diff --git a/lib/libc/sys/ptrace.2 b/lib/libc/sys/ptrace.2 index 5a1763474223..6608c115827c 100644 --- a/lib/libc/sys/ptrace.2 +++ b/lib/libc/sys/ptrace.2 @@ -2,7 +2,7 @@ .\" $NetBSD: ptrace.2,v 1.2 1995/02/27 12:35:37 cgd Exp $ .\" .\" This file is in the public domain. -.Dd June 2, 2018 +.Dd July 15, 2019 .Dt PTRACE 2 .Os .Sh NAME @@ -664,6 +664,52 @@ member of the but not more than the .Fa data bytes in total are copied. +.It Dv PT_GET_SC_RET +Fetch the system call return values on exit from a syscall. +This request is only valid for threads stopped in a syscall +exit (the +.Dv PL_FLAG_SCX +state). +The +.Fa addr +argument specifies a pointer to a +.Vt "struct ptrace_sc_ret" , +which is defined as follows: +.Bd -literal +struct ptrace_sc_ret { + register_t sr_retval[2]; + int sr_error; +}; +.Ed +.Pp +The +.Fa data +argument is set to the size of the structure. +.Pp +If the system call completed successfully, +.Va sr_error +is set to zero and the return values of the system call are saved in +.Va sr_retval . +If the system call failed to execute, +.Va sr_error +field is set to a positive +.Xr errno 2 +value. +If the system call completed in an unusual fashion, +.Va sr_error +is set to a negative value: +.Pp +.Bl -tag -width Dv EJUSTRETURN -compact +.It Dv ERESTART +System call will be restarted. +.It Dv EJUSTRETURN +System call completed sucessfully but did not set a return value +.Po for example, +.Xr setcontext 2 +and +.Xr sigreturn 2 +.Pc . +.El .It Dv PT_FOLLOW_FORK This request controls tracing for new child processes of a traced process. If diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c index b9649ee8053a..0444af49e82f 100644 --- a/sys/kern/sys_process.c +++ b/sys/kern/sys_process.c @@ -76,6 +76,11 @@ struct ptrace_io_desc32 { uint32_t piod_len; }; +struct ptrace_sc_ret32 { + uint32_t sr_retval[2]; + int sr_error; +}; + struct ptrace_vm_entry32 { int pve_entry; int pve_timestamp; @@ -518,6 +523,17 @@ ptrace_lwpinfo_to32(const struct ptrace_lwpinfo *pl, pl32->pl_syscall_code = pl->pl_syscall_code; pl32->pl_syscall_narg = pl->pl_syscall_narg; } + +static void +ptrace_sc_ret_to32(const struct ptrace_sc_ret *psr, + struct ptrace_sc_ret32 *psr32) +{ + + bzero(psr32, sizeof(*psr32)); + psr32->sr_retval[0] = psr->sr_retval[0]; + psr32->sr_retval[1] = psr->sr_retval[1]; + psr32->sr_error = psr->sr_error; +} #endif /* COMPAT_FREEBSD32 */ /* @@ -580,6 +596,7 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap) struct ptrace_vm_entry32 pve32; #endif char args[sizeof(td->td_sa.args)]; + struct ptrace_sc_ret psr; int ptevents; } r; void *addr; @@ -598,6 +615,7 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap) case PT_GET_EVENT_MASK: case PT_LWPINFO: case PT_GET_SC_ARGS: + case PT_GET_SC_RET: break; case PT_GETREGS: BZERO(&r.reg, sizeof r.reg); @@ -668,6 +686,10 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap) error = copyout(r.args, uap->addr, MIN(uap->data, sizeof(r.args))); break; + case PT_GET_SC_RET: + error = copyout(&r.psr, uap->addr, MIN(uap->data, + sizeof(r.psr))); + break; } return (error); @@ -719,6 +741,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) struct thread *td2 = NULL, *td3; struct ptrace_io_desc *piod = NULL; struct ptrace_lwpinfo *pl; + struct ptrace_sc_ret *psr; int error, num, tmp; int proctree_locked = 0; lwpid_t tid = 0, *buf; @@ -726,7 +749,11 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) int wrap32 = 0, safe = 0; struct ptrace_io_desc32 *piod32 = NULL; struct ptrace_lwpinfo32 *pl32 = NULL; - struct ptrace_lwpinfo plr; + struct ptrace_sc_ret32 *psr32 = NULL; + union { + struct ptrace_lwpinfo pl; + struct ptrace_sc_ret psr; + } r; #endif curp = td->td_proc; @@ -1049,6 +1076,38 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) bcopy(td2->td_sa.args, addr, td2->td_sa.narg * sizeof(register_t)); break; + + case PT_GET_SC_RET: + if ((td2->td_dbgflags & (TDB_SCX)) == 0 +#ifdef COMPAT_FREEBSD32 + || (wrap32 && !safe) +#endif + ) { + error = EINVAL; + break; + } +#ifdef COMPAT_FREEBSD32 + if (wrap32) { + psr = &r.psr; + psr32 = addr; + } else +#endif + psr = addr; + bzero(psr, sizeof(*psr)); + psr->sr_error = td2->td_errno; + if (psr->sr_error == 0) { + psr->sr_retval[0] = td2->td_retval[0]; + psr->sr_retval[1] = td2->td_retval[1]; + } +#ifdef COMPAT_FREEBSD32 + if (wrap32) + ptrace_sc_ret_to32(psr, psr32); +#endif + CTR4(KTR_PTRACE, + "PT_GET_SC_RET: pid %d error %d retval %#lx,%#lx", + p->p_pid, psr->sr_error, psr->sr_retval[0], + psr->sr_retval[1]); + break; case PT_STEP: case PT_CONTINUE: @@ -1335,7 +1394,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) } #ifdef COMPAT_FREEBSD32 if (wrap32) { - pl = &plr; + pl = &r.pl; pl32 = addr; } else #endif diff --git a/sys/sys/ptrace.h b/sys/sys/ptrace.h index e41f7a3ef024..1ee42318e57e 100644 --- a/sys/sys/ptrace.h +++ b/sys/sys/ptrace.h @@ -72,6 +72,7 @@ #define PT_SET_EVENT_MASK 26 /* set mask of optional events */ #define PT_GET_SC_ARGS 27 /* fetch syscall args */ +#define PT_GET_SC_RET 28 /* fetch syscall results */ #define PT_GETREGS 33 /* get general-purpose registers */ #define PT_SETREGS 34 /* set general-purpose registers */ @@ -155,6 +156,12 @@ struct ptrace_lwpinfo32 { }; #endif +/* Argument structure for PT_GET_SC_RET. */ +struct ptrace_sc_ret { + register_t sr_retval[2]; /* Only valid if sr_error == 0. */ + int sr_error; +}; + /* Argument structure for PT_VM_ENTRY. */ struct ptrace_vm_entry { int pve_entry; /* Entry number used for iteration. */ diff --git a/tests/sys/kern/ptrace_test.c b/tests/sys/kern/ptrace_test.c index 1bacf0750c57..4e4e3babc998 100644 --- a/tests/sys/kern/ptrace_test.c +++ b/tests/sys/kern/ptrace_test.c @@ -3905,12 +3905,13 @@ ATF_TC_BODY(ptrace__PT_LWPINFO_stale_siginfo, tc) } /* - * A simple test of PT_GET_SC_ARGS. + * A simple test of PT_GET_SC_ARGS and PT_GET_SC_RET. */ ATF_TC_WITHOUT_HEAD(ptrace__syscall_args); ATF_TC_BODY(ptrace__syscall_args, tc) { struct ptrace_lwpinfo pl; + struct ptrace_sc_ret psr; pid_t fpid, wpid; register_t args[2]; int events, status; @@ -3919,6 +3920,7 @@ ATF_TC_BODY(ptrace__syscall_args, tc) if (fpid == 0) { trace_me(); kill(getpid(), 0); + close(3); exit(1); } @@ -3930,9 +3932,9 @@ ATF_TC_BODY(ptrace__syscall_args, tc) /* * Continue the process ignoring the signal, but enabling - * syscall entry traps. + * syscall traps. */ - ATF_REQUIRE(ptrace(PT_TO_SCE, fpid, (caddr_t)1, 0) == 0); + ATF_REQUIRE(ptrace(PT_SYSCALL, fpid, (caddr_t)1, 0) == 0); /* * The next stop should be the syscall entry from getpid(). @@ -3948,6 +3950,25 @@ ATF_TC_BODY(ptrace__syscall_args, tc) ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + /* + * The next stop should be the syscall exit from getpid(). + */ + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1); + ATF_REQUIRE(pl.pl_flags & PL_FLAG_SCX); + ATF_REQUIRE(pl.pl_syscall_code == SYS_getpid); + + ATF_REQUIRE(ptrace(PT_GET_SC_RET, wpid, (caddr_t)&psr, + sizeof(psr)) != -1); + ATF_REQUIRE(psr.sr_error == 0); + ATF_REQUIRE(psr.sr_retval[0] == wpid); + + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + /* * The next stop should be the syscall entry from kill(). */ @@ -3966,6 +3987,61 @@ ATF_TC_BODY(ptrace__syscall_args, tc) ATF_REQUIRE(args[0] == wpid); ATF_REQUIRE(args[1] == 0); + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + + /* + * The next stop should be the syscall exit from kill(). + */ + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1); + ATF_REQUIRE(pl.pl_flags & PL_FLAG_SCX); + ATF_REQUIRE(pl.pl_syscall_code == SYS_kill); + + ATF_REQUIRE(ptrace(PT_GET_SC_RET, wpid, (caddr_t)&psr, + sizeof(psr)) != -1); + ATF_REQUIRE(psr.sr_error == 0); + + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + + /* + * The next stop should be the syscall entry from close(). + */ + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1); + ATF_REQUIRE(pl.pl_flags & PL_FLAG_SCE); + ATF_REQUIRE(pl.pl_syscall_code == SYS_close); + ATF_REQUIRE(pl.pl_syscall_narg == 1); + + ATF_REQUIRE(ptrace(PT_GET_SC_ARGS, wpid, (caddr_t)args, + sizeof(args)) != -1); + ATF_REQUIRE(args[0] == 3); + + ATF_REQUIRE(ptrace(PT_CONTINUE, fpid, (caddr_t)1, 0) == 0); + + /* + * The next stop should be the syscall exit from close(). + */ + wpid = waitpid(fpid, &status, 0); + ATF_REQUIRE(wpid == fpid); + ATF_REQUIRE(WIFSTOPPED(status)); + ATF_REQUIRE(WSTOPSIG(status) == SIGTRAP); + + ATF_REQUIRE(ptrace(PT_LWPINFO, wpid, (caddr_t)&pl, sizeof(pl)) != -1); + ATF_REQUIRE(pl.pl_flags & PL_FLAG_SCX); + ATF_REQUIRE(pl.pl_syscall_code == SYS_close); + + ATF_REQUIRE(ptrace(PT_GET_SC_RET, wpid, (caddr_t)&psr, + sizeof(psr)) != -1); + ATF_REQUIRE(psr.sr_error == EBADF); + /* Disable syscall tracing and continue the child to let it exit. */ ATF_REQUIRE(ptrace(PT_GET_EVENT_MASK, fpid, (caddr_t)&events, sizeof(events)) == 0);