Merge branch 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace

Pull siginfo updates from Eric Biederman:
 "I have been slowly sorting out siginfo and this is the culmination of
  that work.

  The primary result is in several ways the signal infrastructure has
  been made less error prone. The code has been updated so that manually
  specifying SEND_SIG_FORCED is never necessary. The conversion to the
  new siginfo sending functions is now complete, which makes it
  difficult to send a signal without filling in the proper siginfo
  fields.

  At the tail end of the patchset comes the optimization of decreasing
  the size of struct siginfo in the kernel from 128 bytes to about 48
  bytes on 64bit. The fundamental observation that enables this is by
  definition none of the known ways to use struct siginfo uses the extra
  bytes.

  This comes at the cost of a small user space observable difference.
  For the rare case of siginfo being injected into the kernel only what
  can be copied into kernel_siginfo is delivered to the destination, the
  rest of the bytes are set to 0. For cases where the signal and the
  si_code are known this is safe, because we know those bytes are not
  used. For cases where the signal and si_code combination is unknown
  the bits that won't fit into struct kernel_siginfo are tested to
  verify they are zero, and the send fails if they are not.

  I made an extensive search through userspace code and I could not find
  anything that would break because of the above change. If it turns out
  I did break something it will take just the revert of a single change
  to restore kernel_siginfo to the same size as userspace siginfo.

  Testing did reveal dependencies on preferring the signo passed to
  sigqueueinfo over si->signo, so bit the bullet and added the
  complexity necessary to handle that case.

  Testing also revealed bad things can happen if a negative signal
  number is passed into the system calls. Something no sane application
  will do but something a malicious program or a fuzzer might do. So I
  have fixed the code that performs the bounds checks to ensure negative
  signal numbers are handled"

* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (80 commits)
  signal: Guard against negative signal numbers in copy_siginfo_from_user32
  signal: Guard against negative signal numbers in copy_siginfo_from_user
  signal: In sigqueueinfo prefer sig not si_signo
  signal: Use a smaller struct siginfo in the kernel
  signal: Distinguish between kernel_siginfo and siginfo
  signal: Introduce copy_siginfo_from_user and use it's return value
  signal: Remove the need for __ARCH_SI_PREABLE_SIZE and SI_PAD_SIZE
  signal: Fail sigqueueinfo if si_signo != sig
  signal/sparc: Move EMT_TAGOVF into the generic siginfo.h
  signal/unicore32: Use force_sig_fault where appropriate
  signal/unicore32: Generate siginfo in ucs32_notify_die
  signal/unicore32: Use send_sig_fault where appropriate
  signal/arc: Use force_sig_fault where appropriate
  signal/arc: Push siginfo generation into unhandled_exception
  signal/ia64: Use force_sig_fault where appropriate
  signal/ia64: Use the force_sig(SIGSEGV,...) in ia64_rt_sigreturn
  signal/ia64: Use the generic force_sigsegv in setup_frame
  signal/arm/kvm: Use send_sig_mceerr
  signal/arm: Use send_sig_fault where appropriate
  signal/arm: Use force_sig_fault where appropriate
  ...

4 files changed, 60 insertions, 187 deletions

diff --git a/arch/ia64/kernel/brl_emu.c b/arch/ia64/kernel/brl_emu.c
index a61f6c6a36f8..c0239bf77a09 100644
--- a/arch/ia64/kernel/brl_emu.c
+++ b/arch/ia64/kernel/brl_emu.c
@@ -58,11 +58,9 @@ ia64_emulate_brl (struct pt_regs *regs, unsigned long ar_ec)
 	unsigned long bundle[2];
 	unsigned long opcode, btype, qp, offset, cpl;
 	unsigned long next_ip;
-	struct siginfo siginfo;
 	struct illegal_op_return rv;
 	long tmp_taken, unimplemented_address;
 
-	clear_siginfo(&siginfo);
 	rv.fkt = (unsigned long) -1;
 
 	/*
@@ -198,39 +196,22 @@ ia64_emulate_brl (struct pt_regs *regs, unsigned long ar_ec)
 		 *  The target address contains unimplemented bits.
 		 */
 		printk(KERN_DEBUG "Woah! Unimplemented Instruction Address Trap!\n");
-		siginfo.si_signo = SIGILL;
-		siginfo.si_errno = 0;
-		siginfo.si_flags = 0;
-		siginfo.si_isr = 0;
-		siginfo.si_imm = 0;
-		siginfo.si_code = ILL_BADIADDR;
-		force_sig_info(SIGILL, &siginfo, current);
+		force_sig_fault(SIGILL, ILL_BADIADDR, (void __user *)NULL,
+				0, 0, 0, current);
 	} else if (ia64_psr(regs)->tb) {
 		/*
 		 *  Branch Tracing is enabled.
 		 *  Force a taken branch signal.
 		 */
-		siginfo.si_signo = SIGTRAP;
-		siginfo.si_errno = 0;
-		siginfo.si_code = TRAP_BRANCH;
-		siginfo.si_flags = 0;
-		siginfo.si_isr = 0;
-		siginfo.si_addr = 0;
-		siginfo.si_imm = 0;
-		force_sig_info(SIGTRAP, &siginfo, current);
+		force_sig_fault(SIGTRAP, TRAP_BRANCH, (void __user *)NULL,
+				0, 0, 0, current);
 	} else if (ia64_psr(regs)->ss) {
 		/*
 		 *  Single Step is enabled.
 		 *  Force a trace signal.
 		 */
-		siginfo.si_signo = SIGTRAP;
-		siginfo.si_errno = 0;
-		siginfo.si_code = TRAP_TRACE;
-		siginfo.si_flags = 0;
-		siginfo.si_isr = 0;
-		siginfo.si_addr = 0;
-		siginfo.si_imm = 0;
-		force_sig_info(SIGTRAP, &siginfo, current);
+		force_sig_fault(SIGTRAP, TRAP_TRACE, (void __user *)NULL,
+				0, 0, 0, current);
 	}
 	return rv;
 }
diff --git a/arch/ia64/kernel/signal.c b/arch/ia64/kernel/signal.c
index d1234a5ba4c5..9a960829a01d 100644
--- a/arch/ia64/kernel/signal.c
+++ b/arch/ia64/kernel/signal.c
@@ -110,7 +110,6 @@ ia64_rt_sigreturn (struct sigscratch *scr)
 {
 	extern char ia64_strace_leave_kernel, ia64_leave_kernel;
 	struct sigcontext __user *sc;
-	struct siginfo si;
 	sigset_t set;
 	long retval;
 
@@ -153,14 +152,7 @@ ia64_rt_sigreturn (struct sigscratch *scr)
 	return retval;
 
   give_sigsegv:
-	clear_siginfo(&si);
-	si.si_signo = SIGSEGV;
-	si.si_errno = 0;
-	si.si_code = SI_KERNEL;
-	si.si_pid = task_pid_vnr(current);
-	si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
-	si.si_addr = sc;
-	force_sig_info(SIGSEGV, &si, current);
+	force_sig(SIGSEGV, current);
 	return retval;
 }
 
@@ -232,37 +224,6 @@ rbs_on_sig_stack (unsigned long bsp)
 }
 
 static long
-force_sigsegv_info (int sig, void __user *addr)
-{
-	unsigned long flags;
-	struct siginfo si;
-
-	clear_siginfo(&si);
-	if (sig == SIGSEGV) {
-		/*
-		 * Acquiring siglock around the sa_handler-update is almost
-		 * certainly overkill, but this isn't a
-		 * performance-critical path and I'd rather play it safe
-		 * here than having to debug a nasty race if and when
-		 * something changes in kernel/signal.c that would make it
-		 * no longer safe to modify sa_handler without holding the
-		 * lock.
-		 */
-		spin_lock_irqsave(&current->sighand->siglock, flags);
-		current->sighand->action[sig - 1].sa.sa_handler = SIG_DFL;
-		spin_unlock_irqrestore(&current->sighand->siglock, flags);
-	}
-	si.si_signo = SIGSEGV;
-	si.si_errno = 0;
-	si.si_code = SI_KERNEL;
-	si.si_pid = task_pid_vnr(current);
-	si.si_uid = from_kuid_munged(current_user_ns(), current_uid());
-	si.si_addr = addr;
-	force_sig_info(SIGSEGV, &si, current);
-	return 1;
-}
-
-static long
 setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 {
 	extern char __kernel_sigtramp[];
@@ -295,15 +256,18 @@ setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 			 * instead so we will die with SIGSEGV.
 			 */
 			check_sp = (new_sp - sizeof(*frame)) & -STACK_ALIGN;
-			if (!likely(on_sig_stack(check_sp)))
-				return force_sigsegv_info(ksig->sig, (void __user *)
-							  check_sp);
+			if (!likely(on_sig_stack(check_sp))) {
+				force_sigsegv(ksig->sig, current);
+				return 1;
+			}
 		}
 	}
 	frame = (void __user *) ((new_sp - sizeof(*frame)) & -STACK_ALIGN);
 
-	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame)))
-		return force_sigsegv_info(ksig->sig, frame);
+	if (!access_ok(VERIFY_WRITE, frame, sizeof(*frame))) {
+		force_sigsegv(ksig->sig, current);
+		return 1;
+	}
 
 	err  = __put_user(ksig->sig, &frame->arg0);
 	err |= __put_user(&frame->info, &frame->arg1);
@@ -317,8 +281,10 @@ setup_frame(struct ksignal *ksig, sigset_t *set, struct sigscratch *scr)
 	err |= __save_altstack(&frame->sc.sc_stack, scr->pt.r12);
 	err |= setup_sigcontext(&frame->sc, set, scr);
 
-	if (unlikely(err))
-		return force_sigsegv_info(ksig->sig, frame);
+	if (unlikely(err)) {
+		force_sigsegv(ksig->sig, current);
+		return 1;
+	}
 
 	scr->pt.r12 = (unsigned long) frame - 16;	/* new stack pointer */
 	scr->pt.ar_fpsr = FPSR_DEFAULT;			/* reset fpsr for signal handler */
diff --git a/arch/ia64/kernel/traps.c b/arch/ia64/kernel/traps.c
index c6f4932073a1..85d8616ac4f6 100644
--- a/arch/ia64/kernel/traps.c
+++ b/arch/ia64/kernel/traps.c
@@ -100,16 +100,8 @@ die_if_kernel (char *str, struct pt_regs *regs, long err)
 void
 __kprobes ia64_bad_break (unsigned long break_num, struct pt_regs *regs)
 {
-	siginfo_t siginfo;
 	int sig, code;
 
-	/* SIGILL, SIGFPE, SIGSEGV, and SIGBUS want these field initialized: */
-	clear_siginfo(&siginfo);
-	siginfo.si_addr = (void __user *) (regs->cr_iip + ia64_psr(regs)->ri);
-	siginfo.si_imm = break_num;
-	siginfo.si_flags = 0;		/* clear __ISR_VALID */
-	siginfo.si_isr = 0;
-
 	switch (break_num) {
 	      case 0: /* unknown error (used by GCC for __builtin_abort()) */
 		if (notify_die(DIE_BREAK, "break 0", regs, break_num, TRAP_BRKPT, SIGTRAP)
@@ -182,10 +174,9 @@ __kprobes ia64_bad_break (unsigned long break_num, struct pt_regs *regs)
 			sig = SIGTRAP; code = TRAP_BRKPT;
 		}
 	}
-	siginfo.si_signo = sig;
-	siginfo.si_errno = 0;
-	siginfo.si_code = code;
-	force_sig_info(sig, &siginfo, current);
+	force_sig_fault(sig, code,
+			(void __user *) (regs->cr_iip + ia64_psr(regs)->ri),
+			break_num, 0 /* clear __ISR_VALID */, 0, current);
 }
 
 /*
@@ -344,30 +335,25 @@ handle_fpu_swa (int fp_fault, struct pt_regs *regs, unsigned long isr)
 			printk(KERN_ERR "handle_fpu_swa: fp_emulate() returned -1\n");
 			return -1;
 		} else {
-			struct siginfo siginfo;
-
 			/* is next instruction a trap? */
+			int si_code;
+
 			if (exception & 2) {
 				ia64_increment_ip(regs);
 			}
-			clear_siginfo(&siginfo);
-			siginfo.si_signo = SIGFPE;
-			siginfo.si_errno = 0;
-			siginfo.si_code = FPE_FLTUNK;	/* default code */
-			siginfo.si_addr = (void __user *) (regs->cr_iip + ia64_psr(regs)->ri);
+			si_code = FPE_FLTUNK;	/* default code */
 			if (isr & 0x11) {
-				siginfo.si_code = FPE_FLTINV;
+				si_code = FPE_FLTINV;
 			} else if (isr & 0x22) {
 				/* denormal operand gets the same si_code as underflow 
 				* see arch/i386/kernel/traps.c:math_error()  */
-				siginfo.si_code = FPE_FLTUND;
+				si_code = FPE_FLTUND;
 			} else if (isr & 0x44) {
-				siginfo.si_code = FPE_FLTDIV;
+				si_code = FPE_FLTDIV;
 			}
-			siginfo.si_isr = isr;
-			siginfo.si_flags = __ISR_VALID;
-			siginfo.si_imm = 0;
-			force_sig_info(SIGFPE, &siginfo, current);
+			force_sig_fault(SIGFPE, si_code,
+					(void __user *) (regs->cr_iip + ia64_psr(regs)->ri),
+					0, __ISR_VALID, isr, current);
 		}
 	} else {
 		if (exception == -1) {
@@ -375,24 +361,19 @@ handle_fpu_swa (int fp_fault, struct pt_regs *regs, unsigned long isr)
 			return -1;
 		} else if (exception != 0) {
 			/* raise exception */
-			struct siginfo siginfo;
+			int si_code;
 
-			clear_siginfo(&siginfo);
-			siginfo.si_signo = SIGFPE;
-			siginfo.si_errno = 0;
-			siginfo.si_code = FPE_FLTUNK;	/* default code */
-			siginfo.si_addr = (void __user *) (regs->cr_iip + ia64_psr(regs)->ri);
+			si_code = FPE_FLTUNK;	/* default code */
 			if (isr & 0x880) {
-				siginfo.si_code = FPE_FLTOVF;
+				si_code = FPE_FLTOVF;
 			} else if (isr & 0x1100) {
-				siginfo.si_code = FPE_FLTUND;
+				si_code = FPE_FLTUND;
 			} else if (isr & 0x2200) {
-				siginfo.si_code = FPE_FLTRES;
+				si_code = FPE_FLTRES;
 			}
-			siginfo.si_isr = isr;
-			siginfo.si_flags = __ISR_VALID;
-			siginfo.si_imm = 0;
-			force_sig_info(SIGFPE, &siginfo, current);
+			force_sig_fault(SIGFPE, si_code,
+					(void __user *) (regs->cr_iip + ia64_psr(regs)->ri),
+					0, __ISR_VALID, isr, current);
 		}
 	}
 	return 0;
@@ -408,7 +389,6 @@ ia64_illegal_op_fault (unsigned long ec, long arg1, long arg2, long arg3,
 		       struct pt_regs regs)
 {
 	struct illegal_op_return rv;
-	struct siginfo si;
 	char buf[128];
 
 #ifdef CONFIG_IA64_BRL_EMU
@@ -426,11 +406,9 @@ ia64_illegal_op_fault (unsigned long ec, long arg1, long arg2, long arg3,
 	if (die_if_kernel(buf, &regs, 0))
 		return rv;
 
-	clear_siginfo(&si);
-	si.si_signo = SIGILL;
-	si.si_code = ILL_ILLOPC;
-	si.si_addr = (void __user *) (regs.cr_iip + ia64_psr(&regs)->ri);
-	force_sig_info(SIGILL, &si, current);
+	force_sig_fault(SIGILL, ILL_ILLOPC,
+			(void __user *) (regs.cr_iip + ia64_psr(&regs)->ri),
+			0, 0, 0, current);
 	return rv;
 }
 
@@ -441,7 +419,7 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 {
 	unsigned long code, error = isr, iip;
 	char buf[128];
-	int result, sig;
+	int result, sig, si_code;
 	static const char *reason[] = {
 		"IA-64 Illegal Operation fault",
 		"IA-64 Privileged Operation fault",
@@ -490,7 +468,6 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 
 	      case 26: /* NaT Consumption */
 		if (user_mode(&regs)) {
-			struct siginfo siginfo;
 			void __user *addr;
 
 			if (((isr >> 4) & 0xf) == 2) {
@@ -505,15 +482,8 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 				addr = (void __user *) (regs.cr_iip
 							+ ia64_psr(&regs)->ri);
 			}
-			clear_siginfo(&siginfo);
-			siginfo.si_signo = sig;
-			siginfo.si_code = code;
-			siginfo.si_errno = 0;
-			siginfo.si_addr = addr;
-			siginfo.si_imm = vector;
-			siginfo.si_flags = __ISR_VALID;
-			siginfo.si_isr = isr;
-			force_sig_info(sig, &siginfo, current);
+			force_sig_fault(sig, code, addr,
+					vector, __ISR_VALID, isr, current);
 			return;
 		} else if (ia64_done_with_exception(&regs))
 			return;
@@ -522,17 +492,8 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 
 	      case 31: /* Unsupported Data Reference */
 		if (user_mode(&regs)) {
-			struct siginfo siginfo;
-
-			clear_siginfo(&siginfo);
-			siginfo.si_signo = SIGILL;
-			siginfo.si_code = ILL_ILLOPN;
-			siginfo.si_errno = 0;
-			siginfo.si_addr = (void __user *) iip;
-			siginfo.si_imm = vector;
-			siginfo.si_flags = __ISR_VALID;
-			siginfo.si_isr = isr;
-			force_sig_info(SIGILL, &siginfo, current);
+			force_sig_fault(SIGILL, ILL_ILLOPN, (void __user *) iip,
+					vector, __ISR_VALID, isr, current);
 			return;
 		}
 		sprintf(buf, "Unsupported data reference");
@@ -541,10 +502,6 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 	      case 29: /* Debug */
 	      case 35: /* Taken Branch Trap */
 	      case 36: /* Single Step Trap */
-	      {
-		struct siginfo siginfo;
-
-		clear_siginfo(&siginfo);
 		if (fsys_mode(current, &regs)) {
 			extern char __kernel_syscall_via_break[];
 			/*
@@ -568,7 +525,7 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 		switch (vector) {
 		      default:
 		      case 29:
-			siginfo.si_code = TRAP_HWBKPT;
+			si_code = TRAP_HWBKPT;
 #ifdef CONFIG_ITANIUM
 			/*
 			 * Erratum 10 (IFA may contain incorrect address) now has
@@ -578,37 +535,22 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 			  ifa = regs.cr_iip;
 #endif
 			break;
-		      case 35: siginfo.si_code = TRAP_BRANCH; ifa = 0; break;
-		      case 36: siginfo.si_code = TRAP_TRACE; ifa = 0; break;
+		      case 35: si_code = TRAP_BRANCH; ifa = 0; break;
+		      case 36: si_code = TRAP_TRACE; ifa = 0; break;
 		}
-		if (notify_die(DIE_FAULT, "ia64_fault", &regs, vector, siginfo.si_code, SIGTRAP)
+		if (notify_die(DIE_FAULT, "ia64_fault", &regs, vector, si_code, SIGTRAP)
 			       	== NOTIFY_STOP)
 			return;
-		siginfo.si_signo = SIGTRAP;
-		siginfo.si_errno = 0;
-		siginfo.si_addr  = (void __user *) ifa;
-		siginfo.si_imm   = 0;
-		siginfo.si_flags = __ISR_VALID;
-		siginfo.si_isr   = isr;
-		force_sig_info(SIGTRAP, &siginfo, current);
+		force_sig_fault(SIGTRAP, si_code, (void __user *) ifa,
+				0, __ISR_VALID, isr, current);
 		return;
-	      }
 
 	      case 32: /* fp fault */
 	      case 33: /* fp trap */
 		result = handle_fpu_swa((vector == 32) ? 1 : 0, &regs, isr);
 		if ((result < 0) || (current->thread.flags & IA64_THREAD_FPEMU_SIGFPE)) {
-			struct siginfo siginfo;
-
-			clear_siginfo(&siginfo);
-			siginfo.si_signo = SIGFPE;
-			siginfo.si_errno = 0;
-			siginfo.si_code = FPE_FLTINV;
-			siginfo.si_addr = (void __user *) iip;
-			siginfo.si_flags = __ISR_VALID;
-			siginfo.si_isr = isr;
-			siginfo.si_imm = 0;
-			force_sig_info(SIGFPE, &siginfo, current);
+			force_sig_fault(SIGFPE, FPE_FLTINV, (void __user *) iip,
+					0, __ISR_VALID, isr, current);
 		}
 		return;
 
@@ -634,17 +576,9 @@ ia64_fault (unsigned long vector, unsigned long isr, unsigned long ifa,
 		} else {
 			/* Unimplemented Instr. Address Trap */
 			if (user_mode(&regs)) {
-				struct siginfo siginfo;
-
-				clear_siginfo(&siginfo);
-				siginfo.si_signo = SIGILL;
-				siginfo.si_code = ILL_BADIADDR;
-				siginfo.si_errno = 0;
-				siginfo.si_flags = 0;
-				siginfo.si_isr = 0;
-				siginfo.si_imm = 0;
-				siginfo.si_addr = (void __user *) iip;
-				force_sig_info(SIGILL, &siginfo, current);
+				force_sig_fault(SIGILL, ILL_BADIADDR,
+						(void __user *) iip,
+						0, 0, 0, current);
 				return;
 			}
 			sprintf(buf, "Unimplemented Instruction Address fault");
diff --git a/arch/ia64/kernel/unaligned.c b/arch/ia64/kernel/unaligned.c
index e309f9859acc..a167a3824b35 100644
--- a/arch/ia64/kernel/unaligned.c
+++ b/arch/ia64/kernel/unaligned.c
@@ -1298,7 +1298,6 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs)
 	mm_segment_t old_fs = get_fs();
 	unsigned long bundle[2];
 	unsigned long opcode;
-	struct siginfo si;
 	const struct exception_table_entry *eh = NULL;
 	union {
 		unsigned long l;
@@ -1537,14 +1536,7 @@ ia64_handle_unaligned (unsigned long ifa, struct pt_regs *regs)
 		/* NOT_REACHED */
 	}
   force_sigbus:
-	clear_siginfo(&si);
-	si.si_signo = SIGBUS;
-	si.si_errno = 0;
-	si.si_code = BUS_ADRALN;
-	si.si_addr = (void __user *) ifa;
-	si.si_flags = 0;
-	si.si_isr = 0;
-	si.si_imm = 0;
-	force_sig_info(SIGBUS, &si, current);
+	force_sig_fault(SIGBUS, BUS_ADRALN, (void __user *) ifa,
+			0, 0, 0, current);
 	goto done;
 }