[PATCH v3 4/6] signal: Add unsafe_copy_siginfo_to_user32()

[Christophe Leroy]

In the same spirit as commit fb05121fd6a2 ("signal: Add
unsafe_get_compat_sigset()"), implement an 'unsafe' version of
copy_siginfo_to_user32() in order to use it within user access blocks.

To do so, we need inline version of copy_siginfo_to_external32() as we
don't want any function call inside user access blocks.

Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
---
 include/linux/compat.h |  83 +++++++++++++++++++++++++++++-
 include/linux/signal.h |  58 +++++++++++++++++++++
 kernel/signal.c        | 114 +----------------------------------------
 3 files changed, 141 insertions(+), 114 deletions(-)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 8e0598c7d1d1..68823f4b86ee 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -412,6 +412,19 @@ int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
 #ifndef copy_siginfo_to_user32
 #define copy_siginfo_to_user32 __copy_siginfo_to_user32
 #endif
+
+#ifdef CONFIG_COMPAT
+#define unsafe_copy_siginfo_to_user32(to, from, label)	do {		\
+	struct compat_siginfo __user *__ucs_to = to;			\
+	const struct kernel_siginfo *__ucs_from = from;			\
+	struct compat_siginfo __ucs_new = {0};				\
+									\
+	__copy_siginfo_to_external32(&__ucs_new, __ucs_from);		\
+	unsafe_copy_to_user(__ucs_to, &__ucs_new,			\
+			    sizeof(struct compat_siginfo), label);	\
+} while (0)
+#endif
+
 int get_compat_sigevent(struct sigevent *event,
 		const struct compat_sigevent __user *u_event);
 
@@ -992,15 +1005,81 @@ static inline bool in_compat_syscall(void) { return false; }
  * appropriately converted them already.
  */
 #ifndef compat_ptr
-static inline void __user *compat_ptr(compat_uptr_t uptr)
+static __always_inline void __user *compat_ptr(compat_uptr_t uptr)
 {
 	return (void __user *)(unsigned long)uptr;
 }
 #endif
 
-static inline compat_uptr_t ptr_to_compat(void __user *uptr)
+static __always_inline compat_uptr_t ptr_to_compat(void __user *uptr)
 {
 	return (u32)(unsigned long)uptr;
 }
 
+static __always_inline void
+__copy_siginfo_to_external32(struct compat_siginfo *to,
+			     const struct kernel_siginfo *from)
+{
+	to->si_signo = from->si_signo;
+	to->si_errno = from->si_errno;
+	to->si_code  = from->si_code;
+	switch(__siginfo_layout(from->si_signo, from->si_code)) {
+	case SIL_KILL:
+		to->si_pid = from->si_pid;
+		to->si_uid = from->si_uid;
+		break;
+	case SIL_TIMER:
+		to->si_tid     = from->si_tid;
+		to->si_overrun = from->si_overrun;
+		to->si_int     = from->si_int;
+		break;
+	case SIL_POLL:
+		to->si_band = from->si_band;
+		to->si_fd   = from->si_fd;
+		break;
+	case SIL_FAULT:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		break;
+	case SIL_FAULT_TRAPNO:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		to->si_trapno = from->si_trapno;
+		break;
+	case SIL_FAULT_MCEERR:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		to->si_addr_lsb = from->si_addr_lsb;
+		break;
+	case SIL_FAULT_BNDERR:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		to->si_lower = ptr_to_compat(from->si_lower);
+		to->si_upper = ptr_to_compat(from->si_upper);
+		break;
+	case SIL_FAULT_PKUERR:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		to->si_pkey = from->si_pkey;
+		break;
+	case SIL_FAULT_PERF_EVENT:
+		to->si_addr = ptr_to_compat(from->si_addr);
+		to->si_perf_data = from->si_perf_data;
+		to->si_perf_type = from->si_perf_type;
+		break;
+	case SIL_CHLD:
+		to->si_pid = from->si_pid;
+		to->si_uid = from->si_uid;
+		to->si_status = from->si_status;
+		to->si_utime = from->si_utime;
+		to->si_stime = from->si_stime;
+		break;
+	case SIL_RT:
+		to->si_pid = from->si_pid;
+		to->si_uid = from->si_uid;
+		to->si_int = from->si_int;
+		break;
+	case SIL_SYS:
+		to->si_call_addr = ptr_to_compat(from->si_call_addr);
+		to->si_syscall   = from->si_syscall;
+		to->si_arch      = from->si_arch;
+		break;
+	}
+}
+
 #endif /* _LINUX_COMPAT_H */
diff --git a/include/linux/signal.h b/include/linux/signal.h
index 70ea7e741427..637260bc193d 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -65,6 +65,64 @@ enum siginfo_layout {
 	SIL_SYS,
 };
 
+static const struct {
+	unsigned char limit, layout;
+} sig_sicodes[] = {
+	[SIGILL]  = { NSIGILL,  SIL_FAULT },
+	[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
+	[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
+	[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
+	[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
+#if defined(SIGEMT)
+	[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
+#endif
+	[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
+	[SIGPOLL] = { NSIGPOLL, SIL_POLL },
+	[SIGSYS]  = { NSIGSYS,  SIL_SYS },
+};
+
+static __always_inline enum
+siginfo_layout __siginfo_layout(unsigned sig, int si_code)
+{
+	enum siginfo_layout layout = SIL_KILL;
+
+	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
+		if ((sig < ARRAY_SIZE(sig_sicodes)) &&
+		    (si_code <= sig_sicodes[sig].limit)) {
+			layout = sig_sicodes[sig].layout;
+			/* Handle the exceptions */
+			if ((sig == SIGBUS) &&
+			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
+				layout = SIL_FAULT_MCEERR;
+			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
+				layout = SIL_FAULT_BNDERR;
+#ifdef SEGV_PKUERR
+			else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
+				layout = SIL_FAULT_PKUERR;
+#endif
+			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
+				layout = SIL_FAULT_PERF_EVENT;
+			else if (IS_ENABLED(CONFIG_SPARC) &&
+				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
+				layout = SIL_FAULT_TRAPNO;
+			else if (IS_ENABLED(CONFIG_ALPHA) &&
+				 ((sig == SIGFPE) ||
+				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
+				layout = SIL_FAULT_TRAPNO;
+		}
+		else if (si_code <= NSIGPOLL)
+			layout = SIL_POLL;
+	} else {
+		if (si_code == SI_TIMER)
+			layout = SIL_TIMER;
+		else if (si_code == SI_SIGIO)
+			layout = SIL_POLL;
+		else if (si_code < 0)
+			layout = SIL_RT;
+	}
+	return layout;
+}
+
 enum siginfo_layout siginfo_layout(unsigned sig, int si_code);
 
 /*
diff --git a/kernel/signal.c b/kernel/signal.c
index 23f168730b7e..0d402bdb174e 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -3249,22 +3249,6 @@ COMPAT_SYSCALL_DEFINE2(rt_sigpending, compat_sigset_t __user *, uset,
 }
 #endif
 
-static const struct {
-	unsigned char limit, layout;
-} sig_sicodes[] = {
-	[SIGILL]  = { NSIGILL,  SIL_FAULT },
-	[SIGFPE]  = { NSIGFPE,  SIL_FAULT },
-	[SIGSEGV] = { NSIGSEGV, SIL_FAULT },
-	[SIGBUS]  = { NSIGBUS,  SIL_FAULT },
-	[SIGTRAP] = { NSIGTRAP, SIL_FAULT },
-#if defined(SIGEMT)
-	[SIGEMT]  = { NSIGEMT,  SIL_FAULT },
-#endif
-	[SIGCHLD] = { NSIGCHLD, SIL_CHLD },
-	[SIGPOLL] = { NSIGPOLL, SIL_POLL },
-	[SIGSYS]  = { NSIGSYS,  SIL_SYS },
-};
-
 static bool known_siginfo_layout(unsigned sig, int si_code)
 {
 	if (si_code == SI_KERNEL)
@@ -3286,42 +3270,7 @@ static bool known_siginfo_layout(unsigned sig, int si_code)
 
 enum siginfo_layout siginfo_layout(unsigned sig, int si_code)
 {
-	enum siginfo_layout layout = SIL_KILL;
-	if ((si_code > SI_USER) && (si_code < SI_KERNEL)) {
-		if ((sig < ARRAY_SIZE(sig_sicodes)) &&
-		    (si_code <= sig_sicodes[sig].limit)) {
-			layout = sig_sicodes[sig].layout;
-			/* Handle the exceptions */
-			if ((sig == SIGBUS) &&
-			    (si_code >= BUS_MCEERR_AR) && (si_code <= BUS_MCEERR_AO))
-				layout = SIL_FAULT_MCEERR;
-			else if ((sig == SIGSEGV) && (si_code == SEGV_BNDERR))
-				layout = SIL_FAULT_BNDERR;
-#ifdef SEGV_PKUERR
-			else if ((sig == SIGSEGV) && (si_code == SEGV_PKUERR))
-				layout = SIL_FAULT_PKUERR;
-#endif
-			else if ((sig == SIGTRAP) && (si_code == TRAP_PERF))
-				layout = SIL_FAULT_PERF_EVENT;
-			else if (IS_ENABLED(CONFIG_SPARC) &&
-				 (sig == SIGILL) && (si_code == ILL_ILLTRP))
-				layout = SIL_FAULT_TRAPNO;
-			else if (IS_ENABLED(CONFIG_ALPHA) &&
-				 ((sig == SIGFPE) ||
-				  ((sig == SIGTRAP) && (si_code == TRAP_UNK))))
-				layout = SIL_FAULT_TRAPNO;
-		}
-		else if (si_code <= NSIGPOLL)
-			layout = SIL_POLL;
-	} else {
-		if (si_code == SI_TIMER)
-			layout = SIL_TIMER;
-		else if (si_code == SI_SIGIO)
-			layout = SIL_POLL;
-		else if (si_code < 0)
-			layout = SIL_RT;
-	}
-	return layout;
+	return __siginfo_layout(sig, si_code);
 }
 
 int copy_siginfo_to_user(siginfo_t __user *to, const kernel_siginfo_t *from)
@@ -3389,66 +3338,7 @@ void copy_siginfo_to_external32(struct compat_siginfo *to,
 {
 	memset(to, 0, sizeof(*to));
 
-	to->si_signo = from->si_signo;
-	to->si_errno = from->si_errno;
-	to->si_code  = from->si_code;
-	switch(siginfo_layout(from->si_signo, from->si_code)) {
-	case SIL_KILL:
-		to->si_pid = from->si_pid;
-		to->si_uid = from->si_uid;
-		break;
-	case SIL_TIMER:
-		to->si_tid     = from->si_tid;
-		to->si_overrun = from->si_overrun;
-		to->si_int     = from->si_int;
-		break;
-	case SIL_POLL:
-		to->si_band = from->si_band;
-		to->si_fd   = from->si_fd;
-		break;
-	case SIL_FAULT:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		break;
-	case SIL_FAULT_TRAPNO:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_trapno = from->si_trapno;
-		break;
-	case SIL_FAULT_MCEERR:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_addr_lsb = from->si_addr_lsb;
-		break;
-	case SIL_FAULT_BNDERR:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_lower = ptr_to_compat(from->si_lower);
-		to->si_upper = ptr_to_compat(from->si_upper);
-		break;
-	case SIL_FAULT_PKUERR:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_pkey = from->si_pkey;
-		break;
-	case SIL_FAULT_PERF_EVENT:
-		to->si_addr = ptr_to_compat(from->si_addr);
-		to->si_perf_data = from->si_perf_data;
-		to->si_perf_type = from->si_perf_type;
-		break;
-	case SIL_CHLD:
-		to->si_pid = from->si_pid;
-		to->si_uid = from->si_uid;
-		to->si_status = from->si_status;
-		to->si_utime = from->si_utime;
-		to->si_stime = from->si_stime;
-		break;
-	case SIL_RT:
-		to->si_pid = from->si_pid;
-		to->si_uid = from->si_uid;
-		to->si_int = from->si_int;
-		break;
-	case SIL_SYS:
-		to->si_call_addr = ptr_to_compat(from->si_call_addr);
-		to->si_syscall   = from->si_syscall;
-		to->si_arch      = from->si_arch;
-		break;
-	}
+	__copy_siginfo_to_external32(to, from);
 }
 
 int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
-- 
2.31.1