diff options
Diffstat (limited to 'toys/posix')
| -rw-r--r-- | toys/posix/file.c | 61 |
1 files changed, 43 insertions, 18 deletions
diff --git a/toys/posix/file.c b/toys/posix/file.c index 2eeb058b..49c7b22a 100644 --- a/toys/posix/file.c +++ b/toys/posix/file.c @@ -23,13 +23,16 @@ config FILE GLOBALS( int max_name_len; + + off_t len; ) // We don't trust elf.h to be there, and two codepaths for 32/64 is awkward // anyway, so calculate struct offsets manually. (It's a fixed ABI.) -static void do_elf_file(int fd, struct stat *sb) +static void do_elf_file(int fd) { - int endian = toybuf[5], bits = toybuf[4], i, j; + int endian = toybuf[5], bits = toybuf[4], i, j, dynamic = 0, stripped = 1, + phentsize, phnum, shsize, shnum; int64_t (*elf_int)(void *ptr, unsigned size); // Values from include/linux/elf-em.h (plus arch/*/include/asm/elf.h) // Names are linux/arch/ directory (sometimes before 32/64 bit merges) @@ -46,11 +49,8 @@ static void do_elf_file(int fd, struct stat *sb) {191, "tilegx"}, {3, "386"}, {6, "486"}, {62, "x86-64"}, {94, "xtensa"}, {0xabc7, "xtensa-old"} }; - int dynamic = 0; - int stripped = 1; - char *map; + char *map = 0; off_t phoff, shoff; - int phentsize, phnum, shsize, shnum; printf("ELF "); elf_int = (endian==2) ? peek_be : peek_le; @@ -94,6 +94,12 @@ static void do_elf_file(int fd, struct stat *sb) return; } + // Parsing ELF means following tables that may point to data earlier in + // the file, so sequential reading involves buffering unknown amounts of + // data. Just skip it if we can't mmap. + if (MAP_FAILED == (map = mmap(0, TT.len, PROT_READ, MAP_SHARED, fd, 0))) + goto bad; + // Stash what we need from the header; it's okay to reuse toybuf after this. phentsize = elf_int(toybuf+42+12*bits, 2); phnum = elf_int(toybuf+44+12*bits, 2); @@ -105,14 +111,19 @@ static void do_elf_file(int fd, struct stat *sb) // With binutils, phentsize seems to only be non-zero if phnum is non-zero. // Such ELF files are rare, but do exist. (Android's crtbegin files, say.) if (phnum && (phentsize != 32+24*bits)) { - printf(", corrupt phentsize %d?\n", phentsize); - return; + printf(", corrupt phentsize %d?", phentsize); + goto bad; } - map = xmmap(0, sb->st_size, PROT_READ, MAP_SHARED, fd, 0); + // Parsing ELF means following tables that may point to data earlier in + // the file, so sequential reading involves buffering unknown amounts of + // data. Just skip it if we can't mmap. + if (MAP_FAILED == (map = mmap(0, TT.len, PROT_READ, MAP_SHARED, fd, 0))) + goto bad; // We need to read the phdrs for dynamic vs static. // (Note: fields got reordered for 64 bit) + if (phoff+phnum*phentsize>TT.len) goto bad; for (i = 0; i<phnum; i++) { char *phdr = map+phoff+i*phentsize; int p_type = elf_int(phdr, 4); @@ -125,8 +136,10 @@ static void do_elf_file(int fd, struct stat *sb) p_offset = elf_int(phdr+4*j, 4*j); p_filesz = elf_int(phdr+16*j, 4*j); - if (p_type==3 /*PT_INTERP*/) + if (p_type==3 /*PT_INTERP*/) { + if (p_offset+p_filesz>TT.len) goto bad; printf(", dynamic (%.*s)", (int)p_filesz, map+p_offset); + } } if (!dynamic) printf(", static"); @@ -134,6 +147,7 @@ static void do_elf_file(int fd, struct stat *sb) // Notes are in program headers *and* section headers, but some files don't // contain program headers, so we prefer to check here. // (Note: fields got reordered for 64 bit) + if (shoff+i*shnum>TT.len) goto bad; for (i = 0; i<shnum; i++) { char *shdr = map+shoff+i*shsize; int sh_type = elf_int(shdr+4, 4); @@ -146,6 +160,8 @@ static void do_elf_file(int fd, struct stat *sb) } else if (sh_type == 7 /*SHT_NOTE*/) { char *note = map+sh_offset; + if (sh_offset+sh_size>TT.len) goto bad; + // An ELF note is a sequence of entries, each consisting of an // ndhr followed by n_namesz+n_descsz bytes of data (each of those // rounded up to the next 4 bytes, without this being reflected in @@ -158,11 +174,13 @@ static void do_elf_file(int fd, struct stat *sb) if (n_namesz==4 && !memcmp(note+12, "GNU", 4)) { if (n_type==3 /*NT_GNU_BUILD_ID*/) { + if (n_descsz+16>sh_size) goto bad; printf(", BuildID="); for (j = 0; j < n_descsz; ++j) printf("%02x", note[16 + j]); } } else if (n_namesz==8 && !memcmp(note+12, "Android", 8)) { if (n_type==1 /*.android.note.ident*/) { + if (n_descsz+24+64>sh_size) goto bad; printf(", for Android %d", (int)elf_int(note+20, 4)); if (n_descsz > 24) printf(", built by NDK %.64s (%.64s)", note+24, note+24+64); @@ -175,20 +193,24 @@ static void do_elf_file(int fd, struct stat *sb) } } printf(", %sstripped", stripped ? "" : "not "); +bad: xputc('\n'); - munmap(map, sb->st_size); + if (map && map != MAP_FAILED) munmap(map, TT.len); } -static void do_regular_file(int fd, char *name, struct stat *sb) +static void do_regular_file(int fd, char *name) { char *s; - int len = read(fd, s = toybuf, sizeof(toybuf)-256); - int magic; + int len, magic; - if (len<0) perror_msg("%s", name); + // zero through elf shnum, just in case + memset(toybuf, 0, 80); + if ((len = readall(fd, s = toybuf, sizeof(toybuf)))<0) perror_msg("%s", name); - if (len>40 && strstart(&s, "\177ELF")) do_elf_file(fd, sb); + if (!len) xputs("empty"); + // 45 bytes: https://www.muppetlabs.com/~breadbox/software/tiny/teensy.html + else if (len>=45 && strstart(&s, "\177ELF")) do_elf_file(fd); else if (len>=8 && strstart(&s, "!<arch>\n")) xprintf("ar archive\n"); else if (len>28 && strstart(&s, "\x89PNG\x0d\x0a\x1a\x0a")) { // PNG is big-endian: https://www.w3.org/TR/PNG/#7Integers-and-byte-order @@ -360,11 +382,14 @@ void file_main(void) xprintf("%s: %*s", name, (int)(TT.max_name_len - strlen(name)), ""); + sb.st_size = 0; if (fd || !((toys.optflags & FLAG_L) ? stat : lstat)(name, &sb)) { if (fd || S_ISREG(sb.st_mode)) { - if (!sb.st_size) what = "empty"; + TT.len = sb.st_size; + // This test identifies an empty file we don't have permission to read + if (!fd && !sb.st_size) what = "empty"; else if ((fd = openro(name, O_RDONLY)) != -1) { - do_regular_file(fd, name, &sb); + do_regular_file(fd, name); if (fd) close(fd); continue; } |