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linux-kernel-test/arch/sh/kernel/signal_32.c
David Howells ee18d64c1f KEYS: Add a keyctl to install a process's session keyring on its parent [try #6] 
Add a keyctl to install a process's session keyring onto its parent.  This
replaces the parent's session keyring.  Because the COW credential code does
not permit one process to change another process's credentials directly, the
change is deferred until userspace next starts executing again.  Normally this
will be after a wait*() syscall.

To support this, three new security hooks have been provided:
cred_alloc_blank() to allocate unset security creds, cred_transfer() to fill in
the blank security creds and key_session_to_parent() - which asks the LSM if
the process may replace its parent's session keyring.

The replacement may only happen if the process has the same ownership details
as its parent, and the process has LINK permission on the session keyring, and
the session keyring is owned by the process, and the LSM permits it.

Note that this requires alteration to each architecture's notify_resume path.
This has been done for all arches barring blackfin, m68k* and xtensa, all of
which need assembly alteration to support TIF_NOTIFY_RESUME.  This allows the
replacement to be performed at the point the parent process resumes userspace
execution.

This allows the userspace AFS pioctl emulation to fully emulate newpag() and
the VIOCSETTOK and VIOCSETTOK2 pioctls, all of which require the ability to
alter the parent process's PAG membership.  However, since kAFS doesn't use
PAGs per se, but rather dumps the keys into the session keyring, the session
keyring of the parent must be replaced if, for example, VIOCSETTOK is passed
the newpag flag.

This can be tested with the following program:

	#include <stdio.h>
	#include <stdlib.h>
	#include <keyutils.h>

	#define KEYCTL_SESSION_TO_PARENT	18

	#define OSERROR(X, S) do { if ((long)(X) == -1) { perror(S); exit(1); } } while(0)

	int main(int argc, char **argv)
	{
		key_serial_t keyring, key;
		long ret;

		keyring = keyctl_join_session_keyring(argv[1]);
		OSERROR(keyring, "keyctl_join_session_keyring");

		key = add_key("user", "a", "b", 1, keyring);
		OSERROR(key, "add_key");

		ret = keyctl(KEYCTL_SESSION_TO_PARENT);
		OSERROR(ret, "KEYCTL_SESSION_TO_PARENT");

		return 0;
	}

Compiled and linked with -lkeyutils, you should see something like:

	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	355907932 --alswrv   4043    -1   \_ keyring: _uid.4043
	[dhowells@andromeda ~]$ /tmp/newpag
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: _ses
	1055658746 --alswrv   4043  4043   \_ user: a
	[dhowells@andromeda ~]$ /tmp/newpag hello
	[dhowells@andromeda ~]$ keyctl show
	Session Keyring
	       -3 --alswrv   4043  4043  keyring: hello
	340417692 --alswrv   4043  4043   \_ user: a

Where the test program creates a new session keyring, sticks a user key named
'a' into it and then installs it on its parent.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>
2009-09-02 21:29:22 +10:00

647 lines
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/*
* linux/arch/sh/kernel/signal.c
*
* Copyright (C) 1991, 1992 Linus Torvalds
*
* 1997-11-28 Modified for POSIX.1b signals by Richard Henderson
*
* SuperH version: Copyright (C) 1999, 2000 Niibe Yutaka & Kaz Kojima
*
*/
#include <linux/sched.h>
#include <linux/mm.h>
#include <linux/smp.h>
#include <linux/kernel.h>
#include <linux/signal.h>
#include <linux/errno.h>
#include <linux/wait.h>
#include <linux/ptrace.h>
#include <linux/unistd.h>
#include <linux/stddef.h>
#include <linux/tty.h>
#include <linux/elf.h>
#include <linux/personality.h>
#include <linux/binfmts.h>
#include <linux/freezer.h>
#include <linux/io.h>
#include <linux/tracehook.h>
#include <asm/system.h>
#include <asm/ucontext.h>
#include <asm/uaccess.h>
#include <asm/pgtable.h>
#include <asm/cacheflush.h>
#include <asm/syscalls.h>
#include <asm/fpu.h>
#define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
struct fdpic_func_descriptor {
unsigned long text;
unsigned long GOT;
};
/*
* Atomically swap in the new signal mask, and wait for a signal.
*/
asmlinkage int
sys_sigsuspend(old_sigset_t mask,
unsigned long r5, unsigned long r6, unsigned long r7,
struct pt_regs __regs)
{
mask &= _BLOCKABLE;
spin_lock_irq(&current->sighand->siglock);
current->saved_sigmask = current->blocked;
siginitset(&current->blocked, mask);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
current->state = TASK_INTERRUPTIBLE;
schedule();
set_thread_flag(TIF_RESTORE_SIGMASK);
return -ERESTARTNOHAND;
}
asmlinkage int
sys_sigaction(int sig, const struct old_sigaction __user *act,
struct old_sigaction __user *oact)
{
struct k_sigaction new_ka, old_ka;
int ret;
if (act) {
old_sigset_t mask;
if (!access_ok(VERIFY_READ, act, sizeof(*act)) ||
__get_user(new_ka.sa.sa_handler, &act->sa_handler) ||
__get_user(new_ka.sa.sa_restorer, &act->sa_restorer))
return -EFAULT;
__get_user(new_ka.sa.sa_flags, &act->sa_flags);
__get_user(mask, &act->sa_mask);
siginitset(&new_ka.sa.sa_mask, mask);
}
ret = do_sigaction(sig, act ? &new_ka : NULL, oact ? &old_ka : NULL);
if (!ret && oact) {
if (!access_ok(VERIFY_WRITE, oact, sizeof(*oact)) ||
__put_user(old_ka.sa.sa_handler, &oact->sa_handler) ||
__put_user(old_ka.sa.sa_restorer, &oact->sa_restorer))
return -EFAULT;
__put_user(old_ka.sa.sa_flags, &oact->sa_flags);
__put_user(old_ka.sa.sa_mask.sig[0], &oact->sa_mask);
}
return ret;
}
asmlinkage int
sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss,
unsigned long r6, unsigned long r7,
struct pt_regs __regs)
{
struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
return do_sigaltstack(uss, uoss, regs->regs[15]);
}
/*
* Do a signal return; undo the signal stack.
*/
#define MOVW(n) (0x9300|((n)-2)) /* Move mem word at PC+n to R3 */
#if defined(CONFIG_CPU_SH2)
#define TRAP_NOARG 0xc320 /* Syscall w/no args (NR in R3) */
#else
#define TRAP_NOARG 0xc310 /* Syscall w/no args (NR in R3) */
#endif
#define OR_R0_R0 0x200b /* or r0,r0 (insert to avoid hardware bug) */
struct sigframe
{
struct sigcontext sc;
unsigned long extramask[_NSIG_WORDS-1];
u16 retcode[8];
};
struct rt_sigframe
{
struct siginfo info;
struct ucontext uc;
u16 retcode[8];
};
#ifdef CONFIG_SH_FPU
static inline int restore_sigcontext_fpu(struct sigcontext __user *sc)
{
struct task_struct *tsk = current;
if (!(current_cpu_data.flags & CPU_HAS_FPU))
return 0;
set_used_math();
return __copy_from_user(&tsk->thread.fpu.hard, &sc->sc_fpregs[0],
sizeof(long)*(16*2+2));
}
static inline int save_sigcontext_fpu(struct sigcontext __user *sc,
struct pt_regs *regs)
{
struct task_struct *tsk = current;
if (!(current_cpu_data.flags & CPU_HAS_FPU))
return 0;
if (!used_math()) {
__put_user(0, &sc->sc_ownedfp);
return 0;
}
__put_user(1, &sc->sc_ownedfp);
/* This will cause a "finit" to be triggered by the next
attempted FPU operation by the 'current' process.
*/
clear_used_math();
unlazy_fpu(tsk, regs);
return __copy_to_user(&sc->sc_fpregs[0], &tsk->thread.fpu.hard,
sizeof(long)*(16*2+2));
}
#endif /* CONFIG_SH_FPU */
static int
restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *r0_p)
{
unsigned int err = 0;
#define COPY(x) err |= __get_user(regs->x, &sc->sc_##x)
COPY(regs[1]);
COPY(regs[2]); COPY(regs[3]);
COPY(regs[4]); COPY(regs[5]);
COPY(regs[6]); COPY(regs[7]);
COPY(regs[8]); COPY(regs[9]);
COPY(regs[10]); COPY(regs[11]);
COPY(regs[12]); COPY(regs[13]);
COPY(regs[14]); COPY(regs[15]);
COPY(gbr); COPY(mach);
COPY(macl); COPY(pr);
COPY(sr); COPY(pc);
#undef COPY
#ifdef CONFIG_SH_FPU
if (current_cpu_data.flags & CPU_HAS_FPU) {
int owned_fp;
struct task_struct *tsk = current;
regs->sr |= SR_FD; /* Release FPU */
clear_fpu(tsk, regs);
clear_used_math();
__get_user (owned_fp, &sc->sc_ownedfp);
if (owned_fp)
err |= restore_sigcontext_fpu(sc);
}
#endif
regs->tra = -1; /* disable syscall checks */
err |= __get_user(*r0_p, &sc->sc_regs[0]);
return err;
}
asmlinkage int sys_sigreturn(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs __regs)
{
struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
struct sigframe __user *frame = (struct sigframe __user *)regs->regs[15];
sigset_t set;
int r0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__get_user(set.sig[0], &frame->sc.oldmask)
|| (_NSIG_WORDS > 1
&& __copy_from_user(&set.sig[1], &frame->extramask,
sizeof(frame->extramask))))
goto badframe;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->sc, &r0))
goto badframe;
return r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
asmlinkage int sys_rt_sigreturn(unsigned long r4, unsigned long r5,
unsigned long r6, unsigned long r7,
struct pt_regs __regs)
{
struct pt_regs *regs = RELOC_HIDE(&__regs, 0);
struct rt_sigframe __user *frame = (struct rt_sigframe __user *)regs->regs[15];
sigset_t set;
int r0;
/* Always make any pending restarted system calls return -EINTR */
current_thread_info()->restart_block.fn = do_no_restart_syscall;
if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
goto badframe;
if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
goto badframe;
sigdelsetmask(&set, ~_BLOCKABLE);
spin_lock_irq(&current->sighand->siglock);
current->blocked = set;
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
if (restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
goto badframe;
if (do_sigaltstack(&frame->uc.uc_stack, NULL,
regs->regs[15]) == -EFAULT)
goto badframe;
return r0;
badframe:
force_sig(SIGSEGV, current);
return 0;
}
/*
* Set up a signal frame.
*/
static int
setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
unsigned long mask)
{
int err = 0;
#define COPY(x) err |= __put_user(regs->x, &sc->sc_##x)
COPY(regs[0]); COPY(regs[1]);
COPY(regs[2]); COPY(regs[3]);
COPY(regs[4]); COPY(regs[5]);
COPY(regs[6]); COPY(regs[7]);
COPY(regs[8]); COPY(regs[9]);
COPY(regs[10]); COPY(regs[11]);
COPY(regs[12]); COPY(regs[13]);
COPY(regs[14]); COPY(regs[15]);
COPY(gbr); COPY(mach);
COPY(macl); COPY(pr);
COPY(sr); COPY(pc);
#undef COPY
#ifdef CONFIG_SH_FPU
err |= save_sigcontext_fpu(sc, regs);
#endif
/* non-iBCS2 extensions.. */
err |= __put_user(mask, &sc->oldmask);
return err;
}
/*
* Determine which stack to use..
*/
static inline void __user *
get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
{
if (ka->sa.sa_flags & SA_ONSTACK) {
if (sas_ss_flags(sp) == 0)
sp = current->sas_ss_sp + current->sas_ss_size;
}
return (void __user *)((sp - frame_size) & -8ul);
}
/* These symbols are defined with the addresses in the vsyscall page.
See vsyscall-trapa.S. */
extern void __kernel_sigreturn(void);
extern void __kernel_rt_sigreturn(void);
static int setup_frame(int sig, struct k_sigaction *ka,
sigset_t *set, struct pt_regs *regs)
{
struct sigframe __user *frame;
int err = 0;
int signal;
frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
signal = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err |= setup_sigcontext(&frame->sc, regs, set->sig[0]);
if (_NSIG_WORDS > 1)
err |= __copy_to_user(frame->extramask, &set->sig[1],
sizeof(frame->extramask));
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->sa.sa_flags & SA_RESTORER) {
regs->pr = (unsigned long) ka->sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
} else if (likely(current->mm->context.vdso)) {
regs->pr = VDSO_SYM(&__kernel_sigreturn);
#endif
} else {
/* Generate return code (system call to sigreturn) */
err |= __put_user(MOVW(7), &frame->retcode[0]);
err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
err |= __put_user(OR_R0_R0, &frame->retcode[2]);
err |= __put_user(OR_R0_R0, &frame->retcode[3]);
err |= __put_user(OR_R0_R0, &frame->retcode[4]);
err |= __put_user(OR_R0_R0, &frame->retcode[5]);
err |= __put_user(OR_R0_R0, &frame->retcode[6]);
err |= __put_user((__NR_sigreturn), &frame->retcode[7]);
regs->pr = (unsigned long) frame->retcode;
flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
}
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->regs[15] = (unsigned long) frame;
regs->regs[4] = signal; /* Arg for signal handler */
regs->regs[5] = 0;
regs->regs[6] = (unsigned long) &frame->sc;
if (current->personality & FDPIC_FUNCPTRS) {
struct fdpic_func_descriptor __user *funcptr =
(struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
__get_user(regs->pc, &funcptr->text);
__get_user(regs->regs[12], &funcptr->GOT);
} else
regs->pc = (unsigned long)ka->sa.sa_handler;
set_fs(USER_DS);
pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
return 0;
give_sigsegv:
force_sigsegv(sig, current);
return -EFAULT;
}
static int setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *set, struct pt_regs *regs)
{
struct rt_sigframe __user *frame;
int err = 0;
int signal;
frame = get_sigframe(ka, regs->regs[15], sizeof(*frame));
if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
goto give_sigsegv;
signal = current_thread_info()->exec_domain
&& current_thread_info()->exec_domain->signal_invmap
&& sig < 32
? current_thread_info()->exec_domain->signal_invmap[sig]
: sig;
err |= copy_siginfo_to_user(&frame->info, info);
/* Create the ucontext. */
err |= __put_user(0, &frame->uc.uc_flags);
err |= __put_user(NULL, &frame->uc.uc_link);
err |= __put_user((void *)current->sas_ss_sp,
&frame->uc.uc_stack.ss_sp);
err |= __put_user(sas_ss_flags(regs->regs[15]),
&frame->uc.uc_stack.ss_flags);
err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
err |= setup_sigcontext(&frame->uc.uc_mcontext,
regs, set->sig[0]);
err |= __copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
/* Set up to return from userspace. If provided, use a stub
already in userspace. */
if (ka->sa.sa_flags & SA_RESTORER) {
regs->pr = (unsigned long) ka->sa.sa_restorer;
#ifdef CONFIG_VSYSCALL
} else if (likely(current->mm->context.vdso)) {
regs->pr = VDSO_SYM(&__kernel_rt_sigreturn);
#endif
} else {
/* Generate return code (system call to rt_sigreturn) */
err |= __put_user(MOVW(7), &frame->retcode[0]);
err |= __put_user(TRAP_NOARG, &frame->retcode[1]);
err |= __put_user(OR_R0_R0, &frame->retcode[2]);
err |= __put_user(OR_R0_R0, &frame->retcode[3]);
err |= __put_user(OR_R0_R0, &frame->retcode[4]);
err |= __put_user(OR_R0_R0, &frame->retcode[5]);
err |= __put_user(OR_R0_R0, &frame->retcode[6]);
err |= __put_user((__NR_rt_sigreturn), &frame->retcode[7]);
regs->pr = (unsigned long) frame->retcode;
}
if (err)
goto give_sigsegv;
/* Set up registers for signal handler */
regs->regs[15] = (unsigned long) frame;
regs->regs[4] = signal; /* Arg for signal handler */
regs->regs[5] = (unsigned long) &frame->info;
regs->regs[6] = (unsigned long) &frame->uc;
if (current->personality & FDPIC_FUNCPTRS) {
struct fdpic_func_descriptor __user *funcptr =
(struct fdpic_func_descriptor __user *)ka->sa.sa_handler;
__get_user(regs->pc, &funcptr->text);
__get_user(regs->regs[12], &funcptr->GOT);
} else
regs->pc = (unsigned long)ka->sa.sa_handler;
set_fs(USER_DS);
pr_debug("SIG deliver (%s:%d): sp=%p pc=%08lx pr=%08lx\n",
current->comm, task_pid_nr(current), frame, regs->pc, regs->pr);
flush_icache_range(regs->pr, regs->pr + sizeof(frame->retcode));
return 0;
give_sigsegv:
force_sigsegv(sig, current);
return -EFAULT;
}
static inline void
handle_syscall_restart(unsigned long save_r0, struct pt_regs *regs,
struct sigaction *sa)
{
/* If we're not from a syscall, bail out */
if (regs->tra < 0)
return;
/* check for system call restart.. */
switch (regs->regs[0]) {
case -ERESTART_RESTARTBLOCK:
case -ERESTARTNOHAND:
no_system_call_restart:
regs->regs[0] = -EINTR;
break;
case -ERESTARTSYS:
if (!(sa->sa_flags & SA_RESTART))
goto no_system_call_restart;
/* fallthrough */
case -ERESTARTNOINTR:
regs->regs[0] = save_r0;
regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
break;
}
}
/*
* OK, we're invoking a handler
*/
static int
handle_signal(unsigned long sig, struct k_sigaction *ka, siginfo_t *info,
sigset_t *oldset, struct pt_regs *regs, unsigned int save_r0)
{
int ret;
/* Set up the stack frame */
if (ka->sa.sa_flags & SA_SIGINFO)
ret = setup_rt_frame(sig, ka, info, oldset, regs);
else
ret = setup_frame(sig, ka, oldset, regs);
if (ka->sa.sa_flags & SA_ONESHOT)
ka->sa.sa_handler = SIG_DFL;
if (ret == 0) {
spin_lock_irq(&current->sighand->siglock);
sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
if (!(ka->sa.sa_flags & SA_NODEFER))
sigaddset(&current->blocked,sig);
recalc_sigpending();
spin_unlock_irq(&current->sighand->siglock);
}
return ret;
}
/*
* Note that 'init' is a special process: it doesn't get signals it doesn't
* want to handle. Thus you cannot kill init even with a SIGKILL even by
* mistake.
*
* Note that we go through the signals twice: once to check the signals that
* the kernel can handle, and then we build all the user-level signal handling
* stack-frames in one go after that.
*/
static void do_signal(struct pt_regs *regs, unsigned int save_r0)
{
siginfo_t info;
int signr;
struct k_sigaction ka;
sigset_t *oldset;
/*
* We want the common case to go fast, which
* is why we may in certain cases get here from
* kernel mode. Just return without doing anything
* if so.
*/
if (!user_mode(regs))
return;
if (try_to_freeze())
goto no_signal;
if (test_thread_flag(TIF_RESTORE_SIGMASK))
oldset = &current->saved_sigmask;
else
oldset = &current->blocked;
signr = get_signal_to_deliver(&info, &ka, regs, NULL);
if (signr > 0) {
handle_syscall_restart(save_r0, regs, &ka.sa);
/* Whee! Actually deliver the signal. */
if (handle_signal(signr, &ka, &info, oldset,
regs, save_r0) == 0) {
/* 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);
tracehook_signal_handler(signr, &info, &ka, regs,
test_thread_flag(TIF_SINGLESTEP));
}
return;
}
no_signal:
/* Did we come from a system call? */
if (regs->tra >= 0) {
/* Restart the system call - no handlers present */
if (regs->regs[0] == -ERESTARTNOHAND ||
regs->regs[0] == -ERESTARTSYS ||
regs->regs[0] == -ERESTARTNOINTR) {
regs->regs[0] = save_r0;
regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
} else if (regs->regs[0] == -ERESTART_RESTARTBLOCK) {
regs->pc -= instruction_size(ctrl_inw(regs->pc - 4));
regs->regs[3] = __NR_restart_syscall;
}
}
/* if there's no signal to deliver, we just put the saved sigmask
* back */
if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
clear_thread_flag(TIF_RESTORE_SIGMASK);
sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
}
}
asmlinkage void do_notify_resume(struct pt_regs *regs, unsigned int save_r0,
unsigned long thread_info_flags)
{
/* deal with pending signal delivery */
if (thread_info_flags & _TIF_SIGPENDING)
do_signal(regs, save_r0);
if (thread_info_flags & _TIF_NOTIFY_RESUME) {
clear_thread_flag(TIF_NOTIFY_RESUME);
tracehook_notify_resume(regs);
if (current->replacement_session_keyring)
key_replace_session_keyring();
}
}
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