linux-user/linuxload.c

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