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-rw-r--r--debuggerd/crash_dump.cpp48
-rw-r--r--debuggerd/handler/debuggerd_handler.cpp14
-rw-r--r--libcutils/fs_config.c7
3 files changed, 49 insertions, 20 deletions
diff --git a/debuggerd/crash_dump.cpp b/debuggerd/crash_dump.cpp
index 58eaed717..ed6d3b7c0 100644
--- a/debuggerd/crash_dump.cpp
+++ b/debuggerd/crash_dump.cpp
@@ -18,10 +18,12 @@
#include <dirent.h>
#include <fcntl.h>
#include <stdlib.h>
-#include <syscall.h>
+#include <sys/capability.h>
+#include <sys/prctl.h>
#include <sys/ptrace.h>
#include <sys/types.h>
#include <sys/un.h>
+#include <syscall.h>
#include <unistd.h>
#include <limits>
@@ -51,24 +53,25 @@
using android::base::unique_fd;
using android::base::StringPrintf;
-static bool pid_contains_tid(pid_t pid, pid_t tid) {
- std::string task_path = StringPrintf("/proc/%d/task/%d", pid, tid);
- return access(task_path.c_str(), F_OK) == 0;
+static bool pid_contains_tid(int pid_proc_fd, pid_t tid) {
+ struct stat st;
+ std::string task_path = StringPrintf("task/%d", tid);
+ return fstatat(pid_proc_fd, task_path.c_str(), &st, 0) == 0;
}
// Attach to a thread, and verify that it's still a member of the given process
-static bool ptrace_seize_thread(pid_t pid, pid_t tid, std::string* error) {
+static bool ptrace_seize_thread(int pid_proc_fd, pid_t tid, std::string* error) {
if (ptrace(PTRACE_SEIZE, tid, 0, 0) != 0) {
*error = StringPrintf("failed to attach to thread %d: %s", tid, strerror(errno));
return false;
}
// Make sure that the task we attached to is actually part of the pid we're dumping.
- if (!pid_contains_tid(pid, tid)) {
+ if (!pid_contains_tid(pid_proc_fd, tid)) {
if (ptrace(PTRACE_DETACH, tid, 0, 0) != 0) {
PLOG(FATAL) << "failed to detach from thread " << tid;
}
- *error = StringPrintf("thread %d is not in process %d", tid, pid);
+ *error = StringPrintf("thread %d is not in process", tid);
return false;
}
@@ -190,6 +193,24 @@ static void abort_handler(pid_t target, const bool& tombstoned_connected,
_exit(1);
}
+static void drop_capabilities() {
+ __user_cap_header_struct capheader;
+ memset(&capheader, 0, sizeof(capheader));
+ capheader.version = _LINUX_CAPABILITY_VERSION_3;
+ capheader.pid = 0;
+
+ __user_cap_data_struct capdata[2];
+ memset(&capdata, 0, sizeof(capdata));
+
+ if (capset(&capheader, &capdata[0]) == -1) {
+ PLOG(FATAL) << "failed to drop capabilities";
+ }
+
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) != 0) {
+ PLOG(FATAL) << "failed to set PR_SET_NO_NEW_PRIVS";
+ }
+}
+
static void check_process(int proc_fd, pid_t expected_pid) {
android::procinfo::ProcessInfo proc_info;
if (!android::procinfo::GetProcessInfoFromProcPidFd(proc_fd, &proc_info)) {
@@ -263,7 +284,7 @@ int main(int argc, char** argv) {
check_process(target_proc_fd, target);
std::string attach_error;
- if (!ptrace_seize_thread(target, main_tid, &attach_error)) {
+ if (!ptrace_seize_thread(target_proc_fd, main_tid, &attach_error)) {
LOG(FATAL) << attach_error;
}
@@ -304,6 +325,7 @@ int main(int argc, char** argv) {
}
int signo = siginfo.si_signo;
+ bool fatal_signal = signo != DEBUGGER_SIGNAL;
bool backtrace = false;
uintptr_t abort_address = 0;
@@ -319,17 +341,16 @@ int main(int argc, char** argv) {
// Now that we have the signal that kicked things off, attach all of the
// sibling threads, and then proceed.
- bool fatal_signal = signo != DEBUGGER_SIGNAL;
- std::set<pid_t> siblings;
std::set<pid_t> attached_siblings;
- if (fatal_signal || backtrace) {
+ {
+ std::set<pid_t> siblings;
if (!android::procinfo::GetProcessTids(target, &siblings)) {
PLOG(FATAL) << "failed to get process siblings";
}
siblings.erase(main_tid);
for (pid_t sibling_tid : siblings) {
- if (!ptrace_seize_thread(target, sibling_tid, &attach_error)) {
+ if (!ptrace_seize_thread(target_proc_fd, sibling_tid, &attach_error)) {
LOG(WARNING) << attach_error;
} else {
attached_siblings.insert(sibling_tid);
@@ -337,6 +358,9 @@ int main(int argc, char** argv) {
}
}
+ // Drop our capabilities now that we've attached to the threads we care about.
+ drop_capabilities();
+
check_process(target_proc_fd, target);
// TODO: Use seccomp to lock ourselves down.
diff --git a/debuggerd/handler/debuggerd_handler.cpp b/debuggerd/handler/debuggerd_handler.cpp
index 9469bbdeb..156534e19 100644
--- a/debuggerd/handler/debuggerd_handler.cpp
+++ b/debuggerd/handler/debuggerd_handler.cpp
@@ -39,6 +39,7 @@
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/capability.h>
#include <sys/mman.h>
#include <sys/prctl.h>
#include <sys/socket.h>
@@ -207,7 +208,7 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
}
// Don't use fork(2) to avoid calling pthread_atfork handlers.
- int forkpid = clone(nullptr, nullptr, SIGCHLD, nullptr);
+ int forkpid = clone(nullptr, nullptr, 0, nullptr);
if (forkpid == -1) {
__libc_format_log(ANDROID_LOG_FATAL, "libc", "failed to fork in debuggerd signal handler: %s",
strerror(errno));
@@ -216,6 +217,11 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
close(pipefds[0]);
close(pipefds[1]);
+ // Set all of the ambient capability bits we can, so that crash_dump can ptrace us.
+ for (unsigned long i = 0; prctl(PR_CAPBSET_READ, i, 0, 0, 0); ++i) {
+ prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, i, 0, 0);
+ }
+
char buf[10];
snprintf(buf, sizeof(buf), "%d", thread_info->crashing_tid);
execl(CRASH_DUMP_PATH, CRASH_DUMP_NAME, buf, nullptr);
@@ -242,10 +248,12 @@ static int debuggerd_dispatch_pseudothread(void* arg) {
close(pipefds[0]);
// Don't leave a zombie child.
- siginfo_t child_siginfo;
- if (TEMP_FAILURE_RETRY(waitid(P_PID, forkpid, &child_siginfo, WEXITED)) != 0) {
+ int status;
+ if (TEMP_FAILURE_RETRY(waitpid(forkpid, &status, __WCLONE)) == -1 && errno != ECHILD) {
__libc_format_log(ANDROID_LOG_FATAL, "libc", "failed to wait for crash_dump helper: %s",
strerror(errno));
+ } else if (WIFSTOPPED(status) || WIFSIGNALED(status)) {
+ __libc_format_log(ANDROID_LOG_FATAL, "libc", "crash_dump helper crashed or stopped");
thread_info->crash_dump_started = false;
}
}
diff --git a/libcutils/fs_config.c b/libcutils/fs_config.c
index 013999a95..b701bbaae 100644
--- a/libcutils/fs_config.c
+++ b/libcutils/fs_config.c
@@ -177,11 +177,8 @@ static const struct fs_path_config android_files[] = {
CAP_MASK_LONG(CAP_SETPCAP),
"system/bin/webview_zygote64" },
- { 00755, AID_ROOT, AID_SHELL, CAP_MASK_LONG(CAP_SYS_PTRACE),
- "system/bin/crash_dump32" },
- { 00755, AID_ROOT, AID_SHELL, CAP_MASK_LONG(CAP_SYS_PTRACE),
- "system/bin/crash_dump64" },
-
+ { 00755, AID_ROOT, AID_SHELL, 0, "system/bin/crash_dump32" },
+ { 00755, AID_ROOT, AID_SHELL, 0, "system/bin/crash_dump64" },
{ 00755, AID_ROOT, AID_SHELL, 0, "system/bin/debuggerd" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/uncrypt" },
{ 00750, AID_ROOT, AID_ROOT, 0, "system/bin/install-recovery.sh" },
generated by cgit v1.2.3 (git 2.25.1) at 2025-10-04 00:24:01 +0000