1 /* $OpenBSD: exec_subr.c,v 1.55 2018/04/12 17:13:44 deraadt Exp $ */ 2 /* $NetBSD: exec_subr.c,v 1.9 1994/12/04 03:10:42 mycroft Exp $ */ 3 4 /* 5 * Copyright (c) 1993, 1994 Christopher G. Demetriou 6 * All rights reserved. 7 * 8 * Redistribution and use in source and binary forms, with or without 9 * modification, are permitted provided that the following conditions 10 * are met: 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. All advertising materials mentioning features or use of this software 17 * must display the following acknowledgement: 18 * This product includes software developed by Christopher G. Demetriou. 19 * 4. The name of the author may not be used to endorse or promote products 20 * derived from this software without specific prior written permission 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 23 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 24 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 25 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 26 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 27 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 28 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 29 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 30 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 31 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 32 */ 33 34 #include <sys/param.h> 35 #include <sys/systm.h> 36 #include <sys/proc.h> 37 #include <sys/malloc.h> 38 #include <sys/vnode.h> 39 #include <sys/exec.h> 40 #include <sys/mman.h> 41 #include <sys/resourcevar.h> 42 43 #include <uvm/uvm_extern.h> 44 45 #ifdef DEBUG 46 /* 47 * new_vmcmd(): 48 * create a new vmcmd structure and fill in its fields based 49 * on function call arguments. make sure objects ref'd by 50 * the vmcmd are 'held'. 51 * 52 * If not debugging, this is a macro, so it's expanded inline. 53 */ 54 55 void 56 new_vmcmd(struct exec_vmcmd_set *evsp, 57 int (*proc)(struct proc *, struct exec_vmcmd *), u_long len, u_long addr, 58 struct vnode *vp, u_long offset, u_int prot, int flags) 59 { 60 struct exec_vmcmd *vcp; 61 62 if (evsp->evs_used >= evsp->evs_cnt) 63 vmcmdset_extend(evsp); 64 vcp = &evsp->evs_cmds[evsp->evs_used++]; 65 vcp->ev_proc = proc; 66 vcp->ev_len = len; 67 vcp->ev_addr = addr; 68 if ((vcp->ev_vp = vp) != NULL) 69 vref(vp); 70 vcp->ev_offset = offset; 71 vcp->ev_prot = prot; 72 vcp->ev_flags = flags; 73 } 74 #endif /* DEBUG */ 75 76 void 77 vmcmdset_extend(struct exec_vmcmd_set *evsp) 78 { 79 struct exec_vmcmd *nvcp; 80 u_int ocnt; 81 82 #ifdef DIAGNOSTIC 83 if (evsp->evs_used < evsp->evs_cnt) 84 panic("vmcmdset_extend: not necessary"); 85 #endif 86 87 ocnt = evsp->evs_cnt; 88 KASSERT(ocnt > 0); 89 /* figure out number of entries in new set */ 90 evsp->evs_cnt += ocnt; 91 92 /* reallocate the command set */ 93 nvcp = mallocarray(evsp->evs_cnt, sizeof(*nvcp), M_EXEC, 94 M_WAITOK); 95 memcpy(nvcp, evsp->evs_cmds, ocnt * sizeof(*nvcp)); 96 if (evsp->evs_cmds != evsp->evs_start) 97 free(evsp->evs_cmds, M_EXEC, ocnt * sizeof(*nvcp)); 98 evsp->evs_cmds = nvcp; 99 } 100 101 void 102 kill_vmcmds(struct exec_vmcmd_set *evsp) 103 { 104 struct exec_vmcmd *vcp; 105 int i; 106 107 for (i = 0; i < evsp->evs_used; i++) { 108 vcp = &evsp->evs_cmds[i]; 109 if (vcp->ev_vp != NULLVP) 110 vrele(vcp->ev_vp); 111 } 112 113 /* 114 * Free old vmcmds and reset the array. 115 */ 116 evsp->evs_used = 0; 117 if (evsp->evs_cmds != evsp->evs_start) 118 free(evsp->evs_cmds, M_EXEC, 119 evsp->evs_cnt * sizeof(struct exec_vmcmd)); 120 evsp->evs_cmds = evsp->evs_start; 121 evsp->evs_cnt = EXEC_DEFAULT_VMCMD_SETSIZE; 122 } 123 124 int 125 exec_process_vmcmds(struct proc *p, struct exec_package *epp) 126 { 127 struct exec_vmcmd *base_vc = NULL; 128 int error = 0; 129 int i; 130 131 for (i = 0; i < epp->ep_vmcmds.evs_used && !error; i++) { 132 struct exec_vmcmd *vcp; 133 134 vcp = &epp->ep_vmcmds.evs_cmds[i]; 135 136 if (vcp->ev_flags & VMCMD_RELATIVE) { 137 #ifdef DIAGNOSTIC 138 if (base_vc == NULL) 139 panic("exec_process_vmcmds: RELATIVE no base"); 140 #endif 141 vcp->ev_addr += base_vc->ev_addr; 142 } 143 error = (*vcp->ev_proc)(p, vcp); 144 if (vcp->ev_flags & VMCMD_BASE) { 145 base_vc = vcp; 146 } 147 } 148 149 kill_vmcmds(&epp->ep_vmcmds); 150 151 return (error); 152 } 153 154 /* 155 * vmcmd_map_pagedvn(): 156 * handle vmcmd which specifies that a vnode should be mmap'd. 157 * appropriate for handling demand-paged text and data segments. 158 */ 159 160 int 161 vmcmd_map_pagedvn(struct proc *p, struct exec_vmcmd *cmd) 162 { 163 /* 164 * note that if you're going to map part of a process as being 165 * paged from a vnode, that vnode had damn well better be marked as 166 * VTEXT. that's handled in the routine which sets up the vmcmd to 167 * call this routine. 168 */ 169 struct uvm_object *uobj; 170 int error; 171 172 /* 173 * map the vnode in using uvm_map. 174 */ 175 176 if (cmd->ev_len == 0) 177 return (0); 178 if (cmd->ev_offset & PAGE_MASK) 179 return (EINVAL); 180 if (cmd->ev_addr & PAGE_MASK) 181 return (EINVAL); 182 if (cmd->ev_len & PAGE_MASK) 183 return (EINVAL); 184 185 /* 186 * first, attach to the object 187 */ 188 189 uobj = uvn_attach(cmd->ev_vp, PROT_READ | PROT_EXEC); 190 if (uobj == NULL) 191 return (ENOMEM); 192 193 /* 194 * do the map 195 */ 196 197 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, cmd->ev_len, 198 uobj, cmd->ev_offset, 0, 199 UVM_MAPFLAG(cmd->ev_prot, PROT_MASK, MAP_INHERIT_COPY, 200 MADV_NORMAL, UVM_FLAG_COPYONW|UVM_FLAG_FIXED)); 201 202 /* 203 * check for error 204 */ 205 206 if (error) { 207 /* 208 * error: detach from object 209 */ 210 uobj->pgops->pgo_detach(uobj); 211 } 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 */ 222 223 int 224 vmcmd_map_readvn(struct proc *p, struct exec_vmcmd *cmd) 225 { 226 int error; 227 vm_prot_t prot; 228 229 if (cmd->ev_len == 0) 230 return (0); 231 232 prot = cmd->ev_prot; 233 234 cmd->ev_addr = trunc_page(cmd->ev_addr); /* required by uvm_map */ 235 error = uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, 236 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0, 237 UVM_MAPFLAG(prot | PROT_WRITE, PROT_MASK, MAP_INHERIT_COPY, 238 MADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_OVERLAY|UVM_FLAG_COPYONW)); 239 240 if (error) 241 return (error); 242 243 error = vn_rdwr(UIO_READ, cmd->ev_vp, (caddr_t)cmd->ev_addr, 244 cmd->ev_len, cmd->ev_offset, UIO_USERSPACE, IO_UNIT, 245 p->p_ucred, NULL, p); 246 if (error) 247 return (error); 248 249 if ((prot & PROT_WRITE) == 0) { 250 /* 251 * we had to map in the area at PROT_WRITE so that vn_rdwr() 252 * could write to it. however, the caller seems to want 253 * it mapped read-only, so now we are going to have to call 254 * uvm_map_protect() to fix up the protection. ICK. 255 */ 256 return (uvm_map_protect(&p->p_vmspace->vm_map, 257 trunc_page(cmd->ev_addr), 258 round_page(cmd->ev_addr + cmd->ev_len), 259 prot, FALSE)); 260 } 261 return (0); 262 } 263 264 /* 265 * vmcmd_map_zero(): 266 * handle vmcmd which specifies a zero-filled address space region. 267 */ 268 269 int 270 vmcmd_map_zero(struct proc *p, struct exec_vmcmd *cmd) 271 { 272 if (cmd->ev_len == 0) 273 return (0); 274 275 cmd->ev_addr = trunc_page(cmd->ev_addr); /* required by uvm_map */ 276 return (uvm_map(&p->p_vmspace->vm_map, &cmd->ev_addr, 277 round_page(cmd->ev_len), NULL, UVM_UNKNOWN_OFFSET, 0, 278 UVM_MAPFLAG(cmd->ev_prot, PROT_MASK, MAP_INHERIT_COPY, 279 MADV_NORMAL, UVM_FLAG_FIXED|UVM_FLAG_COPYONW | 280 (cmd->ev_flags & VMCMD_STACK ? UVM_FLAG_STACK : 0)))); 281 } 282 283 /* 284 * vmcmd_randomize(): 285 * handle vmcmd which specifies a randomized address space region. 286 */ 287 #define RANDOMIZE_CTX_THRESHOLD 512 288 int 289 vmcmd_randomize(struct proc *p, struct exec_vmcmd *cmd) 290 { 291 int error; 292 struct arc4random_ctx *ctx; 293 char *buf; 294 size_t sublen, off = 0; 295 size_t len = cmd->ev_len; 296 297 if (len == 0) 298 return (0); 299 if (len > ELF_RANDOMIZE_LIMIT) 300 return (EINVAL); 301 302 buf = malloc(PAGE_SIZE, M_TEMP, M_WAITOK); 303 if (len < RANDOMIZE_CTX_THRESHOLD) { 304 arc4random_buf(buf, len); 305 error = copyout(buf, (void *)cmd->ev_addr, len); 306 explicit_bzero(buf, len); 307 } else { 308 ctx = arc4random_ctx_new(); 309 do { 310 sublen = MIN(len, PAGE_SIZE); 311 arc4random_ctx_buf(ctx, buf, sublen); 312 error = copyout(buf, (void *)cmd->ev_addr + off, sublen); 313 if (error) 314 break; 315 off += sublen; 316 len -= sublen; 317 sched_pause(yield); 318 } while (len); 319 arc4random_ctx_free(ctx); 320 explicit_bzero(buf, PAGE_SIZE); 321 } 322 free(buf, M_TEMP, PAGE_SIZE); 323 return (error); 324 } 325 326 #ifndef MAXSSIZ_GUARD 327 #define MAXSSIZ_GUARD (1024 * 1024) 328 #endif 329 330 /* 331 * exec_setup_stack(): Set up the stack segment for an executable. 332 * 333 * Note that the ep_ssize parameter must be set to be the current stack 334 * limit; this is adjusted in the body of execve() to yield the 335 * appropriate stack segment usage once the argument length is 336 * calculated. 337 * 338 * This function returns an int for uniformity with other (future) formats' 339 * stack setup functions. They might have errors to return. 340 */ 341 342 int 343 exec_setup_stack(struct proc *p, struct exec_package *epp) 344 { 345 vaddr_t sgap; 346 347 #ifdef MACHINE_STACK_GROWS_UP 348 epp->ep_maxsaddr = USRSTACK; 349 epp->ep_minsaddr = USRSTACK + MAXSSIZ; 350 #else 351 epp->ep_maxsaddr = USRSTACK - MAXSSIZ - MAXSSIZ_GUARD; 352 epp->ep_minsaddr = USRSTACK; 353 #endif 354 epp->ep_ssize = round_page(p->p_rlimit[RLIMIT_STACK].rlim_cur); 355 356 if (stackgap_random != 0) { 357 sgap = arc4random() & (stackgap_random - 1); 358 sgap = trunc_page(sgap); 359 360 #ifdef MACHINE_STACK_GROWS_UP 361 epp->ep_maxsaddr += sgap; 362 epp->ep_minsaddr += sgap; 363 #else 364 epp->ep_maxsaddr -= sgap; 365 epp->ep_minsaddr -= sgap; 366 #endif 367 } 368 369 /* 370 * set up commands for stack. note that this takes *two*, one to 371 * map the part of the stack which we can access, and one to map 372 * the part which we can't. 373 * 374 * arguably, it could be made into one, but that would require the 375 * addition of another mapping proc, which is unnecessary 376 * 377 * note that in memory, things assumed to be: 0 ....... ep_maxsaddr 378 * <stack> ep_minsaddr 379 */ 380 #ifdef MACHINE_STACK_GROWS_UP 381 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, 382 ((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr), 383 epp->ep_maxsaddr + epp->ep_ssize, NULLVP, 0, 384 PROT_NONE); 385 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize, 386 epp->ep_maxsaddr, NULLVP, 0, 387 PROT_READ | PROT_WRITE, VMCMD_STACK); 388 #else 389 NEW_VMCMD(&epp->ep_vmcmds, vmcmd_map_zero, 390 ((epp->ep_minsaddr - epp->ep_ssize) - epp->ep_maxsaddr), 391 epp->ep_maxsaddr, NULLVP, 0, 392 PROT_NONE); 393 NEW_VMCMD2(&epp->ep_vmcmds, vmcmd_map_zero, epp->ep_ssize, 394 (epp->ep_minsaddr - epp->ep_ssize), NULLVP, 0, 395 PROT_READ | PROT_WRITE, VMCMD_STACK); 396 #endif 397 398 return (0); 399 } 400