| 1 | /* Code for loading Linux executables. Mostly linux kernel code. */ |
| 2 | |
| 3 | #include "qemu/osdep.h" |
| 4 | #include "qemu.h" |
| 5 | #include "user-internals.h" |
| 6 | #include "user-mmap.h" |
| 7 | #include "loader.h" |
| 8 | #include "qapi/error.h" |
| 9 | |
| 10 | #define NGROUPS 32 |
| 11 | |
| 12 | /* ??? This should really be somewhere else. */ |
| 13 | abi_long memcpy_to_target(abi_ulong dest, const void *src, unsigned long len) |
| 14 | { |
| 15 | void *host_ptr; |
| 16 | |
| 17 | host_ptr = lock_user(VERIFY_WRITE, dest, len, 0); |
| 18 | if (!host_ptr) { |
| 19 | return -TARGET_EFAULT; |
| 20 | } |
| 21 | memcpy(host_ptr, src, len); |
| 22 | unlock_user(host_ptr, dest, 1); |
| 23 | return 0; |
| 24 | } |
| 25 | |
| 26 | static int count(char **vec) |
| 27 | { |
| 28 | int i; |
| 29 | |
| 30 | for (i = 0; *vec; i++) { |
| 31 | vec++; |
| 32 | } |
| 33 | return i; |
| 34 | } |
| 35 | |
| 36 | static int prepare_binprm(struct linux_binprm *bprm) |
| 37 | { |
| 38 | struct stat st; |
| 39 | int mode; |
| 40 | int retval; |
| 41 | |
| 42 | if (fstat(bprm->src.fd, &st) < 0) { |
| 43 | return -errno; |
| 44 | } |
| 45 | |
| 46 | mode = st.st_mode; |
| 47 | if (!S_ISREG(mode)) { /* Must be regular file */ |
| 48 | return -EACCES; |
| 49 | } |
| 50 | if (!(mode & 0111)) { /* Must have at least one execute bit set */ |
| 51 | return -EACCES; |
| 52 | } |
| 53 | |
| 54 | bprm->e_uid = geteuid(); |
| 55 | bprm->e_gid = getegid(); |
| 56 | |
| 57 | /* Set-uid? */ |
| 58 | if (mode & S_ISUID) { |
| 59 | bprm->e_uid = st.st_uid; |
| 60 | } |
| 61 | |
| 62 | /* Set-gid? */ |
| 63 | /* |
| 64 | * If setgid is set but no group execute bit then this |
| 65 | * is a candidate for mandatory locking, not a setgid |
| 66 | * executable. |
| 67 | */ |
| 68 | if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) { |
| 69 | bprm->e_gid = st.st_gid; |
| 70 | } |
| 71 | |
| 72 | retval = read(bprm->src.fd, bprm->buf, BPRM_BUF_SIZE); |
| 73 | if (retval < 0) { |
| 74 | perror("prepare_binprm"); |
| 75 | exit(-1); |
| 76 | } |
| 77 | if (retval < BPRM_BUF_SIZE) { |
| 78 | /* Make sure the rest of the loader won't read garbage. */ |
| 79 | memset(bprm->buf + retval, 0, BPRM_BUF_SIZE - retval); |
| 80 | } |
| 81 | |
| 82 | bprm->src.cache = bprm->buf; |
| 83 | bprm->src.cache_size = retval; |
| 84 | |
| 85 | return retval; |
| 86 | } |
| 87 | |
| 88 | /* Construct the envp and argv tables on the target stack. */ |
| 89 | abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp, |
| 90 | abi_ulong stringp, int push_ptr) |
| 91 | { |
| 92 | TaskState *ts = get_task_state(thread_cpu); |
| 93 | int n = sizeof(abi_ulong); |
| 94 | abi_ulong envp; |
| 95 | abi_ulong argv; |
| 96 | |
| 97 | sp -= (envc + 1) * n; |
| 98 | envp = sp; |
| 99 | sp -= (argc + 1) * n; |
| 100 | argv = sp; |
| 101 | ts->info->envp = envp; |
| 102 | ts->info->envc = envc; |
| 103 | ts->info->argv = argv; |
| 104 | ts->info->argc = argc; |
| 105 | |
| 106 | if (push_ptr) { |
| 107 | /* FIXME - handle put_user() failures */ |
| 108 | sp -= n; |
| 109 | put_user_ual(envp, sp); |
| 110 | sp -= n; |
| 111 | put_user_ual(argv, sp); |
| 112 | } |
| 113 | |
| 114 | sp -= n; |
| 115 | /* FIXME - handle put_user() failures */ |
| 116 | put_user_ual(argc, sp); |
| 117 | |
| 118 | ts->info->arg_strings = stringp; |
| 119 | while (argc-- > 0) { |
| 120 | /* FIXME - handle put_user() failures */ |
| 121 | put_user_ual(stringp, argv); |
| 122 | argv += n; |
| 123 | stringp += target_strlen(stringp) + 1; |
| 124 | } |
| 125 | /* FIXME - handle put_user() failures */ |
| 126 | put_user_ual(0, argv); |
| 127 | |
| 128 | ts->info->env_strings = stringp; |
| 129 | while (envc-- > 0) { |
| 130 | /* FIXME - handle put_user() failures */ |
| 131 | put_user_ual(stringp, envp); |
| 132 | envp += n; |
| 133 | stringp += target_strlen(stringp) + 1; |
| 134 | } |
| 135 | /* FIXME - handle put_user() failures */ |
| 136 | put_user_ual(0, envp); |
| 137 | |
| 138 | return sp; |
| 139 | } |
| 140 | |
| 141 | int loader_exec(int fdexec, const char *filename, char **argv, char **envp, |
| 142 | struct image_info *infop, struct linux_binprm *bprm) |
| 143 | { |
| 144 | int retval; |
| 145 | |
| 146 | bprm->src.fd = fdexec; |
| 147 | bprm->filename = (char *)filename; |
| 148 | bprm->argc = count(argv); |
| 149 | bprm->argv = argv; |
| 150 | bprm->envc = count(envp); |
| 151 | bprm->envp = envp; |
| 152 | |
| 153 | retval = prepare_binprm(bprm); |
| 154 | |
| 155 | if (retval < 4) { |
| 156 | return -ENOEXEC; |
| 157 | } |
| 158 | if (bprm->buf[0] == 0x7f |
| 159 | && bprm->buf[1] == 'E' |
| 160 | && bprm->buf[2] == 'L' |
| 161 | && bprm->buf[3] == 'F') { |
| 162 | retval = load_elf_binary(bprm, infop); |
| 163 | #if defined(TARGET_HAS_BFLT) |
| 164 | } else if (bprm->buf[0] == 'b' |
| 165 | && bprm->buf[1] == 'F' |
| 166 | && bprm->buf[2] == 'L' |
| 167 | && bprm->buf[3] == 'T') { |
| 168 | retval = load_flt_binary(bprm, infop); |
| 169 | #endif |
| 170 | } else { |
| 171 | return -ENOEXEC; |
| 172 | } |
| 173 | if (retval < 0) { |
| 174 | return retval; |
| 175 | } |
| 176 | |
| 177 | /* Success. */ |
| 178 | return 0; |
| 179 | } |
| 180 | |
| 181 | bool imgsrc_read(void *dst, off_t offset, size_t len, |
| 182 | const ImageSource *img, Error **errp) |
| 183 | { |
| 184 | ssize_t ret; |
| 185 | |
| 186 | if (offset + len <= img->cache_size) { |
| 187 | memcpy(dst, img->cache + offset, len); |
| 188 | return true; |
| 189 | } |
| 190 | |
| 191 | if (img->fd < 0) { |
| 192 | error_setg(errp, "read past end of buffer"); |
| 193 | return false; |
| 194 | } |
| 195 | |
| 196 | ret = pread(img->fd, dst, len, offset); |
| 197 | if (ret == len) { |
| 198 | return true; |
| 199 | } |
| 200 | if (ret < 0) { |
| 201 | error_setg_errno(errp, errno, "Error reading file header"); |
| 202 | } else { |
| 203 | error_setg(errp, "Incomplete read of file header"); |
| 204 | } |
| 205 | return false; |
| 206 | } |
| 207 | |
| 208 | void *imgsrc_read_alloc(off_t offset, size_t len, |
| 209 | const ImageSource *img, Error **errp) |
| 210 | { |
| 211 | void *alloc = g_malloc(len); |
| 212 | bool ok = imgsrc_read(alloc, offset, len, img, errp); |
| 213 | |
| 214 | if (!ok) { |
| 215 | g_free(alloc); |
| 216 | alloc = NULL; |
| 217 | } |
| 218 | return alloc; |
| 219 | } |
| 220 | |
| 221 | abi_long imgsrc_mmap(abi_ulong start, abi_ulong len, int prot, |
| 222 | int flags, const ImageSource *src, abi_ulong offset) |
| 223 | { |
| 224 | const int prot_write = PROT_READ | PROT_WRITE; |
| 225 | abi_long ret; |
| 226 | void *haddr; |
| 227 | |
| 228 | assert(flags == (MAP_PRIVATE | MAP_FIXED)); |
| 229 | |
| 230 | if (src->fd >= 0) { |
| 231 | return target_mmap(start, len, prot, flags, src->fd, offset); |
| 232 | } |
| 233 | |
| 234 | /* |
| 235 | * This case is for the vdso; we don't expect bad images. |
| 236 | * The mmap may extend beyond the end of the image, especially |
| 237 | * to the end of the page. Zero fill. |
| 238 | */ |
| 239 | assert(offset < src->cache_size); |
| 240 | |
| 241 | ret = target_mmap(start, len, prot_write, flags | MAP_ANON, -1, 0); |
| 242 | if (ret == -1) { |
| 243 | return ret; |
| 244 | } |
| 245 | |
| 246 | haddr = lock_user(VERIFY_WRITE, start, len, 0); |
| 247 | assert(haddr != NULL); |
| 248 | if (offset + len <= src->cache_size) { |
| 249 | memcpy(haddr, src->cache + offset, len); |
| 250 | } else { |
| 251 | size_t rest = src->cache_size - offset; |
| 252 | memcpy(haddr, src->cache + offset, rest); |
| 253 | memset(haddr + rest, 0, len - rest); |
| 254 | } |
| 255 | unlock_user(haddr, start, len); |
| 256 | |
| 257 | if (prot != prot_write) { |
| 258 | target_mprotect(start, len, prot); |
| 259 | } |
| 260 | |
| 261 | return ret; |
| 262 | } |