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Subject[REVIEW][PATCH 4/5] signal: Extend siginfo_layout with SIL_FAULT_{MCEERR|BNDERR|PKUERR}
Update the siginfo_layout function and enum siginfo_layout to represent
all of the possible field layouts of struct siginfo.

This allows the uses of siginfo_layout in um and arm64 where they are testing
for SIL_FAULT to be more accurate as this rules out the other cases.

Further this allows the switch statements on siginfo_layout to be simpler
if perhaps a little more wordy. Making it easier to understand what is
actually going on.

As SIL_FAULT_BNDERR and SIL_FAULT_PKUERR are never expected to appear
in signalfd just treat them as SIL_FAULT. To include them would take
20 extra bytes an pretty much fill up what is left of
signalfd_siginfo.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---
fs/signalfd.c | 24 ++++++++++-----
include/linux/signal.h | 3 ++
kernel/signal.c | 81 ++++++++++++++++++++++++++++++++++----------------
3 files changed, 75 insertions(+), 33 deletions(-)

diff --git a/fs/signalfd.c b/fs/signalfd.c
index f652249f59f9..cbb42f77a2bd 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -112,19 +112,27 @@ static int signalfd_copyinfo(struct signalfd_siginfo __user *uinfo,
new.ssi_band = kinfo->si_band;
new.ssi_fd = kinfo->si_fd;
break;
+ case SIL_FAULT_BNDERR:
+ case SIL_FAULT_PKUERR:
+ /*
+ * Fall through to the SIL_FAULT case. Both SIL_FAULT_BNDERR
+ * and SIL_FAULT_PKUERR are only generated by faults that
+ * deliver them synchronously to userspace. In case someone
+ * injects one of these signals and signalfd catches it treat
+ * it as SIL_FAULT.
+ */
case SIL_FAULT:
new.ssi_addr = (long) kinfo->si_addr;
#ifdef __ARCH_SI_TRAPNO
new.ssi_trapno = kinfo->si_trapno;
#endif
- /*
- * Other callers might not initialize the si_lsb field,
- * so check explicitly for the right codes here.
- */
- if (kinfo->si_signo == SIGBUS &&
- ((kinfo->si_code == BUS_MCEERR_AR) ||
- (kinfo->si_code == BUS_MCEERR_AO)))
- new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
+ break;
+ case SIL_FAULT_MCEERR:
+ new.ssi_addr = (long) kinfo->si_addr;
+#ifdef __ARCH_SI_TRAPNO
+ new.ssi_trapno = kinfo->si_trapno;
+#endif
+ new.ssi_addr_lsb = (short) kinfo->si_addr_lsb;
break;
case SIL_CHLD:
new.ssi_pid = kinfo->si_pid;
diff --git a/include/linux/signal.h b/include/linux/signal.h
index a9bc7e1b077e..3c5200137b24 100644
--- a/include/linux/signal.h
+++ b/include/linux/signal.h
@@ -28,6 +28,9 @@ enum siginfo_layout {
SIL_TIMER,
SIL_POLL,
SIL_FAULT,
+ SIL_FAULT_MCEERR,
+ SIL_FAULT_BNDERR,
+ SIL_FAULT_PKUERR,
SIL_CHLD,
SIL_RT,
SIL_SYS,
diff --git a/kernel/signal.c b/kernel/signal.c
index 376b42f26e6d..8a85da8aaa7c 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2820,8 +2820,19 @@ enum siginfo_layout siginfo_layout(int sig, int si_code)
[SIGPOLL] = { NSIGPOLL, SIL_POLL },
[SIGSYS] = { NSIGSYS, SIL_SYS },
};
- if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit))
+ if ((sig < ARRAY_SIZE(filter)) && (si_code <= filter[sig].limit)) {
layout = filter[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 (si_code <= NSIGPOLL)
layout = SIL_POLL;
} else {
@@ -2878,19 +2889,28 @@ int __copy_siginfo_to_user32(struct compat_siginfo __user *to,
#ifdef __ARCH_SI_TRAPNO
new.si_trapno = from->si_trapno;
#endif
- if ((from->si_signo == SIGBUS) &&
- ((from->si_code == BUS_MCEERR_AR) ||
- (from->si_code == BUS_MCEERR_AO)))
- new.si_addr_lsb = from->si_addr_lsb;
-
- if ((from->si_signo == SIGSEGV) &&
- (from->si_code == SEGV_BNDERR)) {
- new.si_lower = ptr_to_compat(from->si_lower);
- new.si_upper = ptr_to_compat(from->si_upper);
- }
- if ((from->si_signo == SIGSEGV) &&
- (from->si_code == SEGV_PKUERR))
- new.si_pkey = from->si_pkey;
+ break;
+ case SIL_FAULT_MCEERR:
+ new.si_addr = ptr_to_compat(from->si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ new.si_trapno = from->si_trapno;
+#endif
+ new.si_addr_lsb = from->si_addr_lsb;
+ break;
+ case SIL_FAULT_BNDERR:
+ new.si_addr = ptr_to_compat(from->si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ new.si_trapno = from->si_trapno;
+#endif
+ new.si_lower = ptr_to_compat(from->si_lower);
+ new.si_upper = ptr_to_compat(from->si_upper);
+ break;
+ case SIL_FAULT_PKUERR:
+ new.si_addr = ptr_to_compat(from->si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ new.si_trapno = from->si_trapno;
+#endif
+ new.si_pkey = from->si_pkey;
break;
case SIL_CHLD:
new.si_pid = from->si_pid;
@@ -2956,17 +2976,28 @@ int copy_siginfo_from_user32(struct siginfo *to,
#ifdef __ARCH_SI_TRAPNO
to->si_trapno = from.si_trapno;
#endif
- if ((from.si_signo == SIGBUS) &&
- ((from.si_code == BUS_MCEERR_AR) ||
- (from.si_code == BUS_MCEERR_AO)))
- to->si_addr_lsb = from.si_addr_lsb;
-
- if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_BNDERR)) {
- to->si_lower = compat_ptr(from.si_lower);
- to->si_upper = compat_ptr(from.si_upper);
- }
- if ((from.si_signo == SIGSEGV) && (from.si_code == SEGV_PKUERR))
- to->si_pkey = from.si_pkey;
+ break;
+ case SIL_FAULT_MCEERR:
+ to->si_addr = compat_ptr(from.si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ to->si_trapno = from.si_trapno;
+#endif
+ to->si_addr_lsb = from.si_addr_lsb;
+ break;
+ case SIL_FAULT_BNDERR:
+ to->si_addr = compat_ptr(from.si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ to->si_trapno = from.si_trapno;
+#endif
+ to->si_lower = compat_ptr(from.si_lower);
+ to->si_upper = compat_ptr(from.si_upper);
+ break;
+ case SIL_FAULT_PKUERR:
+ to->si_addr = compat_ptr(from.si_addr);
+#ifdef __ARCH_SI_TRAPNO
+ to->si_trapno = from.si_trapno;
+#endif
+ to->si_pkey = from.si_pkey;
break;
case SIL_CHLD:
to->si_pid = from.si_pid;
--
2.14.1
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