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linux_dsm_epyc7002/include/linux/signal.h
Eric W. Biederman cc731525f2 signal: Remove kernel interal si_code magic 
struct siginfo is a union and the kernel since 2.4 has been hiding a union
tag in the high 16bits of si_code using the values:
__SI_KILL
__SI_TIMER
__SI_POLL
__SI_FAULT
__SI_CHLD
__SI_RT
__SI_MESGQ
__SI_SYS

While this looks plausible on the surface, in practice this situation has
not worked well.

- Injected positive signals are not copied to user space properly
  unless they have these magic high bits set.

- Injected positive signals are not reported properly by signalfd
  unless they have these magic high bits set.

- These kernel internal values leaked to userspace via ptrace_peek_siginfo

- It was possible to inject these kernel internal values and cause the
  the kernel to misbehave.

- Kernel developers got confused and expected these kernel internal values
  in userspace in kernel self tests.

- Kernel developers got confused and set si_code to __SI_FAULT which
  is SI_USER in userspace which causes userspace to think an ordinary user
  sent the signal and that it was not kernel generated.

- The values make it impossible to reorganize the code to transform
  siginfo_copy_to_user into a plain copy_to_user.  As si_code must
  be massaged before being passed to userspace.

So remove these kernel internal si codes and make the kernel code simpler
and more maintainable.

To replace these kernel internal magic si_codes introduce the helper
function siginfo_layout, that takes a signal number and an si_code and
computes which union member of siginfo is being used.  Have
siginfo_layout return an enumeration so that gcc will have enough
information to warn if a switch statement does not handle all of union
members.

A couple of architectures have a messed up ABI that defines signal
specific duplications of SI_USER which causes more special cases in
siginfo_layout than I would like.  The good news is only problem
architectures pay the cost.

Update all of the code that used the previous magic __SI_ values to
use the new SIL_ values and to call siginfo_layout to get those
values.  Escept where not all of the cases are handled remove the
defaults in the switch statements so that if a new case is missed in
the future the lack will show up at compile time.

Modify the code that copies siginfo si_code to userspace to just copy
the value and not cast si_code to a short first.  The high bits are no
longer used to hold a magic union member.

Fixup the siginfo header files to stop including the __SI_ values in
their constants and for the headers that were missing it to properly
update the number of si_codes for each signal type.

The fixes to copy_siginfo_from_user32 implementations has the
interesting property that several of them perviously should never have
worked as the __SI_ values they depended up where kernel internal.
With that dependency gone those implementations should work much
better.

The idea of not passing the __SI_ values out to userspace and then
not reinserting them has been tested with criu and criu worked without
changes.

Ref: 2.4.0-test1
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2017-07-24 14:30:28 -05:00

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#ifndef _LINUX_SIGNAL_H
#define _LINUX_SIGNAL_H
#include <linux/bug.h>
#include <linux/signal_types.h>
#include <linux/string.h>
struct task_struct;
/* for sysctl */
extern int print_fatal_signals;
static inline void copy_siginfo(struct siginfo *to, struct siginfo *from)
{
if (from->si_code < 0)
memcpy(to, from, sizeof(*to));
else
/* _sigchld is currently the largest know union member */
memcpy(to, from, __ARCH_SI_PREAMBLE_SIZE + sizeof(from->_sifields._sigchld));
}
int copy_siginfo_to_user(struct siginfo __user *to, const struct siginfo *from);
enum siginfo_layout {
SIL_KILL,
SIL_TIMER,
SIL_POLL,
SIL_FAULT,
SIL_CHLD,
SIL_RT,
#ifdef __ARCH_SIGSYS
SIL_SYS,
#endif
};
enum siginfo_layout siginfo_layout(int sig, int si_code);
/*
* Define some primitives to manipulate sigset_t.
*/
#ifndef __HAVE_ARCH_SIG_BITOPS
#include <linux/bitops.h>
/* We don't use <linux/bitops.h> for these because there is no need to
be atomic. */
static inline void sigaddset(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
set->sig[0] |= 1UL << sig;
else
set->sig[sig / _NSIG_BPW] |= 1UL << (sig % _NSIG_BPW);
}
static inline void sigdelset(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
set->sig[0] &= ~(1UL << sig);
else
set->sig[sig / _NSIG_BPW] &= ~(1UL << (sig % _NSIG_BPW));
}
static inline int sigismember(sigset_t *set, int _sig)
{
unsigned long sig = _sig - 1;
if (_NSIG_WORDS == 1)
return 1 & (set->sig[0] >> sig);
else
return 1 & (set->sig[sig / _NSIG_BPW] >> (sig % _NSIG_BPW));
}
#endif /* __HAVE_ARCH_SIG_BITOPS */
static inline int sigisemptyset(sigset_t *set)
{
switch (_NSIG_WORDS) {
case 4:
return (set->sig[3] | set->sig[2] |
set->sig[1] | set->sig[0]) == 0;
case 2:
return (set->sig[1] | set->sig[0]) == 0;
case 1:
return set->sig[0] == 0;
default:
BUILD_BUG();
return 0;
}
}
static inline int sigequalsets(const sigset_t *set1, const sigset_t *set2)
{
switch (_NSIG_WORDS) {
case 4:
return (set1->sig[3] == set2->sig[3]) &&
(set1->sig[2] == set2->sig[2]) &&
(set1->sig[1] == set2->sig[1]) &&
(set1->sig[0] == set2->sig[0]);
case 2:
return (set1->sig[1] == set2->sig[1]) &&
(set1->sig[0] == set2->sig[0]);
case 1:
return set1->sig[0] == set2->sig[0];
}
return 0;
}
#define sigmask(sig) (1UL << ((sig) - 1))
#ifndef __HAVE_ARCH_SIG_SETOPS
#include <linux/string.h>
#define _SIG_SET_BINOP(name, op) \
static inline void name(sigset_t *r, const sigset_t *a, const sigset_t *b) \
{ \
unsigned long a0, a1, a2, a3, b0, b1, b2, b3; \
\
switch (_NSIG_WORDS) { \
case 4: \
a3 = a->sig[3]; a2 = a->sig[2]; \
b3 = b->sig[3]; b2 = b->sig[2]; \
r->sig[3] = op(a3, b3); \
r->sig[2] = op(a2, b2); \
case 2: \
a1 = a->sig[1]; b1 = b->sig[1]; \
r->sig[1] = op(a1, b1); \
case 1: \
a0 = a->sig[0]; b0 = b->sig[0]; \
r->sig[0] = op(a0, b0); \
break; \
default: \
BUILD_BUG(); \
} \
}
#define _sig_or(x,y) ((x) | (y))
_SIG_SET_BINOP(sigorsets, _sig_or)
#define _sig_and(x,y) ((x) & (y))
_SIG_SET_BINOP(sigandsets, _sig_and)
#define _sig_andn(x,y) ((x) & ~(y))
_SIG_SET_BINOP(sigandnsets, _sig_andn)
#undef _SIG_SET_BINOP
#undef _sig_or
#undef _sig_and
#undef _sig_andn
#define _SIG_SET_OP(name, op) \
static inline void name(sigset_t *set) \
{ \
switch (_NSIG_WORDS) { \
case 4: set->sig[3] = op(set->sig[3]); \
set->sig[2] = op(set->sig[2]); \
case 2: set->sig[1] = op(set->sig[1]); \
case 1: set->sig[0] = op(set->sig[0]); \
break; \
default: \
BUILD_BUG(); \
} \
}
#define _sig_not(x) (~(x))
_SIG_SET_OP(signotset, _sig_not)
#undef _SIG_SET_OP
#undef _sig_not
static inline void sigemptyset(sigset_t *set)
{
switch (_NSIG_WORDS) {
default:
memset(set, 0, sizeof(sigset_t));
break;
case 2: set->sig[1] = 0;
case 1: set->sig[0] = 0;
break;
}
}
static inline void sigfillset(sigset_t *set)
{
switch (_NSIG_WORDS) {
default:
memset(set, -1, sizeof(sigset_t));
break;
case 2: set->sig[1] = -1;
case 1: set->sig[0] = -1;
break;
}
}
/* Some extensions for manipulating the low 32 signals in particular. */
static inline void sigaddsetmask(sigset_t *set, unsigned long mask)
{
set->sig[0] |= mask;
}
static inline void sigdelsetmask(sigset_t *set, unsigned long mask)
{
set->sig[0] &= ~mask;
}
static inline int sigtestsetmask(sigset_t *set, unsigned long mask)
{
return (set->sig[0] & mask) != 0;
}
static inline void siginitset(sigset_t *set, unsigned long mask)
{
set->sig[0] = mask;
switch (_NSIG_WORDS) {
default:
memset(&set->sig[1], 0, sizeof(long)*(_NSIG_WORDS-1));
break;
case 2: set->sig[1] = 0;
case 1: ;
}
}
static inline void siginitsetinv(sigset_t *set, unsigned long mask)
{
set->sig[0] = ~mask;
switch (_NSIG_WORDS) {
default:
memset(&set->sig[1], -1, sizeof(long)*(_NSIG_WORDS-1));
break;
case 2: set->sig[1] = -1;
case 1: ;
}
}
#endif /* __HAVE_ARCH_SIG_SETOPS */
static inline void init_sigpending(struct sigpending *sig)
{
sigemptyset(&sig->signal);
INIT_LIST_HEAD(&sig->list);
}
extern void flush_sigqueue(struct sigpending *queue);
/* Test if 'sig' is valid signal. Use this instead of testing _NSIG directly */
static inline int valid_signal(unsigned long sig)
{
return sig <= _NSIG ? 1 : 0;
}
struct timespec;
struct pt_regs;
extern int next_signal(struct sigpending *pending, sigset_t *mask);
extern int do_send_sig_info(int sig, struct siginfo *info,
struct task_struct *p, bool group);
extern int group_send_sig_info(int sig, struct siginfo *info, struct task_struct *p);
extern int __group_send_sig_info(int, struct siginfo *, struct task_struct *);
extern int sigprocmask(int, sigset_t *, sigset_t *);
extern void set_current_blocked(sigset_t *);
extern void __set_current_blocked(const sigset_t *);
extern int show_unhandled_signals;
extern int get_signal(struct ksignal *ksig);
extern void signal_setup_done(int failed, struct ksignal *ksig, int stepping);
extern void exit_signals(struct task_struct *tsk);
extern void kernel_sigaction(int, __sighandler_t);
static inline void allow_signal(int sig)
{
/*
* Kernel threads handle their own signals. Let the signal code
* know it'll be handled, so that they don't get converted to
* SIGKILL or just silently dropped.
*/
kernel_sigaction(sig, (__force __sighandler_t)2);
}
static inline void disallow_signal(int sig)
{
kernel_sigaction(sig, SIG_IGN);
}
extern struct kmem_cache *sighand_cachep;
int unhandled_signal(struct task_struct *tsk, int sig);
/*
* In POSIX a signal is sent either to a specific thread (Linux task)
* or to the process as a whole (Linux thread group). How the signal
* is sent determines whether it's to one thread or the whole group,
* which determines which signal mask(s) are involved in blocking it
* from being delivered until later. When the signal is delivered,
* either it's caught or ignored by a user handler or it has a default
* effect that applies to the whole thread group (POSIX process).
*
* The possible effects an unblocked signal set to SIG_DFL can have are:
* ignore - Nothing Happens
* terminate - kill the process, i.e. all threads in the group,
* similar to exit_group. The group leader (only) reports
* WIFSIGNALED status to its parent.
* coredump - write a core dump file describing all threads using
* the same mm and then kill all those threads
* stop - stop all the threads in the group, i.e. TASK_STOPPED state
*
* SIGKILL and SIGSTOP cannot be caught, blocked, or ignored.
* Other signals when not blocked and set to SIG_DFL behaves as follows.
* The job control signals also have other special effects.
*
* +--------------------+------------------+
* | POSIX signal | default action |
* +--------------------+------------------+
* | SIGHUP | terminate |
* | SIGINT | terminate |
* | SIGQUIT | coredump |
* | SIGILL | coredump |
* | SIGTRAP | coredump |
* | SIGABRT/SIGIOT | coredump |
* | SIGBUS | coredump |
* | SIGFPE | coredump |
* | SIGKILL | terminate(+) |
* | SIGUSR1 | terminate |
* | SIGSEGV | coredump |
* | SIGUSR2 | terminate |
* | SIGPIPE | terminate |
* | SIGALRM | terminate |
* | SIGTERM | terminate |
* | SIGCHLD | ignore |
* | SIGCONT | ignore(*) |
* | SIGSTOP | stop(*)(+) |
* | SIGTSTP | stop(*) |
* | SIGTTIN | stop(*) |
* | SIGTTOU | stop(*) |
* | SIGURG | ignore |
* | SIGXCPU | coredump |
* | SIGXFSZ | coredump |
* | SIGVTALRM | terminate |
* | SIGPROF | terminate |
* | SIGPOLL/SIGIO | terminate |
* | SIGSYS/SIGUNUSED | coredump |
* | SIGSTKFLT | terminate |
* | SIGWINCH | ignore |
* | SIGPWR | terminate |
* | SIGRTMIN-SIGRTMAX | terminate |
* +--------------------+------------------+
* | non-POSIX signal | default action |
* +--------------------+------------------+
* | SIGEMT | coredump |
* +--------------------+------------------+
*
* (+) For SIGKILL and SIGSTOP the action is "always", not just "default".
* (*) Special job control effects:
* When SIGCONT is sent, it resumes the process (all threads in the group)
* from TASK_STOPPED state and also clears any pending/queued stop signals
* (any of those marked with "stop(*)"). This happens regardless of blocking,
* catching, or ignoring SIGCONT. When any stop signal is sent, it clears
* any pending/queued SIGCONT signals; this happens regardless of blocking,
* catching, or ignored the stop signal, though (except for SIGSTOP) the
* default action of stopping the process may happen later or never.
*/
#ifdef SIGEMT
#define SIGEMT_MASK rt_sigmask(SIGEMT)
#else
#define SIGEMT_MASK 0
#endif
#if SIGRTMIN > BITS_PER_LONG
#define rt_sigmask(sig) (1ULL << ((sig)-1))
#else
#define rt_sigmask(sig) sigmask(sig)
#endif
#define siginmask(sig, mask) \
((sig) < SIGRTMIN && (rt_sigmask(sig) & (mask)))
#define SIG_KERNEL_ONLY_MASK (\
rt_sigmask(SIGKILL) | rt_sigmask(SIGSTOP))
#define SIG_KERNEL_STOP_MASK (\
rt_sigmask(SIGSTOP) | rt_sigmask(SIGTSTP) | \
rt_sigmask(SIGTTIN) | rt_sigmask(SIGTTOU) )
#define SIG_KERNEL_COREDUMP_MASK (\
rt_sigmask(SIGQUIT) | rt_sigmask(SIGILL) | \
rt_sigmask(SIGTRAP) | rt_sigmask(SIGABRT) | \
rt_sigmask(SIGFPE) | rt_sigmask(SIGSEGV) | \
rt_sigmask(SIGBUS) | rt_sigmask(SIGSYS) | \
rt_sigmask(SIGXCPU) | rt_sigmask(SIGXFSZ) | \
SIGEMT_MASK )
#define SIG_KERNEL_IGNORE_MASK (\
rt_sigmask(SIGCONT) | rt_sigmask(SIGCHLD) | \
rt_sigmask(SIGWINCH) | rt_sigmask(SIGURG) )
#define SIG_SPECIFIC_SICODES_MASK (\
rt_sigmask(SIGILL) | rt_sigmask(SIGFPE) | \
rt_sigmask(SIGSEGV) | rt_sigmask(SIGBUS) | \
rt_sigmask(SIGTRAP) | rt_sigmask(SIGCHLD) | \
rt_sigmask(SIGPOLL) | rt_sigmask(SIGSYS) | \
SIGEMT_MASK )
#define sig_kernel_only(sig) siginmask(sig, SIG_KERNEL_ONLY_MASK)
#define sig_kernel_coredump(sig) siginmask(sig, SIG_KERNEL_COREDUMP_MASK)
#define sig_kernel_ignore(sig) siginmask(sig, SIG_KERNEL_IGNORE_MASK)
#define sig_kernel_stop(sig) siginmask(sig, SIG_KERNEL_STOP_MASK)
#define sig_specific_sicodes(sig) siginmask(sig, SIG_SPECIFIC_SICODES_MASK)
#define sig_fatal(t, signr) \
(!siginmask(signr, SIG_KERNEL_IGNORE_MASK|SIG_KERNEL_STOP_MASK) && \
(t)->sighand->action[(signr)-1].sa.sa_handler == SIG_DFL)
void signals_init(void);
int restore_altstack(const stack_t __user *);
int __save_altstack(stack_t __user *, unsigned long);
#define save_altstack_ex(uss, sp) do { \
stack_t __user *__uss = uss; \
struct task_struct *t = current; \
put_user_ex((void __user *)t->sas_ss_sp, &__uss->ss_sp); \
put_user_ex(t->sas_ss_flags, &__uss->ss_flags); \
put_user_ex(t->sas_ss_size, &__uss->ss_size); \
if (t->sas_ss_flags & SS_AUTODISARM) \
sas_ss_reset(t); \
} while (0);
#ifdef CONFIG_PROC_FS
struct seq_file;
extern void render_sigset_t(struct seq_file *, const char *, sigset_t *);
#endif
#endif /* _LINUX_SIGNAL_H */
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