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comparison dyncallback/dyncall_alloc_wx_mmap.c @ 202:030fbb70aa1b

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- changed allocwx code: * to introduce a call allowing to switch the written page to be executable (e.g. using mprotect) * changed mmap based code so page is always W^X
author Tassilo Philipp
date Mon, 20 Mar 2017 23:12:58 +0100
parents a41bc98e101c
children 3f7c69fadfc3
comparison
equal deleted inserted replaced
201:136409adbdd1 202:030fbb70aa1b
39 # error "Platform implementation missing for anonymous rwx memory" 39 # error "Platform implementation missing for anonymous rwx memory"
40 # endif 40 # endif
41 #endif 41 #endif
42 42
43 43
44 int dcAllocWX(size_t size, void** pp) 44 DCerror dcAllocWX(size_t size, void** pp)
45 { 45 {
46 void* p; 46 void* p;
47 #if !defined(MAP_ANON) && defined(DC_UNIX) 47 #if !defined(MAP_ANON) && defined(DC_UNIX)
48 // Hack around not having POSIX' MAP_ANON by going through /dev/zero; store 48 // Hack around not having POSIX' MAP_ANON by going through /dev/zero; store
49 // file descriptor to close on dcFreeWX at beginning of memory, as tiny hack 49 // file descriptor to close on dcFreeWX at beginning of memory, as tiny hack
50 int fd = open("/dev/zero", O_RDWR); 50 int fd = open("/dev/zero", O_RDWR);
51 if(fd == -1) 51 if(fd == -1)
52 return -1; 52 return -1;
53 p = mmap(0, size+sizeof(int), PROT_EXEC|PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0); 53 p = mmap(0, size+sizeof(int), PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
54 if(p == MAP_FAILED) { 54 if(p == MAP_FAILED) {
55 close(fd); 55 close(fd);
56 return -1; 56 return -1;
57 } 57 }
58 *(int*)p = fd; 58 *(int*)p = fd;
59 p += sizeof(int); 59 p += sizeof(int);
60 #else 60 #else
61 p = mmap(0, size, PROT_EXEC|PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0); 61 p = mmap(0, size, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, -1, 0);
62 if(p == MAP_FAILED) 62 if(p == MAP_FAILED)
63 return -1; 63 return -1;
64 #endif 64 #endif
65 65
66 *pp = p; 66 *pp = p;
67 return 0; 67 return 0;
68 }
69
70 DCerror dcInitExecWX(void* p, size_t size)
71 {
72 return mprotect(p, size, PROT_READ|PROT_EXEC);
68 } 73 }
69 74
70 void dcFreeWX(void* p, size_t size) 75 void dcFreeWX(void* p, size_t size)
71 { 76 {
72 #if !defined(MAP_ANON) && defined(DC_UNIX) 77 #if !defined(MAP_ANON) && defined(DC_UNIX)