| /* |
| User-mode exec |
| |
| This bootstraps Valgrind. This code decides on the layout of the |
| client and Valgrind address spaces, loads valgrind.so and the |
| skin.so into the valgrind part, loads the client executable (and the |
| dynamic linker, if necessary) into the client part, and calls into |
| Valgrind proper. |
| |
| The code is careful not to allow spurious mappings to appear in the |
| wrong parts of the address space. In particular, to make sure |
| dlopen puts things in the right place, it will pad out the forbidden |
| chunks of address space so that dlopen is forced to put things where |
| we want them. |
| |
| The memory map it creates is: |
| |
| CLIENT_BASE +-------------------------+ |
| | client address space | |
| : : |
| : : |
| | client stack | |
| client_end +-------------------------+ |
| | redzone | |
| shadow_base +-------------------------+ |
| | | |
| : shadow memory for skins : |
| | (may be 0 sized) | |
| shadow_end +-------------------------+ |
| : gap (may be 0 sized) : |
| valgrind_base +-------------------------+ |
| | valgrind .so files | |
| | and mappings | |
| valgrind_mmap_end - |
| | kickstart executable | |
| - - |
| | valgrind heap vvvvvvvvv| |
| valgrind_end - - |
| | valgrind stack ^^^^^^^^^| |
| +-------------------------+ |
| : kernel : |
| */ |
| |
| #define _GNU_SOURCE |
| #define _FILE_OFFSET_BITS 64 |
| |
| #include "vg_include.h" |
| |
| #include <stddef.h> |
| #include <sys/mman.h> |
| #include <fcntl.h> |
| #include <errno.h> |
| #include <elf.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <stdlib.h> |
| #include <unistd.h> |
| #include <asm/unistd.h> |
| #include <sys/stat.h> |
| #include <sys/sysmacros.h> |
| #include <dlfcn.h> |
| #include <assert.h> |
| |
| #include "ume.h" |
| |
| static int padfile = -1; |
| static struct stat padstat; |
| |
| extern int kickstart_base; /* linker created */ |
| |
| void foreach_map(int (*fn)(void *start, void *end, |
| const char *perm, off_t offset, |
| int maj, int min, int ino)) |
| { |
| 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]; |
| off_t offset; |
| int maj, min; |
| int ino; |
| void *segstart, *segend; |
| |
| sscanf(bufptr, "%p-%p %s %Lx %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)) |
| break; |
| } |
| } |
| |
| /* pad all the empty spaces in a range of address space to stop |
| interlopers */ |
| void as_pad(void *start, void *end) |
| { |
| char buf[1024]; |
| char *addr; |
| |
| int fillgap(void *segstart, void *segend, const char *perm, off_t off, |
| int maj, int min, int ino) { |
| if (segstart >= end) |
| return 0; |
| |
| if ((char *)segstart > addr) |
| mmap(addr, (char *)segstart-addr, PROT_NONE, MAP_FIXED|MAP_PRIVATE, |
| padfile, 0); |
| addr = segend; |
| |
| return 1; |
| } |
| |
| if (padfile == -1) { |
| int seq = 1; |
| do { |
| sprintf(buf, "/tmp/.pad.%d.%d", getpid(), seq++); |
| padfile = open(buf, O_RDWR|O_CREAT|O_EXCL, 0); |
| unlink(buf); |
| if (padfile == -1 && errno != EEXIST) |
| exit(44); |
| } while(padfile == -1); |
| fstat(padfile, &padstat); |
| } |
| |
| addr = start; |
| |
| foreach_map(fillgap); |
| |
| if (addr < (char *)end) |
| mmap(addr, (char *)end-addr, PROT_NONE, MAP_FIXED|MAP_PRIVATE, |
| padfile, 0); |
| } |
| |
| /* remove padding from a range of address space - padding is always a |
| mapping of padfile*/ |
| void as_unpad(void *start, void *end) |
| { |
| int killpad(void *segstart, void *segend, const char *perm, off_t off, |
| int maj, int min, int ino) { |
| void *b, *e; |
| |
| if (padstat.st_dev != makedev(maj, min) || padstat.st_ino != ino) |
| return 1; |
| |
| if (segend <= start || segstart >= end) |
| return 1; |
| |
| if (segstart <= start) |
| b = start; |
| else |
| b = segstart; |
| |
| if (segend >= end) |
| e = end; |
| else |
| e = segend; |
| |
| munmap(b, (char *)e-(char *)b); |
| |
| return 1; |
| } |
| |
| if (padfile == -1) /* no padfile, no padding */ |
| return; |
| |
| foreach_map(killpad); |
| } |
| |
| void as_closepadfile(void) |
| { |
| /* don't unpad */ |
| close(padfile); |
| padfile = -1; |
| } |
| |
| int as_getpadfd(void) |
| { |
| return padfile; |
| } |
| |
| void as_setpadfd(int fd) |
| { |
| as_closepadfile(); |
| padfile = fd; |
| fstat(padfile, &padstat); |
| } |
| |
| struct ume_auxv *find_auxv(int *esp) |
| { |
| esp++; /* skip argc */ |
| |
| while(*esp != 0) /* skip argv */ |
| esp++; |
| esp++; |
| |
| while(*esp != 0) /* skip env */ |
| esp++; |
| esp++; |
| |
| return (struct ume_auxv *)esp; |
| } |
| |
| |
| struct elfinfo *readelf(int fd, const char *filename) |
| { |
| struct elfinfo *e = malloc(sizeof(*e)); |
| int phsz; |
| |
| e->fd = fd; |
| |
| if (pread(fd, &e->e, sizeof(e->e), 0) != sizeof(e->e)) { |
| fprintf(stderr, "%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, "%s: bad ELF magic\n", |
| filename); |
| return NULL; |
| } |
| if (e->e.e_ident[EI_CLASS] != ELFCLASS32) { |
| fprintf(stderr, "Can only handle 32-bit executables\n"); |
| return NULL; |
| } |
| if (e->e.e_ident[EI_DATA] != ELFDATA2LSB) { |
| fprintf(stderr, "Expecting little-endian\n"); |
| return NULL; |
| } |
| if (!(e->e.e_type == ET_EXEC || e->e.e_type == ET_DYN)) { |
| fprintf(stderr, "need executable\n"); |
| return NULL; |
| } |
| |
| if (e->e.e_machine != EM_386) { |
| fprintf(stderr, "need x86\n"); |
| return NULL; |
| } |
| |
| if (e->e.e_phentsize != sizeof(ESZ(Phdr))) { |
| fprintf(stderr, "sizeof Phdr wrong\n"); |
| return NULL; |
| } |
| |
| phsz = sizeof(ESZ(Phdr)) * e->e.e_phnum; |
| e->p = malloc(phsz); |
| |
| if (pread(fd, e->p, phsz, e->e.e_phoff) != phsz) { |
| fprintf(stderr, "can't read phdr: %s\n", strerror(errno)); |
| return NULL; |
| } |
| |
| return e; |
| } |
| |
| #define REMAINS(x, a) ((x) & ((a)-1)) |
| |
| /* Map an ELF file. Returns the brk address. */ |
| ESZ(Addr) mapelf(struct elfinfo *e, ESZ(Addr) base, int setbrk) |
| { |
| int i; |
| 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; |
| } |
| |
| if (setbrk) { |
| /* sneaking up on the brk limit works better than actually |
| jumping directly there. Unfortunately, setting the brk is |
| tested against the datasize rlimit, even though we're not |
| actually using any memory. */ |
| char *b = sbrk(0); |
| char *initb = (char *)PGROUNDUP(b); |
| |
| while(b < (char *)elfbrk) { |
| unsigned delta = (char *)elfbrk - b; |
| static const unsigned limit = 256*1024*1024; |
| char *bb; |
| |
| if (delta > limit) |
| delta = limit; |
| //printf("elfbrk=%p b=%p delta=%u\n", elfbrk, b, delta); |
| bb = sbrk(delta); |
| if (bb != b) { |
| fprintf(stderr, "sbrk failed while adjusting brk base: " |
| "perhaps we hit the datasize ulimit?\n"); |
| break; |
| } |
| b += delta; |
| } |
| munmap(initb, (char *)PGROUNDDN(elfbrk)-initb); |
| } |
| |
| 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; |
| ESZ(Word) align; |
| 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; |
| |
| align = ph->p_align; |
| |
| addr = ph->p_vaddr+base; |
| off = ph->p_offset; |
| filesz = ph->p_filesz; |
| bss = addr+filesz; |
| memsz = ph->p_memsz; |
| brkaddr = addr+memsz; |
| |
| mmap((char *)ROUNDDN(addr, align), ROUNDUP(bss, align)-ROUNDDN(addr, align), |
| prot, MAP_FIXED|MAP_PRIVATE, e->fd, ROUNDDN(off, align)); |
| |
| /* if memsz > filesz, then we need to fill the remainder with zeroed pages */ |
| if (memsz > filesz) { |
| UInt bytes; |
| |
| bytes = ROUNDUP(brkaddr, align)-ROUNDUP(bss, align); |
| if (bytes > 0) |
| mmap((char *)ROUNDUP(bss, align), bytes, |
| prot, MAP_FIXED|MAP_ANONYMOUS|MAP_PRIVATE, -1, 0); |
| |
| bytes = bss & (VKI_BYTES_PER_PAGE - 1); |
| if (bytes > 0) { |
| bytes = VKI_BYTES_PER_PAGE - bytes; |
| memset((char *)bss, 0, bytes); |
| } |
| } |
| } |
| |
| return elfbrk; |
| } |
| |
| |
| 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; |
| ESZ(Addr) maxaddr = 0; |
| ESZ(Addr) interp_addr = 0; |
| ESZ(Word) interp_size = 0; |
| int i; |
| void *entry; |
| |
| e = readelf(fd, name); |
| |
| if (e == NULL) |
| return ENOEXEC; |
| |
| info->phnum = e->e.e_phnum; |
| info->entry = e->e.e_entry; |
| |
| 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; |
| 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; |
| |
| 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; |
| 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; |
| } |
| } |
| } |
| |
| if (info->exe_base != info->exe_end) { |
| if (minaddr >= maxaddr || |
| (minaddr < info->exe_base || |
| maxaddr > info->exe_end)) { |
| fprintf(stderr, "Executable is mapped outside of range %p-%p\n", |
| (void *)info->exe_base, (void *)info->exe_end); |
| return ENOMEM; |
| } |
| } |
| |
| info->brkbase = mapelf(e, 0, info->setbrk); /* map the executable */ |
| |
| if (interp != NULL) { |
| /* reserve a chunk of address space for interpreter */ |
| char *base = (char *)info->exe_base; |
| char *baseoff; |
| int flags = MAP_PRIVATE|MAP_ANONYMOUS; |
| |
| if (info->map_base != 0) { |
| base = (char *)info->map_base; |
| flags |= MAP_FIXED; |
| } |
| |
| base = mmap(base, interp_size, PROT_NONE, flags, -1, 0); |
| |
| baseoff = base - interp_addr; |
| |
| mapelf(interp, (ESZ(Addr))baseoff, 0); |
| |
| close(interp->fd); |
| free(interp); |
| |
| entry = baseoff + interp->e.e_entry; |
| info->interp_base = (ESZ(Addr))base; |
| } else |
| entry = (void *)e->e.e_entry; |
| |
| info->exe_base = minaddr; |
| info->exe_end = maxaddr; |
| |
| info->init_eip = (addr_t)entry; |
| |
| 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->argv0 = strdup(interp); |
| if (arg != NULL && *arg != '\0') |
| info->argv1 = strdup(arg); |
| |
| if (info->argv && info->argv[0] != NULL) |
| info->argv[0] = (char *)name; |
| |
| if (0) |
| printf("#! script: argv0=\"%s\" argv1=\"%s\"\n", |
| info->argv0, info->argv1); |
| |
| return do_exec_inner(interp, info); |
| } |
| |
| struct binfmt { |
| int (*match)(const char *hdr, int len); |
| int (*load) ( char *hdr, int len, int fd, const char *name, struct exeinfo *); |
| }; |
| |
| static const struct binfmt formats[] = { |
| { match_ELF, load_ELF }, |
| { match_script, load_script }, |
| }; |
| |
| |
| static int do_exec_inner(const char *exe, struct exeinfo *info) |
| { |
| int fd; |
| char buf[VKI_BYTES_PER_PAGE]; |
| int bufsz; |
| int i; |
| int ret; |
| struct stat st; |
| |
| fd = open(exe, O_RDONLY); |
| if (fd == -1) { |
| if (0) |
| fprintf(stderr, "Can't open executable %s: %s\n", |
| exe, strerror(errno)); |
| return errno; |
| } |
| |
| if (fstat(fd, &st) == -1) |
| return errno; |
| else { |
| uid_t uid = geteuid(); |
| gid_t gid = getegid(); |
| gid_t groups[32]; |
| int ngrp = getgroups(32, groups); |
| |
| if (st.st_mode & (S_ISUID | S_ISGID)) { |
| fprintf(stderr, "Can't execute suid/sgid executable %s\n", exe); |
| return EACCES; |
| } |
| |
| if (uid == st.st_uid && !(st.st_mode & S_IXUSR)) |
| return EACCES; |
| |
| if (gid == st.st_gid && !(st.st_mode & S_IXGRP)) |
| return EACCES; |
| |
| for(i = 0; i < ngrp; i++) |
| if (groups[i] == st.st_gid && !(st.st_mode & S_IXGRP)) |
| return EACCES; |
| |
| if (!(st.st_mode & S_IXOTH)) |
| return EACCES; |
| } |
| |
| 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; |
| } |
| |
| int do_exec(const char *exe, struct exeinfo *info) |
| { |
| info->argv0 = NULL; |
| info->argv1 = NULL; |
| |
| return do_exec_inner(exe, info); |
| } |