mirror of
https://github.com/golang/go
synced 2024-11-19 23:04:40 -07:00
8eee153bc8
Changeset 36c9c7810f14 broke support for grsec-patched kernels. Those do not give back the address requested without MAP_FIXED, so when verifying an mmap without this flag for success, the resulting address must not be compared against the requested address since it may have succeeded at a different location. R=golang-dev, rsc, gustavo, iant CC=golang-dev https://golang.org/cl/5650072
132 lines
3.1 KiB
C
132 lines
3.1 KiB
C
// Copyright 2010 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "runtime.h"
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#include "arch_GOARCH.h"
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#include "defs_GOOS_GOARCH.h"
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#include "os_GOOS.h"
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#include "malloc.h"
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enum
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{
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ENOMEM = 12,
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_PAGE_SIZE = 4096,
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};
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static int32
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addrspace_free(void *v, uintptr n)
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{
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int32 errval;
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uintptr chunk;
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uintptr off;
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static byte vec[4096];
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for(off = 0; off < n; off += chunk) {
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chunk = _PAGE_SIZE * sizeof vec;
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if(chunk > (n - off))
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chunk = n - off;
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errval = runtime·mincore((int8*)v + off, chunk, vec);
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// errval is 0 if success, or -(error_code) if error.
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if (errval == 0 || errval != -ENOMEM)
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return 0;
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}
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return 1;
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}
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static void *
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mmap_fixed(byte *v, uintptr n, int32 prot, int32 flags, int32 fd, uint32 offset)
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{
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void *p;
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p = runtime·mmap(v, n, prot, flags, fd, offset);
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if(p != v && addrspace_free(v, n)) {
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// On some systems, mmap ignores v without
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// MAP_FIXED, so retry if the address space is free.
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if(p > (void*)4096)
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runtime·munmap(p, n);
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p = runtime·mmap(v, n, prot, flags|MAP_FIXED, fd, offset);
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}
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return p;
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}
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void*
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runtime·SysAlloc(uintptr n)
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{
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void *p;
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mstats.sys += n;
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p = runtime·mmap(nil, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
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if(p < (void*)4096) {
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if(p == (void*)EACCES) {
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runtime·printf("runtime: mmap: access denied\n");
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runtime·printf("if you're running SELinux, enable execmem for this process.\n");
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runtime·exit(2);
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}
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return nil;
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}
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return p;
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}
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void
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runtime·SysUnused(void *v, uintptr n)
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{
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runtime·madvise(v, n, MADV_DONTNEED);
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}
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void
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runtime·SysFree(void *v, uintptr n)
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{
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mstats.sys -= n;
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runtime·munmap(v, n);
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}
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void*
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runtime·SysReserve(void *v, uintptr n)
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{
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void *p;
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// On 64-bit, people with ulimit -v set complain if we reserve too
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// much address space. Instead, assume that the reservation is okay
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// if we can reserve at least 64K and check the assumption in SysMap.
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// Only user-mode Linux (UML) rejects these requests.
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if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
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p = mmap_fixed(v, 64<<10, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
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if (p != v)
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return nil;
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runtime·munmap(p, 64<<10);
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return v;
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}
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p = runtime·mmap(v, n, PROT_NONE, MAP_ANON|MAP_PRIVATE, -1, 0);
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if((uintptr)p < 4096 || -(uintptr)p < 4096)
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return nil;
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return p;
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}
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void
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runtime·SysMap(void *v, uintptr n)
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{
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void *p;
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mstats.sys += n;
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// On 64-bit, we don't actually have v reserved, so tread carefully.
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if(sizeof(void*) == 8 && (uintptr)v >= 0xffffffffU) {
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p = mmap_fixed(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_PRIVATE, -1, 0);
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if(p == (void*)ENOMEM)
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runtime·throw("runtime: out of memory");
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if(p != v) {
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runtime·printf("runtime: address space conflict: map(%p) = %p\n", v, p);
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runtime·throw("runtime: address space conflict");
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}
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return;
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}
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p = runtime·mmap(v, n, PROT_READ|PROT_WRITE|PROT_EXEC, MAP_ANON|MAP_FIXED|MAP_PRIVATE, -1, 0);
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if(p == (void*)ENOMEM)
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runtime·throw("runtime: out of memory");
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if(p != v)
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runtime·throw("runtime: cannot map pages in arena address space");
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}
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