From d8ff44b79fbd51d18c44f242bb61f85296c8555d Mon Sep 17 00:00:00 2001 From: Maxim Sobolev Date: Sun, 13 Feb 2005 16:42:08 +0000 Subject: [PATCH] Split out kill(2) syscall service routine into user-level and kernel part, the 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 --- sys/alpha/osf1/osf1_signal.c | 2 +- sys/compat/linux/linux_signal.c | 2 +- sys/compat/svr4/svr4_signal.c | 2 +- sys/i386/ibcs2/ibcs2_signal.c | 2 +- sys/kern/kern_prot.c | 9 ++++----- sys/kern/kern_sig.c | 33 ++++++++++++++++++++++----------- sys/sys/proc.h | 6 ++++-- sys/sys/syscallsubr.h | 2 ++ 8 files changed, 36 insertions(+), 22 deletions(-) diff --git a/sys/alpha/osf1/osf1_signal.c b/sys/alpha/osf1/osf1_signal.c index 355cb1c20e9..7a96223ef3b 100644 --- a/sys/alpha/osf1/osf1_signal.c +++ b/sys/alpha/osf1/osf1_signal.c @@ -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); } diff --git a/sys/compat/linux/linux_signal.c b/sys/compat/linux/linux_signal.c index fc25e3f7bfb..fa4ae7b8a28 100644 --- a/sys/compat/linux/linux_signal.c +++ b/sys/compat/linux/linux_signal.c @@ -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)); } diff --git a/sys/compat/svr4/svr4_signal.c b/sys/compat/svr4/svr4_signal.c index 1a3f7f1c9c6..2ccebd5c4d4 100644 --- a/sys/compat/svr4/svr4_signal.c +++ b/sys/compat/svr4/svr4_signal.c @@ -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); } diff --git a/sys/i386/ibcs2/ibcs2_signal.c b/sys/i386/ibcs2/ibcs2_signal.c index b2f339338fc..0cb3b9add83 100644 --- a/sys/i386/ibcs2/ibcs2_signal.c +++ b/sys/i386/ibcs2/ibcs2_signal.c @@ -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); } diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c index 21f277f8a63..d989ab3f334 100644 --- a/sys/kern/kern_prot.c +++ b/sys/kern/kern_prot.c @@ -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)); } /*- diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c index 2889adb7174..097480105e8 100644 --- a/sys/kern/kern_sig.c +++ b/sys/kern/kern_sig.c @@ -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 */ diff --git a/sys/sys/proc.h b/sys/sys/proc.h index 52b47efe4a2..cda4ccfa8f4 100644 --- a/sys/sys/proc.h +++ b/sys/sys/proc.h @@ -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); diff --git a/sys/sys/syscallsubr.h b/sys/sys/syscallsubr.h index a996ba71806..04f007c00ea 100644 --- a/sys/sys/syscallsubr.h +++ b/sys/sys/syscallsubr.h @@ -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,