp(&nbuf[nameoffset], "CORE", 4) == 0) || (nh_namesz == 5 && strcmp(&nbuf[nameoffset], "CORE") == 0)) { os_style = OS_STYLE_SVR4; } else if ((nh_namesz == 8 && strcmp(&nbuf[nameoffset], "FreeBSD") == 0)) { os_style = OS_STYLE_FREEBSD; } else if ((nh_namesz >= 11 && strncmp(&nbuf[nameoffset], "NetBSD-CORE", 11) == 0)) { os_style = OS_STYLE_NETBSD; } else continue; printf(", %s-style", os_style_names[os_style]); } 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. */ printf(", from '%.31s'", &nbuf[offset + 0x7c]); /* * Extract the signal number. It is at * offset 0x08. */ memcpy(&signo, &nbuf[offset + 0x08], sizeof(signo)); printf(" (signal %u)", getu32(swap, signo)); } else if (os_style != OS_STYLE_NETBSD && nh_type == NT_PRPSINFO) { /* * 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++) { reloffset = prpsoffsets(i); noffset = offset + 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 >= bufsize) 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 >= nh_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. */ printf(", from '%.16s'", &nbuf[offset + prpsoffsets(i)]); break; tryanother: ; } break; } offset += nh_descsz; offset = ((offset + 3)/4)*4; } } } #endif void tryelf(int fd, unsigned char *buf, int nbytes) { union { int32_t l; char c[sizeof (int32_t)]; } u; int class; int swap; /* * If we can't seek, it must be a pipe, socket or fifo. */ if((lseek(fd, (off_t)0, SEEK_SET) == (off_t)-1) && (errno == ESPIPE)) fd = pipe2file(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; class = buf[4]; if (class == ELFCLASS32) { Elf32_Ehdr elfhdr; if (nbytes <= sizeof (Elf32_Ehdr)) return; 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 dophn_core(class, swap, fd, getu32(swap, elfhdr.e_phoff), getu16(swap, elfhdr.e_phnum), getu16(swap, elfhdr.e_phentsize)); #else ; #endif else { if (getu16(swap, elfhdr.e_type) == ET_EXEC) { dophn_exec(class, swap, fd, getu32(swap, elfhdr.e_phoff), getu16(swap, elfhdr.e_phnum), getu16(swap, elfhdr.e_phentsize)); } doshn(class, swap, fd, getu32(swap, elfhdr.e_shoff), getu16(swap, elfhdr.e_shnum), getu16(swap, elfhdr.e_shentsize)); } return; } if (class == ELFCLASS64) { Elf64_Ehdr elfhdr; if (nbytes <= sizeof (Elf64_Ehdr)) return; 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 dophn_core(class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES getu32(swap, elfhdr.e_phoff[1]), #else getu64(swap, elfhdr.e_phoff), #endif getu16(swap, elfhdr.e_phnum), getu16(swap, elfhdr.e_phentsize)); #else ; #endif else { if (getu16(swap, elfhdr.e_type) == ET_EXEC) { dophn_exec(class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES getu32(swap, elfhdr.e_phoff[1]), #else getu64(swap, elfhdr.e_phoff), #endif getu16(swap, elfhdr.e_phnum), getu16(swap, elfhdr.e_phentsize)); } doshn(class, swap, fd, #ifdef USE_ARRAY_FOR_64BIT_TYPES getu32(swap, elfhdr.e_shoff[1]), #else getu64(swap, elfhdr.e_shoff), #endif getu16(swap, elfhdr.e_shnum), getu16(swap, elfhdr.e_shentsize)); } return; } } #endif