97271920bf
Add a hook that's called upon file descriptor creation to libc, and a
library that uses it to capture backtraces for file descriptor creation,
to make it easier to hunt down file descriptor leaks.
Currently, this doesn't capture all of the ways of creating a file
descriptor, but completeness isn't required for this to be useful as
long as leaked file descriptors are created with a function that is
tracked. The primary unhandled case is binder, which receives file
descriptors as a payload in a not-trivially-parsable byte blob, but
there's a chance that the leak we're currently trying to track down
isn't of a file descriptor received over binder, so leave that for
later.
Bug: http://b/140703823
Test: manual
Change-Id: I308a14c2e234cdba4207157b634ab6b8bc539dd9
(cherry picked from commit b7eccd4b15)
87 lines
3 KiB
C++
87 lines
3 KiB
C++
/*
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* Copyright (C) 2019 The Android Open Source Project
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
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* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <string.h>
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#include <sys/socket.h>
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#include <async_safe/log.h>
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#include "private/bionic_fdtrack.h"
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extern "C" ssize_t __recvmsg(int __fd, struct msghdr* __msg, int __flags);
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extern "C" int __recvmmsg(int __fd, struct mmsghdr* __msgs, unsigned int __msg_count, int __flags,
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const struct timespec* __timeout);
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static inline __attribute__((artificial)) __attribute__((always_inline)) void track_fds(
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struct msghdr* msg, const char* function_name) {
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if (!__android_fdtrack_hook) {
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return;
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}
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for (struct cmsghdr* cmsg = CMSG_FIRSTHDR(msg); cmsg; cmsg = CMSG_NXTHDR(msg, cmsg)) {
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if (cmsg->cmsg_type != SCM_RIGHTS) {
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continue;
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}
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if (cmsg->cmsg_len <= sizeof(struct cmsghdr)) {
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continue;
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}
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size_t data_length = cmsg->cmsg_len - sizeof(struct cmsghdr);
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if (data_length % sizeof(int) != 0) {
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async_safe_fatal("invalid cmsg length: %zu", data_length);
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}
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for (size_t offset = 0; offset < data_length; offset += sizeof(int)) {
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int fd;
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memcpy(&fd, CMSG_DATA(cmsg) + offset, sizeof(int));
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FDTRACK_CREATE_NAME(function_name, fd);
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}
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}
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}
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ssize_t recvmsg(int __fd, struct msghdr* __msg, int __flags) {
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ssize_t rc = __recvmsg(__fd, __msg, __flags);
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if (rc == -1) {
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return -1;
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}
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track_fds(__msg, "recvmsg");
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return rc;
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}
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int recvmmsg(int __fd, struct mmsghdr* __msgs, unsigned int __msg_count, int __flags,
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const struct timespec* __timeout) {
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int rc = __recvmmsg(__fd, __msgs, __msg_count, __flags, __timeout);
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if (rc == -1) {
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return -1;
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}
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for (int i = 0; i < rc; ++i) {
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track_fds(&__msgs[i].msg_hdr, "recvmmsg");
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}
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return rc;
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}
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