1 /* $NetBSD: exec_subr.c,v 1.76 2016/05/22 14:26:09 christos Exp $ */ 2 3 /* 4 * Copyright (c) 1993, 1994, 1996 Christopher G. Demetriou 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 1. Redistributions of source code must retain the above copyright 11 * notice, this list of conditions and the following disclaimer. 12 * 2. Redistributions in binary form must reproduce the above copyright 13 * notice, this list of conditions and the following disclaimer in the 14 * documentation and/or other materials provided with the distribution. 15 * 3. All advertising materials mentioning features or use of this software 16 * must display the following acknowledgement: 17 * This product includes software developed by Christopher G. Demetriou. 18 * 4. The name of the author may not be used to endorse or promote products 19 * derived from this software without specific prior written permission 20 * 21 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 22 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 23 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 24 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 25 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 26 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 30 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 31 */ 32 33 #include <sys/cdefs.h> 34 __KERNEL_RCSID(0, "$NetBSD: exec_subr.c,v 1.76 2016/05/22 14:26:09 christos Exp $"); 35 36 #include "opt_pax.h" 37 38 #include <sys/param.h> 39 #include <sys/systm.h> 40 #include <sys/proc.h> 41 #include <sys/kmem.h> 42 #include <sys/vnode.h> 43 #include <sys/filedesc.h> 44 #include <sys/exec.h> 45 #include <sys/mman.h> 46 #include <sys/resourcevar.h> 47 #include <sys/device.h> 48 #include <sys/pax.h> 49 50 #include <uvm/uvm_extern.h> 51 52 #define VMCMD_EVCNT_DECL(name) \ 53 static struct evcnt vmcmd_ev_##name = \ 54 EVCNT_INITIALIZER(EVCNT_TYPE_MISC, NULL, "vmcmd", #name); \ 55 EVCNT_ATTACH_STATIC(vmcmd_ev_##name) 56 57 #define VMCMD_EVCNT_INCR(name) \ 58 vmcmd_ev_##name.ev_count++ 59 60 VMCMD_EVCNT_DECL(calls); 61 VMCMD_EVCNT_DECL(extends); 62 VMCMD_EVCNT_DECL(kills); 63 64 #ifdef DEBUG_STACK 65 #define DPRINTF(a) uprintf a 66 #else 67 #define DPRINTF(a) 68 #endif 69 70 /* 71 * new_vmcmd(): 72 * create a new vmcmd structure and fill in its fields based 73 * on function call arguments. make sure objects ref'd by 74 * the vmcmd are 'held'. 75 */ 76 77 void 78 new_vmcmd(struct exec_vmcmd_set *evsp, 79 int (*proc)(struct lwp * l, struct exec_vmcmd *), 80 vsize_t len, vaddr_t addr, struct vnode *vp, u_long offset, 81 u_int prot, int flags) 82 { 83 struct exec_vmcmd *vcp; 84 85 VMCMD_EVCNT_INCR(calls); 86 KASSERT(proc != vmcmd_map_pagedvn || (vp->v_iflag & VI_TEXT)); 87 KASSERT(vp == NULL || vp->v_usecount > 0); 88 89 if (evsp->evs_used >= evsp->evs_cnt) 90 vmcmdset_extend(evsp); 91 vcp = &evsp->evs_cmds[evsp->evs_used++]; 92 vcp->ev_proc = proc; 93 vcp->ev_len = len; 94 vcp->ev_addr = addr; 95 if ((vcp->ev_vp = vp) != NULL) 96 vref(vp); 97 vcp->ev_offset = offset; 98 vcp->ev_prot = prot; 99 vcp->ev_flags = flags; 100 } 101 102 void 103 vmcmdset_extend(struct exec_vmcmd_set *evsp) 104 { 105 struct exec_vmcmd *nvcp; 106 u_int ocnt; 107 108 #ifdef DIAGNOSTIC 109 if (evsp->evs_used < evsp->evs_cnt) 110 panic("vmcmdset_extend: not necessary"); 111 #endif 112 113 /* figure out number of entries in new set */ 114 if ((ocnt = evsp->evs_cnt) != 0) { 115 evsp->evs_cnt += ocnt; 116 VMCMD_EVCNT_INCR(extends); 117 } else 118 evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE; 119 120 /* allocate it */ 121 nvcp = kmem_alloc(evsp->evs_cnt * sizeof(struct exec_vmcmd), KM_SLEEP); 122 123 /* free the old struct, if there was one, and record the new one */ 124 if (ocnt) { 125 memcpy(nvcp, evsp->evs_cmds, 126 (ocnt * sizeof(struct exec_vmcmd))); 127 kmem_free(evsp->evs_cmds, ocnt * sizeof(struct exec_vmcmd)); 128 } 129 evsp->evs_cmds = nvcp; 130 } 131 132 void 133 kill_vmcmds(struct exec_vmcmd_set *evsp) 134 { 135 struct exec_vmcmd *vcp; 136 u_int i; 137 138 VMCMD_EVCNT_INCR(kills); 139 140 if (evsp->evs_cnt == 0) 141 return; 142 143 for (i = 0; i < evsp->evs_used; i++) { 144 vcp = &evsp->evs_cmds[i]; 145 if (vcp->ev_vp != NULL) 146 vrele(vcp->ev_vp); 147 } 148 kmem_free(evsp->evs_cmds, evsp->evs_cnt * sizeof(struct exec_vmcmd)); 149 evsp->evs_used = evsp->evs_cnt = 0; 150 } 151 152 /* 153 * vmcmd_map_pagedvn(): 154 * handle vmcmd which specifies that a vnode should be mmap'd. 155 * appropriate for handling demand-paged text and data segments. 156 */ 157 158 int 159 vmcmd_map_pagedvn(struct lwp *l, struct exec_vmcmd *cmd) 160 { 161 struct uvm_object *uobj; 162 struct vnode *vp = cmd->ev_vp; 163 struct proc *p = l->l_proc; 164 int error; 165 vm_prot_t prot, maxprot; 166 167 KASSERT(vp->v_iflag & VI_TEXT); 168 169 /* 170 * map the vnode in using uvm_map. 171 */ 172 173 if (cmd->ev_len == 0) 174 return 0; 175 if (cmd->ev_offset & PAGE_MASK) 176 return EINVAL; 177 if (cmd->ev_addr & PAGE_MASK) 178 return EINVAL; 179 if (cmd->ev_len & PAGE_MASK) 180 return EINVAL; 181 182 prot = cmd->ev_prot; 183 maxprot = UVM_PROT_ALL; 184 PAX_MPROTECT_ADJUST(l, &prot, &maxprot); 185 186 /* 187 * check the file system's opinion about mmapping the file 188 */ 189 190 error = VOP_MMAP(vp, prot, l->l_cred); 191 if (error) 192 return error; 193 194 if ((vp->v_vflag & VV_MAPPED) == 0) { 195 vn_lock(vp, LK_EXCLUSIVE | LK_RETRY); 196 vp->v_vflag |= VV_MAPPED; 197 VOP_UNLOCK(vp); 198 } 199 200 /* 201 * do the map, reference the object for this map entry 202 */ 203 uobj = &vp->v_uobj; 204 vref(vp); 205 206 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len, 207 uobj, cmd->ev_offset, 0, 208 UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY, 209 UVM_ADV_NORMAL, UVM_FLAG_COPYONW|UVM_FLAG_FIXED)); 210 if (error) { 211 uobj->pgops->pgo_detach(uobj); 212 } 213 return error; 214 } 215 216 /* 217 * vmcmd_map_readvn(): 218 * handle vmcmd which specifies that a vnode should be read from. 219 * appropriate for non-demand-paged text/data segments, i.e. impure 220 * objects (a la OMAGIC and NMAGIC). 221 */ 222 int 223 vmcmd_map_readvn(struct lwp *l, struct exec_vmcmd *cmd) 224 { 225 struct proc *p = l->l_proc; 226 int error; 227 long diff; 228 229 if (cmd->ev_len == 0) 230 return 0; 231 232 diff = cmd->ev_addr - trunc_page(cmd->ev_addr); 233 cmd->ev_addr -= diff; /* required by uvm_map */ 234 cmd->ev_offset -= diff; 235 cmd->ev_len += diff; 236 237 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, 238 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0, 239 UVM_MAPFLAG(UVM_PROT_ALL, UVM_PROT_ALL, UVM_INH_COPY, 240 UVM_ADV_NORMAL, 241 UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW)); 242 243 if (error) 244 return error; 245 246 return vmcmd_readvn(l, cmd); 247 } 248 249 int 250 vmcmd_readvn(struct lwp *l, struct exec_vmcmd *cmd) 251 { 252 struct proc *p = l->l_proc; 253 int error; 254 vm_prot_t prot, maxprot; 255 256 error = vn_rdwr(UIO_READ, cmd->ev_vp, (void *)cmd->ev_addr, 257 cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT, 258 l->l_cred, NULL, l); 259 if (error) 260 return error; 261 262 prot = cmd->ev_prot; 263 maxprot = VM_PROT_ALL; 264 PAX_MPROTECT_ADJUST(l, &prot, &maxprot); 265 266 #ifdef PMAP_NEED_PROCWR 267 /* 268 * we had to write the process, make sure the pages are synched 269 * with the instruction cache. 270 */ 271 if (prot & VM_PROT_EXECUTE) 272 pmap_procwr(p, cmd->ev_addr, cmd->ev_len); 273 #endif 274 275 /* 276 * we had to map in the area at PROT_ALL so that vn_rdwr() 277 * could write to it. however, the caller seems to want 278 * it mapped read-only, so now we are going to have to call 279 * uvm_map_protect() to fix up the protection. ICK. 280 */ 281 if (maxprot != VM_PROT_ALL) { 282 error = uvm_map_protect(&p->p_vmspace->vm_map, 283 trunc_page(cmd->ev_addr), 284 round_page(cmd->ev_addr + cmd->ev_len), 285 maxprot, true); 286 if (error) 287 return error; 288 } 289 290 if (prot != maxprot) { 291 error = uvm_map_protect(&p->p_vmspace->vm_map, 292 trunc_page(cmd->ev_addr), 293 round_page(cmd->ev_addr + cmd->ev_len), 294 prot, false); 295 if (error) 296 return error; 297 } 298 299 return 0; 300 } 301 302 /* 303 * vmcmd_map_zero(): 304 * handle vmcmd which specifies a zero-filled address space region. The 305 * address range must be first allocated, then protected appropriately. 306 */ 307 308 int 309 vmcmd_map_zero(struct lwp *l, struct exec_vmcmd *cmd) 310 { 311 struct proc *p = l->l_proc; 312 int error; 313 long diff; 314 vm_prot_t prot, maxprot; 315 316 diff = cmd->ev_addr - trunc_page(cmd->ev_addr); 317 cmd->ev_addr -= diff; /* required by uvm_map */ 318 cmd->ev_len += diff; 319 320 prot = cmd->ev_prot; 321 maxprot = UVM_PROT_ALL; 322 PAX_MPROTECT_ADJUST(l, &prot, &maxprot); 323 324 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, 325 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0, 326 UVM_MAPFLAG(prot, maxprot, UVM_INH_COPY, 327 UVM_ADV_NORMAL, 328 UVM_FLAG_FIXED|UVM_FLAG_COPYONW)); 329 if (cmd->ev_flags & VMCMD_STACK) 330 curproc->p_vmspace->vm_issize += atop(round_page(cmd->ev_len)); 331 return error; 332 } 333 334 /* 335 * exec_read_from(): 336 * 337 * Read from vnode into buffer at offset. 338 */ 339 int 340 exec_read_from(struct lwp *l, struct vnode *vp, u_long off, void *bf, 341 size_t size) 342 { 343 int error; 344 size_t resid; 345 346 if ((error = vn_rdwr(UIO_READ, vp, bf, size, off, UIO_SYSSPACE, 347 0, l->l_cred, &resid, NULL)) != 0) 348 return error; 349 /* 350 * See if we got all of it 351 */ 352 if (resid != 0) 353 return ENOEXEC; 354 return 0; 355 } 356 357 /* 358 * exec_setup_stack(): Set up the stack segment for an elf 359 * executable. 360 * 361 * Note that the ep_ssize parameter must be set to be the current stack 362 * limit; this is adjusted in the body of execve() to yield the 363 * appropriate stack segment usage once the argument length is 364 * calculated. 365 * 366 * This function returns an int for uniformity with other (future) formats' 367 * stack setup functions. They might have errors to return. 368 */ 369 370 int 371 exec_setup_stack(struct lwp *l, struct exec_package *epp) 372 { 373 vsize_t max_stack_size; 374 vaddr_t access_linear_min; 375 vsize_t access_size; 376 vaddr_t noaccess_linear_min; 377 vsize_t noaccess_size; 378 379 #ifndef USRSTACK32 380 #define USRSTACK32 (0x00000000ffffffffL&~PGOFSET) 381 #endif 382 #ifndef MAXSSIZ32 383 #define MAXSSIZ32 (MAXSSIZ >> 2) 384 #endif 385 386 if (epp->ep_flags & EXEC_32) { 387 epp->ep_minsaddr = USRSTACK32; 388 max_stack_size = MAXSSIZ32; 389 } else { 390 epp->ep_minsaddr = USRSTACK; 391 max_stack_size = MAXSSIZ; 392 } 393 394 DPRINTF(("ep_minsaddr=%#jx max_stack_size=%#jx\n", 395 (uintmax_t)epp->ep_minsaddr, (uintmax_t)max_stack_size)); 396 397 pax_aslr_stack(epp, &max_stack_size); 398 399 DPRINTF(("[RLIMIT_STACK].lim_cur=%#jx max_stack_size=%#jx\n", 400 (uintmax_t)l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur, 401 (uintmax_t)max_stack_size)); 402 epp->ep_ssize = MIN(l->l_proc->p_rlimit[RLIMIT_STACK].rlim_cur, 403 max_stack_size); 404 405 l->l_proc->p_stackbase = epp->ep_minsaddr; 406 407 epp->ep_maxsaddr = (vaddr_t)STACK_GROW(epp->ep_minsaddr, 408 max_stack_size); 409 410 DPRINTF(("ep_ssize=%#jx ep_minsaddr=%#jx ep_maxsaddr=%#jx\n", 411 (uintmax_t)epp->ep_ssize, (uintmax_t)epp->ep_minsaddr, 412 (uintmax_t)epp->ep_maxsaddr)); 413 414 /* 415 * set up commands for stack. note that this takes *two*, one to 416 * map the part of the stack which we can access, and one to map 417 * the part which we can't. 418 * 419 * arguably, it could be made into one, but that would require the 420 * addition of another mapping proc, which is unnecessary 421 */ 422 access_size = epp->ep_ssize; 423 access_linear_min = (vaddr_t)STACK_ALLOC(epp->ep_minsaddr, access_size); 424 noaccess_size = max_stack_size - access_size; 425 noaccess_linear_min = (vaddr_t)STACK_ALLOC(STACK_GROW(epp->ep_minsaddr, 426 access_size), noaccess_size); 427 428 DPRINTF(("access_size=%#jx, access_linear_min=%#jx, " 429 "noaccess_size=%#jx, noaccess_linear_min=%#jx\n", 430 (uintmax_t)access_size, (uintmax_t)access_linear_min, 431 (uintmax_t)noaccess_size, (uintmax_t)noaccess_linear_min)); 432 433 if (noaccess_size > 0 && noaccess_size <= MAXSSIZ) { 434 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, noaccess_size, 435 noaccess_linear_min, NULL, 0, VM_PROT_NONE, VMCMD_STACK); 436 } 437 KASSERT(access_size > 0 && access_size <= MAXSSIZ); 438 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, access_size, 439 access_linear_min, NULL, 0, VM_PROT_READ | VM_PROT_WRITE, 440 VMCMD_STACK); 441 442 return 0; 443 } 444