From: Will Drewry <wad@chromium.org>
To: linux-kernel@vger.kernel.org
Cc: linux-arch@vger.kernel.org, linux-doc@vger.kernel.org,
kernel-hardening@lists.openwall.com, netdev@vger.kernel.org,
x86@kernel.org, arnd@arndb.de, davem@davemloft.net,
hpa@zytor.com, mingo@redhat.com, oleg@redhat.com,
peterz@infradead.org, rdunlap@xenotime.net,
mcgrathr@chromium.org, tglx@linutronix.de, luto@mit.edu,
eparis@redhat.com, serge.hallyn@canonical.com, djm@mindrot.org,
scarybeasts@gmail.com, indan@nul.nu, pmoore@redhat.com,
akpm@linux-foundation.org, corbet@lwn.net,
eric.dumazet@gmail.com, markus@chromium.org,
coreyb@linux.vnet.ibm.com, keescook@chromium.org,
Will Drewry <wad@chromium.org>
Subject: [PATCH v15 11/13] ptrace,seccomp: Add PTRACE_SECCOMP support
Date: Wed, 14 Mar 2012 22:12:03 -0500 [thread overview]
Message-ID: <1331781125-15658-12-git-send-email-wad@chromium.org> (raw)
In-Reply-To: <1331781125-15658-1-git-send-email-wad@chromium.org>
This change adds support for a new ptrace option, PTRACE_O_TRACESECCOMP,
and a new return value for seccomp BPF programs, SECCOMP_RET_TRACE.
When a tracer specifies the PTRACE_O_TRACESECCOMP ptrace option, the
tracer will be notified, via PTRACE_EVENT_SECCOMP, for any syscall that
results in a BPF program returning SECCOMP_RET_TRACE. The 16-bit
SECCOMP_RET_DATA mask of the BPF program return value will be passed as
the ptrace_message and may be retrieved using PTRACE_GETEVENTMSG.
If the subordinate process is not using seccomp filter, then no
system call notifications will occur even if the option is specified.
If there is no tracer with PTRACE_O_TRACESECCOMP when SECCOMP_RET_TRACE
is returned, the system call will not be executed and an -ENOSYS errno
will be returned to userspace.
This change adds a dependency on the system call slow path. Any future
efforts to use the system call fast path for seccomp filter will need to
address this restriction.
v15: - add audit support for non-zero return codes
- clean up style (indan@nul.nu)
v14: - rebase/nochanges
v13: - rebase on to 88ebdda6159ffc15699f204c33feb3e431bf9bdc
(Brings back a change to ptrace.c and the masks.)
v12: - rebase to linux-next
- use ptrace_event and update arch/Kconfig to mention slow-path dependency
- drop all tracehook changes and inclusion (oleg@redhat.com)
v11: - invert the logic to just make it a PTRACE_SYSCALL accelerator
(indan@nul.nu)
v10: - moved to PTRACE_O_SECCOMP / PT_TRACE_SECCOMP
v9: - n/a
v8: - guarded PTRACE_SECCOMP use with an ifdef
v7: - introduced
Signed-off-by: Will Drewry <wad@chromium.org>
---
arch/Kconfig | 11 ++++++-----
include/linux/ptrace.h | 7 +++++--
include/linux/seccomp.h | 1 +
kernel/ptrace.c | 3 +++
kernel/seccomp.c | 13 +++++++++++--
5 files changed, 26 insertions(+), 9 deletions(-)
diff --git a/arch/Kconfig b/arch/Kconfig
index d92a78e..3f8132c 100644
--- a/arch/Kconfig
+++ b/arch/Kconfig
@@ -202,15 +202,16 @@ config HAVE_CMPXCHG_DOUBLE
config HAVE_ARCH_SECCOMP_FILTER
bool
help
- This symbol should be selected by an architecure if it provides:
- asm/syscall.h:
+ An arch should select this symbol if it provides all of these things:
- syscall_get_arch()
- syscall_get_arguments()
- syscall_rollback()
- syscall_set_return_value()
- SIGSYS siginfo_t support must be implemented.
- __secure_computing_int()/secure_computing()'s return value must be
- checked, with -1 resulting in the syscall being skipped.
+ - SIGSYS siginfo_t support
+ - uses __secure_computing_int() or secure_computing()
+ - secure_computing is called from a ptrace_event()-safe context
+ - secure_computing return value is checked and a return value of -1
+ results in the system call being skipped immediately.
config SECCOMP_FILTER
def_bool y
diff --git a/include/linux/ptrace.h b/include/linux/ptrace.h
index c2f1f6a..84b3418 100644
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -62,8 +62,9 @@
#define PTRACE_O_TRACEEXEC 0x00000010
#define PTRACE_O_TRACEVFORKDONE 0x00000020
#define PTRACE_O_TRACEEXIT 0x00000040
+#define PTRACE_O_TRACESECCOMP 0x00000080
-#define PTRACE_O_MASK 0x0000007f
+#define PTRACE_O_MASK 0x000000ff
/* Wait extended result codes for the above trace options. */
#define PTRACE_EVENT_FORK 1
@@ -73,6 +74,7 @@
#define PTRACE_EVENT_VFORK_DONE 5
#define PTRACE_EVENT_EXIT 6
#define PTRACE_EVENT_STOP 7
+#define PTRACE_EVENT_SECCOMP 8
#include <asm/ptrace.h>
@@ -101,8 +103,9 @@
#define PT_TRACE_EXEC PT_EVENT_FLAG(PTRACE_EVENT_EXEC)
#define PT_TRACE_VFORK_DONE PT_EVENT_FLAG(PTRACE_EVENT_VFORK_DONE)
#define PT_TRACE_EXIT PT_EVENT_FLAG(PTRACE_EVENT_EXIT)
+#define PT_TRACE_SECCOMP PT_EVENT_FLAG(PTRACE_EVENT_SECCOMP)
-#define PT_TRACE_MASK 0x000003f4
+#define PT_TRACE_MASK 0x00000ff4
/* single stepping state bits (used on ARM and PA-RISC) */
#define PT_SINGLESTEP_BIT 31
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index a5078fb..306733e 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -21,6 +21,7 @@
#define SECCOMP_RET_KILL 0x00000000U /* kill the task immediately */
#define SECCOMP_RET_TRAP 0x00030000U /* disallow and force a SIGSYS */
#define SECCOMP_RET_ERRNO 0x00050000U /* returns an errno */
+#define SECCOMP_RET_TRACE 0x7ff00000U /* pass to a tracer or disallow */
#define SECCOMP_RET_ALLOW 0x7fff0000U /* allow */
/* Masks for the return value sections. */
diff --git a/kernel/ptrace.c b/kernel/ptrace.c
index 00ab2ca..8cf6da1 100644
--- a/kernel/ptrace.c
+++ b/kernel/ptrace.c
@@ -551,6 +551,9 @@ static int ptrace_setoptions(struct task_struct *child, unsigned long data)
if (data & PTRACE_O_TRACEEXIT)
child->ptrace |= PT_TRACE_EXIT;
+ if (data & PTRACE_O_TRACESECCOMP)
+ child->ptrace |= PT_TRACE_SECCOMP;
+
return (data & ~PTRACE_O_MASK) ? -EINVAL : 0;
}
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index fb3b993..725e83e 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -17,13 +17,13 @@
#include <linux/audit.h>
#include <linux/compat.h>
#include <linux/filter.h>
+#include <linux/ptrace.h>
#include <linux/sched.h>
#include <linux/seccomp.h>
#include <linux/security.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
-#include <linux/tracehook.h>
#include <asm/syscall.h>
/* #define SECCOMP_DEBUG 1 */
@@ -398,7 +398,7 @@ int __secure_computing_int(int this_syscall)
case SECCOMP_MODE_FILTER:
ret = seccomp_run_filters(this_syscall);
data = ret & SECCOMP_RET_DATA;
- switch (code & SECCOMP_RET_ACTION) {
+ switch (ret & SECCOMP_RET_ACTION) {
case SECCOMP_RET_ERRNO:
/* Set the low-order 16-bits as a errno. */
syscall_set_return_value(current, task_pt_regs(current),
@@ -410,6 +410,15 @@ int __secure_computing_int(int this_syscall)
/* Let the filter pass back 16 bits of data. */
seccomp_send_sigsys(this_syscall, data);
goto skip;
+ case SECCOMP_RET_TRACE:
+ /* Skip these calls if there is no tracer. */
+ if (!ptrace_event_enabled(current, PTRACE_EVENT_SECCOMP))
+ goto skip;
+ /* Allow the BPF to provide the event message */
+ ptrace_event(PTRACE_EVENT_SECCOMP, data);
+ if (fatal_signal_pending(current))
+ break;
+ return 0;
case SECCOMP_RET_ALLOW:
return 0;
case SECCOMP_RET_KILL:
--
1.7.5.4
next prev parent reply other threads:[~2012-03-15 3:14 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-03-15 3:11 [PATCH v15 00/13] seccomp_filter: syscall filtering using BPF Will Drewry
2012-03-15 3:11 ` [PATCH v15 01/13] sk_run_filter: add BPF_S_ANC_SECCOMP_LD_W Will Drewry
2012-03-16 18:15 ` Eric Dumazet
2012-03-15 3:11 ` [PATCH v15 02/13] net/compat.c,linux/filter.h: share compat_sock_fprog Will Drewry
2012-03-16 18:16 ` Eric Dumazet
2012-03-16 19:23 ` Will Drewry
2012-03-15 3:11 ` [PATCH v15 03/13] seccomp: kill the seccomp_t typedef Will Drewry
2012-03-15 3:11 ` [PATCH v15 04/13] arch/x86: add syscall_get_arch to syscall.h Will Drewry
2012-03-25 19:34 ` H. Peter Anvin
2012-04-11 3:13 ` Will Drewry
2012-04-11 3:16 ` H. Peter Anvin
2012-04-11 3:20 ` H. Peter Anvin
2012-04-11 15:41 ` Will Drewry
2012-03-15 3:11 ` [PATCH v15 05/13] asm/syscall.h: add syscall_get_arch Will Drewry
2012-03-15 3:11 ` [PATCH v15 06/13] seccomp: add system call filtering using BPF Will Drewry
2012-03-25 7:31 ` Vladimir Murzin
2012-03-15 3:11 ` [PATCH v15 07/13] seccomp: remove duplicated failure logging Will Drewry
2012-03-15 3:12 ` [PATCH v15 08/13] seccomp: add SECCOMP_RET_ERRNO Will Drewry
2012-03-15 3:12 ` [PATCH v15 09/13] signal, x86: add SIGSYS info and make it synchronous Will Drewry
2012-03-15 3:12 ` [PATCH v15 10/13] seccomp: Add SECCOMP_RET_TRAP Will Drewry
2012-03-15 3:12 ` Will Drewry [this message]
2012-03-15 4:49 ` [PATCH v15 11/13] ptrace,seccomp: Add PTRACE_SECCOMP support Indan Zupancic
2012-03-15 14:40 ` Will Drewry
2012-03-15 3:12 ` [PATCH v15 12/13] x86: Enable HAVE_ARCH_SECCOMP_FILTER Will Drewry
2012-03-15 3:12 ` [PATCH v15 13/13] Documentation: prctl/seccomp_filter Will Drewry
2012-03-25 19:36 ` [PATCH v15 00/13] seccomp_filter: syscall filtering using BPF H. Peter Anvin
2012-03-26 16:53 ` Will Drewry
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