1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
/*
* Copyright (C) 2000 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
* Licensed under the GPL
*/
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/sched.h>
#include <asm/siginfo.h>
#include <asm/signal.h>
#include <asm/unistd.h>
#include "frame_kern.h"
#include "kern_util.h"
#include <sysdep/sigcontext.h>
EXPORT_SYMBOL(block_signals);
EXPORT_SYMBOL(unblock_signals);
#define _S(nr) (1<<((nr)-1))
#define _BLOCKABLE (~(_S(SIGKILL) | _S(SIGSTOP)))
/*
* OK, we're invoking a handler
*/
static int handle_signal(struct pt_regs *regs, unsigned long signr,
struct k_sigaction *ka, siginfo_t *info,
sigset_t *oldset)
{
unsigned long sp;
int err;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
/* Did we come from a system call? */
if (PT_REGS_SYSCALL_NR(regs) >= 0) {
/* If so, check system call restarting.. */
switch (PT_REGS_SYSCALL_RET(regs)) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
PT_REGS_SYSCALL_RET(regs) = -EINTR;
break;
case -ERESTARTSYS:
if (!(ka->sa.sa_flags & SA_RESTART)) {
PT_REGS_SYSCALL_RET(regs) = -EINTR;
break;
}
/* fallthrough */
case -ERESTARTNOINTR:
PT_REGS_RESTART_SYSCALL(regs);
PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
break;
}
}
sp = PT_REGS_SP(regs);
if ((ka->sa.sa_flags & SA_ONSTACK) && (sas_ss_flags(sp) == 0))
sp = current->sas_ss_sp + current->sas_ss_size;
#ifdef CONFIG_ARCH_HAS_SC_SIGNALS
if (!(ka->sa.sa_flags & SA_SIGINFO))
err = setup_signal_stack_sc(sp, signr, ka, regs, oldset);
else
#endif
err = setup_signal_stack_si(sp, signr, ka, regs, info, oldset);
if (err) {
spin_lock_irq(¤t->sighand->siglock);
current->blocked = *oldset;
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
force_sigsegv(signr, current);
} else {
spin_lock_irq(¤t->sighand->siglock);
sigorsets(¤t->blocked, ¤t->blocked,
&ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(¤t->blocked, signr);
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
}
return err;
}
static int kern_do_signal(struct pt_regs *regs)
{
struct k_sigaction ka_copy;
siginfo_t info;
sigset_t *oldset;
int sig, handled_sig = 0;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = ¤t->saved_sigmask;
else
oldset = ¤t->blocked;
while ((sig = get_signal_to_deliver(&info, &ka_copy, regs, NULL)) > 0) {
handled_sig = 1;
/* Whee! Actually deliver the signal. */
if (!handle_signal(regs, sig, &ka_copy, &info, oldset)) {
/*
* a signal was successfully delivered; the saved
* sigmask will have been stored in the signal frame,
* and will be restored by sigreturn, so we can simply
* clear the TIF_RESTORE_SIGMASK flag
*/
if (test_thread_flag(TIF_RESTORE_SIGMASK))
clear_thread_flag(TIF_RESTORE_SIGMASK);
break;
}
}
/* Did we come from a system call? */
if (!handled_sig && (PT_REGS_SYSCALL_NR(regs) >= 0)) {
/* Restart the system call - no handlers present */
switch (PT_REGS_SYSCALL_RET(regs)) {
case -ERESTARTNOHAND:
case -ERESTARTSYS:
case -ERESTARTNOINTR:
PT_REGS_ORIG_SYSCALL(regs) = PT_REGS_SYSCALL_NR(regs);
PT_REGS_RESTART_SYSCALL(regs);
break;
case -ERESTART_RESTARTBLOCK:
PT_REGS_ORIG_SYSCALL(regs) = __NR_restart_syscall;
PT_REGS_RESTART_SYSCALL(regs);
break;
}
}
/*
* This closes a way to execute a system call on the host. If
* you set a breakpoint on a system call instruction and singlestep
* from it, the tracing thread used to PTRACE_SINGLESTEP the process
* rather than PTRACE_SYSCALL it, allowing the system call to execute
* on the host. The tracing thread will check this flag and
* PTRACE_SYSCALL if necessary.
*/
if (current->ptrace & PT_DTRACE)
current->thread.singlestep_syscall =
is_syscall(PT_REGS_IP(¤t->thread.regs));
/*
* if there's no signal to deliver, we just put the saved sigmask
* back
*/
if (!handled_sig && test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
sigprocmask(SIG_SETMASK, ¤t->saved_sigmask, NULL);
}
return handled_sig;
}
int do_signal(void)
{
return kern_do_signal(¤t->thread.regs);
}
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
long sys_sigsuspend(int history0, int history1, old_sigset_t mask)
{
mask &= _BLOCKABLE;
spin_lock_irq(¤t->sighand->siglock);
current->saved_sigmask = current->blocked;
siginitset(¤t->blocked, mask);
recalc_sigpending();
spin_unlock_irq(¤t->sighand->siglock);
current->state = TASK_INTERRUPTIBLE;
schedule();
set_thread_flag(TIF_RESTORE_SIGMASK);
return -ERESTARTNOHAND;
}
long sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
{
return do_sigaltstack(uss, uoss, PT_REGS_SP(¤t->thread.regs));
}
|
