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Date: Tue, 23 Jan 2018 15:07:17 -0600
From: "Eric W. Biederman" <ebiederm@...ssion.com>
To: linux-kernel@...r.kernel.org
Cc: Al Viro <viro@...iv.linux.org.uk>, Oleg Nesterov <oleg@...hat.com>,
linux-arch@...r.kernel.org, Ram Pai <linuxram@...ibm.com>,
"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 08/10] signal/ptrace: Add force_sig_ptrace_errno_trap and use it where needed
There are so many places that build struct siginfo by hand that at
least one of them is bound to get it wrong. A handful of cases in the
kernel arguably did just that when using the errno field of siginfo to
pass no errno values to userspace. The usage is limited to a single
si_code so at least does not mess up anything else.
Encapsulate this questionable pattern in a helper function so
that the userspace ABI is preserved.
Update all of the places that use this pattern to use the new helper
function.
Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>
---
arch/arm/kernel/ptrace.c | 8 +-------
arch/arm64/kernel/ptrace.c | 6 ++++--
arch/powerpc/kernel/process.c | 9 ++-------
arch/xtensa/kernel/ptrace.c | 8 +-------
include/linux/sched/signal.h | 2 ++
kernel/signal.c | 15 +++++++++++++++
6 files changed, 25 insertions(+), 23 deletions(-)
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 58e3771e4c5b..7724b0f661b3 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -390,7 +390,6 @@ static void ptrace_hbptriggered(struct perf_event *bp,
struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
long num;
int i;
- siginfo_t info;
for (i = 0; i < ARM_MAX_HBP_SLOTS; ++i)
if (current->thread.debug.hbp[i] == bp)
@@ -398,12 +397,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
num = (i == ARM_MAX_HBP_SLOTS) ? 0 : ptrace_hbp_idx_to_num(i);
- info.si_signo = SIGTRAP;
- info.si_errno = (int)num;
- info.si_code = TRAP_HWBKPT;
- info.si_addr = (void __user *)(bkpt->trigger);
-
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_ptrace_errno_trap((int)num, (void __user *)(bkpt->trigger));
}
/*
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index 95daa1478a7c..6618036ae6d4 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -190,21 +190,23 @@ static void ptrace_hbptriggered(struct perf_event *bp,
#ifdef CONFIG_COMPAT
if (is_compat_task()) {
+ int si_errno = 0;
int i;
for (i = 0; i < ARM_MAX_BRP; ++i) {
if (current->thread.debug.hbp_break[i] == bp) {
- info.si_errno = (i << 1) + 1;
+ si_errno = (i << 1) + 1;
break;
}
}
for (i = 0; i < ARM_MAX_WRP; ++i) {
if (current->thread.debug.hbp_watch[i] == bp) {
- info.si_errno = -((i << 1) + 1);
+ si_errno = -((i << 1) + 1);
break;
}
}
+ force_sig_ptrace_errno_trap(si_errno, (void __user *)bkpt->trigger);
}
#endif
force_sig_info(SIGTRAP, &info, current);
diff --git a/arch/powerpc/kernel/process.c b/arch/powerpc/kernel/process.c
index bfb48cf56bc3..4208cbe2fb7f 100644
--- a/arch/powerpc/kernel/process.c
+++ b/arch/powerpc/kernel/process.c
@@ -603,19 +603,14 @@ EXPORT_SYMBOL(flush_all_to_thread);
void do_send_trap(struct pt_regs *regs, unsigned long address,
unsigned long error_code, int breakpt)
{
- siginfo_t info;
-
current->thread.trap_nr = TRAP_HWBKPT;
if (notify_die(DIE_DABR_MATCH, "dabr_match", regs, error_code,
11, SIGSEGV) == NOTIFY_STOP)
return;
/* Deliver the signal to userspace */
- info.si_signo = SIGTRAP;
- info.si_errno = breakpt; /* breakpoint or watchpoint id */
- info.si_code = TRAP_HWBKPT;
- info.si_addr = (void __user *)address;
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_ptrace_errno_trap(breakpt, /* breakpoint or watchpoint id */
+ (void __user *)address);
}
#else /* !CONFIG_PPC_ADV_DEBUG_REGS */
void do_break (struct pt_regs *regs, unsigned long address,
diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c
index e2461968efb2..c0845cb1cbb9 100644
--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -278,7 +278,6 @@ static void ptrace_hbptriggered(struct perf_event *bp,
struct pt_regs *regs)
{
int i;
- siginfo_t info;
struct arch_hw_breakpoint *bkpt = counter_arch_bp(bp);
if (bp->attr.bp_type & HW_BREAKPOINT_X) {
@@ -293,12 +292,7 @@ static void ptrace_hbptriggered(struct perf_event *bp,
i = (i << 1) | 1;
}
- info.si_signo = SIGTRAP;
- info.si_errno = i;
- info.si_code = TRAP_HWBKPT;
- info.si_addr = (void __user *)bkpt->address;
-
- force_sig_info(SIGTRAP, &info, current);
+ force_sig_ptrace_errno_trap(i, (void __user *)bkpt->address);
}
static struct perf_event *ptrace_hbp_create(struct task_struct *tsk, int type)
diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h
index 944fe6356f4a..23b4f9cb82db 100644
--- a/include/linux/sched/signal.h
+++ b/include/linux/sched/signal.h
@@ -311,6 +311,8 @@ int send_sig_mceerr(int code, void __user *, short, struct task_struct *);
int force_sig_bnderr(void __user *addr, void __user *lower, void __user *upper);
int force_sig_pkuerr(void __user *addr, u32 pkey);
+int force_sig_ptrace_errno_trap(int errno, void __user *addr);
+
extern int send_sig_info(int, struct siginfo *, struct task_struct *);
extern int force_sigsegv(int, struct task_struct *);
extern int force_sig_info(int, struct siginfo *, struct task_struct *);
diff --git a/kernel/signal.c b/kernel/signal.c
index 4f6300ef8062..e549174c0831 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1599,6 +1599,21 @@ int force_sig_pkuerr(void __user *addr, u32 pkey)
}
#endif
+/* For the crazy architectures that include trap information in
+ * the errno field, instead of an actual errno value.
+ */
+int force_sig_ptrace_errno_trap(int errno, void __user *addr)
+{
+ struct siginfo info;
+
+ clear_siginfo(&info);
+ info.si_signo = SIGTRAP;
+ info.si_errno = errno;
+ info.si_code = TRAP_HWBKPT;
+ info.si_addr = addr;
+ return force_sig_info(info.si_signo, &info, current);
+}
+
int kill_pgrp(struct pid *pid, int sig, int priv)
{
int ret;
--
2.14.1
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