/* $OpenBSD: elfrdsetroot.c,v 1.13 2008/09/02 19:21:28 drahn Exp $ */ /* $NetBSD: rdsetroot.c,v 1.2 1995/10/13 16:38:39 gwr Exp $ */ /* * Copyright (c) 1994 Gordon W. Ross * All rights reserved. * * ELF modifications Copyright (c) 1997 Per Fogelstrom. * * 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, 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 ``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 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. */ /* * Copy a ramdisk image into the space reserved for it. * Kernel variables: rd_root_size, rd_root_image */ #include #include #include #include #include #include #include #include #ifdef __LP64__ #define ELFSIZE 64 #else #define ELFSIZE 32 #endif #include char *file; /* Virtual addresses of the symbols we frob. */ long rd_root_image_va, rd_root_size_va; /* Offsets relative to start of data segment. */ long rd_root_image_off, rd_root_size_off; /* value in the location at rd_root_size_off */ off_t rd_root_size_val; /* pointers to pieces of mapped file */ char *dataseg; /* parameters to mmap digged out from program header */ off_t mmap_offs; size_t mmap_size; int find_rd_root_image(char *, Elf_Ehdr *, Elf_Phdr *, int); __dead void usage(void); int main(int argc, char **argv) { int ch, fd, n, xflag = 0, found = 0, phsize; u_int32_t *ip; Elf_Ehdr eh; Elf_Phdr *ph; while ((ch = getopt(argc, argv, "x")) != -1) { switch (ch) { case 'x': xflag = 1; break; default: usage(); } } argc -= optind; argv += optind; if (argc != 1) usage(); file = argv[0]; fd = open(file, O_RDWR, 0644); if (fd < 0) { perror(file); exit(1); } n = read(fd, &eh, sizeof(eh)); if (n < sizeof(eh)) { printf("%s: reading header\n", file); exit(1); } if (!IS_ELF(eh)) { printf("%s: not elf\n", file); exit(1); } phsize = eh.e_phnum * sizeof(Elf_Phdr); ph = (Elf_Phdr *)malloc(phsize); lseek(fd, eh.e_phoff, SEEK_SET); if (read(fd, (char *)ph, phsize) != phsize) { printf("%s: can't read phdr area\n", file); exit(1); } for (n = 0; n < eh.e_phnum && !found; n++) { if (ph[n].p_type == PT_LOAD) found = find_rd_root_image(file, &eh, &ph[n], n); } if (!found) { printf("%s: can't locate space for rd_root_image!\n", file); exit(1); } /* * Map in the whole data segment. * The file offset needs to be page aligned. */ dataseg = mmap(NULL, mmap_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, mmap_offs); if (dataseg == MAP_FAILED) { printf("%s: can not map data seg\n", file); perror(file); exit(1); } /* * Find value in the location: rd_root_size */ ip = (u_int32_t*) (dataseg + rd_root_size_off); rd_root_size_val = *ip; #ifdef DEBUG printf("rd_root_size val: 0x%08X (%d blocks)\n", (u_int32_t)rd_root_size_val, (u_int32_t)(rd_root_size_val >> 9)); #endif /* * Copy the symbol table and string table. */ #ifdef DEBUG printf("copying root image...\n"); #endif if (xflag) { n = write(STDOUT_FILENO, dataseg + rd_root_image_off, rd_root_size_val); if (n != rd_root_size_val) { perror("write"); exit(1); } } else { struct stat sstat; if (fstat(STDIN_FILENO, &sstat) == -1) { perror("fstat"); exit(1); } if (S_ISREG(sstat.st_mode) && sstat.st_size > rd_root_size_val) { fprintf(stderr, "ramdisk too small 0x%x 0x%x\n", (long)sstat.st_size, rd_root_size_val); exit(1); } n = read(STDIN_FILENO, dataseg + rd_root_image_off, rd_root_size_val); if (n < 0) { perror("read"); exit(1); } msync(dataseg, mmap_size, 0); } #ifdef DEBUG printf("...copied %d bytes\n", n); #endif close(fd); exit(0); } /* * Find locations of the symbols to patch. */ struct nlist wantsyms[] = { { "_rd_root_size", 0 }, { "_rd_root_image", 0 }, { NULL, 0 } }; int find_rd_root_image(char *file, Elf_Ehdr *eh, Elf_Phdr *ph, int segment) { unsigned long kernel_start, kernel_size; if (nlist(file, wantsyms)) { printf("%s: no rd_root_image symbols?\n", file); exit(1); } kernel_start = ph->p_paddr; kernel_size = ph->p_filesz; rd_root_size_off = wantsyms[0].n_value - kernel_start; rd_root_size_off -= (ph->p_vaddr - ph->p_paddr); rd_root_image_off = wantsyms[1].n_value - kernel_start; rd_root_image_off -= (ph->p_vaddr - ph->p_paddr); #ifdef DEBUG printf("segment %d rd_root_size_off = 0x%x\n", segment, rd_root_size_off); if ((ph->p_vaddr - ph->p_paddr) != 0) printf("root_off v %x p %x, diff %x altered %x\n", ph->p_vaddr, ph->p_paddr, (ph->p_vaddr - ph->p_paddr), rd_root_size_off - (ph->p_vaddr - ph->p_paddr)); printf("rd_root_image_off = 0x%x\n", rd_root_image_off); #endif /* * Sanity check locations of db_* symbols */ if (rd_root_image_off < 0 || rd_root_image_off >= kernel_size) return(0); if (rd_root_size_off < 0 || rd_root_size_off >= kernel_size) { printf("%s: rd_root_size not in data segment?\n", file); return(0); } mmap_offs = ph->p_offset; mmap_size = kernel_size; return(1); } __dead void usage(void) { extern char *__progname; fprintf(stderr, "usage: %s [-x] file_name\n", __progname); exit(1); }