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platform_system_core
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debuggerd_handler: use syscall(__NR_close) instead of close. 

Avoid bionic's file descriptor ownership checks by calling the close
syscall manually.

Test: debuggerd_test
Change-Id: I10af6aca0e66fe030fd7a53506ae61c87695641d
This commit is contained in:
Josh Gao 2018-06-01 15:47:20 -07:00
parent fcf2c01b55
commit c954ec09c5
2 changed files with 19 additions and 5 deletions
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10
base/include/android-base/unique_fd.h
View File

@ -151,7 +151,8 @@ using unique_fd = unique_fd_impl<DefaultCloser>;
#if !defined(_WIN32)
// Inline functions, so that they can be used header-only.
inline bool Pipe(unique_fd* read, unique_fd* write) {
template <typename Closer>
inline bool Pipe(unique_fd_impl<Closer>* read, unique_fd_impl<Closer>* write) {
int pipefd[2];
#if defined(__linux__)
@ -175,7 +176,9 @@ inline bool Pipe(unique_fd* read, unique_fd* write) {
return true;
}
inline bool Socketpair(int domain, int type, int protocol, unique_fd* left, unique_fd* right) {
template <typename Closer>
inline bool Socketpair(int domain, int type, int protocol, unique_fd_impl<Closer>* left,
unique_fd_impl<Closer>* right) {
int sockfd[2];
if (socketpair(domain, type, protocol, sockfd) != 0) {
return false;
@ -185,7 +188,8 @@ inline bool Socketpair(int domain, int type, int protocol, unique_fd* left, uniq
return true;
}
inline bool Socketpair(int type, unique_fd* left, unique_fd* right) {
template <typename Closer>
inline bool Socketpair(int type, unique_fd_impl<Closer>* left, unique_fd_impl<Closer>* right) {
return Socketpair(AF_UNIX, type, 0, left, right);
}

14
debuggerd/handler/debuggerd_handler.cpp
View File

@ -59,7 +59,16 @@
#include "protocol.h"
using android::base::Pipe;
using android::base::unique_fd;
// We muck with our fds in a 'thread' that doesn't share the same fd table.
// Close fds in that thread with a raw close syscall instead of going through libc.
struct FdsanBypassCloser {
static void Close(int fd) {
syscall(__NR_close, fd);
}
};
using unique_fd = android::base::unique_fd_impl<FdsanBypassCloser>;
// see man(2) prctl, specifically the section about PR_GET_NAME
#define MAX_TASK_NAME_LEN (16)
@ -299,7 +308,8 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
debugger_thread_info* thread_info = static_cast<debugger_thread_info*>(arg);
for (int i = 0; i < 1024; ++i) {
close(i);
// Don't use close to avoid bionic's file descriptor ownership checks.
syscall(__NR_close, i);
}
int devnull = TEMP_FAILURE_RETRY(open("/dev/null", O_RDWR));