+/* sig.c 4.3 11/9/80 */
+
+#include "../h/param.h"
+#include "../h/systm.h"
+#include "../h/dir.h"
+#include "../h/user.h"
+#include "../h/proc.h"
+#include "../h/inode.h"
+#include "../h/reg.h"
+#include "../h/text.h"
+#include "../h/seg.h"
+#include "../h/mtpr.h"
+#include "../h/pte.h"
+#include "../h/psl.h"
+#include "../h/vm.h"
+#include "../h/buf.h"
+#include "../h/vlimit.h"
+
+/*
+ * Priority for tracing
+ */
+#define IPCPRI PZERO
+
+/*
+ * Tracing variables.
+ * Used to pass trace command from
+ * parent to child being traced.
+ * This data base cannot be
+ * shared and is locked
+ * per user.
+ */
+struct
+{
+ int ip_lock;
+ int ip_req;
+ int *ip_addr;
+ int ip_data;
+} ipc;
+
+/*
+ * Send the specified signal to
+ * all processes with 'pgrp' as
+ * process group.
+ * Called by tty.c for quits and
+ * interrupts.
+ */
+gsignal(pgrp, sig)
+register pgrp;
+{
+ register struct proc *p;
+
+ if(pgrp == 0)
+ return;
+ for(p = &proc[0]; p < &proc[NPROC]; p++)
+ if(p->p_pgrp == pgrp)
+ psignal(p, sig);
+}
+
+/*
+ * Send the specified signal to
+ * the specified process.
+ */
+psignal(p, sig)
+register struct proc *p;
+register int sig;
+{
+ register s;
+ register int (*action)();
+ long sigmask;
+
+ if((unsigned)sig >= NSIG)
+ return;
+ sigmask = (1L << (sig-1));
+
+ /*
+ * If proc is traced, always give parent a chance.
+ * Otherwise get the signal action from the bits in the proc table.
+ */
+ if (p->p_flag & STRC)
+ action = SIG_DFL;
+ else {
+ s = (p->p_siga1&sigmask) != 0;
+ s <<= 1;
+ s |= (p->p_siga0&sigmask) != 0;
+ action = (int(*)())s;
+ /*
+ * If the signal is ignored, we forget about it immediately.
+ */
+ if (action == SIG_IGN)
+ return;
+ }
+ if (sig)
+ p->p_sig |= sigmask;
+ /*
+ * Defer further processing for signals which are held.
+ */
+ if (action == SIG_HOLD)
+ return;
+ s = spl6();
+ switch (p->p_stat) {
+
+ case SSLEEP:
+ /*
+ * If process is sleeping at negative priority
+ * we can't interrupt the sleep... the signal will
+ * be noticed when the process returns through
+ * trap() or syscall().
+ */
+ if (p->p_pri <= PZERO)
+ goto out;
+ /*
+ * Process is sleeping and traced... make it runnable
+ * so it can discover the signal in issig() and stop
+ * for the parent.
+ */
+ if (p->p_flag&STRC)
+ goto run;
+ switch (sig) {
+
+ case SIGSTOP:
+ case SIGTSTP:
+ case SIGTTIN:
+ case SIGTTOU:
+ /*
+ * These are the signals which by default
+ * stop a process.
+ */
+ if (action != SIG_DFL)
+ goto run;
+ /*
+ * Don't clog system with children of init
+ * stopped from the keyboard.
+ */
+ if (sig != SIGSTOP && p->p_pptr == &proc[1]) {
+ psignal(p, SIGKILL);
+ p->p_sig &= ~sigmask;
+ return;
+ }
+ /*
+ * If a child in vfork(), stopping could
+ * cause deadlock.
+ */
+ if (p->p_flag&SVFORK)
+ goto out;
+ p->p_sig &= ~sigmask;
+ p->p_cursig = sig;
+ stop(p);
+ goto out;
+
+ case SIGTINT:
+ case SIGCHLD:
+ /*
+ * These signals are special in that they
+ * don't get propogated... if the process
+ * isn't interested, forget it.
+ */
+ if (action != SIG_DFL)
+ goto run;
+ p->p_sig &= ~sigmask; /* take it away */
+ goto out;
+
+ default:
+ /*
+ * All other signals cause the process to run
+ */
+ goto run;
+ }
+ /*NOTREACHED*/
+
+ case SSTOP:
+ /*
+ * If traced process is already stopped,
+ * then no further action is necessary.
+ */
+ if (p->p_flag&STRC)
+ goto out;
+ switch (sig) {
+
+ case SIGKILL:
+ /*
+ * Kill signal always sets processes running.
+ */
+ goto run;
+
+ case SIGCONT:
+ /*
+ * If the process catches SIGCONT, let it handle
+ * the signal itself. If it isn't waiting on
+ * an event, then it goes back to run state.
+ * Otherwise, process goes back to sleep state.
+ */
+ if (action != SIG_DFL || p->p_wchan == 0)
+ goto run;
+ p->p_stat = SSLEEP;
+ goto out;
+
+ case SIGSTOP:
+ case SIGTSTP:
+ case SIGTTIN:
+ case SIGTTOU:
+ /*
+ * Already stopped, don't need to stop again.
+ * (If we did the shell could get confused.)
+ */
+ p->p_sig &= ~sigmask; /* take it away */
+ goto out;
+
+ default:
+ /*
+ * If process is sleeping interruptibly, then
+ * unstick it so that when it is continued
+ * it can look at the signal.
+ * But don't setrun the process as its not to
+ * be unstopped by the signal alone.
+ */
+ if (p->p_wchan && p->p_pri > PZERO)
+ unsleep(p);
+ goto out;
+ }
+ /*NOTREACHED*/
+
+ default:
+ /*
+ * SRUN, SIDL, SZOMB do nothing with the signal.
+ * It will either never be noticed, or noticed very soon.
+ */
+ goto out;
+ }
+ /*NOTREACHED*/
+run:
+ /*
+ * Raise priority to at least PUSER.
+ */
+ if (p->p_pri > PUSER)
+ if ((p != u.u_procp || noproc) && p->p_stat == SRUN &&
+ (p->p_flag & SLOAD)) {
+ remrq(p);
+ p->p_pri = PUSER;
+ setrq(p);
+ } else
+ p->p_pri = PUSER;
+ setrun(p);
+out:
+ splx(s);
+}
+
+/*
+ * Returns true if the current
+ * process has a signal to process.
+ * The signal to process is put in p_cursig.
+ * This is asked at least once each time a process enters the
+ * system (though this can usually be done without actually
+ * calling issig by checking the pending signal masks.)
+ * A signal does not do anything
+ * directly to a process; it sets
+ * a flag that asks the process to
+ * do something to itself.
+ */
+issig()
+{
+ register struct proc *p;
+ register int sig;
+ long sigbits;
+ long sigmask;
+
+ p = u.u_procp;
+ for (;;) {
+ sigbits = p->p_sig;
+ if ((p->p_flag&STRC) == 0)
+ sigbits &= ~p->p_ignsig;
+ if (p->p_flag&SVFORK)
+#define bit(a) (1<<(a-1))
+ sigbits &= ~(bit(SIGSTOP)|bit(SIGTSTP)|bit(SIGTTIN)|bit(SIGTTOU));
+ if (sigbits == 0)
+ break;
+ sig = ffs(sigbits);
+ sigmask = 1L << (sig-1);
+ p->p_sig &= ~sigmask; /* take the signal! */
+ p->p_cursig = sig;
+ if (p->p_flag&STRC && (p->p_flag&SVFORK)==0) {
+ /*
+ * If traced, always stop, and stay
+ * stopped until released by the parent.
+ */
+ do {
+ stop(p);
+ swtch();
+ } while (!procxmt() && p->p_flag&STRC);
+ /*
+ * If parent wants us to take the signal,
+ * then it will leave it in p->p_cursig;
+ * otherwise we just look for signals again.
+ */
+ sig = p->p_cursig;
+ if (sig == 0)
+ continue;
+ }
+ switch (u.u_signal[sig]) {
+
+ case SIG_DFL:
+ /*
+ * Don't take default actions on system processes.
+ */
+ if (p <= &proc[2])
+ break;
+ switch (sig) {
+
+ case SIGTSTP:
+ case SIGTTIN:
+ case SIGTTOU:
+ /*
+ * Children of init aren't allowed to stop
+ * on signals from the keyboard.
+ */
+ if (p->p_pptr == &proc[1]) {
+ psignal(p, SIGKILL);
+ continue;
+ }
+ /* fall into ... */
+
+ case SIGSTOP:
+ if (p->p_flag&STRC)
+ continue;
+ stop(p);
+ swtch();
+ continue;
+
+ case SIGTINT:
+ case SIGCONT:
+ case SIGCHLD:
+ /*
+ * These signals are normally not
+ * sent if the action is the default.
+ * This can happen only if you reset the
+ * signal action from an action which was
+ * not deferred to SIG_DFL before the
+ * system gets a chance to post the signal.
+ */
+ continue; /* == ignore */
+
+ default:
+ goto send;
+ }
+ /*NOTREACHED*/
+
+ case SIG_HOLD:
+ case SIG_IGN:
+ /*
+ * Masking above should prevent us
+ * ever trying to take action on a held
+ * or ignored signal, unless process is traced.
+ */
+ if ((p->p_flag&STRC) == 0)
+ printf("issig\n");
+ continue;
+
+ default:
+ /*
+ * This signal has an action, let
+ * psig process it.
+ */
+ goto send;
+ }
+ /*NOTREACHED*/
+ }
+ /*
+ * Didn't find a signal to send.
+ */
+ p->p_cursig = 0;
+ return (0);
+
+send:
+ /*
+ * Let psig process the signal.
+ */
+ return (sig);
+}
+
+ffs(mask)
+register long mask;
+{
+ register int i;
+
+ for(i=1; i<NSIG; i++) {
+ if(mask & 1)
+ return(i);
+ mask >>= 1;
+ }
+ return(0);
+}
+
+/*
+ * Put the argument process into the stopped
+ * state and notify the parent via wakeup and/or signal.
+ */
+stop(p)
+ register struct proc *p;
+{
+
+ p->p_stat = SSTOP;
+ p->p_flag &= ~SWTED;
+ wakeup((caddr_t)p->p_pptr);
+ /*
+ * Avoid sending signal to parent if process is traced
+ */
+ if (p->p_flag&STRC)
+ return;
+ psignal(p->p_pptr, SIGCHLD);
+}
+
+/*
+ * Perform the action specified by
+ * the current signal.
+ * The usual sequence is:
+ * if(issig())
+ * psig();
+ * The signal bit has already been cleared by issig,
+ * and the current signal number stored in p->p_cursig.
+ */
+psig()
+{
+ register struct proc *rp = u.u_procp;
+ register int n = rp->p_cursig;
+ long sigmask = 1L << (n-1);
+ register int (*action)();
+
+ if (rp->p_cursig == 0)
+ panic("psig");
+ action = u.u_signal[n];
+ if (action != SIG_DFL) {
+ if (action == SIG_IGN || action == SIG_HOLD)
+ panic("psig action");
+ u.u_error = 0;
+ if(n != SIGILL && n != SIGTRAP)
+ u.u_signal[n] = 0;
+ /*
+ * If this catch value indicates automatic holding of
+ * subsequent signals, set the hold value.
+ */
+ if (SIGISDEFER(action)) {
+ (void) spl6();
+ if ((int)SIG_HOLD & 1)
+ rp->p_siga0 |= sigmask;
+ else
+ rp->p_siga0 &= ~sigmask;
+ if ((int)SIG_HOLD & 2)
+ rp->p_siga1 |= sigmask;
+ else
+ rp->p_siga1 &= ~sigmask;
+ u.u_signal[n] = SIG_HOLD;
+ (void) spl0();
+ action = SIGUNDEFER(action);
+ }
+ sendsig(action, n);
+ rp->p_cursig = 0;
+ return;
+ }
+ switch (n) {
+
+ case SIGILL:
+ case SIGIOT:
+ case SIGBUS:
+ case SIGQUIT:
+ case SIGTRAP:
+ case SIGEMT:
+ case SIGFPE:
+ case SIGSEGV:
+ case SIGSYS:
+ u.u_arg[0] = n;
+ if(core())
+ n += 0200;
+ }
+ exit(n);
+}
+
+/*
+ * Create a core image on the file "core"
+ * If you are looking for protection glitches,
+ * there are probably a wealth of them here
+ * when this occurs to a suid command.
+ *
+ * It writes UPAGES block of the
+ * user.h area followed by the entire
+ * data+stack segments.
+ */
+
+core()
+{
+ register struct inode *ip;
+ extern schar();
+
+/*
+ if (coresw)
+ panic("core");
+*/
+ if (coresw) {
+ int i;
+ for (i = 0; i < 10; i++)
+ if (u.u_comm[i])
+ putchar(u.u_comm[i], 0);
+ printf(", uid %d\n", u.u_uid);
+ if (coresw&2)
+ asm("halt");
+ }
+ if (ctob(UPAGES+u.u_dsize+u.u_ssize) >= u.u_limit[LIM_CORE])
+ return (0);
+ u.u_error = 0;
+ u.u_dirp = "core";
+ ip = namei(schar, 1);
+ if(ip == NULL) {
+ if(u.u_error)
+ return(0);
+ ip = maknode(0666);
+ if (ip==NULL)
+ return(0);
+ }
+ if(!access(ip, IWRITE) &&
+ (ip->i_mode&IFMT) == IFREG && ip->i_vfdcnt == 0 &&
+#ifdef UCB
+ u.u_uid == u.u_ruid && ip->i_nlink == 1) {
+#else
+ u.u_uid == u.u_ruid) {
+#endif
+ itrunc(ip);
+ u.u_offset = 0;
+ u.u_base = (caddr_t)&u;
+ u.u_count = ctob(UPAGES);
+ u.u_segflg = 1;
+ writei(ip);
+ u.u_base = (char *)ctob(u.u_tsize);
+ u.u_count = ctob(u.u_dsize);
+ u.u_segflg = 0;
+ writei(ip);
+ u.u_base = (char *)(USRSTACK - ctob(u.u_ssize));
+ u.u_count = ctob(u.u_ssize);
+ writei(ip);
+ } else
+ u.u_error = EFAULT;
+ iput(ip);
+ return(u.u_error==0);
+}
+
+/*
+ * grow the stack to include the SP
+ * true return if successful.
+ */
+grow(sp)
+unsigned sp;
+{
+ register si;
+
+ if(sp >= USRSTACK-ctob(u.u_ssize))
+ return(0);
+ si = clrnd(btoc((USRSTACK-sp)) - u.u_ssize + SINCR);
+ if (ctob(u.u_ssize+si) > u.u_limit[LIM_STACK])
+ return(0);
+ if (chksize(u.u_tsize, u.u_dsize, u.u_ssize+si))
+ return(0);
+ if (swpexpand(u.u_dsize, u.u_ssize+si, &u.u_dmap, &u.u_smap)==0)
+ return(0);
+
+ expand(si, P1BR);
+ return(1);
+}
+
+/*
+ * sys-trace system call.
+ */
+ptrace()
+{
+ register struct proc *p;
+ register struct a {
+ int req;
+ int pid;
+ int *addr;
+ int data;
+ } *uap;
+
+ uap = (struct a *)u.u_ap;
+ if (uap->req <= 0) {
+ u.u_procp->p_flag |= STRC;
+ return;
+ }
+ p = pfind(uap->pid);
+ if (p == 0 || p->p_stat != SSTOP || p->p_ppid != u.u_procp->p_pid) {
+ u.u_error = ESRCH;
+ return;
+ }
+ while (ipc.ip_lock)
+ sleep((caddr_t)&ipc, IPCPRI);
+ ipc.ip_lock = p->p_pid;
+ ipc.ip_data = uap->data;
+ ipc.ip_addr = uap->addr;
+ ipc.ip_req = uap->req;
+ p->p_flag &= ~SWTED;
+ while (ipc.ip_req > 0) {
+ if (p->p_stat==SSTOP)
+ setrun(p);
+ sleep((caddr_t)&ipc, IPCPRI);
+ }
+ u.u_r.r_val1 = ipc.ip_data;
+ if (ipc.ip_req < 0)
+ u.u_error = EIO;
+ ipc.ip_lock = 0;
+ wakeup((caddr_t)&ipc);
+}
+
+int ipcreg[] = {R0, R1, R2, R3, R4, R5, R6, R7, R8, R9, R10, R11, AP, FP, SP, PC};
+/*
+ * Code that the child process
+ * executes to implement the command
+ * of the parent process in tracing.
+ */
+procxmt()
+{
+ register int i;
+ register *p;
+ register struct text *xp;
+
+ if (ipc.ip_lock != u.u_procp->p_pid)
+ return(0);
+ u.u_procp->p_slptime = 0;
+ i = ipc.ip_req;
+ ipc.ip_req = 0;
+ switch (i) {
+
+ /* read user I */
+ case 1:
+ if (!useracc((caddr_t)ipc.ip_addr, 4, B_READ))
+ goto error;
+ ipc.ip_data = fuiword((caddr_t)ipc.ip_addr);
+ break;
+
+ /* read user D */
+ case 2:
+ if (!useracc((caddr_t)ipc.ip_addr, 4, B_READ))
+ goto error;
+ ipc.ip_data = fuword((caddr_t)ipc.ip_addr);
+ break;
+
+ /* read u */
+ case 3:
+ i = (int)ipc.ip_addr;
+ if (i<0 || i >= ctob(UPAGES))
+ goto error;
+ ipc.ip_data = ((physadr)&u)->r[i>>2];
+ break;
+
+ /* write user I */
+ /* Must set up to allow writing */
+ case 4:
+ /*
+ * If text, must assure exclusive use
+ */
+ if (xp = u.u_procp->p_textp) {
+ if (xp->x_count!=1 || xp->x_iptr->i_mode&ISVTX)
+ goto error;
+ xp->x_iptr->i_flag &= ~ITEXT;
+ }
+ i = -1;
+ if (chgprot((caddr_t)ipc.ip_addr, RW) &&
+ chgprot((caddr_t)ipc.ip_addr+(sizeof(int)-1), RW))
+ i = suiword((caddr_t)ipc.ip_addr, ipc.ip_data);
+ (void) chgprot((caddr_t)ipc.ip_addr, RO);
+ (void) chgprot((caddr_t)ipc.ip_addr+(sizeof(int)-1), RO);
+ if (i < 0)
+ goto error;
+ if (xp)
+ xp->x_flag |= XWRIT;
+ break;
+
+ /* write user D */
+ case 5:
+ if (suword((caddr_t)ipc.ip_addr, 0) < 0)
+ goto error;
+ (void) suword((caddr_t)ipc.ip_addr, ipc.ip_data);
+ break;
+
+ /* write u */
+ case 6:
+ i = (int)ipc.ip_addr;
+ p = (int *)&((physadr)&u)->r[i>>2];
+ for (i=0; i<16; i++)
+ if (p == &u.u_ar0[ipcreg[i]])
+ goto ok;
+ if (p == &u.u_ar0[PS]) {
+ ipc.ip_data |= PSL_CURMOD|PSL_PRVMOD;
+ ipc.ip_data &= ~PSL_USERCLR;
+ goto ok;
+ }
+ goto error;
+
+ ok:
+ *p = ipc.ip_data;
+ break;
+
+ /* set signal and continue */
+ /* one version causes a trace-trap */
+ case 9:
+ case 7:
+ if ((int)ipc.ip_addr != 1)
+ u.u_ar0[PC] = (int)ipc.ip_addr;
+ if ((unsigned)ipc.ip_data > NSIG)
+ goto error;
+ u.u_procp->p_cursig = ipc.ip_data; /* see issig */
+ if (i == 9)
+ u.u_ar0[PS] |= PSL_T;
+ wakeup((caddr_t)&ipc);
+ return (1);
+
+ /* force exit */
+ case 8:
+ wakeup((caddr_t)&ipc);
+ exit(u.u_procp->p_cursig);
+
+ default:
+ error:
+ ipc.ip_req = -1;
+ }
+ wakeup((caddr_t)&ipc);
+ return(0);
+}
projects / unix-history / commitdiff