130 lines
4.4 KiB
C++
130 lines
4.4 KiB
C++
//===-- sanitizer_tls_get_addr.cc -----------------------------------------===//
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Handle the __tls_get_addr call.
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//
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//===----------------------------------------------------------------------===//
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#include "sanitizer_tls_get_addr.h"
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#include "sanitizer_flags.h"
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#include "sanitizer_platform_interceptors.h"
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namespace __sanitizer {
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#if SANITIZER_INTERCEPT_TLS_GET_ADDR
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// The actual parameter that comes to __tls_get_addr
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// is a pointer to a struct with two words in it:
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struct TlsGetAddrParam {
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uptr dso_id;
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uptr offset;
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};
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// Glibc starting from 2.19 allocates tls using __signal_safe_memalign,
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// which has such header.
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struct Glibc_2_19_tls_header {
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uptr size;
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uptr start;
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};
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// This must be static TLS
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__attribute__((tls_model("initial-exec")))
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static __thread DTLS dtls;
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// Make sure we properly destroy the DTLS objects:
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// this counter should never get too large.
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static atomic_uintptr_t number_of_live_dtls;
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static const uptr kDestroyedThread = -1;
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static inline void DTLS_Deallocate(DTLS::DTV *dtv, uptr size) {
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if (!size) return;
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VPrintf(2, "__tls_get_addr: DTLS_Deallocate %p %zd\n", dtv, size);
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UnmapOrDie(dtv, size * sizeof(DTLS::DTV));
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atomic_fetch_sub(&number_of_live_dtls, 1, memory_order_relaxed);
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}
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static inline void DTLS_Resize(uptr new_size) {
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if (dtls.dtv_size >= new_size) return;
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new_size = RoundUpToPowerOfTwo(new_size);
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new_size = Max(new_size, 4096UL / sizeof(DTLS::DTV));
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DTLS::DTV *new_dtv =
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(DTLS::DTV *)MmapOrDie(new_size * sizeof(DTLS::DTV), "DTLS_Resize");
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uptr num_live_dtls =
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atomic_fetch_add(&number_of_live_dtls, 1, memory_order_relaxed);
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VPrintf(2, "__tls_get_addr: DTLS_Resize %p %zd\n", &dtls, num_live_dtls);
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CHECK_LT(num_live_dtls, 1 << 20);
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uptr old_dtv_size = dtls.dtv_size;
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DTLS::DTV *old_dtv = dtls.dtv;
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if (old_dtv_size)
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internal_memcpy(new_dtv, dtls.dtv, dtls.dtv_size * sizeof(DTLS::DTV));
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dtls.dtv = new_dtv;
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dtls.dtv_size = new_size;
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if (old_dtv_size)
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DTLS_Deallocate(old_dtv, old_dtv_size);
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}
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void DTLS_Destroy() {
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if (!common_flags()->intercept_tls_get_addr) return;
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VPrintf(2, "__tls_get_addr: DTLS_Destroy %p %zd\n", &dtls, dtls.dtv_size);
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uptr s = dtls.dtv_size;
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dtls.dtv_size = kDestroyedThread; // Do this before unmap for AS-safety.
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DTLS_Deallocate(dtls.dtv, s);
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}
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DTLS::DTV *DTLS_on_tls_get_addr(void *arg_void, void *res) {
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if (!common_flags()->intercept_tls_get_addr) return 0;
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TlsGetAddrParam *arg = reinterpret_cast<TlsGetAddrParam *>(arg_void);
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uptr dso_id = arg->dso_id;
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if (dtls.dtv_size == kDestroyedThread) return 0;
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DTLS_Resize(dso_id + 1);
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if (dtls.dtv[dso_id].beg) return 0;
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uptr tls_size = 0;
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uptr tls_beg = reinterpret_cast<uptr>(res) - arg->offset;
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VPrintf(2, "__tls_get_addr: %p {%p,%p} => %p; tls_beg: %p; sp: %p "
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"num_live_dtls %zd\n",
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arg, arg->dso_id, arg->offset, res, tls_beg, &tls_beg,
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atomic_load(&number_of_live_dtls, memory_order_relaxed));
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if (dtls.last_memalign_ptr == tls_beg) {
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tls_size = dtls.last_memalign_size;
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VPrintf(2, "__tls_get_addr: glibc <=2.18 suspected; tls={%p,%p}\n",
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tls_beg, tls_size);
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} else if ((tls_beg % 4096) == sizeof(Glibc_2_19_tls_header)) {
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// We may want to check gnu_get_libc_version().
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Glibc_2_19_tls_header *header = (Glibc_2_19_tls_header *)tls_beg - 1;
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tls_size = header->size;
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tls_beg = header->start;
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VPrintf(2, "__tls_get_addr: glibc >=2.19 suspected; tls={%p %p}\n",
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tls_beg, tls_size);
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} else {
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VPrintf(2, "__tls_get_addr: Can't guess glibc version\n");
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// This may happen inside the DTOR of main thread, so just ignore it.
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tls_size = 0;
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}
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dtls.dtv[dso_id].beg = tls_beg;
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dtls.dtv[dso_id].size = tls_size;
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return dtls.dtv + dso_id;
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}
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void DTLS_on_libc_memalign(void *ptr, uptr size) {
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if (!common_flags()->intercept_tls_get_addr) return;
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VPrintf(2, "DTLS_on_libc_memalign: %p %p\n", ptr, size);
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dtls.last_memalign_ptr = reinterpret_cast<uptr>(ptr);
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dtls.last_memalign_size = size;
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}
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DTLS *DTLS_Get() { return &dtls; }
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#else
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void DTLS_on_libc_memalign(void *ptr, uptr size) {}
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DTLS::DTV *DTLS_on_tls_get_addr(void *arg, void *res) { return 0; }
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DTLS *DTLS_Get() { return 0; }
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void DTLS_Destroy() {}
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#endif // SANITIZER_INTERCEPT_TLS_GET_ADDR
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} // namespace __sanitizer
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