1 /*- 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 */ 26 27 #include <sys/cdefs.h> 28 __FBSDID("$FreeBSD$"); 29 30 #include <sys/param.h> 31 #include <sys/systm.h> 32 #include <sys/sysproto.h> 33 #include <sys/exec.h> 34 #include <sys/imgact.h> 35 #include <sys/kernel.h> 36 37 #if BYTE_ORDER == LITTLE_ENDIAN 38 #define SHELLMAGIC 0x2123 /* #! */ 39 #else 40 #define SHELLMAGIC 0x2321 41 #endif 42 43 /* 44 * Shell interpreter image activator. An interpreter name beginning 45 * at imgp->args->begin_argv is the minimal successful exit requirement. 46 */ 47 int 48 exec_shell_imgact(imgp) 49 struct image_params *imgp; 50 { 51 const char *image_header = imgp->image_header; 52 const char *ihp; 53 int error, offset; 54 size_t length; 55 56 /* a shell script? */ 57 if (((const short *) image_header)[0] != SHELLMAGIC) 58 return(-1); 59 60 /* 61 * Don't allow a shell script to be the shell for a shell 62 * script. :-) 63 */ 64 if (imgp->interpreted) 65 return(ENOEXEC); 66 67 imgp->interpreted = 1; 68 69 /* 70 * Figure out the number of bytes that need to be reserved in the 71 * argument string to copy the contents of the interpreter's command 72 * line into the argument string. 73 */ 74 ihp = &image_header[2]; 75 offset = 0; 76 while (ihp < &image_header[MAXSHELLCMDLEN]) { 77 /* Skip any whitespace */ 78 while ((*ihp == ' ') || (*ihp == '\t')) { 79 ihp++; 80 continue; 81 } 82 83 /* End of line? */ 84 if ((*ihp == '\n') || (*ihp == '#')) 85 break; 86 87 /* Found a token */ 88 while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && 89 (*ihp != '#')) { 90 offset++; 91 ihp++; 92 } 93 /* Include terminating nulls in the offset */ 94 offset++; 95 } 96 97 /* If the script gives a null line as the interpreter, we bail */ 98 if (offset == 0) 99 return (ENOEXEC); 100 101 /* Check that we aren't too big */ 102 if (offset > MAXSHELLCMDLEN) 103 return (ENAMETOOLONG); 104 105 /* 106 * The full path name of the original script file must be tagged 107 * onto the end, adjust the offset to deal with it. 108 * 109 * The original argv[0] is being replaced, set 'length' to the number 110 * of bytes being removed. So 'offset' is the number of bytes being 111 * added and 'length' is the number of bytes being removed. 112 */ 113 offset += strlen(imgp->args->fname) + 1; /* add fname */ 114 length = (imgp->args->argc == 0) ? 0 : 115 strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ 116 117 if (offset - length > imgp->args->stringspace) 118 return (E2BIG); 119 120 bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, 121 imgp->args->endp - (imgp->args->begin_argv + length)); 122 123 offset -= length; /* calculate actual adjustment */ 124 imgp->args->begin_envv += offset; 125 imgp->args->endp += offset; 126 imgp->args->stringspace -= offset; 127 128 /* 129 * If there were no arguments then we've added one, otherwise 130 * decr argc remove old argv[0], incr argc for fname add, net 0 131 */ 132 if (imgp->args->argc == 0) 133 imgp->args->argc = 1; 134 135 /* 136 * Loop through the interpreter name yet again, copying as 137 * we go. 138 */ 139 ihp = &image_header[2]; 140 offset = 0; 141 while (ihp < &image_header[MAXSHELLCMDLEN]) { 142 /* Skip whitespace */ 143 while ((*ihp == ' ' || *ihp == '\t')) { 144 ihp++; 145 continue; 146 } 147 148 /* End of line? */ 149 if ((*ihp == '\n') || (*ihp == '#')) 150 break; 151 152 /* Found a token, copy it */ 153 while ((*ihp != ' ') && (*ihp != '\t') && 154 (*ihp != '\n') && (*ihp != '#')) { 155 imgp->args->begin_argv[offset++] = *ihp++; 156 } 157 imgp->args->begin_argv[offset++] = '\0'; 158 imgp->args->argc++; 159 } 160 161 /* 162 * Finally, add the filename onto the end for the interpreter to 163 * use and copy the interpreter's name to imgp->interpreter_name 164 * for exec to use. 165 */ 166 error = copystr(imgp->args->fname, imgp->args->buf + offset, 167 imgp->args->stringspace, &length); 168 169 if (error == 0) 170 error = copystr(imgp->args->begin_argv, imgp->interpreter_name, 171 MAXSHELLCMDLEN, &length); 172 173 return (error); 174 } 175 176 /* 177 * Tell kern_execve.c about it, with a little help from the linker. 178 */ 179 static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 180 EXEC_SET(shell, shell_execsw); 181