File:  [Qemu by Fabrice Bellard] / qemu / linux-user / linuxload.c
Revision 1.1.1.7 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 18:35:49 2018 UTC (3 years, 3 months ago) by root
Branches: qemu, MAIN
CVS tags: qemu0150, qemu0141, qemu0140, HEAD
qemu 0.14.0

    1: /* Code for loading Linux executables.  Mostly linux kernel code.  */
    2: 
    3: #include <sys/types.h>
    4: #include <sys/stat.h>
    5: #include <fcntl.h>
    6: #include <errno.h>
    7: #include <unistd.h>
    8: #include <stdio.h>
    9: #include <stdlib.h>
   10: 
   11: #include "qemu.h"
   12: 
   13: #define NGROUPS 32
   14: 
   15: /* ??? This should really be somewhere else.  */
   16: abi_long memcpy_to_target(abi_ulong dest, const void *src,
   17:                           unsigned long len)
   18: {
   19:     void *host_ptr;
   20: 
   21:     host_ptr = lock_user(VERIFY_WRITE, dest, len, 0);
   22:     if (!host_ptr)
   23:         return -TARGET_EFAULT;
   24:     memcpy(host_ptr, src, len);
   25:     unlock_user(host_ptr, dest, 1);
   26:     return 0;
   27: }
   28: 
   29: static int in_group_p(gid_t g)
   30: {
   31:     /* return TRUE if we're in the specified group, FALSE otherwise */
   32:     int		ngroup;
   33:     int		i;
   34:     gid_t	grouplist[NGROUPS];
   35: 
   36:     ngroup = getgroups(NGROUPS, grouplist);
   37:     for(i = 0; i < ngroup; i++) {
   38: 	if(grouplist[i] == g) {
   39: 	    return 1;
   40: 	}
   41:     }
   42:     return 0;
   43: }
   44: 
   45: static int count(char ** vec)
   46: {
   47:     int		i;
   48: 
   49:     for(i = 0; *vec; i++) {
   50:         vec++;
   51:     }
   52: 
   53:     return(i);
   54: }
   55: 
   56: static int prepare_binprm(struct linux_binprm *bprm)
   57: {
   58:     struct stat		st;
   59:     int mode;
   60:     int retval, id_change;
   61: 
   62:     if(fstat(bprm->fd, &st) < 0) {
   63: 	return(-errno);
   64:     }
   65: 
   66:     mode = st.st_mode;
   67:     if(!S_ISREG(mode)) {	/* Must be regular file */
   68: 	return(-EACCES);
   69:     }
   70:     if(!(mode & 0111)) {	/* Must have at least one execute bit set */
   71: 	return(-EACCES);
   72:     }
   73: 
   74:     bprm->e_uid = geteuid();
   75:     bprm->e_gid = getegid();
   76:     id_change = 0;
   77: 
   78:     /* Set-uid? */
   79:     if(mode & S_ISUID) {
   80:     	bprm->e_uid = st.st_uid;
   81: 	if(bprm->e_uid != geteuid()) {
   82: 	    id_change = 1;
   83: 	}
   84:     }
   85: 
   86:     /* Set-gid? */
   87:     /*
   88:      * If setgid is set but no group execute bit then this
   89:      * is a candidate for mandatory locking, not a setgid
   90:      * executable.
   91:      */
   92:     if ((mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) {
   93: 	bprm->e_gid = st.st_gid;
   94: 	if (!in_group_p(bprm->e_gid)) {
   95: 		id_change = 1;
   96: 	}
   97:     }
   98: 
   99:     retval = read(bprm->fd, bprm->buf, BPRM_BUF_SIZE);
  100:     if (retval < 0) {
  101: 	perror("prepare_binprm");
  102: 	exit(-1);
  103:     }
  104:     if (retval < BPRM_BUF_SIZE) {
  105:         /* Make sure the rest of the loader won't read garbage.  */
  106:         memset(bprm->buf + retval, 0, BPRM_BUF_SIZE - retval);
  107:     }
  108:     return retval;
  109: }
  110: 
  111: /* Construct the envp and argv tables on the target stack.  */
  112: abi_ulong loader_build_argptr(int envc, int argc, abi_ulong sp,
  113:                               abi_ulong stringp, int push_ptr)
  114: {
  115:     TaskState *ts = (TaskState *)thread_env->opaque;
  116:     int n = sizeof(abi_ulong);
  117:     abi_ulong envp;
  118:     abi_ulong argv;
  119: 
  120:     sp -= (envc + 1) * n;
  121:     envp = sp;
  122:     sp -= (argc + 1) * n;
  123:     argv = sp;
  124:     if (push_ptr) {
  125:         /* FIXME - handle put_user() failures */
  126:         sp -= n;
  127:         put_user_ual(envp, sp);
  128:         sp -= n;
  129:         put_user_ual(argv, sp);
  130:     }
  131:     sp -= n;
  132:     /* FIXME - handle put_user() failures */
  133:     put_user_ual(argc, sp);
  134:     ts->info->arg_start = stringp;
  135:     while (argc-- > 0) {
  136:         /* FIXME - handle put_user() failures */
  137:         put_user_ual(stringp, argv);
  138:         argv += n;
  139:         stringp += target_strlen(stringp) + 1;
  140:     }
  141:     ts->info->arg_end = stringp;
  142:     /* FIXME - handle put_user() failures */
  143:     put_user_ual(0, argv);
  144:     while (envc-- > 0) {
  145:         /* FIXME - handle put_user() failures */
  146:         put_user_ual(stringp, envp);
  147:         envp += n;
  148:         stringp += target_strlen(stringp) + 1;
  149:     }
  150:     /* FIXME - handle put_user() failures */
  151:     put_user_ual(0, envp);
  152: 
  153:     return sp;
  154: }
  155: 
  156: int loader_exec(const char * filename, char ** argv, char ** envp,
  157:              struct target_pt_regs * regs, struct image_info *infop,
  158:              struct linux_binprm *bprm)
  159: {
  160:     int retval;
  161:     int i;
  162: 
  163:     bprm->p = TARGET_PAGE_SIZE*MAX_ARG_PAGES-sizeof(unsigned int);
  164:     memset(bprm->page, 0, sizeof(bprm->page));
  165:     retval = open(filename, O_RDONLY);
  166:     if (retval < 0)
  167:         return retval;
  168:     bprm->fd = retval;
  169:     bprm->filename = (char *)filename;
  170:     bprm->argc = count(argv);
  171:     bprm->argv = argv;
  172:     bprm->envc = count(envp);
  173:     bprm->envp = envp;
  174: 
  175:     retval = prepare_binprm(bprm);
  176: 
  177:     if(retval>=0) {
  178:         if (bprm->buf[0] == 0x7f
  179:                 && bprm->buf[1] == 'E'
  180:                 && bprm->buf[2] == 'L'
  181:                 && bprm->buf[3] == 'F') {
  182:             retval = load_elf_binary(bprm, regs, infop);
  183: #if defined(TARGET_HAS_BFLT)
  184:         } else if (bprm->buf[0] == 'b'
  185:                 && bprm->buf[1] == 'F'
  186:                 && bprm->buf[2] == 'L'
  187:                 && bprm->buf[3] == 'T') {
  188:             retval = load_flt_binary(bprm,regs,infop);
  189: #endif
  190:         } else {
  191:             fprintf(stderr, "Unknown binary format\n");
  192:             return -1;
  193:         }
  194:     }
  195: 
  196:     if(retval>=0) {
  197:         /* success.  Initialize important registers */
  198:         do_init_thread(regs, infop);
  199:         return retval;
  200:     }
  201: 
  202:     /* Something went wrong, return the inode and free the argument pages*/
  203:     for (i=0 ; i<MAX_ARG_PAGES ; i++) {
  204:         free(bprm->page[i]);
  205:     }
  206:     return(retval);
  207: }

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