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linux: implement PTRACE_GET_SYSCALL_INFO

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This is one of the pieces required to make modern (ie Focal)
strace(1) work.

Reviewed By:	jhb (earlier version)
Sponsored by:	EPSRC
Differential Revision:	https://reviews.freebsd.org/D28212
This commit is contained in:
Edward Tomasz Napierala 2021-09-12 11:31:10 +00:00
parent 6f43f86bf3
commit bdf0f24bb1
5 changed files with 120 additions and 4 deletions
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2
lib/libsysdecode/mktables
View File

@ -116,7 +116,7 @@ gen_table "nfssvcflags" "NFSSVC_[A-Z0-9]+[[:space:]]+0x[0-9]+" "nfs/
gen_table "pathconfname" "_PC_[A-Z4_]+[[:space:]]+[0-9]+" "sys/unistd.h"
gen_table "prio" "PRIO_[A-Z]+[[:space:]]+[0-9]" "sys/resource.h"
gen_table "procctlcmd" "PROC_[A-Z_]+[[:space:]]+[0-9]" "sys/procctl.h" "PROC_TRACE_CTL_"
gen_table "ptraceop" "PT_[[:alnum:]_]+[[:space:]]+[0-9]+" "sys/ptrace.h"
gen_table "ptraceop" "PT_[[:alnum:]_]+[[:space:]]+[0-9]+" "sys/ptrace.h" "PT_GET_SC_ARGS_ALL"
gen_table "quotactlcmds" "Q_[A-Z]+[[:space:]]+0x[0-9]+" "ufs/ufs/quota.h"
gen_table "rebootopt" "RB_[A-Z]+[[:space:]]+0x[0-9]+" "sys/reboot.h"
gen_table "rforkflags" "RF[A-Z]+[[:space:]]+\([0-9]+<<[0-9]+\)" "sys/unistd.h"

98
sys/amd64/linux/linux_ptrace.c
View File

@ -93,6 +93,12 @@ __FBSDID("$FreeBSD$");
LINUX_PTRACE_O_TRACESECCOMP | LINUX_PTRACE_O_EXITKILL | \
LINUX_PTRACE_O_SUSPEND_SECCOMP)
#define LINUX_PTRACE_SYSCALL_INFO_NONE 0
#define LINUX_PTRACE_SYSCALL_INFO_ENTRY 1
#define LINUX_PTRACE_SYSCALL_INFO_EXIT 2
#define LINUX_ARCH_AMD64 0xc000003e
static int
map_signum(int lsig, int *bsigp)
{
@ -172,6 +178,28 @@ struct linux_pt_reg {
l_ulong ss;
};
struct syscall_info {
uint8_t op;
uint32_t arch;
uint64_t instruction_pointer;
uint64_t stack_pointer;
union {
struct {
uint64_t nr;
uint64_t args[6];
} entry;
struct {
int64_t rval;
uint8_t is_error;
} exit;
struct {
uint64_t nr;
uint64_t args[6];
uint32_t ret_data;
} seccomp;
};
};
/*
* Translate amd64 ptrace registers between Linux and FreeBSD formats.
* The translation is pretty straighforward, for all registers but
@ -495,11 +523,75 @@ linux_ptrace_seize(struct thread *td, pid_t pid, l_ulong addr, l_ulong data)
}
static int
linux_ptrace_get_syscall_info(struct thread *td, pid_t pid, l_ulong addr, l_ulong data)
linux_ptrace_get_syscall_info(struct thread *td, pid_t pid,
l_ulong addr, l_ulong data)
{
struct ptrace_lwpinfo lwpinfo;
struct ptrace_sc_ret sr;
struct reg b_reg;
struct syscall_info si;
int error;
linux_msg(td, "PTRACE_GET_SYSCALL_INFO not implemented; returning EINVAL");
return (EINVAL);
error = kern_ptrace(td, PT_LWPINFO, pid, &lwpinfo, sizeof(lwpinfo));
if (error != 0) {
linux_msg(td, "PT_LWPINFO failed with error %d", error);
return (error);
}
memset(&si, 0, sizeof(si));
if (lwpinfo.pl_flags & PL_FLAG_SCE) {
si.op = LINUX_PTRACE_SYSCALL_INFO_ENTRY;
si.entry.nr = lwpinfo.pl_syscall_code;
/*
* The reason for using PT_GET_SC_ARGS_ALL instead
* of PT_GET_SC_ARGS is to emulate Linux bug which strace(1)
* depends on: at initialization it tests whether ptrace works
* by calling close(2), or some other single-argument syscall,
* _with six arguments_, and then verifies whether it can
* fetch them all using this API; otherwise it bails out.
*/
error = kern_ptrace(td, PT_GET_SC_ARGS_ALL, pid,
&si.entry.args, sizeof(si.entry.args));
if (error != 0) {
linux_msg(td, "PT_GET_SC_ARGS_ALL failed with error %d",
error);
return (error);
}
} else if (lwpinfo.pl_flags & PL_FLAG_SCX) {
si.op = LINUX_PTRACE_SYSCALL_INFO_EXIT;
error = kern_ptrace(td, PT_GET_SC_RET, pid, &sr, sizeof(sr));
if (error != 0) {
linux_msg(td, "PT_GET_SC_RET failed with error %d",
error);
return (error);
}
if (sr.sr_error == 0) {
si.exit.rval = sr.sr_retval[0];
si.exit.is_error = 0;
} else {
si.exit.rval = bsd_to_linux_errno(sr.sr_error);
si.exit.is_error = 1;
}
} else {
si.op = LINUX_PTRACE_SYSCALL_INFO_NONE;
}
error = kern_ptrace(td, PT_GETREGS, pid, &b_reg, 0);
if (error != 0)
return (error);
si.arch = LINUX_ARCH_AMD64;
si.instruction_pointer = b_reg.r_rip;
si.stack_pointer = b_reg.r_rsp;
error = copyout(&si, (void *)data, sizeof(si));
if (error == 0)
td->td_retval[0] = sizeof(si);
return (error);
}
int

3
sys/compat/freebsd32/freebsd32_misc.c
View File

@ -1032,6 +1032,9 @@ freebsd32_ptrace(struct thread *td, struct freebsd32_ptrace_args *uap)
r.pc.pc_limit = PAIR32TO64(off_t, r32.pc.pc_limit);
data = sizeof(r.pc);
break;
case PT_GET_SC_ARGS_ALL:
error = EINVAL;
break;
default:
addr = uap->addr;
break;

17
sys/kern/sys_process.c
View File

@ -527,6 +527,9 @@ sys_ptrace(struct thread *td, struct ptrace_args *uap)
else
error = copyin(uap->addr, &r.pc, uap->data);
break;
case PT_GET_SC_ARGS_ALL:
error = EINVAL;
break;
default:
addr = uap->addr;
break;
@ -708,6 +711,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
case PT_SET_EVENT_MASK:
case PT_DETACH:
case PT_GET_SC_ARGS:
case PT_GET_SC_ARGS_ALL:
sx_xlock(&proctree_lock);
proctree_locked = true;
break;
@ -1011,6 +1015,19 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data)
sizeof(register_t));
break;
case PT_GET_SC_ARGS_ALL:
CTR1(KTR_PTRACE, "PT_GET_SC_ARGS_ALL: pid %d", p->p_pid);
if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) == 0
#ifdef COMPAT_FREEBSD32
|| (wrap32 && !safe)
#endif
) {
error = EINVAL;
break;
}
bcopy(td2->td_sa.args, addr, sizeof(td2->td_sa.args));
break;
case PT_GET_SC_RET:
if ((td2->td_dbgflags & (TDB_SCX)) == 0
#ifdef COMPAT_FREEBSD32

4
sys/sys/ptrace.h
View File

@ -86,6 +86,10 @@
#define PT_VM_TIMESTAMP 40 /* Get VM version (timestamp) */
#define PT_VM_ENTRY 41 /* Get VM map (entry) */
#ifdef _KERNEL
#define PT_GET_SC_ARGS_ALL 42 /* Used by linux(4) */
#endif
#define PT_FIRSTMACH 64 /* for machine-specific requests */
#include <machine/ptrace.h> /* machine-specific requests, if any */