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IABSD.fr/src/sys/kern/exec_subr.c
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/* $OpenBSD: exec_subr.c,v 1.71 2025/11/08 17:23:22 mpi 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_vnode.h> /* * 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 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; } 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 != NULL) 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 flags = UVM_FLAG_COPYONW | UVM_FLAG_FIXED; 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 */ 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, flags)); /* * check for error */ if (error) { /* * error: detach from object */ uobj->pgops->pgo_detach(uobj); } else { if (cmd->ev_flags & VMCMD_IMMUTABLE) uvm_map_immutable(&p->p_vmspace->vm_map, cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len), 1); #ifdef PMAP_CHECK_COPYIN if (PMAP_CHECK_COPYIN && ((cmd->ev_flags & VMCMD_IMMUTABLE) && (cmd->ev_prot & PROT_EXEC))) uvm_map_check_copyin_add(&p->p_vmspace->vm_map, cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len)); #endif } 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; KASSERT((cmd->ev_addr & PAGE_MASK) == 0); 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. */ error = (uvm_map_protect(&p->p_vmspace->vm_map, cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len), prot, 0, FALSE, TRUE)); } if (error == 0) { if (cmd->ev_flags & VMCMD_IMMUTABLE) uvm_map_immutable(&p->p_vmspace->vm_map, cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len), 1); } return (error); } /* * vmcmd_map_zero(): * handle vmcmd which specifies a zero-filled address space region. */ int vmcmd_map_zero(struct proc *p, struct exec_vmcmd *cmd) { int error; if (cmd->ev_len == 0) return (0); KASSERT((cmd->ev_addr & PAGE_MASK) == 0); error = 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))); if (cmd->ev_flags & VMCMD_IMMUTABLE) uvm_map_immutable(&p->p_vmspace->vm_map, cmd->ev_addr, round_page(cmd->ev_addr + cmd->ev_len), 1); return error; } /* * vmcmd_mutable(): * handle vmcmd which changes an address space region.back to mutable */ int vmcmd_mutable(struct proc *p, struct exec_vmcmd *cmd) { if (cmd->ev_len == 0) return (0); /* ev_addr, ev_len may be misaligned, so maximize the region */ uvm_map_immutable(&p->p_vmspace->vm_map, trunc_page(cmd->ev_addr), round_page(cmd->ev_addr + cmd->ev_len), 0); return 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) { vsize_t dist = 0; #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)); #ifdef VM_MIN_STACK_ADDRESS dist = USRSTACK - MAXSSIZ - MAXSSIZ_GUARD - VM_MIN_STACK_ADDRESS; if (dist >> PAGE_SHIFT > 0xffffffff) dist = (vsize_t)arc4random() << PAGE_SHIFT; else dist = (vsize_t)arc4random_uniform(dist >> PAGE_SHIFT) << PAGE_SHIFT; #else if (stackgap_random != 0) { dist = arc4random() & (stackgap_random - 1); dist = trunc_page(dist); } #endif #ifdef MACHINE_STACK_GROWS_UP epp->ep_maxsaddr += dist; epp->ep_minsaddr += dist; #else epp->ep_maxsaddr -= dist; epp->ep_minsaddr -= dist; #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_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, ((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr), epp->ep_maxsaddr + epp->ep_ssize, NULL, 0, PROT_NONE, VMCMD_IMMUTABLE); NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize, epp->ep_maxsaddr, NULL, 0, PROT_READ | PROT_WRITE, VMCMD_STACK | VMCMD_IMMUTABLE); #else NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, ((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr), epp->ep_maxsaddr, NULL, 0, PROT_NONE, VMCMD_IMMUTABLE); NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize, (epp->ep_minsaddr - epp->ep_ssize), NULL, 0, PROT_READ | PROT_WRITE, VMCMD_STACK | VMCMD_IMMUTABLE); #endif return (0); }