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/vnode.h> 32 #include <sys/proc.h> 33 #include <sys/systm.h> 34 #include <sys/sysproto.h> 35 #include <sys/exec.h> 36 #include <sys/imgact.h> 37 #include <sys/kernel.h> 38 39 #if BYTE_ORDER == LITTLE_ENDIAN 40 #define SHELLMAGIC 0x2123 /* #! */ 41 #else 42 #define SHELLMAGIC 0x2321 43 #endif 44 45 /* 46 * Shell interpreter image activator. An interpreter name beginning 47 * at imgp->args->begin_argv is the minimal successful exit requirement. 48 */ 49 int 50 exec_shell_imgact(imgp) 51 struct image_params *imgp; 52 { 53 const char *image_header = imgp->image_header; 54 const char *ihp; 55 int error, offset; 56 size_t length, clength; 57 struct vattr vattr; 58 59 /* a shell script? */ 60 if (((const short *) image_header)[0] != SHELLMAGIC) 61 return(-1); 62 63 /* 64 * Don't allow a shell script to be the shell for a shell 65 * script. :-) 66 */ 67 if (imgp->interpreted) 68 return(ENOEXEC); 69 70 imgp->interpreted = 1; 71 72 /* 73 * At this point we have the first page of the file mapped. 74 * However, we don't know how far into the page the contents are 75 * valid -- the actual file might be much shorter than the page. 76 * So find out the file size. 77 */ 78 error = VOP_GETATTR(imgp->vp, &vattr, imgp->proc->p_ucred, curthread); 79 if (error) 80 return (error); 81 82 clength = (vattr.va_size > MAXSHELLCMDLEN) ? 83 MAXSHELLCMDLEN : vattr.va_size; 84 /* 85 * Figure out the number of bytes that need to be reserved in the 86 * argument string to copy the contents of the interpreter's command 87 * line into the argument string. 88 */ 89 ihp = &image_header[2]; 90 offset = 0; 91 while (ihp < &image_header[clength]) { 92 /* Skip any whitespace */ 93 if ((*ihp == ' ') || (*ihp == '\t')) { 94 ihp++; 95 continue; 96 } 97 98 /* End of line? */ 99 if ((*ihp == '\n') || (*ihp == '#') || (*ihp == '\0')) 100 break; 101 102 /* Found a token */ 103 do { 104 offset++; 105 ihp++; 106 } while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && 107 (*ihp != '#') && (*ihp != '\0') && 108 (ihp < &image_header[clength])); 109 /* Include terminating nulls in the offset */ 110 offset++; 111 } 112 113 /* If the script gives a null line as the interpreter, we bail */ 114 if (offset == 0) 115 return (ENOEXEC); 116 117 /* Check that we aren't too big */ 118 if (ihp == &image_header[MAXSHELLCMDLEN]) 119 return (ENAMETOOLONG); 120 121 /* 122 * The full path name of the original script file must be tagged 123 * onto the end, adjust the offset to deal with it. 124 * 125 * The original argv[0] is being replaced, set 'length' to the number 126 * of bytes being removed. So 'offset' is the number of bytes being 127 * added and 'length' is the number of bytes being removed. 128 */ 129 offset += strlen(imgp->args->fname) + 1; /* add fname */ 130 length = (imgp->args->argc == 0) ? 0 : 131 strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ 132 133 if (offset - length > imgp->args->stringspace) 134 return (E2BIG); 135 136 bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, 137 imgp->args->endp - (imgp->args->begin_argv + length)); 138 139 offset -= length; /* calculate actual adjustment */ 140 imgp->args->begin_envv += offset; 141 imgp->args->endp += offset; 142 imgp->args->stringspace -= offset; 143 144 /* 145 * If there were no arguments then we've added one, otherwise 146 * decr argc remove old argv[0], incr argc for fname add, net 0 147 */ 148 if (imgp->args->argc == 0) 149 imgp->args->argc = 1; 150 151 /* 152 * Loop through the interpreter name yet again, copying as 153 * we go. 154 */ 155 ihp = &image_header[2]; 156 offset = 0; 157 while (ihp < &image_header[clength]) { 158 /* Skip whitespace */ 159 if ((*ihp == ' ') || (*ihp == '\t')) { 160 ihp++; 161 continue; 162 } 163 164 /* End of line? */ 165 if ((*ihp == '\n') || (*ihp == '#') || (*ihp == '\0')) 166 break; 167 168 /* Found a token, copy it */ 169 do { 170 imgp->args->begin_argv[offset++] = *ihp++; 171 } while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && 172 (*ihp != '#') && (*ihp != '\0') && 173 (ihp < &image_header[MAXSHELLCMDLEN])); 174 imgp->args->begin_argv[offset++] = '\0'; 175 imgp->args->argc++; 176 } 177 178 /* 179 * Finally, add the filename onto the end for the interpreter to 180 * use and copy the interpreter's name to imgp->interpreter_name 181 * for exec to use. 182 */ 183 error = copystr(imgp->args->fname, imgp->args->buf + offset, 184 imgp->args->stringspace, &length); 185 186 if (error == 0) 187 error = copystr(imgp->args->begin_argv, imgp->interpreter_name, 188 MAXSHELLCMDLEN, &length); 189 190 return (error); 191 } 192 193 /* 194 * Tell kern_execve.c about it, with a little help from the linker. 195 */ 196 static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; 197 EXEC_SET(shell, shell_execsw); 198