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https://github.com/RGBCube/serenity
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Add some basic signal support.
It only works for sending a signal to a process that's in userspace code. We implement reception by synthesizing a PUSHA+PUSHF in the receiving process (operating on values in the TSS.) The TSS CS:EIP is then rerouted to the signal handler and a tiny return trampoline is constructed in a dedicated region in the receiving process. Also hacked up /bin/kill to be able to send arbitrary signals (kill -N PID)
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13 changed files with 240 additions and 30 deletions
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@ -1,7 +1,9 @@
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#include <LibC/stdio.h>
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#include <LibC/unistd.h>
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#include <LibC/errno.h>
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#include <LibC/string.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <errno.h>
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#include <string.h>
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#include <stdlib.h>
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#include <assert.h>
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int main(int argc, char** argv)
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{
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@ -1,6 +1,7 @@
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#include <LibC/unistd.h>
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#include <LibC/stdio.h>
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#include <LibC/signal.h>
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#include <unistd.h>
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#include <stdio.h>
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#include <signal.h>
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#include <stdlib.h>
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#include <AK/String.h>
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static unsigned parseUInt(const String& str, bool& ok)
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@ -18,20 +19,36 @@ static unsigned parseUInt(const String& str, bool& ok)
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return value;
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}
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static void print_usage_and_exit()
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{
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printf("usage: kill [-signal] <PID>\n");
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exit(1);
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}
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int main(int argc, char** argv)
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{
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if (argc < 2) {
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printf("usage: kill <PID>\n");
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return 1;
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}
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if (argc != 2 && argc != 3)
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print_usage_and_exit();
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bool ok;
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unsigned value = parseUInt(argv[1], ok);
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unsigned signum = SIGTERM;
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int pid_argi = 1;
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if (argc == 3) {
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pid_argi = 2;
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if (argv[1][0] != '-')
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print_usage_and_exit();
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signum = parseUInt(&argv[1][1], ok);
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if (!ok) {
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printf("%s is not a valid signal number\n", &argv[1][1]);
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return 2;
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}
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}
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unsigned pid = parseUInt(argv[pid_argi], ok);
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if (!ok) {
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printf("%s is not a valid PID\n", argv[1]);
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return 2;
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printf("%s is not a valid PID\n", argv[pid_argi]);
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return 3;
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}
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kill((pid_t)value, SIGKILL);
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kill((pid_t)pid, signum);
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return 0;
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}
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@ -6,6 +6,7 @@
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#include <LibC/stdlib.h>
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#include <LibC/utsname.h>
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#include <LibC/pwd.h>
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#include <signal.h>
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#include <AK/FileSystemPath.h>
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struct GlobalState {
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@ -32,6 +33,29 @@ static int sh_pwd(int, const char**)
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return 0;
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}
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void did_receive_signal(int signum)
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{
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printf("\nMy word, I've received a signal with number %d\n", signum);
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//exit(0);
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}
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static int sh_busy(int, const char**)
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{
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struct sigaction sa;
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sa.sa_handler = did_receive_signal;
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sa.sa_flags = 0;
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sa.sa_mask = 0;
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sa.sa_restorer = nullptr;
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int rc = sigaction(SIGUSR1, &sa, nullptr);
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assert(rc == 0);
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printf("listening for SIGUSR1 while looping in userspace...\n");
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for (;;) {
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for (volatile int i = 0; i < 100000; ++i)
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;
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}
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return 0;
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}
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static int sh_fork(int, const char**)
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{
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pid_t pid = fork();
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@ -147,6 +171,10 @@ static bool handle_builtin(int argc, const char** argv, int& retval)
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retval = sh_fef(argc, argv);
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return true;
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}
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if (!strcmp(argv[0], "busy")) {
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retval = sh_busy(argc, argv);
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return true;
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}
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if (!strcmp(argv[0], "wt")) {
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retval = sh_wt(argc, argv);
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return true;
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