FreeBSD/Linux Kernel Cross Reference
sys/kern/exec_subr.c

     /*      $NetBSD: exec_subr.c,v 1.61.8.2 2010/08/31 10:55:00 bouyer Exp $        */
     
     /*
      * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou
      * 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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by Christopher G. Demetriou.
     * 4. The name of the author may not be used to endorse or promote products
     *    derived from this software without specific prior written permission
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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 <sys/cdefs.h>
    __KERNEL_RCSID(0, "$NetBSD: exec_subr.c,v 1.61.8.2 2010/08/31 10:55:00 bouyer Exp $");
    
    #include "opt_pax.h"
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/proc.h>
    #include <sys/kmem.h>
    #include <sys/vnode.h>
    #include <sys/filedesc.h>
    #include <sys/exec.h>
    #include <sys/mman.h>
    #include <sys/resourcevar.h>
    #include <sys/device.h>
    
    #ifdef PAX_MPROTECT
    #include <sys/pax.h>
    #endif /* PAX_MPROTECT */
    
    #include <uvm/uvm.h>
    
    #define VMCMD_EVCNT_DECL(name)                                  \
    static struct evcnt vmcmd_ev_##name =                           \
        EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "vmcmd", #name);   \
    EVCNT_ATTACH_STATIC(vmcmd_ev_##name)
    
    #define VMCMD_EVCNT_INCR(name)                                  \
        vmcmd_ev_##name.ev_count++
    
    VMCMD_EVCNT_DECL(calls);
    VMCMD_EVCNT_DECL(extends);
    VMCMD_EVCNT_DECL(kills);
    
    /*
     * new_vmcmd():
     *      create a new vmcmd structure and fill in its fields based
     *      on function call arguments.  make sure objects ref'd by
     *      the vmcmd are 'held'.
     */
    
    void
    new_vmcmd(struct exec_vmcmd_set *evsp,
        int (*proc)(struct lwp * l, struct exec_vmcmd *),
        u_long len, u_long addr, struct vnode *vp, u_long offset,
        u_int prot, int flags)
    {
            struct exec_vmcmd    *vcp;
    
            VMCMD_EVCNT_INCR(calls);
    
            if (evsp->evs_used >= evsp->evs_cnt)
                    vmcmdset_extend(evsp);
            vcp = &evsp->evs_cmds[evsp->evs_used++];
            vcp->ev_proc = proc;
            vcp->ev_len = len;
            vcp->ev_addr = addr;
            if ((vcp->ev_vp = vp) != NULL)
                    vref(vp);
            vcp->ev_offset = offset;
            vcp->ev_prot = prot;
            vcp->ev_flags = flags;
    }
    
    void
    vmcmdset_extend(struct exec_vmcmd_set *evsp)
    {
           struct exec_vmcmd *nvcp;
           u_int ocnt;
   
   #ifdef DIAGNOSTIC
           if (evsp->evs_used < evsp->evs_cnt)
                   panic("vmcmdset_extend: not necessary");
   #endif
   
           /* figure out number of entries in new set */
           if ((ocnt = evsp->evs_cnt) != 0) {
                   evsp->evs_cnt += ocnt;
                   VMCMD_EVCNT_INCR(extends);
           } else
                   evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE;
   
           /* allocate it */
           nvcp = kmem_alloc(evsp->evs_cnt * sizeof(struct exec_vmcmd), KM_SLEEP);
   
           /* free the old struct, if there was one, and record the new one */
           if (ocnt) {
                   memcpy(nvcp, evsp->evs_cmds,
                       (ocnt * sizeof(struct exec_vmcmd)));
                   kmem_free(evsp->evs_cmds, ocnt * sizeof(struct exec_vmcmd));
           }
           evsp->evs_cmds = nvcp;
   }
   
   void
   kill_vmcmds(struct exec_vmcmd_set *evsp)
   {
           struct exec_vmcmd *vcp;
           u_int i;
   
           VMCMD_EVCNT_INCR(kills);
   
           if (evsp->evs_cnt == 0)
                   return;
   
           for (i = 0; i < evsp->evs_used; i++) {
                   vcp = &evsp->evs_cmds[i];
                   if (vcp->ev_vp != NULL)
                           vrele(vcp->ev_vp);
           }
           kmem_free(evsp->evs_cmds, evsp->evs_cnt * sizeof(struct exec_vmcmd));
           evsp->evs_used = evsp->evs_cnt = 0;
   }
   
   /*
    * vmcmd_map_pagedvn():
    *      handle vmcmd which specifies that a vnode should be mmap'd.
    *      appropriate for handling demand-paged text and data segments.
    */
   
   int
   vmcmd_map_pagedvn(struct lwp *l, struct exec_vmcmd *cmd)
   {
           struct uvm_object *uobj;
           struct vnode *vp = cmd->ev_vp;
           struct proc *p = l->l_proc;
           int error;
           vm_prot_t prot, maxprot;
   
           KASSERT(vp->v_iflag & VI_TEXT);
   
           /*
            * map the vnode in using uvm_map.
            */
   
           if (cmd->ev_len == 0)
                   return(0);
           if (cmd->ev_offset & PAGE_MASK)
                   return(EINVAL);
           if (cmd->ev_addr & PAGE_MASK)
                   return(EINVAL);
           if (cmd->ev_len & PAGE_MASK)
                   return(EINVAL);
   
           prot = cmd->ev_prot;
           maxprot = UVM_PROT_ALL;
   #ifdef PAX_MPROTECT
           pax_mprotect(l, &prot, &maxprot);
   #endif /* PAX_MPROTECT */
   
           /*
            * check the file system's opinion about mmapping the file
            */
   
           error = VOP_MMAP(vp, prot, l->l_cred);
           if (error)
                   return error;
   
           if ((vp->v_vflag & VV_MAPPED) == 0) {
                   vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
                   vp->v_vflag |= VV_MAPPED;
                   VOP_UNLOCK(vp, 0);
           }
   
           /*
            * do the map, reference the object for this map entry
            */
           uobj = &vp->v_uobj;
           vref(vp);
   
           error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len,
                   uobj, cmd->ev_offset, 0,
                   UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
                           UVM_ADV_NORMAL, UVM_FLAG_COPYONW|UVM_FLAG_FIXED));
           if (error) {
                   uobj->pgops->pgo_detach(uobj);
           }
           return error;
   }
   
   /*
    * vmcmd_map_readvn():
    *      handle vmcmd which specifies that a vnode should be read from.
    *      appropriate for non-demand-paged text/data segments, i.e. impure
    *      objects (a la OMAGIC and NMAGIC).
    */
   int
   vmcmd_map_readvn(struct lwp *l, struct exec_vmcmd *cmd)
   {
           struct proc *p = l->l_proc;
           int error;
           long diff;
   
           if (cmd->ev_len == 0)
                   return 0;
   
           diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
           cmd->ev_addr -= diff;                   /* required by uvm_map */
           cmd->ev_offset -= diff;
           cmd->ev_len += diff;
   
           error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
                           round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
                           UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_COPY,
                           UVM_ADV_NORMAL,
                           UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW));
   
           if (error)
                   return error;
   
           return vmcmd_readvn(l, cmd);
   }
   
   int
   vmcmd_readvn(struct lwp *l, struct exec_vmcmd *cmd)
   {
           struct proc *p = l->l_proc;
           int error;
           vm_prot_t prot, maxprot;
   
           error = vn_rdwr(UIO_READ, cmd->ev_vp, (void *)cmd->ev_addr,
               cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT,
               l->l_cred, NULL, l);
           if (error)
                   return error;
   
           prot = cmd->ev_prot;
           maxprot = VM_PROT_ALL;
   #ifdef PAX_MPROTECT
           pax_mprotect(l, &prot, &maxprot);
   #endif /* PAX_MPROTECT */
   
   #ifdef PMAP_NEED_PROCWR
           /*
            * we had to write the process, make sure the pages are synched
            * with the instruction cache.
            */
           if (prot & VM_PROT_EXECUTE)
                   pmap_procwr(p, cmd->ev_addr, cmd->ev_len);
   #endif
   
           /*
            * we had to map in the area at PROT_ALL so that vn_rdwr()
            * could write to it.   however, the caller seems to want
            * it mapped read-only, so now we are going to have to call
            * uvm_map_protect() to fix up the protection.  ICK.
            */
           if (maxprot != VM_PROT_ALL) {
                   error = uvm_map_protect(&p->p_vmspace->vm_map,
                                   trunc_page(cmd->ev_addr),
                                   round_page(cmd->ev_addr + cmd->ev_len),
                                   maxprot, true);
                   if (error)
                           return (error);
           }
   
           if (prot != maxprot) {
                   error = uvm_map_protect(&p->p_vmspace->vm_map,
                                   trunc_page(cmd->ev_addr),
                                   round_page(cmd->ev_addr + cmd->ev_len),
                                   prot, false);
                   if (error)
                           return (error);
           }
   
           return 0;
   }
   
   /*
    * vmcmd_map_zero():
    *      handle vmcmd which specifies a zero-filled address space region.  The
    *      address range must be first allocated, then protected appropriately.
    */
   
   int
   vmcmd_map_zero(struct lwp *l, struct exec_vmcmd *cmd)
   {
           struct proc *p = l->l_proc;
           int error;
           long diff;
           vm_prot_t prot, maxprot;
   
           diff = cmd->ev_addr - trunc_page(cmd->ev_addr);
           cmd->ev_addr -= diff;                   /* required by uvm_map */
           cmd->ev_len += diff;
   
           prot = cmd->ev_prot;
           maxprot = UVM_PROT_ALL;
   #ifdef PAX_MPROTECT
           pax_mprotect(l, &prot, &maxprot);
   #endif /* PAX_MPROTECT */
   
           error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
                           round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
                           UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY,
                           UVM_ADV_NORMAL,
                           UVM_FLAG_FIXED|UVM_FLAG_COPYONW));
           if (cmd->ev_flags & VMCMD_STACK)
                   curproc->p_vmspace->vm_issize += atop(round_page(cmd->ev_len));
           return error;
   }
   
   /*
    * exec_read_from():
    *
    *      Read from vnode into buffer at offset.
    */
   int
   exec_read_from(struct lwp *l, struct vnode *vp, u_long off, void *bf,
       size_t size)
   {
           int error;
           size_t resid;
   
           if ((error = vn_rdwr(UIO_READ, vp, bf, size, off, UIO_SYSSPACE,
               0, l->l_cred, &resid, NULL)) != 0)
                   return error;
           /*
            * See if we got all of it
            */
           if (resid != 0)
                   return ENOEXEC;
           return 0;
   }
   
   /*
    * exec_setup_stack(): Set up the stack segment for an elf
    * executable.
    *
    * Note that the ep_ssize parameter must be set to be the current stack
    * limit; this is adjusted in the body of execve() to yield the
    * appropriate stack segment usage once the argument length is
    * calculated.
    *
    * This function returns an int for uniformity with other (future) formats'
    * stack setup functions.  They might have errors to return.
    */
   
   int
   exec_setup_stack(struct lwp *l, struct exec_package *epp)
   {
           u_long max_stack_size;
           u_long access_linear_min, access_size;
           u_long noaccess_linear_min, noaccess_size;
   
   #ifndef USRSTACK32
   #define USRSTACK32      (0x00000000ffffffffL&~PGOFSET)
   #endif
   
           if (epp->ep_flags & EXEC_32) {
                   epp->ep_minsaddr = USRSTACK32;
                   max_stack_size = MAXSSIZ;
           } else {
                   epp->ep_minsaddr = USRSTACK;
                   max_stack_size = MAXSSIZ;
           }
           epp->ep_ssize = l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur;
   
   #ifdef PAX_ASLR
           pax_aslr_stack(l, epp, &max_stack_size);
   #endif /* PAX_ASLR */
   
           l->l_proc->p_stackbase = epp->ep_minsaddr;
           
           epp->ep_maxsaddr = (u_long)STACK_GROW(epp->ep_minsaddr,
                   max_stack_size);
   
           /*
            * set up commands for stack.  note that this takes *two*, one to
            * map the part of the stack which we can access, and one to map
            * the part which we can't.
            *
            * arguably, it could be made into one, but that would require the
            * addition of another mapping proc, which is unnecessary
            */
           access_size = epp->ep_ssize;
           access_linear_min = (u_long)STACK_ALLOC(epp->ep_minsaddr, access_size);
           noaccess_size = max_stack_size - access_size;
           noaccess_linear_min = (u_long)STACK_ALLOC(STACK_GROW(epp->ep_minsaddr,
               access_size), noaccess_size);
           if (noaccess_size > 0 && noaccess_size <= MAXSSIZ) {
                   NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, noaccess_size,
                       noaccess_linear_min, NULL, 0, VM_PROT_NONE, VMCMD_STACK);
           }
           KASSERT(access_size > 0 && access_size <= MAXSSIZ);
           NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, access_size,
               access_linear_min, NULL, 0, VM_PROT_READ | VM_PROT_WRITE,
               VMCMD_STACK);
   
           return 0;
   }

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