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/* $OpenBSD: exec_subr.c,v 1.58 2022/10/07 14:59:39 deraadt Exp $ */
/* $NetBSD: exec_subr.c,v 1.9 1994/12/04 03:10:42 mycroft Exp $ */
/*
* Copyright (c) 1993, 1994 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/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/malloc.h>
#include <sys/vnode.h>
#include <sys/exec.h>
#include <sys/mman.h>
#include <sys/resourcevar.h>
#include <uvm/uvm_extern.h>
#ifdef DEBUG
/*
* 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'.
*
* If not debugging, this is a macro, so it's expanded inline.
*/
void
new_vmcmd(struct exec_vmcmd_set *evsp,
int (*proc)(struct proc *, struct exec_vmcmd *), u_long len, u_long addr,
struct vnode *vp, u_long offset, u_int prot, int flags)
{
struct exec_vmcmd *vcp;
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;
}
#endif /* DEBUG */
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
ocnt = evsp->evs_cnt;
KASSERT(ocnt > 0);
/* figure out number of entries in new set */
evsp->evs_cnt += ocnt;
/* reallocate the command set */
nvcp = mallocarray(evsp->evs_cnt, sizeof(*nvcp), M_EXEC,
M_WAITOK);
memcpy(nvcp, evsp->evs_cmds, ocnt * sizeof(*nvcp));
if (evsp->evs_cmds != evsp->evs_start)
free(evsp->evs_cmds, M_EXEC, ocnt * sizeof(*nvcp));
evsp->evs_cmds = nvcp;
}
void
kill_vmcmds(struct exec_vmcmd_set *evsp)
{
struct exec_vmcmd *vcp;
int i;
for (i = 0; i < evsp->evs_used; i++) {
vcp = &evsp->evs_cmds[i];
if (vcp->ev_vp != NULLVP)
vrele(vcp->ev_vp);
}
/*
* Free old vmcmds and reset the array.
*/
evsp->evs_used = 0;
if (evsp->evs_cmds != evsp->evs_start)
free(evsp->evs_cmds, M_EXEC,
evsp->evs_cnt * sizeof(struct exec_vmcmd));
evsp->evs_cmds = evsp->evs_start;
evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE;
}
int
exec_process_vmcmds(struct proc *p, struct exec_package *epp)
{
struct exec_vmcmd *base_vc = NULL;
int error = 0;
int i;
for (i = 0; i < epp->ep_vmcmds.evs_used && !error; i++) {
struct exec_vmcmd *vcp;
vcp = &epp->ep_vmcmds.evs_cmds[i];
if (vcp->ev_flags & VMCMD_RELATIVE) {
#ifdef DIAGNOSTIC
if (base_vc == NULL)
panic("exec_process_vmcmds: RELATIVE no base");
#endif
vcp->ev_addr += base_vc->ev_addr;
}
error = (*vcp->ev_proc)(p, vcp);
if (vcp->ev_flags & VMCMD_BASE) {
base_vc = vcp;
}
}
kill_vmcmds(&epp->ep_vmcmds);
return (error);
}
/*
* 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 proc *p, struct exec_vmcmd *cmd)
{
/*
* note that if you're going to map part of a process as being
* paged from a vnode, that vnode had damn well better be marked as
* VTEXT. that's handled in the routine which sets up the vmcmd to
* call this routine.
*/
struct uvm_object *uobj;
unsigned int syscalls = 0;
int error;
/*
* 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);
/*
* first, attach to the object
*/
uobj = uvn_attach(cmd->ev_vp, PROT_READ | PROT_EXEC);
if (uobj == NULL)
return (ENOMEM);
/*
* do the map
*/
if ((cmd->ev_flags & VMCMD_SYSCALL) && (cmd->ev_prot & PROT_EXEC))
syscalls |= UVM_FLAG_SYSCALL;
error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len,
uobj, cmd->ev_offset, 0,
UVM_MAPFLAG(cmd->ev_prot, PROT_MASK, MAP_INHERIT_COPY,
MADV_NORMAL, UVM_FLAG_COPYONW | UVM_FLAG_FIXED | syscalls));
/*
* check for error
*/
if (error) {
/*
* error: detach from object
*/
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 proc *p, struct exec_vmcmd *cmd)
{
int error;
vm_prot_t prot;
if (cmd->ev_len == 0)
return (0);
prot = cmd->ev_prot;
cmd->ev_addr = trunc_page(cmd->ev_addr); /* required by uvm_map */
error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
UVM_MAPFLAG(prot | PROT_WRITE, PROT_MASK, MAP_INHERIT_COPY,
MADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW));
if (error)
return (error);
error = vn_rdwr(UIO_READ, cmd->ev_vp, (caddr_t)cmd->ev_addr,
cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT,
p->p_ucred, NULL, p);
if (error)
return (error);
if ((prot & PROT_WRITE) == 0) {
/*
* we had to map in the area at PROT_WRITE 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.
*/
return (uvm_map_protect(&p->p_vmspace->vm_map,
trunc_page(cmd->ev_addr),
round_page(cmd->ev_addr + cmd->ev_len),
prot, FALSE, TRUE));
}
return (0);
}
/*
* vmcmd_map_zero():
* handle vmcmd which specifies a zero-filled address space region.
*/
int
vmcmd_map_zero(struct proc *p, struct exec_vmcmd *cmd)
{
if (cmd->ev_len == 0)
return (0);
cmd->ev_addr = trunc_page(cmd->ev_addr); /* required by uvm_map */
return (uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr,
round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0,
UVM_MAPFLAG(cmd->ev_prot, PROT_MASK, MAP_INHERIT_COPY,
MADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_COPYONW |
(cmd->ev_flags & VMCMD_STACK ? UVM_FLAG_STACK : 0))));
}
/*
* vmcmd_randomize():
* handle vmcmd which specifies a randomized address space region.
*/
#define RANDOMIZE_CTX_THRESHOLD 512
int
vmcmd_randomize(struct proc *p, struct exec_vmcmd *cmd)
{
int error;
struct arc4random_ctx *ctx;
char *buf;
size_t sublen, off = 0;
size_t len = cmd->ev_len;
if (len == 0)
return (0);
if (len > ELF_RANDOMIZE_LIMIT)
return (EINVAL);
buf = malloc(PAGE_SIZE, M_TEMP, M_WAITOK);
if (len < RANDOMIZE_CTX_THRESHOLD) {
arc4random_buf(buf, len);
error = copyout(buf, (void *)cmd->ev_addr, len);
explicit_bzero(buf, len);
} else {
ctx = arc4random_ctx_new();
do {
sublen = MIN(len, PAGE_SIZE);
arc4random_ctx_buf(ctx, buf, sublen);
error = copyout(buf, (void *)cmd->ev_addr + off, sublen);
if (error)
break;
off += sublen;
len -= sublen;
sched_pause(yield);
} while (len);
arc4random_ctx_free(ctx);
explicit_bzero(buf, PAGE_SIZE);
}
free(buf, M_TEMP, PAGE_SIZE);
return (error);
}
#ifndef MAXSSIZ_GUARD
#define MAXSSIZ_GUARD (1024 * 1024)
#endif
/*
* exec_setup_stack(): Set up the stack segment for an 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 proc *p, struct exec_package *epp)
{
vaddr_t sgap;
#ifdef MACHINE_STACK_GROWS_UP
epp->ep_maxsaddr = USRSTACK;
epp->ep_minsaddr = USRSTACK + MAXSSIZ;
#else
epp->ep_maxsaddr = USRSTACK - MAXSSIZ - MAXSSIZ_GUARD;
epp->ep_minsaddr = USRSTACK;
#endif
epp->ep_ssize = round_page(lim_cur(RLIMIT_STACK));
if (stackgap_random != 0) {
sgap = arc4random() & (stackgap_random - 1);
sgap = trunc_page(sgap);
#ifdef MACHINE_STACK_GROWS_UP
epp->ep_maxsaddr += sgap;
epp->ep_minsaddr += sgap;
#else
epp->ep_maxsaddr -= sgap;
epp->ep_minsaddr -= sgap;
#endif
}
/*
* 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
*
* note that in memory, things assumed to be: 0 ....... ep_maxsaddr
* <stack> ep_minsaddr
*/
#ifdef MACHINE_STACK_GROWS_UP
NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero,
((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr),
epp->ep_maxsaddr + epp->ep_ssize, NULLVP, 0,
PROT_NONE);
NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize,
epp->ep_maxsaddr, NULLVP, 0,
PROT_READ | PROT_WRITE, VMCMD_STACK);
#else
NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero,
((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr),
epp->ep_maxsaddr, NULLVP, 0,
PROT_NONE);
NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize,
(epp->ep_minsaddr - epp->ep_ssize), NULLVP, 0,
PROT_READ | PROT_WRITE, VMCMD_STACK);
#endif
return (0);
}
|