signalfd should be called with the flag SFD_RAW for that.
signalfd_siginfo is not full for siginfo with a negative si_code.
copy_siginfo_to_user() is copied a full siginfo to user-space, if
si_code is negative. signalfd_copyinfo() doesn't do that and can't be
expanded, because it has not compatiable format with siginfo_t.
Another problem is that a constant __SI_* is removed from si_code.
It's not a problem for ussual applications, because they expect
a defined type of siginfo (internal logic).
When we want to dump pending signals, we can't predict a type of
siginfo, so we should get it from kernel.
This fuctionality is required for checkpointing pending signals.
Cc: Alexander Viro <v...@zeniv.linux.org.uk>
Cc: "Paul E. McKenney" <paul...@linux.vnet.ibm.com>
Cc: David Howells <dhowe...@redhat.com>
Cc: Thomas Gleixner <t...@linutronix.de>
Cc: Oleg Nesterov <o...@redhat.com>
Cc: Michael Kerrisk <mtk.manpa...@gmail.com>
Cc: Pavel Emelyanov <xe...@parallels.com>
CC: Cyrill Gorcunov <gorcu...@openvz.org>
Signed-off-by: Andrey Vagin <ava...@openvz.org>
---
fs/signalfd.c | 31 +++++++++++++++++++++++++++++--
include/uapi/linux/signalfd.h | 1 +
2 files changed, 30 insertions(+), 2 deletions(-)
diff --git a/fs/signalfd.c b/fs/signalfd.c
index b534869..95f1444 100644
--- a/fs/signalfd.c
+++ b/fs/signalfd.c
@@ -73,6 +73,21 @@ static unsigned int signalfd_poll(struct file *file,
poll_table *wait)
return events;
}
+static int signalfd_copy_raw_info(struct signalfd_siginfo __user *siginfo,
+ siginfo_t *kinfo)
+{
+ siginfo_t *uinfo = (siginfo_t *) siginfo;
+ int err;
+
+ BUILD_BUG_ON(sizeof(siginfo_t) != sizeof(struct signalfd_siginfo));
+
+ err = __clear_user(uinfo, sizeof(*uinfo));
+ err |= copy_siginfo_to_user(uinfo, kinfo);
+ err |= __put_user(kinfo->si_code, &uinfo->si_code);
+
+ return err ? -EFAULT: sizeof(*uinfo);
+}
+
/*
* Copied from copy_siginfo_to_user() in kernel/signal.c
*/
@@ -205,6 +220,7 @@ static ssize_t signalfd_read(struct file *file, char __user
*buf, size_t count,
struct signalfd_ctx *ctx = file->private_data;
struct signalfd_siginfo __user *siginfo;
int nonblock = file->f_flags & O_NONBLOCK;
+ bool raw = file->f_flags & SFD_RAW;
ssize_t ret, total = 0;
siginfo_t info;
@@ -217,9 +233,15 @@ static ssize_t signalfd_read(struct file *file, char
__user *buf, size_t count,
ret = signalfd_dequeue(ctx, &info, nonblock);
if (unlikely(ret <= 0))
break;
- ret = signalfd_copyinfo(siginfo, &info);
+
+ if (raw)
+ ret = signalfd_copy_raw_info(siginfo, &info);
+ else
+ ret = signalfd_copyinfo(siginfo, &info);
+
if (ret < 0)
break;
+
siginfo++;
total += ret;
nonblock = 1;
@@ -262,7 +284,7 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *,
user_mask,
BUILD_BUG_ON(SFD_CLOEXEC != O_CLOEXEC);
BUILD_BUG_ON(SFD_NONBLOCK != O_NONBLOCK);
- if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK))
+ if (flags & ~(SFD_CLOEXEC | SFD_NONBLOCK | SFD_RAW))
return -EINVAL;
if (sizemask != sizeof(sigset_t) ||
@@ -286,6 +308,11 @@ SYSCALL_DEFINE4(signalfd4, int, ufd, sigset_t __user *,
user_mask,
O_RDWR | (flags & (O_CLOEXEC |
O_NONBLOCK)));
if (ufd < 0)
kfree(ctx);
+ else if (flags & SFD_RAW) {
+ struct fd f = fdget(ufd);
+ f.file->f_flags |= flags & SFD_RAW;
+ fdput(f);
+ }
} else {
struct fd f = fdget(ufd);
if (!f.file)
diff --git a/include/uapi/linux/signalfd.h b/include/uapi/linux/signalfd.h
index 492c6de..bc31849 100644
--- a/include/uapi/linux/signalfd.h
+++ b/include/uapi/linux/signalfd.h
@@ -15,6 +15,7 @@
/* Flags for signalfd4. */
#define SFD_CLOEXEC O_CLOEXEC
#define SFD_NONBLOCK O_NONBLOCK
+#define SFD_RAW O_DIRECT
struct signalfd_siginfo {
__u32 ssi_signo;
--
1.7.11.7
--
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