Add the missing pieces in order to enable SECCOMP_FILTER on PowerPC
architectures, and enable this support.
Testing has been pursued using libseccomp with the latest ppc support patches
[1][2], on Freescale platforms for both ppc and ppc64. Support on ppc64le has
also been tested, courtesy of Mike Strosaker.
[1] https://groups.google.com/forum/#!topic/libseccomp/oz42LfMDsxg
[2] https://groups.google.com/forum/#!topic/libseccomp/TQWfCt_nD7c
v4:
- rebased on top of 3.19
v3:
- keep setting ENOSYS in syscall entry assembly when syscall tracing is disabled
v2:
- move setting ENOSYS from syscall entry assembly to do_syscall_trace_enter
Bogdan Purcareata (3):
powerpc: Don't force ENOSYS as error on syscall fail
powerpc: Relax secure computing on syscall entry trace
powerpc: Enable HAVE_ARCH_SECCOMP_FILTER
arch/powerpc/Kconfig | 1 +
arch/powerpc/kernel/entry_32.S | 7 ++++++-
arch/powerpc/kernel/entry_64.S | 5 +++--
arch/powerpc/kernel/ptrace.c | 8 ++++++--
4 files changed, 16 insertions(+), 5 deletions(-)
--
2.1.4
In certain scenarios - e.g. seccomp filtering with ERRNO as default action -
the system call fails for other reasons than the syscall not being available.
The seccomp filter can be configured to store a user-defined error code on
return from a blacklisted syscall. Don't always set ENOSYS on
do_syscall_trace_enter failure.
Delegate setting ENOSYS in case of failure, where appropriate, to
do_syscall_trace_enter.
v4:
- update syscall_exit to be local label on 64bit, after rebasing on top of 3.19
v3:
- keep setting ENOSYS in the syscall entry assembly for scenarios without
syscall tracing
v2:
- move setting ENOSYS as errno from the syscall entry assembly to
do_syscall_trace_enter, only in the specific case
Signed-off-by: Bogdan Purcareata <[email protected]>
---
arch/powerpc/kernel/entry_32.S | 7 ++++++-
arch/powerpc/kernel/entry_64.S | 5 +++--
arch/powerpc/kernel/ptrace.c | 4 +++-
3 files changed, 12 insertions(+), 4 deletions(-)
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 46fc0f4..b2f88cd 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -333,12 +333,12 @@ _GLOBAL(DoSyscall)
lwz r11,TI_FLAGS(r10)
andi. r11,r11,_TIF_SYSCALL_DOTRACE
bne- syscall_dotrace
-syscall_dotrace_cont:
cmplwi 0,r0,NR_syscalls
lis r10,sys_call_table@h
ori r10,r10,sys_call_table@l
slwi r0,r0,2
bge- 66f
+syscall_dotrace_cont:
lwzx r10,r10,r0 /* Fetch system call handler [ptr] */
mtlr r10
addi r9,r1,STACK_FRAME_OVERHEAD
@@ -457,6 +457,11 @@ syscall_dotrace:
lwz r7,GPR7(r1)
lwz r8,GPR8(r1)
REST_NVGPRS(r1)
+ cmplwi 0,r0,NR_syscalls
+ lis r10,sys_call_table@h
+ ori r10,r10,sys_call_table@l
+ slwi r0,r0,2
+ bge- ret_from_syscall
b syscall_dotrace_cont
syscall_exit_work:
diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S
index d180caf2..5e7434e 100644
--- a/arch/powerpc/kernel/entry_64.S
+++ b/arch/powerpc/kernel/entry_64.S
@@ -144,7 +144,6 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR)
ld r10,TI_FLAGS(r11)
andi. r11,r10,_TIF_SYSCALL_DOTRACE
bne syscall_dotrace
-.Lsyscall_dotrace_cont:
cmpldi 0,r0,NR_syscalls
bge- syscall_enosys
@@ -253,7 +252,9 @@ syscall_dotrace:
addi r9,r1,STACK_FRAME_OVERHEAD
CURRENT_THREAD_INFO(r10, r1)
ld r10,TI_FLAGS(r10)
- b .Lsyscall_dotrace_cont
+ cmpldi 0,r0,NR_syscalls
+ bge- .Lsyscall_exit
+ b system_call
syscall_enosys:
li r3,-ENOSYS
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index f21897b..2edae06 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1775,13 +1775,15 @@ long do_syscall_trace_enter(struct pt_regs *regs)
secure_computing_strict(regs->gpr[0]);
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
- tracehook_report_syscall_entry(regs))
+ tracehook_report_syscall_entry(regs)) {
/*
* Tracing decided this syscall should not happen.
* We'll return a bogus call number to get an ENOSYS
* error, but leave the original number in regs->gpr[0].
*/
ret = -1L;
+ syscall_set_return_value(current, regs, ENOSYS, 0);
+ }
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->gpr[0]);
--
2.1.4
The secure_computing_strict will just force the kernel to panic on
secure_computing failure. Once SECCOMP_FILTER support is enabled in the kernel,
syscalls can be denied without system failure.
v4:
- rebase on top of 3.19
v3,v2: no changes
Signed-off-by: Bogdan Purcareata <[email protected]>
---
arch/powerpc/kernel/ptrace.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c
index 2edae06..cb9fd33 100644
--- a/arch/powerpc/kernel/ptrace.c
+++ b/arch/powerpc/kernel/ptrace.c
@@ -1772,7 +1772,9 @@ long do_syscall_trace_enter(struct pt_regs *regs)
user_exit();
- secure_computing_strict(regs->gpr[0]);
+ /* Do the secure computing check first; failures should be fast. */
+ if (secure_computing() == -1)
+ return -1L;
if (test_thread_flag(TIF_SYSCALL_TRACE) &&
tracehook_report_syscall_entry(regs)) {
--
2.1.4
Signed-off-by: Bogdan Purcareata <[email protected]>
---
arch/powerpc/Kconfig | 1 +
1 file changed, 1 insertion(+)
diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
index 22b0940..2588b57 100644
--- a/arch/powerpc/Kconfig
+++ b/arch/powerpc/Kconfig
@@ -104,6 +104,7 @@ config PPC
select HAVE_EFFICIENT_UNALIGNED_ACCESS if !CPU_LITTLE_ENDIAN
select HAVE_KPROBES
select HAVE_ARCH_KGDB
+ select HAVE_ARCH_SECCOMP_FILTER
select HAVE_KRETPROBES
select HAVE_ARCH_TRACEHOOK
select HAVE_MEMBLOCK
--
2.1.4
Ping?
On 18.02.2015 10:16, Bogdan Purcareata wrote:
> Add the missing pieces in order to enable SECCOMP_FILTER on PowerPC
> architectures, and enable this support.
>
> Testing has been pursued using libseccomp with the latest ppc support patches
> [1][2], on Freescale platforms for both ppc and ppc64. Support on ppc64le has
> also been tested, courtesy of Mike Strosaker.
>
> [1] https://groups.google.com/forum/#!topic/libseccomp/oz42LfMDsxg
> [2] https://groups.google.com/forum/#!topic/libseccomp/TQWfCt_nD7c
>
> v4:
> - rebased on top of 3.19
>
> v3:
> - keep setting ENOSYS in syscall entry assembly when syscall tracing is disabled
>
> v2:
> - move setting ENOSYS from syscall entry assembly to do_syscall_trace_enter
>
> Bogdan Purcareata (3):
> powerpc: Don't force ENOSYS as error on syscall fail
> powerpc: Relax secure computing on syscall entry trace
> powerpc: Enable HAVE_ARCH_SECCOMP_FILTER
>
> arch/powerpc/Kconfig | 1 +
> arch/powerpc/kernel/entry_32.S | 7 ++++++-
> arch/powerpc/kernel/entry_64.S | 5 +++--
> arch/powerpc/kernel/ptrace.c | 8 ++++++--
> 4 files changed, 16 insertions(+), 5 deletions(-)
>
On Fri, 2015-02-27 at 09:28 +0200, Purcareata Bogdan wrote:
> Ping?
What is the ping for ?
Ben.
> On 18.02.2015 10:16, Bogdan Purcareata wrote:
> > Add the missing pieces in order to enable SECCOMP_FILTER on PowerPC
> > architectures, and enable this support.
> >
> > Testing has been pursued using libseccomp with the latest ppc support patches
> > [1][2], on Freescale platforms for both ppc and ppc64. Support on ppc64le has
> > also been tested, courtesy of Mike Strosaker.
> >
> > [1] https://groups.google.com/forum/#!topic/libseccomp/oz42LfMDsxg
> > [2] https://groups.google.com/forum/#!topic/libseccomp/TQWfCt_nD7c
> >
> > v4:
> > - rebased on top of 3.19
> >
> > v3:
> > - keep setting ENOSYS in syscall entry assembly when syscall tracing is disabled
> >
> > v2:
> > - move setting ENOSYS from syscall entry assembly to do_syscall_trace_enter
> >
> > Bogdan Purcareata (3):
> > powerpc: Don't force ENOSYS as error on syscall fail
> > powerpc: Relax secure computing on syscall entry trace
> > powerpc: Enable HAVE_ARCH_SECCOMP_FILTER
> >
> > arch/powerpc/Kconfig | 1 +
> > arch/powerpc/kernel/entry_32.S | 7 ++++++-
> > arch/powerpc/kernel/entry_64.S | 5 +++--
> > arch/powerpc/kernel/ptrace.c | 8 ++++++--
> > 4 files changed, 16 insertions(+), 5 deletions(-)
> >