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Add PROC_TRAPCAP procctl(2) controls and global sysctl kern.trap_enocap.

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Both can be used to cause processes in capability mode to receive
SIGTRAP when ENOTCAPABLE or ECAPMODE errors are returned from
syscalls.

Idea by:	emaste
Reviewed by:	oshogbo (previous version), emaste
Sponsored by:	The FreeBSD Foundation
MFC after:	1 week
Differential revision:	https://reviews.freebsd.org/D7965
This commit is contained in:
Konstantin Belousov 2016-09-21 08:23:33 +00:00
parent 5271129cd6
commit 643f6f47fd
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=306081
9 changed files with 69 additions and 2 deletions
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3
sys/compat/freebsd32/freebsd32_misc.c
View File

@ -3048,6 +3048,7 @@ freebsd32_procctl(struct thread *td, struct freebsd32_procctl_args *uap)
switch (uap->com) {
case PROC_SPROTECT:
case PROC_TRACE_CTL:
case PROC_TRAPCAP_CTL:
error = copyin(PTRIN(uap->data), &flags, sizeof(flags));
if (error != 0)
return (error);
@ -3077,6 +3078,7 @@ freebsd32_procctl(struct thread *td, struct freebsd32_procctl_args *uap)
data = &x.rk;
break;
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
data = &flags;
break;
default:
@ -3095,6 +3097,7 @@ freebsd32_procctl(struct thread *td, struct freebsd32_procctl_args *uap)
error = error1;
break;
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
if (error == 0)
error = copyout(&flags, uap->data, sizeof(flags));
break;

2
sys/kern/kern_fork.c
View File

@ -497,7 +497,7 @@ do_fork(struct thread *td, struct fork_req *fr, struct proc *p2, struct thread *
* Increase reference counts on shared objects.
*/
p2->p_flag = P_INMEM;
p2->p_flag2 = p1->p_flag2 & (P2_NOTRACE | P2_NOTRACE_EXEC);
p2->p_flag2 = p1->p_flag2 & (P2_NOTRACE | P2_NOTRACE_EXEC | P2_TRAPCAP);
p2->p_swtick = ticks;
if (p1->p_flag & P_PROFIL)
startprofclock(p2);

38
sys/kern/kern_procctl.c
View File

@ -336,6 +336,34 @@ trace_status(struct thread *td, struct proc *p, int *data)
return (0);
}
static int
trapcap_ctl(struct thread *td, struct proc *p, int state)
{
PROC_LOCK_ASSERT(p, MA_OWNED);
switch (state) {
case PROC_TRAPCAP_CTL_ENABLE:
p->p_flag2 |= P2_TRAPCAP;
break;
case PROC_TRAPCAP_CTL_DISABLE:
p->p_flag2 &= ~P2_TRAPCAP;
break;
default:
return (EINVAL);
}
return (0);
}
static int
trapcap_status(struct thread *td, struct proc *p, int *data)
{
*data = (p->p_flag2 & P2_TRAPCAP) != 0 ? PROC_TRAPCAP_CTL_ENABLE :
PROC_TRAPCAP_CTL_DISABLE;
return (0);
}
#ifndef _SYS_SYSPROTO_H_
struct procctl_args {
idtype_t idtype;
@ -359,6 +387,7 @@ sys_procctl(struct thread *td, struct procctl_args *uap)
switch (uap->com) {
case PROC_SPROTECT:
case PROC_TRACE_CTL:
case PROC_TRAPCAP_CTL:
error = copyin(uap->data, &flags, sizeof(flags));
if (error != 0)
return (error);
@ -386,6 +415,7 @@ sys_procctl(struct thread *td, struct procctl_args *uap)
data = &x.rk;
break;
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
data = &flags;
break;
default:
@ -403,6 +433,7 @@ sys_procctl(struct thread *td, struct procctl_args *uap)
error = error1;
break;
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
if (error == 0)
error = copyout(&flags, uap->data, sizeof(flags));
break;
@ -432,6 +463,10 @@ kern_procctl_single(struct thread *td, struct proc *p, int com, void *data)
return (trace_ctl(td, p, *(int *)data));
case PROC_TRACE_STATUS:
return (trace_status(td, p, data));
case PROC_TRAPCAP_CTL:
return (trapcap_ctl(td, p, *(int *)data));
case PROC_TRAPCAP_STATUS:
return (trapcap_status(td, p, data));
default:
return (EINVAL);
}
@ -452,6 +487,7 @@ kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data)
case PROC_REAP_GETPIDS:
case PROC_REAP_KILL:
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
if (idtype != P_PID)
return (EINVAL);
}
@ -462,6 +498,7 @@ kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data)
case PROC_REAP_GETPIDS:
case PROC_REAP_KILL:
case PROC_TRACE_CTL:
case PROC_TRAPCAP_CTL:
sx_slock(&proctree_lock);
tree_locked = true;
break;
@ -471,6 +508,7 @@ kern_procctl(struct thread *td, idtype_t idtype, id_t id, int com, void *data)
tree_locked = true;
break;
case PROC_TRACE_STATUS:
case PROC_TRAPCAP_STATUS:
tree_locked = false;
break;
default:

15
sys/kern/subr_syscall.c
View File

@ -165,12 +165,25 @@ static inline void
syscallret(struct thread *td, int error, struct syscall_args *sa)
{
struct proc *p, *p2;
int traced;
ksiginfo_t ksi;
int traced, error1;
KASSERT((td->td_pflags & TDP_FORKING) == 0,
("fork() did not clear TDP_FORKING upon completion"));
p = td->td_proc;
if ((trap_enotcap || (p->p_flag2 & P2_TRAPCAP) != 0) &&
IN_CAPABILITY_MODE(td)) {
error1 = (td->td_pflags & TDP_NERRNO) == 0 ? error :
td->td_errno;
if (error1 == ENOTCAPABLE || error1 == ECAPMODE) {
ksiginfo_init_trap(&ksi);
ksi.ksi_signo = SIGTRAP;
ksi.ksi_errno = error1;
ksi.ksi_code = TRAP_CAP;
trapsignal(td, &ksi);
}
}
/*
* Handle reschedule and other end-of-syscall issues

4
sys/kern/sys_capability.c
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@ -83,6 +83,10 @@ __FBSDID("$FreeBSD$");
#include <vm/uma.h>
#include <vm/vm.h>
int trap_enotcap;
SYSCTL_INT(_kern, OID_AUTO, trap_enotcap, CTLFLAG_RW, &trap_enotcap, 0,
"Deliver SIGTRAP on ENOTCAPABLE");
#ifdef CAPABILITY_MODE
FEATURE(security_capability_mode, "Capsicum Capability Mode");

2
sys/sys/capsicum.h
View File

@ -368,6 +368,8 @@ int cap_ioctl_check(struct filedesc *fdp, int fd, u_long cmd);
int cap_fcntl_check_fde(struct filedescent *fde, int cmd);
int cap_fcntl_check(struct filedesc *fdp, int fd, int cmd);
extern int trap_enotcap;
#else /* !_KERNEL */
__BEGIN_DECLS

1
sys/sys/proc.h
View File

@ -716,6 +716,7 @@ struct proc {
#define P2_NOTRACE_EXEC 0x00000004 /* Keep P2_NOPTRACE on exec(2). */
#define P2_AST_SU 0x00000008 /* Handles SU ast for kthreads. */
#define P2_PTRACE_FSTP 0x00000010 /* SIGSTOP from PT_ATTACH not yet handled. */
#define P2_TRAPCAP 0x00000020 /* SIGTRAP on ENOTCAPABLE */
/* Flags protected by proctree_lock, kept in p_treeflags. */
#define P_TREE_ORPHANED 0x00000001 /* Reparented, on orphan list */

5
sys/sys/procctl.h
View File

@ -43,6 +43,8 @@
#define PROC_REAP_KILL 6 /* kill descendants */
#define PROC_TRACE_CTL 7 /* en/dis ptrace and coredumps */
#define PROC_TRACE_STATUS 8 /* query tracing status */
#define PROC_TRAPCAP_CTL 9 /* trap capability errors */
#define PROC_TRAPCAP_STATUS 10 /* query trap capability status */
/* Operations for PROC_SPROTECT (passed in integer arg). */
#define PPROT_OP(x) ((x) & 0xf)
@ -102,6 +104,9 @@ struct procctl_reaper_kill {
#define PROC_TRACE_CTL_DISABLE 2
#define PROC_TRACE_CTL_DISABLE_EXEC 3
#define PROC_TRAPCAP_CTL_ENABLE 1
#define PROC_TRAPCAP_CTL_DISABLE 2
#ifndef _KERNEL
__BEGIN_DECLS
int procctl(idtype_t, id_t, int, void *);

1
sys/sys/signal.h
View File

@ -291,6 +291,7 @@ typedef struct __siginfo {
#define TRAP_BRKPT 1 /* Process breakpoint. */
#define TRAP_TRACE 2 /* Process trace trap. */
#define TRAP_DTRACE 3 /* DTrace induced trap. */
#define TRAP_CAP 4 /* Capabilities protective trap. */
/* codes for SIGCHLD */
#define CLD_EXITED 1 /* Child has exited */