Hi,
These trivial fixes apply to today's linux.git (5.4-rc3, or maybe -rc4, by
the time I send this).
I found these while polishing up the Next And Final get_user_pages()+dma
tracking patchset (which is in final testing and passing nicely...so far).
Anyway, as these two patches apply cleanly both before and after the larger
gup/dma upcoming patchset, I thought it best to send this out separately,
in order to avoid muddying the waters more than usual.
Cc: Christoph Hellwig <hch(a)lst.de>
Cc: Aneesh Kumar K.V <aneesh.kumar(a)linux.ibm.com>
Cc: Kirill A. Shutemov <kirill.shutemov(a)linux.intel.com>
Cc: Keith Busch <keith.busch(a)intel.com>
Cc: Shuah Khan <shuah(a)kernel.org>
Cc: linux-kselftest(a)vger.kernel.org
John Hubbard (2):
mm/gup_benchmark: add a missing "w" to getopt string
mm/gup: fix a misnamed "write" argument: should be "flags"
mm/gup.c | 12 +++++++-----
tools/testing/selftests/vm/gup_benchmark.c | 2 +-
2 files changed, 8 insertions(+), 6 deletions(-)
--
2.23.0
Reset all signal handlers of the child not set to SIG_IGN to SIG_DFL.
Mutually exclusive with CLONE_SIGHAND to not disturb other thread's
signal handler.
In the spirit of closer cooperation between glibc developers and kernel
developers (cf. [2]) this patchset came out of a discussion on the glibc
mailing list for improving posix_spawn() (cf. [1], [3], [4]). Kernel
support for this feature has been explicitly requested by glibc and I
see no reason not to help them with this.
The child helper process on Linux posix_spawn must ensure that no signal
handlers are enabled, so the signal disposition must be either SIG_DFL
or SIG_IGN. However, it requires a sigprocmask to obtain the current
signal mask and at least _NSIG sigaction calls to reset the signal
handlers for each posix_spawn call or complex state tracking that might
lead to data corruption in glibc. Adding this flags lets glibc avoid
these problems.
[1]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00149.html
[3]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00158.html
[4]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00160.html
[2]: https://lwn.net/Articles/799331/
'[...] by asking for better cooperation with the C-library projects
in general. They should be copied on patches containing ABI
changes, for example. I noted that there are often times where
C-library developers wish the kernel community had done things
differently; how could those be avoided in the future? Members of
the audience suggested that more glibc developers should perhaps
join the linux-api list. The other suggestion was to "copy Florian
on everything".'
Cc: Oleg Nesterov <oleg(a)redhat.com>
Cc: Florian Weimer <fweimer(a)redhat.com>
Cc: libc-alpha(a)sourceware.org
Signed-off-by: Christian Brauner <christian.brauner(a)ubuntu.com>
---
include/uapi/linux/sched.h | 3 +++
kernel/fork.c | 11 ++++++++++-
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index 99335e1f4a27..c583720f689f 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -33,6 +33,9 @@
#define CLONE_NEWNET 0x40000000 /* New network namespace */
#define CLONE_IO 0x80000000 /* Clone io context */
+/* Flags for the clone3() syscall */
+#define CLONE3_CLEAR_SIGHAND 0x100000000ULL /* Clear any signal handler and reset to SIG_DFL. */
+
#ifndef __ASSEMBLY__
/**
* struct clone_args - arguments for the clone3 syscall
diff --git a/kernel/fork.c b/kernel/fork.c
index 1f6c45f6a734..661f8d1f3881 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1517,6 +1517,11 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
spin_lock_irq(¤t->sighand->siglock);
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
spin_unlock_irq(¤t->sighand->siglock);
+
+ /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
+ if (clone_flags & CLONE3_CLEAR_SIGHAND)
+ flush_signal_handlers(tsk, 0);
+
return 0;
}
@@ -2567,7 +2572,7 @@ static bool clone3_args_valid(const struct kernel_clone_args *kargs)
* All lower bits of the flag word are taken.
* Verify that no other unknown flags are passed along.
*/
- if (kargs->flags & ~CLONE_LEGACY_FLAGS)
+ if (kargs->flags & ~(CLONE_LEGACY_FLAGS | CLONE3_CLEAR_SIGHAND))
return false;
/*
@@ -2577,6 +2582,10 @@ static bool clone3_args_valid(const struct kernel_clone_args *kargs)
if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
return false;
+ if ((kargs->flags & (CLONE_SIGHAND | CLONE3_CLEAR_SIGHAND)) ==
+ (CLONE_SIGHAND | CLONE3_CLEAR_SIGHAND))
+ return false;
+
if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
kargs->exit_signal)
return false;
--
2.23.0
Reset all signal handlers of the child not set to SIG_IGN to SIG_DFL.
Mutually exclusive with CLONE_SIGHAND to not disturb other thread's
signal handler.
In the spirit of closer cooperation between glibc developers and kernel
developers (cf. [2]) this patchset came out of a discussion on the glibc
mailing list for improving posix_spawn() (cf. [1], [3], [4]). Kernel
support for this feature has been explicitly requested by glibc and I
see no reason not to help them with this.
The child helper process on Linux posix_spawn must ensure that no signal
handlers are enabled, so the signal disposition must be either SIG_DFL
or SIG_IGN. However, it requires a sigprocmask to obtain the current
signal mask and at least _NSIG sigaction calls to reset the signal
handlers for each posix_spawn call or complex state tracking that might
lead to data corruption in glibc. Adding this flags lets glibc avoid
these problems.
[1]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00149.html
[3]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00158.html
[4]: https://www.sourceware.org/ml/libc-alpha/2019-10/msg00160.html
[2]: https://lwn.net/Articles/799331/
'[...] by asking for better cooperation with the C-library projects
in general. They should be copied on patches containing ABI
changes, for example. I noted that there are often times where
C-library developers wish the kernel community had done things
differently; how could those be avoided in the future? Members of
the audience suggested that more glibc developers should perhaps
join the linux-api list. The other suggestion was to "copy Florian
on everything".'
Cc: Oleg Nesterov <oleg(a)redhat.com>
Cc: Florian Weimer <fweimer(a)redhat.com>
Cc: libc-alpha(a)sourceware.org
Cc: linux-api(a)vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner(a)ubuntu.com>
---
/* v1 */
Link: https://lore.kernel.org/r/20191010133518.5420-1-christian.brauner@ubuntu.com
/* v2 */
- Florian Weimer <fweimer(a)redhat.com>:
- update comment in clone3_args_valid()
---
include/uapi/linux/sched.h | 3 +++
kernel/fork.c | 16 +++++++++++-----
2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/include/uapi/linux/sched.h b/include/uapi/linux/sched.h
index 99335e1f4a27..c583720f689f 100644
--- a/include/uapi/linux/sched.h
+++ b/include/uapi/linux/sched.h
@@ -33,6 +33,9 @@
#define CLONE_NEWNET 0x40000000 /* New network namespace */
#define CLONE_IO 0x80000000 /* Clone io context */
+/* Flags for the clone3() syscall */
+#define CLONE3_CLEAR_SIGHAND 0x100000000ULL /* Clear any signal handler and reset to SIG_DFL. */
+
#ifndef __ASSEMBLY__
/**
* struct clone_args - arguments for the clone3 syscall
diff --git a/kernel/fork.c b/kernel/fork.c
index 1f6c45f6a734..0a0269cb2c18 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1517,6 +1517,11 @@ static int copy_sighand(unsigned long clone_flags, struct task_struct *tsk)
spin_lock_irq(¤t->sighand->siglock);
memcpy(sig->action, current->sighand->action, sizeof(sig->action));
spin_unlock_irq(¤t->sighand->siglock);
+
+ /* Reset all signal handler not set to SIG_IGN to SIG_DFL. */
+ if (clone_flags & CLONE3_CLEAR_SIGHAND)
+ flush_signal_handlers(tsk, 0);
+
return 0;
}
@@ -2563,11 +2568,8 @@ noinline static int copy_clone_args_from_user(struct kernel_clone_args *kargs,
static bool clone3_args_valid(const struct kernel_clone_args *kargs)
{
- /*
- * All lower bits of the flag word are taken.
- * Verify that no other unknown flags are passed along.
- */
- if (kargs->flags & ~CLONE_LEGACY_FLAGS)
+ /* Verify that no unknown flags are passed along. */
+ if (kargs->flags & ~(CLONE_LEGACY_FLAGS | CLONE3_CLEAR_SIGHAND))
return false;
/*
@@ -2577,6 +2579,10 @@ static bool clone3_args_valid(const struct kernel_clone_args *kargs)
if (kargs->flags & (CLONE_DETACHED | CSIGNAL))
return false;
+ if ((kargs->flags & (CLONE_SIGHAND | CLONE3_CLEAR_SIGHAND)) ==
+ (CLONE_SIGHAND | CLONE3_CLEAR_SIGHAND))
+ return false;
+
if ((kargs->flags & (CLONE_THREAD | CLONE_PARENT)) &&
kargs->exit_signal)
return false;
--
2.23.0
Hey everyone,
/* v2 */
This is the patchset coming out of the KSummit session Kees and I gave
in Lisbon last week (cf. [3] which also contains slides with more
details on related things such as deep argument inspection).
The simple idea is to extend the seccomp notifier to allow for the
continuation of a syscall. The rationale for this can be found in the
commit message to [1]. For the curious there is more detail in [2].
This patchset would unblock supervising an extended set of syscalls such
as mount() where a privileged process is supervising the syscalls of a
lesser privileged process and emulates the syscall for the latter in
userspace.
For more comments on security see [1] and the comments in
include/uapi/linux/seccomp.h added by this patchset.
Kees, if you prefer a pr the series can be pulled from:
git@gitolite.kernel.org:pub/scm/linux/kernel/git/brauner/linux tags/seccomp-notify-syscall-continue-v5.5
For anyone who wants to play with this it's sitting in:
https://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git/log/?h=se…
/* v1 */
Link: https://lore.kernel.org/r/20190919095903.19370-1-christian.brauner@ubuntu.c…
- Kees Cook <keescook(a)chromium.org>:
- dropped patch because it is already present in linux-next
[PATCH 2/4] seccomp: add two missing ptrace ifdefines
Link: https://lore.kernel.org/r/20190918084833.9369-3-christian.brauner@ubuntu.com
/* v0 */
Link: https://lore.kernel.org/r/20190918084833.9369-1-christian.brauner@ubuntu.com
Thanks!
Christian
*** BLURB HERE ***
Christian Brauner (3):
seccomp: add SECCOMP_USER_NOTIF_FLAG_CONTINUE
seccomp: avoid overflow in implicit constant conversion
seccomp: test SECCOMP_USER_NOTIF_FLAG_CONTINUE
include/uapi/linux/seccomp.h | 28 +++++
kernel/seccomp.c | 28 ++++-
tools/testing/selftests/seccomp/seccomp_bpf.c | 110 +++++++++++++++++-
3 files changed, 159 insertions(+), 7 deletions(-)
--
2.23.0
First attempt at wrapping the Syzkaller reproducers in the LTP library. I am
posting this in case anyone wants to experiment with it early or has a
radically different approach in mind.
This just uses exec to run the reproducer executables as per Metan's
suggestion. There is a simple script which creates a runtest file allowing it
to work with existing LTP test runners, albeit with a bit of extra work for
now.
This would benefit from the following LTP library patch:
https://patchwork.ozlabs.org/patch/935568/
Running it without KASAN and the other kernel debugging options is not a good
idea. We can easily detect when the kernel config is wrong and print a
warning or even refuse to run, but I haven't added it yet.
Having to download, compile and install the reproducers seperately is annoying
and I bet most users won't do it. We can probably automate that as part of the
install, it is just a question of how much we do as default.
---
runtest/.gitignore | 1 +
testcases/kernel/Makefile | 1 +
testcases/kernel/syzkaller-repros/.gitignore | 1 +
testcases/kernel/syzkaller-repros/Makefile | 10 +++
testcases/kernel/syzkaller-repros/README.md | 39 +++++++++
.../kernel/syzkaller-repros/gen-runtest.sh | 8 ++
testcases/kernel/syzkaller-repros/syzwrap.c | 85 +++++++++++++++++++
7 files changed, 145 insertions(+)
create mode 100644 runtest/.gitignore
create mode 100644 testcases/kernel/syzkaller-repros/.gitignore
create mode 100644 testcases/kernel/syzkaller-repros/Makefile
create mode 100644 testcases/kernel/syzkaller-repros/README.md
create mode 100755 testcases/kernel/syzkaller-repros/gen-runtest.sh
create mode 100644 testcases/kernel/syzkaller-repros/syzwrap.c
diff --git a/runtest/.gitignore b/runtest/.gitignore
new file mode 100644
index 000000000..e3725dd42
--- /dev/null
+++ b/runtest/.gitignore
@@ -0,0 +1 @@
+syzkaller-repros
diff --git a/testcases/kernel/Makefile b/testcases/kernel/Makefile
index 3319b3163..0150cfb4f 100644
--- a/testcases/kernel/Makefile
+++ b/testcases/kernel/Makefile
@@ -53,6 +53,7 @@ SUBDIRS += connectors \
sched \
security \
sound \
+ syzkaller-repros \
tracing \
uevents \
diff --git a/testcases/kernel/syzkaller-repros/.gitignore b/testcases/kernel/syzkaller-repros/.gitignore
new file mode 100644
index 000000000..dbda1c71f
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/.gitignore
@@ -0,0 +1 @@
+syzwrap
diff --git a/testcases/kernel/syzkaller-repros/Makefile b/testcases/kernel/syzkaller-repros/Makefile
new file mode 100644
index 000000000..8e74805c2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/Makefile
@@ -0,0 +1,10 @@
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2019 Linux Test Project
+
+top_srcdir ?= ../../..
+
+include $(top_srcdir)/include/mk/testcases.mk
+
+CFLAGS += -D_GNU_SOURCE
+
+include $(top_srcdir)/include/mk/generic_leaf_target.mk
diff --git a/testcases/kernel/syzkaller-repros/README.md b/testcases/kernel/syzkaller-repros/README.md
new file mode 100644
index 000000000..e95ae19e2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/README.md
@@ -0,0 +1,39 @@
+LTP wrapper for Syzkaller reproducers
+=====================================
+
+This allows you to run the autogenerated bug reproducers from the Syzkaller
+fuzzer within the LTP framework. Meaning that you may use an existing test
+runner compatible with the LTP.
+
+However some extra setup is currently required.
+
+Instructions
+------------
+
+1. Download and compile the reproducers.
+2. Build the LTP as normal
+3. Use the gen-runtest.sh script to create a runtest file
+4. Install the LTP and the reproducers to the SUT
+5. Execute the tests in the syzkaller-repros runtest file
+
+For now you can download the reproducers from here:
+https://github.com/dvyukov/syzkaller-repros. Soon they will be available on
+kernel.org.
+
+The gen-runtest takes two arguments:
+
+1. The directory where the reproducer executables are currently accessible
+2. The *absolute* path to the directory where they will be on the SUT (If
+ different, can be omitted)
+
+For example:
+```
+./gen-runtest.sh ~/qa/syzkaller-repros/bin /mnt/syzkaller-repros/bin >
+~/qa/ltp-build/runtest/syzkaller-repros
+```
+
+For the LTP, just doing `make install` will copy all the relevant files
+(assuming you put the runtest file in the runtest folder). However you will
+need to copy the reproducers yourself.
+
+
diff --git a/testcases/kernel/syzkaller-repros/gen-runtest.sh b/testcases/kernel/syzkaller-repros/gen-runtest.sh
new file mode 100755
index 000000000..091818fb2
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/gen-runtest.sh
@@ -0,0 +1,8 @@
+#!/usr/bin/sh
+
+BUILD_DIR=$1
+SUT_DIR=$2
+
+for f in $(ls $BUILD_DIR); do
+ echo $f syzwrap -d ${SUT_DIR:-$BUILD_DIR} -n $f
+done
diff --git a/testcases/kernel/syzkaller-repros/syzwrap.c b/testcases/kernel/syzkaller-repros/syzwrap.c
new file mode 100644
index 000000000..7951d1819
--- /dev/null
+++ b/testcases/kernel/syzkaller-repros/syzwrap.c
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2019 Richard Palethorpe <rpalethorpe(a)suse.com>
+ *
+ * Run a single reproducer generated by the Syzkaller fuzzer.
+ */
+
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <signal.h>
+#include <stdio.h>
+
+#include "tst_test.h"
+#include "tst_taint.h"
+#include "tst_safe_stdio.h"
+
+static char *dir;
+static char *name;
+static char *path;
+
+static struct tst_option options[] = {
+ {"d:", &dir, "Mandatory directory containing reproducers"},
+ {"n:", &name, "Mandatory executable name of reproducer"},
+ {NULL, NULL, NULL}
+};
+
+static void setup(void)
+{
+ tst_taint_init(TST_TAINT_W | TST_TAINT_D);
+
+ if (!dir)
+ tst_brk(TBROK, "No reproducer directory specified");
+
+ if (!name)
+ tst_brk(TBROK, "No reproducer name specified");
+
+ tst_res(TINFO, "https://syzkaller.appspot.com/bug?id=%s", name);
+
+ SAFE_ASPRINTF(&path, "%s/%s", dir, name);
+ tst_res(TINFO, "%s", path);
+}
+
+static void run(void)
+{
+ unsigned int backoff = 100;
+ int rem, status, sent_kill = 0;
+ float exec_time_start = (float)tst_timeout_remaining();
+ int pid = SAFE_FORK();
+
+ if (!pid) {
+ execle(path, name, environ);
+ tst_brk(TBROK | TERRNO, "Failed to exec reproducer");
+ }
+
+ while (!waitpid(pid, &status, WNOHANG)) {
+ rem = tst_timeout_remaining();
+
+ if (!sent_kill && rem / exec_time_start < 0.98) {
+ tst_res(TINFO, "Timeout; killing reproducer");
+
+ TEST(kill(pid, SIGKILL));
+ if (TST_RET == -1)
+ tst_res(TWARN | TTERRNO, "kill() failed");
+ else
+ sent_kill = 1;
+ }
+
+ usleep(backoff);
+ backoff = MIN(2 * backoff, 1000000);
+ }
+
+ if (tst_taint_check()) {
+ tst_res(TFAIL, "Kernel is tainted");
+ } else {
+ tst_res(TPASS, "Kernel is not tainted");
+ }
+}
+
+static struct tst_test test = {
+ .setup = setup,
+ .test_all = run,
+ .options = options,
+ .needs_tmpdir = 1,
+ .forks_child = 1,
+};
--
2.23.0