ADD ABILITY TO EXECUTE FILES WITH "#!" MAGIC NUMBER

	If the first two characters of a file are "#!", this constitutes
a "magic number" which indicates that the file is a shell script and that
the character string following the "#!" should be executed, and that the
shell script itself should be used as stdin for the program executed.

AUTHOR:		Paul Kranenburg (pk@cs.few.eur.nl)
386BSD-Patchkit: patch00025

diff --git a/usr/src/sys.386bsd/kern/kern_execve.c b/usr/src/sys.386bsd/kern/kern_execve.c
index c838350..41cf010 100644 (file)
--- a/usr/src/sys.386bsd/kern/kern_execve.c
+++ b/usr/src/sys.386bsd/kern/kern_execve.c
@@ -52,9 +52,10 @@
  *
  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
  * --------------------         -----   ----------------------
  *
  * PATCHES MAGIC                LEVEL   PATCH THAT GOT US HERE
  * --------------------         -----   ----------------------

- * CURRENT PATCH LEVEL:         1       00024
+ * CURRENT PATCH LEVEL:         2       00025

  * --------------------         -----   ----------------------
  *
  * --------------------         -----   ----------------------
  *

+ * 05 Aug 92   Paul Kranenburg         Fixed #! as a magic number

  * 29 Jul 92   Mark Tinguely           Fixed execute permission enforcement
  * 15 Aug 92    Terry Lambert           Fixed CMOS RAM size bug
  */
  * 29 Jul 92   Mark Tinguely           Fixed execute permission enforcement
  * 15 Aug 92    Terry Lambert           Fixed CMOS RAM size bug
  */


@@ -100,7 +101,6 @@ execve(p, uap, retval)
 {
        register struct nameidata *ndp;
        struct nameidata nd;
 {
        register struct nameidata *ndp;
        struct nameidata nd;

-       struct exec hdr;

        char **argbuf, **argbufp, *stringbuf, *stringbufp;
        char **vectp, *ep;
        int needsenv, limitonargs, stringlen, addr, size, len,
        char **argbuf, **argbufp, *stringbuf, *stringbufp;
        char **vectp, *ep;
        int needsenv, limitonargs, stringlen, addr, size, len,


@@ -108,15 +108,23 @@ execve(p, uap, retval)
        struct vattr attr;
        struct vmspace *vs;
        caddr_t newframe;
        struct vattr attr;
        struct vmspace *vs;
        caddr_t newframe;

+       char shellname[MAXINTERP];                      /* 05 Aug 92*/
+       union {
+               char    ex_shell[MAXINTERP];    /* #! and interpreter name */
+               struct  exec ex_hdr;
+       } exdata;
+       int indir = 0;

 
        /*
         * Step 1. Lookup filename to see if we have something to execute.
         */
        ndp = &nd;
 
        /*
         * Step 1. Lookup filename to see if we have something to execute.
         */
        ndp = &nd;

-       ndp->ni_nameiop = LOOKUP | LOCKLEAF | FOLLOW | SAVENAME;

        ndp->ni_segflg = UIO_USERSPACE;
        ndp->ni_dirp = uap->fname;
 
        ndp->ni_segflg = UIO_USERSPACE;
        ndp->ni_dirp = uap->fname;
 

+again:                                                 /* 05 Aug 92*/
+       ndp->ni_nameiop = LOOKUP | LOCKLEAF | FOLLOW | SAVENAME;
+

        /* is it there? */
        if (rv = namei(ndp, p))
                return (rv);
        /* is it there? */
        if (rv = namei(ndp, p))
                return (rv);


@@ -126,6 +134,11 @@ execve(p, uap, retval)
        if (rv)
                goto exec_fail;
 
        if (rv)
                goto exec_fail;
 

+       if (ndp->ni_vp->v_mount->mnt_flag & MNT_NOEXEC) { /* no exec on fs ?*/
+               rv = EACCES;
+               goto exec_fail;
+       }
+

        /* is it executable, and a regular file? */
        if ((ndp->ni_vp->v_mount->mnt_flag & MNT_NOEXEC) ||     /* 29 Jul 92*/
                (VOP_ACCESS(ndp->ni_vp, VEXEC, p->p_ucred, p)) ||
        /* is it executable, and a regular file? */
        if ((ndp->ni_vp->v_mount->mnt_flag & MNT_NOEXEC) ||     /* 29 Jul 92*/
                (VOP_ACCESS(ndp->ni_vp, VEXEC, p->p_ucred, p)) ||


@@ -138,40 +151,84 @@ execve(p, uap, retval)
        /*
         * Step 2. Does the file contain a format we can
         * understand and execute
        /*
         * Step 2. Does the file contain a format we can
         * understand and execute

+        *
+        * XXX 05 Aug 92
+        * Read in first few bytes of file for segment sizes, magic number:
+        *      ZMAGIC = demand paged RO text
+        * Also an ASCII line beginning with #! is
+        * the file name of a ``shell'' and arguments may be prepended
+        * to the argument list if given here.

         */
         */

-       rv = vn_rdwr(UIO_READ, ndp->ni_vp, (caddr_t)&hdr, sizeof(hdr),
+       exdata.ex_shell[0] = '\0';      /* for zero length files */
+
+       rv = vn_rdwr(UIO_READ, ndp->ni_vp, (caddr_t)&exdata, sizeof(exdata),

                0, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &amt, p);
 
        /* big enough to hold a header? */
        if (rv)
                goto exec_fail;
                0, UIO_SYSSPACE, IO_NODELOCKED, p->p_ucred, &amt, p);
 
        /* big enough to hold a header? */
        if (rv)
                goto exec_fail;

-       
+

        /* ... that we recognize? */
        rv = ENOEXEC;
        /* ... that we recognize? */
        rv = ENOEXEC;

-       if (hdr.a_magic != ZMAGIC)
-               goto exec_fail;
+       if (exdata.ex_hdr.a_magic != ZMAGIC) {
+               char *cp, *sp;
+
+               if (exdata.ex_shell[0] != '#' ||
+                   exdata.ex_shell[1] != '!' || indir) {
+                       rv = ENOEXEC;
+                       goto exec_fail;
+               }
+               for (cp = &exdata.ex_shell[2];; ++cp) {
+                       if (cp >= &exdata.ex_shell[MAXINTERP]) {
+                               rv = ENOEXEC;
+                               goto exec_fail;
+                       }
+                       if (*cp == '\n') {
+                               *cp = '\0';
+                               break;
+                       }
+                       if (*cp == '\t')
+                               *cp = ' ';
+               }
+               cp = &exdata.ex_shell[2];       /* get shell interpreter name */
+               while (*cp == ' ')
+                       cp++;
+
+               sp = shellname;
+               while (*cp && *cp != ' ')
+                       *sp++ = *cp++;
+               *sp = '\0';
+
+               indir = 1;              /* indicate this is a script file */
+               vput(ndp->ni_vp);
+               FREE(ndp->ni_pnbuf, M_NAMEI);
+
+               ndp->ni_dirp = shellname;       /* find shell interpreter */
+               ndp->ni_segflg = UIO_SYSSPACE;
+               goto again;
+       }

 
        /* sanity check  "ain't not such thing as a sanity clause" -groucho */
        rv = ENOMEM;
 
        /* sanity check  "ain't not such thing as a sanity clause" -groucho */
        rv = ENOMEM;

-       if (/*hdr.a_text == 0 || */ hdr.a_text > MAXTSIZ
-               || hdr.a_text % NBPG || hdr.a_text > attr.va_size)
+       if (/*exdata.ex_hdr.a_text == 0 || */ exdata.ex_hdr.a_text > MAXTSIZ ||
+           exdata.ex_hdr.a_text % NBPG || exdata.ex_hdr.a_text > attr.va_size)

                goto exec_fail;
 
                goto exec_fail;
 

-       if (hdr.a_data == 0 || hdr.a_data > DFLDSIZ
-               || hdr.a_data > attr.va_size
-               || hdr.a_data + hdr.a_text > attr.va_size)
+       if (exdata.ex_hdr.a_data == 0 || exdata.ex_hdr.a_data > DFLDSIZ
+               || exdata.ex_hdr.a_data > attr.va_size
+               || exdata.ex_hdr.a_data + exdata.ex_hdr.a_text > attr.va_size)

                goto exec_fail;
 
                goto exec_fail;
 

-       if (hdr.a_bss > MAXDSIZ)
+       if (exdata.ex_hdr.a_bss > MAXDSIZ)

                goto exec_fail;
        
                goto exec_fail;
        

-       if (hdr.a_text + hdr.a_data + hdr.a_bss > MAXTSIZ + MAXDSIZ)
+       if (exdata.ex_hdr.a_text + exdata.ex_hdr.a_data + exdata.ex_hdr.a_bss > MAXTSIZ + MAXDSIZ)

                goto exec_fail;
 
                goto exec_fail;
 

-       if (hdr.a_data + hdr.a_bss > p->p_rlimit[RLIMIT_DATA].rlim_cur)
+       if (exdata.ex_hdr.a_data + exdata.ex_hdr.a_bss > p->p_rlimit[RLIMIT_DATA].rlim_cur)

                goto exec_fail;
 
                goto exec_fail;
 

-       if (hdr.a_entry > hdr.a_text + hdr.a_data)
+       if (exdata.ex_hdr.a_entry > exdata.ex_hdr.a_text + exdata.ex_hdr.a_data)

                goto exec_fail;
        
        /*
                goto exec_fail;
        
        /*


@@ -212,6 +269,41 @@ execve(p, uap, retval)
        limitonargs = ARG_MAX;
        cnt = 0;
 
        limitonargs = ARG_MAX;
        cnt = 0;
 

+       /* first, do (shell name if any then) args */
+       if (indir)  {
+               ep = shellname;
+twice:
+               if (ep) {
+                       /* did we outgrow initial argbuf, if so, die */
+                       if (argbufp >= (char **)stringbuf) {
+                               rv = E2BIG;
+                               goto exec_dealloc;
+                       }
+
+                       if (rv = copyoutstr(ep, stringbufp,
+                               (u_int)limitonargs, (u_int *)&stringlen)) {
+                               if (rv == ENAMETOOLONG)
+                                       rv = E2BIG;
+                               goto exec_dealloc;
+                       }
+                       suword(argbufp++, (int)stringbufp);
+                       cnt++;
+                       stringbufp += stringlen;
+                       limitonargs -= stringlen;
+               }
+
+               if (indir) {
+                       indir = 0;
+                       /* orginal executable is 1st argument with scripts */
+                       ep = uap->fname;
+                       goto twice;
+               }
+               /* terminate in case no more args to script */
+               suword(argbufp, 0);
+               if (vectp = uap->argp) vectp++; /* manually doing the first
+                                                  argument with scripts */
+       }
+

 do_env_as_well:
        if(vectp == 0) goto dont_bother;
 
 do_env_as_well:
        if(vectp == 0) goto dont_bother;
 


@@ -300,17 +392,17 @@ dont_bother:
        addr = 0;
 
        /* screwball mode -- special case of 413 to save space for floppy */
        addr = 0;
 
        /* screwball mode -- special case of 413 to save space for floppy */

-       if (hdr.a_text == 0) {
+       if (exdata.ex_hdr.a_text == 0) {

                foff = tsize = 0;
                foff = tsize = 0;

-               hdr.a_data += hdr.a_text;
+               exdata.ex_hdr.a_data += exdata.ex_hdr.a_text;

        } else {
        } else {

-               tsize = roundup(hdr.a_text, NBPG);
+               tsize = roundup(exdata.ex_hdr.a_text, NBPG);

                foff = NBPG;
        }
 
        /* treat text and data in terms of integral page size */
                foff = NBPG;
        }
 
        /* treat text and data in terms of integral page size */

-       dsize = roundup(hdr.a_data, NBPG);
-       bsize = roundup(hdr.a_bss + dsize, NBPG);
+       dsize = roundup(exdata.ex_hdr.a_data, NBPG);
+       bsize = roundup(exdata.ex_hdr.a_bss + dsize, NBPG);

        bsize -= dsize;
 
        /* map text & data in file, as being "paged in" on demand */
        bsize -= dsize;
 
        /* map text & data in file, as being "paged in" on demand */


@@ -377,7 +469,7 @@ dont_bother:
 
        /* setup initial register state */
        p->p_regs[SP] = (unsigned) (argbuf - 1);
 
        /* setup initial register state */
        p->p_regs[SP] = (unsigned) (argbuf - 1);

-       setregs(p, hdr.a_entry);
+       setregs(p, exdata.ex_hdr.a_entry);

 
        vput(ndp->ni_vp);
        FREE(ndp->ni_pnbuf, M_NAMEI);
 
        vput(ndp->ni_vp);
        FREE(ndp->ni_pnbuf, M_NAMEI);