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Among signal generation syscalls, only sigqueue(2) is allowed by POSIX

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to fail due to lack of resources to queue siginfo. Add KSI_SIGQ flag
that allows sigqueue_add() to fail while trying to allocate memory for
new siginfo. When the flag is not set, behaviour is the same as for
KSI_TRAP: if memory cannot be allocated, set bit in sq_kill. KSI_TRAP is
kept to preserve KBI.

Add SI_KERNEL si_code, to be used in siginfo.si_code when signal is
generated by kernel. Deliver siginfo when signal is generated by kill(2)
family of syscalls (SI_USER with properly filled si_uid and si_pid), or
by kernel (SI_KERNEL, mostly job control or SIGIO). Since KSI_SIGQ flag
is not set for the ksi, low memory condition cause old behaviour.

Keep psignal(9) KBI intact, but modify it to generate SI_KERNEL
si_code. Pgsignal(9) and gsignal(9) now take ksi explicitely. Add
pksignal(9) that behaves like psignal but takes ksi, and ddb kill
command implemented as pksignal(..., ksi = NULL) to not do allocation
while in debugger.

While there, remove some register specifiers and use ANSI C prototypes.

Reviewed by:	davidxu
MFC after:	1 month
This commit is contained in:
kib 2009-11-17 11:39:15 +00:00
parent 45887d4e28
commit 2d08f816e1
5 changed files with 74 additions and 35 deletions
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2
sys/ddb/db_command.c
View File

@ -652,7 +652,7 @@ db_kill(dummy1, dummy2, dummy3, dummy4)
if (PROC_TRYLOCK(p) == 0)
DB_ERROR(("Can't lock process with pid %ld\n", (long) pid));
else {
psignal(p, sig);
pksignal(p, sig, NULL);
PROC_UNLOCK(p);
}

82
sys/kern/kern_sig.c
View File

@ -99,7 +99,8 @@ SDT_PROBE_ARGTYPE(proc, kernel, , signal_discard, 2, "int");
static int coredump(struct thread *);
static char *expand_name(const char *, uid_t, pid_t);
static int killpg1(struct thread *td, int sig, int pgid, int all);
static int killpg1(struct thread *td, int sig, int pgid, int all,
ksiginfo_t *ksi);
static int issignal(struct thread *td, int stop_allowed);
static int sigprop(int sig);
static void tdsigwakeup(struct thread *, int, sig_t, int);
@ -381,7 +382,8 @@ sigqueue_add(sigqueue_t *sq, int signo, ksiginfo_t *si)
ksi->ksi_sigq = sq;
}
if ((si->ksi_flags & KSI_TRAP) != 0) {
if ((si->ksi_flags & KSI_TRAP) != 0 ||
(si->ksi_flags & KSI_SIGQ) == 0) {
if (ret != 0)
SIGADDSET(sq->sq_kill, signo);
ret = 0;
@ -1611,11 +1613,9 @@ kern_sigaltstack(struct thread *td, stack_t *ss, stack_t *oss)
* cp is calling process.
*/
static int
killpg1(td, sig, pgid, all)
register struct thread *td;
int sig, pgid, all;
killpg1(struct thread *td, int sig, int pgid, int all, ksiginfo_t *ksi)
{
register struct proc *p;
struct proc *p;
struct pgrp *pgrp;
int nfound = 0;
@ -1634,7 +1634,7 @@ killpg1(td, sig, pgid, all)
if (p_cansignal(td, p, sig) == 0) {
nfound++;
if (sig)
psignal(p, sig);
pksignal(p, sig, ksi);
}
PROC_UNLOCK(p);
}
@ -1665,7 +1665,7 @@ killpg1(td, sig, pgid, all)
if (p_cansignal(td, p, sig) == 0) {
nfound++;
if (sig)
psignal(p, sig);
pksignal(p, sig, ksi);
}
PROC_UNLOCK(p);
}
@ -1682,11 +1682,10 @@ struct kill_args {
#endif
/* ARGSUSED */
int
kill(td, uap)
register struct thread *td;
register struct kill_args *uap;
kill(struct thread *td, struct kill_args *uap)
{
register struct proc *p;
ksiginfo_t ksi;
struct proc *p;
int error;
AUDIT_ARG_SIGNUM(uap->signum);
@ -1694,6 +1693,12 @@ kill(td, uap)
if ((u_int)uap->signum > _SIG_MAXSIG)
return (EINVAL);
ksiginfo_init(&ksi);
ksi.ksi_signo = uap->signum;
ksi.ksi_code = SI_USER;
ksi.ksi_pid = td->td_proc->p_pid;
ksi.ksi_uid = td->td_ucred->cr_ruid;
if (uap->pid > 0) {
/* kill single process */
if ((p = pfind(uap->pid)) == NULL) {
@ -1703,17 +1708,17 @@ kill(td, uap)
AUDIT_ARG_PROCESS(p);
error = p_cansignal(td, p, uap->signum);
if (error == 0 && uap->signum)
psignal(p, uap->signum);
pksignal(p, uap->signum, &ksi);
PROC_UNLOCK(p);
return (error);
}
switch (uap->pid) {
case -1: /* broadcast signal */
return (killpg1(td, uap->signum, 0, 1));
return (killpg1(td, uap->signum, 0, 1, &ksi));
case 0: /* signal own process group */
return (killpg1(td, uap->signum, 0, 0));
return (killpg1(td, uap->signum, 0, 0, &ksi));
default: /* negative explicit process group */
return (killpg1(td, uap->signum, -uap->pid, 0));
return (killpg1(td, uap->signum, -uap->pid, 0, &ksi));
}
/* NOTREACHED */
}
@ -1727,17 +1732,21 @@ struct okillpg_args {
#endif
/* ARGSUSED */
int
okillpg(td, uap)
struct thread *td;
register struct okillpg_args *uap;
okillpg(struct thread *td, struct okillpg_args *uap)
{
ksiginfo_t ksi;
AUDIT_ARG_SIGNUM(uap->signum);
AUDIT_ARG_PID(uap->pgid);
if ((u_int)uap->signum > _SIG_MAXSIG)
return (EINVAL);
return (killpg1(td, uap->signum, uap->pgid, 0));
ksiginfo_init(&ksi);
ksi.ksi_signo = uap->signum;
ksi.ksi_code = SI_USER;
ksi.ksi_pid = td->td_proc->p_pid;
ksi.ksi_uid = td->td_ucred->cr_ruid;
return (killpg1(td, uap->signum, uap->pgid, 0, &ksi));
}
#endif /* COMPAT_43 */
@ -1772,6 +1781,7 @@ sigqueue(struct thread *td, struct sigqueue_args *uap)
error = p_cansignal(td, p, uap->signum);
if (error == 0 && uap->signum != 0) {
ksiginfo_init(&ksi);
ksi.ksi_flags = KSI_SIGQ;
ksi.ksi_signo = uap->signum;
ksi.ksi_code = SI_QUEUE;
ksi.ksi_pid = td->td_proc->p_pid;
@ -1787,8 +1797,7 @@ sigqueue(struct thread *td, struct sigqueue_args *uap)
* Send a signal to a process group.
*/
void
gsignal(pgid, sig)
int pgid, sig;
gsignal(int pgid, int sig, ksiginfo_t *ksi)
{
struct pgrp *pgrp;
@ -1797,7 +1806,7 @@ gsignal(pgid, sig)
pgrp = pgfind(pgid);
sx_sunlock(&proctree_lock);
if (pgrp != NULL) {
pgsignal(pgrp, sig, 0);
pgsignal(pgrp, sig, 0, ksi);
PGRP_UNLOCK(pgrp);
}
}
@ -1808,18 +1817,16 @@ gsignal(pgid, sig)
* limit to members which have a controlling terminal.
*/
void
pgsignal(pgrp, sig, checkctty)
struct pgrp *pgrp;
int sig, checkctty;
pgsignal(struct pgrp *pgrp, int sig, int checkctty, ksiginfo_t *ksi)
{
register struct proc *p;
struct proc *p;
if (pgrp) {
PGRP_LOCK_ASSERT(pgrp, MA_OWNED);
LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
PROC_LOCK(p);
if (checkctty == 0 || p->p_flag & P_CONTROLT)
psignal(p, sig);
pksignal(p, sig, ksi);
PROC_UNLOCK(p);
}
}
@ -1940,7 +1947,19 @@ sigtd(struct proc *p, int sig, int prop)
void
psignal(struct proc *p, int sig)
{
(void) tdsignal(p, NULL, sig, NULL);
ksiginfo_t ksi;
ksiginfo_init(&ksi);
ksi.ksi_signo = sig;
ksi.ksi_code = SI_KERNEL;
(void) tdsignal(p, NULL, sig, &ksi);
}
void
pksignal(struct proc *p, int sig, ksiginfo_t *ksi)
{
(void) tdsignal(p, NULL, sig, ksi);
}
int
@ -3143,8 +3162,13 @@ pgsigio(sigiop, sig, checkctty)
struct sigio **sigiop;
int sig, checkctty;
{
ksiginfo_t ksi;
struct sigio *sigio;
ksiginfo_init(&ksi);
ksi.ksi_signo = sig;
ksi.ksi_code = SI_KERNEL;
SIGIO_LOCK();
sigio = *sigiop;
if (sigio == NULL) {

16
sys/kern/tty.c
View File

@ -355,6 +355,7 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig)
{
struct proc *p = td->td_proc;
struct pgrp *pg;
ksiginfo_t ksi;
int error;
MPASS(sig == SIGTTIN || sig == SIGTTOU);
@ -396,8 +397,14 @@ tty_wait_background(struct tty *tp, struct thread *td, int sig)
* Send the signal and sleep until we're the new
* foreground process group.
*/
if (sig != 0) {
ksiginfo_init(&ksi);
ksi.ksi_code = SI_KERNEL;
ksi.ksi_signo = sig;
sig = 0;
}
PGRP_LOCK(pg);
pgsignal(pg, sig, 1);
pgsignal(pg, ksi.ksi_signo, 1, &ksi);
PGRP_UNLOCK(pg);
error = tty_wait(tp, &tp->t_bgwait);
@ -1240,6 +1247,8 @@ tty_signal_sessleader(struct tty *tp, int sig)
void
tty_signal_pgrp(struct tty *tp, int sig)
{
ksiginfo_t ksi;
tty_lock_assert(tp, MA_OWNED);
MPASS(sig >= 1 && sig < NSIG);
@ -1249,8 +1258,11 @@ tty_signal_pgrp(struct tty *tp, int sig)
if (sig == SIGINFO && !(tp->t_termios.c_lflag & NOKERNINFO))
tty_info(tp);
if (tp->t_pgrp != NULL) {
ksiginfo_init(&ksi);
ksi.ksi_signo = sig;
ksi.ksi_code = SI_KERNEL;
PGRP_LOCK(tp->t_pgrp);
pgsignal(tp->t_pgrp, sig, 1);
pgsignal(tp->t_pgrp, sig, 1, &ksi);
PGRP_UNLOCK(tp->t_pgrp);
}
}

1
sys/sys/signal.h
View File

@ -338,6 +338,7 @@ struct sigaction {
/* an asynchronous I/O request.*/
#define SI_MESGQ 0x10005 /* Signal generated by arrival of a */
/* message on an empty message queue. */
#define SI_KERNEL 0x10006
#endif
#if __BSD_VISIBLE
#define SI_UNDEFINED 0

8
sys/sys/signalvar.h
View File

@ -233,7 +233,8 @@ typedef struct ksiginfo {
#define KSI_TRAP 0x01 /* Generated by trap. */
#define KSI_EXT 0x02 /* Externally managed ksi. */
#define KSI_INS 0x04 /* Directly insert ksi, not the copy */
#define KSI_COPYMASK KSI_TRAP
#define KSI_SIGQ 0x08 /* Generated by sigqueue, might ret EGAIN. */
#define KSI_COPYMASK (KSI_TRAP|KSI_SIGQ)
#define KSI_ONQ(ksi) ((ksi)->ksi_sigq != NULL)
@ -326,10 +327,11 @@ extern int kern_logsigexit; /* Sysctl variable kern.logsigexit */
*/
int cursig(struct thread *td, int stop_allowed);
void execsigs(struct proc *p);
void gsignal(int pgid, int sig);
void gsignal(int pgid, int sig, ksiginfo_t *ksi);
void killproc(struct proc *p, char *why);
void pksignal(struct proc *p, int sig, ksiginfo_t *ksi);
void pgsigio(struct sigio **, int signum, int checkctty);
void pgsignal(struct pgrp *pgrp, int sig, int checkctty);
void pgsignal(struct pgrp *pgrp, int sig, int checkctty, ksiginfo_t *ksi);
int postsig(int sig);
void psignal(struct proc *p, int sig);
int psignal_event(struct proc *p, struct sigevent *, ksiginfo_t *);