| |
| /*--------------------------------------------------------------------*/ |
| /*--- User-mode execve(), and other stuff shared between stage1 ---*/ |
| /*--- and stage2. ume.c ---*/ |
| /*--------------------------------------------------------------------*/ |
| |
| /* |
| This file is part of Valgrind, a dynamic binary instrumentation |
| framework. |
| |
| Copyright (C) 2000-2005 Julian Seward |
| jseward@acm.org |
| |
| This program is free software; you can redistribute it and/or |
| modify it under the terms of the GNU General Public License as |
| published by the Free Software Foundation; either version 2 of the |
| License, or (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA |
| 02111-1307, USA. |
| |
| The GNU General Public License is contained in the file COPYING. |
| */ |
| |
| |
| #define _GNU_SOURCE |
| #define _FILE_OFFSET_BITS 64 |
| |
| #include "core.h" |
| |
| #include <sys/mman.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <assert.h> |
| |
| #include "ume.h" |
| |
| #if ELFSZ == 64 |
| #define ESZ(x) Elf64_##x |
| #elif ELFSZ == 32 |
| #define ESZ(x) Elf32_##x |
| #else |
| #error ELFSZ needs to ==32 or ==64 |
| #endif |
| |
| struct elfinfo |
| { |
| ESZ(Ehdr) e; |
| ESZ(Phdr) *p; |
| int fd; |
| }; |
| |
| static void check_mmap(void* res, void* base, int len) |
| { |
| if ((void*)-1 == res) { |
| fprintf(stderr, "valgrind: mmap(%p, %d) failed in UME.\n", base, len); |
| exit(1); |
| } |
| } |
| |
| // 'extra' allows the caller to pass in extra args to 'fn', like free |
| // variables to a closure. |
| void foreach_map(int (*fn)(char *start, char *end, |
| const char *perm, off_t offset, |
| int maj, int min, int ino, void* extra), |
| void* extra) |
| { |
| static char buf[10240]; |
| char *bufptr = buf; |
| int ret, fd; |
| |
| fd = open("/proc/self/maps", O_RDONLY); |
| |
| if (fd == -1) { |
| perror("open /proc/self/maps"); |
| return; |
| } |
| |
| ret = read(fd, buf, sizeof(buf)); |
| |
| if (ret == -1) { |
| perror("read /proc/self/maps"); |
| close(fd); |
| return; |
| } |
| close(fd); |
| |
| if (ret == sizeof(buf)) { |
| fprintf(stderr, "buf too small\n"); |
| return; |
| } |
| |
| while(bufptr && bufptr < buf+ret) { |
| char perm[5]; |
| ULong offset; |
| int maj, min; |
| int ino; |
| void *segstart, *segend; |
| |
| sscanf(bufptr, "%p-%p %s %llx %x:%x %d", |
| &segstart, &segend, perm, &offset, &maj, &min, &ino); |
| bufptr = strchr(bufptr, '\n'); |
| if (bufptr != NULL) |
| bufptr++; /* skip \n */ |
| |
| if (!(*fn)(segstart, segend, perm, offset, maj, min, ino, extra)) |
| break; |
| } |
| } |
| |
| /*------------------------------------------------------------*/ |
| /*--- Finding auxv on the stack ---*/ |
| /*------------------------------------------------------------*/ |
| |
| struct ume_auxv *find_auxv(UWord* sp) |
| { |
| sp++; // skip argc (Nb: is word-sized, not int-sized!) |
| |
| while (*sp != 0) // skip argv |
| sp++; |
| sp++; |
| |
| while (*sp != 0) // skip env |
| sp++; |
| sp++; |
| |
| return (struct ume_auxv *)sp; |
| } |
| |
| /*------------------------------------------------------------*/ |
| /*--- Loading ELF files ---*/ |
| /*------------------------------------------------------------*/ |
| |
| static |
| struct elfinfo *readelf(int fd, const char *filename) |
| { |
| struct elfinfo *e = malloc(sizeof(*e)); |
| int phsz; |
| |
| assert(e); |
| e->fd = fd; |
| |
| if (pread(fd, &e->e, sizeof(e->e), 0) != sizeof(e->e)) { |
| fprintf(stderr, "valgrind: %s: can't read elf header: %s\n", |
| filename, strerror(errno)); |
| return NULL; |
| } |
| |
| if (memcmp(&e->e.e_ident[0], ELFMAG, SELFMAG) != 0) { |
| fprintf(stderr, "valgrind: %s: bad ELF magic\n", filename); |
| return NULL; |
| } |
| if (e->e.e_ident[EI_CLASS] != VG_ELF_CLASS) { |
| fprintf(stderr, "valgrind: wrong executable class (eg. 32-bit instead\n" |
| "valgrind: of 64-bit)\n"); |
| return NULL; |
| } |
| if (e->e.e_ident[EI_DATA] != VG_ELF_ENDIANNESS) { |
| fprintf(stderr, "valgrind: wrong endian-ness\n"); |
| return NULL; |
| } |
| if (!(e->e.e_type == ET_EXEC || e->e.e_type == ET_DYN)) { |
| fprintf(stderr, "valgrind: need executable\n"); |
| return NULL; |
| } |
| |
| if (e->e.e_machine != VG_ELF_MACHINE) { |
| fprintf(stderr, "valgrind: wrong architecture\n"); |
| return NULL; |
| } |
| |
| if (e->e.e_phentsize != sizeof(ESZ(Phdr))) { |
| fprintf(stderr, "valgrind: sizeof Phdr wrong\n"); |
| return NULL; |
| } |
| |
| phsz = sizeof(ESZ(Phdr)) * e->e.e_phnum; |
| e->p = malloc(phsz); |
| assert(e->p); |
| |
| if (pread(fd, e->p, phsz, e->e.e_phoff) != phsz) { |
| fprintf(stderr, "valgrind: can't read phdr: %s\n", strerror(errno)); |
| return NULL; |
| } |
| |
| return e; |
| } |
| |
| /* Map an ELF file. Returns the brk address. */ |
| static |
| ESZ(Addr) mapelf(struct elfinfo *e, ESZ(Addr) base) |
| { |
| int i; |
| void* res; |
| ESZ(Addr) elfbrk = 0; |
| |
| for(i = 0; i < e->e.e_phnum; i++) { |
| ESZ(Phdr) *ph = &e->p[i]; |
| ESZ(Addr) addr, brkaddr; |
| ESZ(Word) memsz; |
| |
| if (ph->p_type != PT_LOAD) |
| continue; |
| |
| addr = ph->p_vaddr+base; |
| memsz = ph->p_memsz; |
| brkaddr = addr+memsz; |
| |
| if (brkaddr > elfbrk) |
| elfbrk = brkaddr; |
| } |
| |
| for(i = 0; i < e->e.e_phnum; i++) { |
| ESZ(Phdr) *ph = &e->p[i]; |
| ESZ(Addr) addr, bss, brkaddr; |
| ESZ(Off) off; |
| ESZ(Word) filesz; |
| ESZ(Word) memsz; |
| unsigned prot = 0; |
| |
| if (ph->p_type != PT_LOAD) |
| continue; |
| |
| if (ph->p_flags & PF_X) prot |= PROT_EXEC; |
| if (ph->p_flags & PF_W) prot |= PROT_WRITE; |
| if (ph->p_flags & PF_R) prot |= PROT_READ; |
| |
| addr = ph->p_vaddr+base; |
| off = ph->p_offset; |
| filesz = ph->p_filesz; |
| bss = addr+filesz; |
| memsz = ph->p_memsz; |
| brkaddr = addr+memsz; |
| |
| // Tom says: In the following, do what the Linux kernel does and only |
| // map the pages that are required instead of rounding everything to |
| // the specified alignment (ph->p_align). (AMD64 doesn't work if you |
| // use ph->p_align -- part of stage2's memory gets trashed somehow.) |
| |
| res = mmap((char *)PGROUNDDN(addr), PGROUNDUP(bss)-PGROUNDDN(addr), |
| prot, MAP_FIXED|MAP_PRIVATE, e->fd, PGROUNDDN(off)); |
| check_mmap(res, (char*)PGROUNDDN(addr), |
| PGROUNDUP(bss)-PGROUNDDN(addr)); |
| |
| // if memsz > filesz, fill the remainder with zeroed pages |
| if (memsz > filesz) { |
| UInt bytes; |
| |
| bytes = PGROUNDUP(brkaddr)-PGROUNDUP(bss); |
| if (bytes > 0) { |
| res = mmap((char *)PGROUNDUP(bss), bytes, |
| prot, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); |
| check_mmap(res, (char*)PGROUNDUP(bss), bytes); |
| } |
| |
| bytes = bss & (VKI_PAGE_SIZE - 1); |
| if (bytes > 0) { |
| bytes = VKI_PAGE_SIZE - bytes; |
| memset((char *)bss, 0, bytes); |
| } |
| } |
| } |
| |
| return elfbrk; |
| } |
| |
| // Forward declaration. |
| static int do_exec_inner(const char *exe, struct exeinfo *info); |
| |
| static int match_ELF(const char *hdr, int len) |
| { |
| ESZ(Ehdr) *e = (ESZ(Ehdr) *)hdr; |
| return (len > sizeof(*e)) && memcmp(&e->e_ident[0], ELFMAG, SELFMAG) == 0; |
| } |
| |
| static int load_ELF(char *hdr, int len, int fd, const char *name, |
| struct exeinfo *info) |
| { |
| struct elfinfo *e; |
| struct elfinfo *interp = NULL; |
| ESZ(Addr) minaddr = ~0; /* lowest mapped address */ |
| ESZ(Addr) maxaddr = 0; /* highest mapped address */ |
| ESZ(Addr) interp_addr = 0; /* interpreter (ld.so) address */ |
| ESZ(Word) interp_size = 0; /* interpreter size */ |
| ESZ(Word) interp_align = VKI_PAGE_SIZE; |
| int i; |
| void *entry; |
| ESZ(Addr) ebase = 0; |
| |
| #ifdef HAVE_PIE |
| ebase = info->exe_base; |
| #endif |
| |
| e = readelf(fd, name); |
| |
| if (e == NULL) |
| return ENOEXEC; |
| |
| info->phnum = e->e.e_phnum; |
| info->entry = e->e.e_entry + ebase; |
| info->phdr = 0; |
| |
| for(i = 0; i < e->e.e_phnum; i++) { |
| ESZ(Phdr) *ph = &e->p[i]; |
| |
| switch(ph->p_type) { |
| case PT_PHDR: |
| info->phdr = ph->p_vaddr + ebase; |
| break; |
| |
| case PT_LOAD: |
| if (ph->p_vaddr < minaddr) |
| minaddr = ph->p_vaddr; |
| if (ph->p_vaddr+ph->p_memsz > maxaddr) |
| maxaddr = ph->p_vaddr+ph->p_memsz; |
| break; |
| |
| case PT_INTERP: { |
| char *buf = malloc(ph->p_filesz+1); |
| int j; |
| int intfd; |
| int baseaddr_set; |
| |
| assert(buf); |
| pread(fd, buf, ph->p_filesz, ph->p_offset); |
| buf[ph->p_filesz] = '\0'; |
| |
| intfd = open(buf, O_RDONLY); |
| if (intfd == -1) { |
| perror("open interp"); |
| exit(1); |
| } |
| |
| interp = readelf(intfd, buf); |
| if (interp == NULL) { |
| fprintf(stderr, "Can't read interpreter\n"); |
| return 1; |
| } |
| free(buf); |
| |
| baseaddr_set = 0; |
| for(j = 0; j < interp->e.e_phnum; j++) { |
| ESZ(Phdr) *iph = &interp->p[j]; |
| ESZ(Addr) end; |
| |
| if (iph->p_type != PT_LOAD) |
| continue; |
| |
| if (!baseaddr_set) { |
| interp_addr = iph->p_vaddr; |
| interp_align = iph->p_align; |
| baseaddr_set = 1; |
| } |
| |
| /* assumes that all segments in the interp are close */ |
| end = (iph->p_vaddr - interp_addr) + iph->p_memsz; |
| |
| if (end > interp_size) |
| interp_size = end; |
| } |
| break; |
| |
| default: |
| // do nothing |
| break; |
| } |
| } |
| } |
| |
| if (info->phdr == 0) |
| info->phdr = minaddr + e->e.e_phoff; |
| |
| if (info->exe_base != info->exe_end) { |
| if (minaddr >= maxaddr || |
| (minaddr + ebase < info->exe_base || |
| maxaddr + ebase > info->exe_end)) { |
| fprintf(stderr, "Executable range %p-%p is outside the\n" |
| "acceptable range %p-%p\n", |
| (void *)minaddr + ebase, (void *)maxaddr + ebase, |
| (void *)info->exe_base, (void *)info->exe_end); |
| return ENOMEM; |
| } |
| } |
| |
| info->brkbase = mapelf(e, ebase); /* map the executable */ |
| |
| if (info->brkbase == 0) |
| return ENOMEM; |
| |
| if (interp != NULL) { |
| /* reserve a chunk of address space for interpreter */ |
| void* res; |
| char* base = (char *)info->exe_base; |
| char* baseoff; |
| int flags = MAP_PRIVATE|MAP_ANONYMOUS; |
| |
| if (info->map_base != 0) { |
| base = (char *)ROUNDUP(info->map_base, interp_align); |
| flags |= MAP_FIXED; |
| } |
| |
| res = mmap(base, interp_size, PROT_NONE, flags, -1, 0); |
| check_mmap(res, base, interp_size); |
| base = res; |
| |
| baseoff = base - interp_addr; |
| |
| mapelf(interp, (ESZ(Addr))baseoff); |
| |
| close(interp->fd); |
| |
| entry = baseoff + interp->e.e_entry; |
| info->interp_base = (ESZ(Addr))base; |
| |
| free(interp->p); |
| free(interp); |
| } else |
| entry = (void *)e->e.e_entry; |
| |
| info->exe_base = minaddr + ebase; |
| info->exe_end = maxaddr + ebase; |
| |
| info->init_eip = (Addr)entry; |
| |
| free(e->p); |
| free(e); |
| |
| return 0; |
| } |
| |
| |
| static int match_script(const char *hdr, Int len) |
| { |
| return (len > 2) && memcmp(hdr, "#!", 2) == 0; |
| } |
| |
| static int load_script(char *hdr, int len, int fd, const char *name, |
| struct exeinfo *info) |
| { |
| char *interp; |
| char *const end = hdr+len; |
| char *cp; |
| char *arg = NULL; |
| int eol; |
| |
| interp = hdr + 2; |
| while(interp < end && (*interp == ' ' || *interp == '\t')) |
| interp++; |
| |
| if (*interp != '/') |
| return ENOEXEC; /* absolute path only for interpreter */ |
| |
| /* skip over interpreter name */ |
| for(cp = interp; cp < end && *cp != ' ' && *cp != '\t' && *cp != '\n'; cp++) |
| ; |
| |
| eol = (*cp == '\n'); |
| |
| *cp++ = '\0'; |
| |
| if (!eol && cp < end) { |
| /* skip space before arg */ |
| while (cp < end && (*cp == '\t' || *cp == ' ')) |
| cp++; |
| |
| /* arg is from here to eol */ |
| arg = cp; |
| while (cp < end && *cp != '\n') |
| cp++; |
| *cp = '\0'; |
| } |
| |
| info->interp_name = strdup(interp); |
| assert(NULL != info->interp_name); |
| if (arg != NULL && *arg != '\0') { |
| info->interp_args = strdup(arg); |
| assert(NULL != info->interp_args); |
| } |
| |
| if (info->argv && info->argv[0] != NULL) |
| info->argv[0] = (char *)name; |
| |
| if (0) |
| printf("#! script: interp_name=\"%s\" interp_args=\"%s\"\n", |
| info->interp_name, info->interp_args); |
| |
| return do_exec_inner(interp, info); |
| } |
| |
| /* |
| Emulate the normal Unix permissions checking algorithm. |
| |
| If owner matches, then use the owner permissions, else |
| if group matches, then use the group permissions, else |
| use other permissions. |
| |
| Note that we can't deal with SUID/SGID, so we refuse to run them |
| (otherwise the executable may misbehave if it doesn't have the |
| permissions it thinks it does). |
| */ |
| static int check_perms(int fd) |
| { |
| struct stat st; |
| |
| if (fstat(fd, &st) == -1) |
| return errno; |
| |
| if (st.st_mode & (S_ISUID | S_ISGID)) { |
| //fprintf(stderr, "Can't execute suid/sgid executable %s\n", exe); |
| return EACCES; |
| } |
| |
| if (geteuid() == st.st_uid) { |
| if (!(st.st_mode & S_IXUSR)) |
| return EACCES; |
| } else { |
| int grpmatch = 0; |
| |
| if (getegid() == st.st_gid) |
| grpmatch = 1; |
| else { |
| gid_t groups[32]; |
| int ngrp = getgroups(32, groups); |
| int i; |
| |
| for(i = 0; i < ngrp; i++) |
| if (groups[i] == st.st_gid) { |
| grpmatch = 1; |
| break; |
| } |
| } |
| |
| if (grpmatch) { |
| if (!(st.st_mode & S_IXGRP)) |
| return EACCES; |
| } else if (!(st.st_mode & S_IXOTH)) |
| return EACCES; |
| } |
| |
| return 0; |
| } |
| |
| static int do_exec_inner(const char *exe, struct exeinfo *info) |
| { |
| int fd; |
| int err; |
| char buf[VKI_PAGE_SIZE]; |
| int bufsz; |
| int i; |
| int ret; |
| static const struct { |
| int (*match)(const char *hdr, int len); |
| int (*load) ( char *hdr, int len, int fd2, const char *name, |
| struct exeinfo *); |
| } formats[] = { |
| { match_ELF, load_ELF }, |
| { match_script, load_script }, |
| }; |
| |
| fd = open(exe, O_RDONLY); |
| if (fd == -1) { |
| if (0) |
| fprintf(stderr, "Can't open executable %s: %s\n", |
| exe, strerror(errno)); |
| return errno; |
| } |
| |
| err = check_perms(fd); |
| if (err != 0) { |
| close(fd); |
| return err; |
| } |
| |
| bufsz = pread(fd, buf, sizeof(buf), 0); |
| if (bufsz < 0) { |
| fprintf(stderr, "Can't read executable header: %s\n", |
| strerror(errno)); |
| close(fd); |
| return errno; |
| } |
| |
| ret = ENOEXEC; |
| for(i = 0; i < sizeof(formats)/sizeof(*formats); i++) { |
| if ((formats[i].match)(buf, bufsz)) { |
| ret = (formats[i].load)(buf, bufsz, fd, exe, info); |
| break; |
| } |
| } |
| |
| close(fd); |
| |
| return ret; |
| } |
| |
| // See ume.h for an indication of which entries of 'info' are inputs, which |
| // are outputs, and which are both. |
| int do_exec(const char *exe, struct exeinfo *info) |
| { |
| info->interp_name = NULL; |
| info->interp_args = NULL; |
| |
| return do_exec_inner(exe, info); |
| } |
| |
| /*--------------------------------------------------------------------*/ |
| /*--- end ume.c ---*/ |
| /*--------------------------------------------------------------------*/ |