/*- * Copyright (c) 1993, David Greenman * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #include __FBSDID("$FreeBSD: src/sys/kern/imgact_shell.c,v 1.32 2005/02/25 10:17:53 sobomax Exp $"); #include #include #include #include #include #include #include #include #define KEEP_OLDCODE 1 #if BYTE_ORDER == LITTLE_ENDIAN /* temp for OLD_CODE kludge */ #define DBG_MAGIC 0x2B23 /* #+ in "little-endian" */ #define OLD_MAGIC 0x3C23 /* #< */ #else #define DBG_MAGIC 0x232B /* #+ in big-endian */ #define OLD_MAGIC 0x233C /* #< */ #endif #if BYTE_ORDER == LITTLE_ENDIAN #define SHELLMAGIC 0x2123 /* #! */ #else #define SHELLMAGIC 0x2321 #endif /* * At the time of this writing, MAXSHELLCMDLEN == PAGE_SIZE. This is * significant because the caller has only mapped in one page of the * file we're reading. This code should be changed to know how to * read in the second page, but I'm not doing that just yet... */ #if MAXSHELLCMDLEN > PAGE_SIZE #error "MAXSHELLCMDLEN is larger than a single page!" #endif /** * Shell interpreter image activator. An interpreter name beginning at * imgp->args->begin_argv is the minimal successful exit requirement. * * If the given file is a shell-script, then the first line will start * with the two characters `#!' (aka SHELLMAGIC), followed by the name * of the shell-interpreter to run, followed by zero or more tokens. * * If there are *any* tokens, then we start up the interpreter such that * it will see: * arg[0] -> The name of interpreter as specified after `#!' in the * first line of the script. The interpreter name must * not be longer than MAXSHELLCMDLEN bytes. * arg[1] -> *If* there are any additional tokens on the first line, * then we add a new arg[1], which is a copy of the rest of * that line. The copy starts at the first token after the * interpreter name. We leave it to the interpreter to * parse the tokens in that value. * arg[x] -> the full pathname of the script. This will either be * arg[2] or arg[1], depending on whether or not tokens * were found after the interpreter name. * arg[x+1] -> whatever arguments that were specified on the original * command line (if the user had specified any). * * This processing is described in the execve(2) man page. */ /* * HISTORICAL NOTE: From 1993 to mid-2005, FreeBSD parsed out the tokens as * found on the first line of the script, and setup each token as a separate * value in arg[]. This extra processing did not match the behavior of other * OS's, and caused a few subtle problems. For one, it meant the kernel was * deciding how those values should be parsed (wrt characters for quoting or * comments, etc), while the interpreter might have other rules for parsing. * It also meant the interpreter had no way of knowing which arguments came * from the first line of the shell script, and which arguments were specified * by the user on the command line. * * Luckily, only few things in the base system would notice that non-standard * processing (mainly /bin/sh and /usr/bin/env). And for programs which are * not in the base system, the "newer" behavior matches how NetBSD, OpenBSD, * Linux, Solaris, AIX, IRIX, and some other Unixes have always setup the * arg-list for the interpreter. So if a program can handle this behavior on * any of those other OS's, it should be able to handle it for FreeBSD too. */ int exec_shell_imgact(imgp) struct image_params *imgp; { const char *image_header = imgp->image_header; const char *ihp, *interpb, *interpe, *maxp, *optb, *opte; int error, offset; size_t length, clength; struct vattr vattr; /* a shell script? */ if (((const short *) image_header)[0] != SHELLMAGIC) return(-1); /* * Don't allow a shell script to be the shell for a shell * script. :-) */ if (imgp->interpreted) return(ENOEXEC); imgp->interpreted = 1; /* * At this point we have the first page of the file mapped. * However, we don't know how far into the page the contents are * valid -- the actual file might be much shorter than the page. * So find out the file size. */ error = VOP_GETATTR(imgp->vp, &vattr, imgp->proc->p_ucred, curthread); if (error) return (error); /* * Copy shell name and arguments from image_header into a string * buffer. Remember that the caller has mapped only the * first page of the file into memory. */ clength = (vattr.va_size > PAGE_SIZE) ? PAGE_SIZE : vattr.va_size; maxp = &image_header[clength]; ihp = &image_header[2]; #if KEEP_OLDCODE /* * XXX - Temporarily provide a quick-and-dirty way to get the * older, non-standard option-parsing behavior, just in case * someone finds themselves in an emergency where they need it. * This will not be documented. It is only for initial testing. */ if (*(const short *)ihp == OLD_MAGIC) ihp += 2; else goto new_code; interpb = ihp; /* * Figure out the number of bytes that need to be reserved in the * argument string to copy the contents of the interpreter's command * line into the argument string. */ ihp = interpb; offset = 0; while (ihp < &image_header[clength]) { /* Skip any whitespace */ if ((*ihp == ' ') || (*ihp == '\t')) { ihp++; continue; } /* End of line? */ if ((*ihp == '\n') || (*ihp == '#') || (*ihp == '\0')) break; /* Found a token */ do { offset++; ihp++; } while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && (*ihp != '#') && (*ihp != '\0') && (ihp < &image_header[clength])); /* Include terminating nulls in the offset */ offset++; } /* If the script gives a null line as the interpreter, we bail */ if (offset == 0) return (ENOEXEC); /* Check that we aren't too big */ if (ihp == &image_header[MAXSHELLCMDLEN]) return (ENAMETOOLONG); /* * The full path name of the original script file must be tagged * onto the end, adjust the offset to deal with it. * * The original argv[0] is being replaced, set 'length' to the number * of bytes being removed. So 'offset' is the number of bytes being * added and 'length' is the number of bytes being removed. */ offset += strlen(imgp->args->fname) + 1; /* add fname */ length = (imgp->args->argc == 0) ? 0 : strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ if (offset - length > imgp->args->stringspace) return (E2BIG); bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, imgp->args->endp - (imgp->args->begin_argv + length)); offset -= length; /* calculate actual adjustment */ imgp->args->begin_envv += offset; imgp->args->endp += offset; imgp->args->stringspace -= offset; /* * If there were no arguments then we've added one, otherwise * decr argc remove old argv[0], incr argc for fname add, net 0 */ if (imgp->args->argc == 0) imgp->args->argc = 1; /* * Loop through the interpreter name yet again, copying as * we go. */ ihp = interpb; offset = 0; while (ihp < &image_header[clength]) { /* Skip whitespace */ if ((*ihp == ' ') || (*ihp == '\t')) { ihp++; continue; } /* End of line? */ if ((*ihp == '\n') || (*ihp == '#') || (*ihp == '\0')) break; /* Found a token, copy it */ do { imgp->args->begin_argv[offset++] = *ihp++; } while ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && (*ihp != '#') && (*ihp != '\0') && (ihp < &image_header[MAXSHELLCMDLEN])); imgp->args->begin_argv[offset++] = '\0'; imgp->args->argc++; } goto common_end; new_code: #endif /* * Find the beginning and end of the interpreter_name. If the * line does not include any interpreter, or if the name which * was found is too long, we bail out. */ while (ihp < maxp && ((*ihp == ' ') || (*ihp == '\t'))) ihp++; interpb = ihp; while (ihp < maxp && ((*ihp != ' ') && (*ihp != '\t') && (*ihp != '\n') && (*ihp != '\0'))) ihp++; interpe = ihp; if (interpb == interpe) return (ENOEXEC); if ((interpe - interpb) >= MAXSHELLCMDLEN) return (ENAMETOOLONG); /* * Find the beginning of the options (if any), and the end-of-line. * Then trim the trailing blanks off the value. Note that some * other operating systems do *not* trim the trailing whitespace... */ while (ihp < maxp && ((*ihp == ' ') || (*ihp == '\t'))) ihp++; optb = ihp; while (ihp < maxp && ((*ihp != '\n') && (*ihp != '\0'))) ihp++; opte = ihp; while (--ihp > interpe && ((*ihp == ' ') || (*ihp == '\t'))) opte = ihp; /* * We need to "pop" (remove) the present value of arg[0], and "push" * either two or three new values in the arg[] list. To do this, * we first shift all the other values in the `begin_argv' area to * provide the exact amount of room for the values added. Set up * `offset' as the number of bytes to be added to the `begin_argv' * area, and 'length' as the number of bytes being removed. */ offset = interpe - interpb + 1; /* interpreter */ if (opte != optb) /* options (if any) */ offset += opte - optb + 1; offset += strlen(imgp->args->fname) + 1; /* fname of script */ length = (imgp->args->argc == 0) ? 0 : strlen(imgp->args->begin_argv) + 1; /* bytes to delete */ if (offset - length > imgp->args->stringspace) return (E2BIG); bcopy(imgp->args->begin_argv + length, imgp->args->begin_argv + offset, imgp->args->endp - (imgp->args->begin_argv + length)); offset -= length; /* calculate actual adjustment */ imgp->args->begin_envv += offset; imgp->args->endp += offset; imgp->args->stringspace -= offset; /* * If there was no arg[0] when we started, then the interpreter_name * is adding an argument (instead of replacing the arg[0] we started * with). And we're always adding an argument when we include the * full pathname of the original script. */ if (imgp->args->argc == 0) imgp->args->argc = 1; imgp->args->argc++; /* * The original arg[] list has been shifted appropriately. Copy in * the interpreter name and options-string. */ length = interpe - interpb; bcopy(interpb, imgp->args->buf, length); *(imgp->args->buf + length) = '\0'; offset = length + 1; if (opte != optb) { length = opte - optb; bcopy(optb, imgp->args->buf + offset, length); *(imgp->args->buf + offset + length) = '\0'; offset += length + 1; imgp->args->argc++; } #if KEEP_OLDCODE common_end: #endif /* * Finally, add the filename onto the end for the interpreter to * use and copy the interpreter's name to imgp->interpreter_name * for exec to use. */ error = copystr(imgp->args->fname, imgp->args->buf + offset, imgp->args->stringspace, &length); if (error == 0) error = copystr(imgp->args->begin_argv, imgp->interpreter_name, MAXSHELLCMDLEN, &length); return (error); } /* * Tell kern_execve.c about it, with a little help from the linker. */ static struct execsw shell_execsw = { exec_shell_imgact, "#!" }; EXEC_SET(shell, shell_execsw);