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Split out kill(2) syscall service routine into user-level and kernel part, the

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former is callable from user space and the latter from the kernel one. Make
kernel version take additional argument which tells if the respective call
should check for additional restrictions for sending signals to suid/sugid
applications or not.

Make all emulation layers using non-checked version, since signal numbers in
emulation layers can have different meaning that in native mode and such
protection can cause misbehaviour.

As a result remove LIBTHR from the signals allowed to be delivered to a
suid/sugid application.

Requested (sorta) by:	rwatson
MFC after:	2 weeks
This commit is contained in:
sobomax 2005-02-13 16:42:08 +00:00
parent 42e1f241cf
commit 52609f5f8a
8 changed files with 36 additions and 22 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
sys/alpha/osf1/osf1_signal.c
View File

@ -445,7 +445,7 @@ osf1_kill(td, uap)
ka.pid = uap->pid;
ka.signum = uap->signum;
return kill(td, &ka);
return kern_kill(td, &ka, 0);
}

2
sys/compat/linux/linux_signal.c
View File

@ -435,5 +435,5 @@ linux_kill(struct thread *td, struct linux_kill_args *args)
tmp.signum = args->signum;
tmp.pid = args->pid;
return (kill(td, &tmp));
return (kern_kill(td, &tmp, 0));
}

2
sys/compat/svr4/svr4_signal.c
View File

@ -521,7 +521,7 @@ svr4_sys_kill(td, uap)
return (EINVAL);
ka.pid = uap->pid;
ka.signum = SVR4_SVR42BSD_SIG(uap->signum);
return kill(td, &ka);
return kern_kill(td, &ka, 0);
}

2
sys/i386/ibcs2/ibcs2_signal.c
View File

@ -437,5 +437,5 @@ ibcs2_kill(td, uap)
return (EINVAL);
ka.pid = uap->pid;
ka.signum = ibcs2_to_bsd_sig[_SIG_IDX(uap->signo)];
return kill(td, &ka);
return kern_kill(td, &ka, 0);
}

9
sys/kern/kern_prot.c
View File

@ -1427,7 +1427,7 @@ SYSCTL_INT(_security_bsd, OID_AUTO, conservative_signals, CTLFLAG_RW,
* References: cred and proc must be valid for the lifetime of the call.
*/
int
cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
cr_cansignal(struct ucred *cred, struct proc *proc, int signum, int pedantic)
{
int error;
@ -1453,7 +1453,7 @@ cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
* bit on the target process. If the bit is set, then additional
* restrictions are placed on the set of available signals.
*/
if (conservative_signals && (proc->p_flag & P_SUGID)) {
if (conservative_signals && (proc->p_flag & P_SUGID) && pedantic) {
switch (signum) {
case 0:
case SIGKILL:
@ -1467,7 +1467,6 @@ cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
case SIGHUP:
case SIGUSR1:
case SIGUSR2:
case SIGTHR:
/*
* Generally, permit job and terminal control
* signals.
@ -1508,7 +1507,7 @@ cr_cansignal(struct ucred *cred, struct proc *proc, int signum)
* References: td and p must be valid for the lifetime of the call
*/
int
p_cansignal(struct thread *td, struct proc *p, int signum)
p_cansignal(struct thread *td, struct proc *p, int signum, int pedantic)
{
KASSERT(td == curthread, ("%s: td not curthread", __func__));
@ -1525,7 +1524,7 @@ p_cansignal(struct thread *td, struct proc *p, int signum)
if (signum == SIGCONT && td->td_proc->p_session == p->p_session)
return (0);
return (cr_cansignal(td->td_ucred, p, signum));
return (cr_cansignal(td->td_ucred, p, signum, pedantic));
}
/*-

33
sys/kern/kern_sig.c
View File

@ -82,7 +82,8 @@ __FBSDID("$FreeBSD$");
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,
int pedantic);
static int issignal(struct thread *p);
static int sigprop(int sig);
static void stop(struct proc *);
@ -1299,9 +1300,9 @@ kern_sigaltstack(struct thread *td, stack_t *ss, stack_t *oss)
* cp is calling process.
*/
static int
killpg1(td, sig, pgid, all)
killpg1(td, sig, pgid, all, pedantic)
register struct thread *td;
int sig, pgid, all;
int sig, pgid, all, pedantic;
{
register struct proc *p;
struct pgrp *pgrp;
@ -1319,7 +1320,7 @@ killpg1(td, sig, pgid, all)
PROC_UNLOCK(p);
continue;
}
if (p_cansignal(td, p, sig) == 0) {
if (p_cansignal(td, p, sig, pedantic) == 0) {
nfound++;
if (sig)
psignal(p, sig);
@ -1344,12 +1345,12 @@ killpg1(td, sig, pgid, all)
}
sx_sunlock(&proctree_lock);
LIST_FOREACH(p, &pgrp->pg_members, p_pglist) {
PROC_LOCK(p);
PROC_LOCK(p);
if (p->p_pid <= 1 || p->p_flag & P_SYSTEM) {
PROC_UNLOCK(p);
continue;
}
if (p_cansignal(td, p, sig) == 0) {
if (p_cansignal(td, p, sig, pedantic) == 0) {
nfound++;
if (sig)
psignal(p, sig);
@ -1376,6 +1377,16 @@ kill(td, uap)
register struct thread *td;
register struct kill_args *uap;
{
return kern_kill(td, uap, 1);
}
int
kern_kill(td, uap, pedantic)
struct thread *td;
struct kill_args *uap;
int pedantic;
{
register struct proc *p;
int error;
@ -1388,7 +1399,7 @@ kill(td, uap)
if ((p = zpfind(uap->pid)) == NULL)
return (ESRCH);
}
error = p_cansignal(td, p, uap->signum);
error = p_cansignal(td, p, uap->signum, pedantic);
if (error == 0 && uap->signum)
psignal(p, uap->signum);
PROC_UNLOCK(p);
@ -1396,11 +1407,11 @@ kill(td, uap)
}
switch (uap->pid) {
case -1: /* broadcast signal */
return (killpg1(td, uap->signum, 0, 1));
return (killpg1(td, uap->signum, 0, 1, pedantic));
case 0: /* signal own process group */
return (killpg1(td, uap->signum, 0, 0));
return (killpg1(td, uap->signum, 0, 0, pedantic));
default: /* negative explicit process group */
return (killpg1(td, uap->signum, -uap->pid, 0));
return (killpg1(td, uap->signum, -uap->pid, 0, pedantic));
}
/* NOTREACHED */
}
@ -1424,7 +1435,7 @@ okillpg(td, uap)
if ((u_int)uap->signum > _SIG_MAXSIG)
return (EINVAL);
return (killpg1(td, uap->signum, uap->pgid, 0));
return (killpg1(td, uap->signum, uap->pgid, 0, 1));
}
#endif /* COMPAT_43 */

6
sys/sys/proc.h
View File

@ -831,7 +831,8 @@ struct proc *zpfind(pid_t); /* Find zombie process by id. */
void adjustrunqueue(struct thread *, int newpri);
void ast(struct trapframe *framep);
struct thread *choosethread(void);
int cr_cansignal(struct ucred *cred, struct proc *proc, int signum);
int cr_cansignal(struct ucred *cred, struct proc *proc, int signum,
int pedantic);
int enterpgrp(struct proc *p, pid_t pgid, struct pgrp *pgrp,
struct session *sess);
int enterthispgrp(struct proc *p, struct pgrp *pgrp);
@ -848,7 +849,8 @@ void mi_switch(int flags, struct thread *newtd);
int p_candebug(struct thread *td, struct proc *p);
int p_cansee(struct thread *td, struct proc *p);
int p_cansched(struct thread *td, struct proc *p);
int p_cansignal(struct thread *td, struct proc *p, int signum);
int p_cansignal(struct thread *td, struct proc *p, int signum,
int pedantic);
struct pargs *pargs_alloc(int len);
void pargs_drop(struct pargs *pa);
void pargs_free(struct pargs *pa);

2
sys/sys/syscallsubr.h
View File

@ -42,6 +42,7 @@ struct msqid_ds;
struct rlimit;
struct rusage;
struct sockaddr;
struct kill_args;
struct stat;
int kern___getcwd(struct thread *td, u_char *buf, enum uio_seg bufseg,
@ -69,6 +70,7 @@ int kern_getitimer(struct thread *, u_int, struct itimerval *);
int kern_getrusage(struct thread *td, int who, struct rusage *rup);
int kern_getsockopt(struct thread *td, int s, int level, int name,
void *optval, enum uio_seg valseg, socklen_t *valsize);
int kern_kill(struct thread *, struct kill_args *, int);
int kern_lchown(struct thread *td, char *path, enum uio_seg pathseg,
int uid, int gid);
int kern_link(struct thread *td, char *path, char *link,