diff mbox series

[v4,16/30] riscv/shstk: If needed allocate a new shadow stack on clone

Message ID 20240912231650.3740732-17-debug@rivosinc.com
State New
Headers show
Series riscv control-flow integrity for usermode | expand

Commit Message

Deepak Gupta Sept. 12, 2024, 11:16 p.m. UTC 
Userspace specifies CLONE_VM to share address space and spawn new thread.
`clone` allow userspace to specify a new stack for new thread. However
there is no way to specify new shadow stack base address without changing
API. This patch allocates a new shadow stack whenever CLONE_VM is given.

In case of CLONE_VFORK, parent is suspended until child finishes and thus
can child use parent shadow stack. In case of !CLONE_VM, COW kicks in
because entire address space is copied from parent to child.

`clone3` is extensible and can provide mechanisms using which shadow stack
as an input parameter can be provided. This is not settled yet and being
extensively discussed on mailing list. Once that's settled, this commit
will adapt to that.

Signed-off-by: Deepak Gupta <debug@rivosinc.com>
---
 arch/riscv/include/asm/usercfi.h |  45 ++++++++++++
 arch/riscv/kernel/process.c      |  12 ++-
 arch/riscv/kernel/usercfi.c      | 121 +++++++++++++++++++++++++++++++
 3 files changed, 177 insertions(+), 1 deletion(-)

Comments

kernel test robot Sept. 14, 2024, 1:54 a.m. UTC | #1 
Hi Deepak,

kernel test robot noticed the following build warnings:

[auto build test WARNING on shuah-kselftest/next]
[also build test WARNING on shuah-kselftest/fixes tip/x86/core robh/for-next tip/smp/core kees/for-next/execve linus/master v6.11-rc7]
[cannot apply to akpm-mm/mm-everything next-20240913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Deepak-Gupta/mm-Introduce-ARCH_HAS_USER_SHADOW_STACK/20240913-072124
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
patch link:    https://lore.kernel.org/r/20240912231650.3740732-17-debug%40rivosinc.com
patch subject: [PATCH v4 16/30] riscv/shstk: If needed allocate a new shadow stack on clone
config: riscv-defconfig (https://download.01.org/0day-ci/archive/20240914/202409140913.73qFCOmB-lkp@intel.com/config)
compiler: clang version 20.0.0git (https://github.com/llvm/llvm-project bf684034844c660b778f0eba103582f582b710c9)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240914/202409140913.73qFCOmB-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409140913.73qFCOmB-lkp@intel.com/

All warnings (new ones prefixed by >>):

   In file included from arch/riscv/kernel/asm-offsets.c:10:
   In file included from include/linux/mm.h:7:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:8:
   In file included from include/linux/spinlock.h:56:
   In file included from include/linux/preempt.h:79:
   In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
   In file included from include/asm-generic/preempt.h:5:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/riscv/include/asm/thread_info.h:37:
   In file included from arch/riscv/include/asm/processor.h:17:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^
   arch/riscv/include/asm/usercfi.h:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         | ^
         | static 
   In file included from arch/riscv/kernel/asm-offsets.c:10:
   In file included from include/linux/mm.h:2233:
   include/linux/vmstat.h:514:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     514 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
   2 warnings generated.
--
   In file included from arch/riscv/kernel/soc.c:7:
   In file included from include/linux/pgtable.h:6:
   In file included from arch/riscv/include/asm/pgtable.h:9:
   In file included from include/linux/mmzone.h:8:
   In file included from include/linux/spinlock.h:56:
   In file included from include/linux/preempt.h:79:
   In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
   In file included from include/asm-generic/preempt.h:5:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/riscv/include/asm/thread_info.h:37:
   In file included from arch/riscv/include/asm/processor.h:17:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^
   arch/riscv/include/asm/usercfi.h:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         | ^
         | static 
   1 warning generated.
--
   In file included from arch/riscv/kernel/asm-offsets.c:10:
   In file included from include/linux/mm.h:7:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:8:
   In file included from include/linux/spinlock.h:56:
   In file included from include/linux/preempt.h:79:
   In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
   In file included from include/asm-generic/preempt.h:5:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/riscv/include/asm/thread_info.h:37:
   In file included from arch/riscv/include/asm/processor.h:17:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^
   arch/riscv/include/asm/usercfi.h:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         | ^
         | static 
   In file included from arch/riscv/kernel/asm-offsets.c:10:
   In file included from include/linux/mm.h:2233:
   include/linux/vmstat.h:514:36: warning: arithmetic between different enumeration types ('enum node_stat_item' and 'enum lru_list') [-Wenum-enum-conversion]
     514 |         return node_stat_name(NR_LRU_BASE + lru) + 3; // skip "nr_"
         |                               ~~~~~~~~~~~ ^ ~~~
   2 warnings generated.


vim +/get_shstk_base +44 arch/riscv/include/asm/usercfi.h

    43	
  > 44	unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
    45	{
    46		return 0;
    47	}
    48
kernel test robot Sept. 14, 2024, 3:06 a.m. UTC | #2 
Hi Deepak,

kernel test robot noticed the following build errors:

[auto build test ERROR on shuah-kselftest/next]
[also build test ERROR on shuah-kselftest/fixes tip/x86/core robh/for-next arnd-asm-generic/master tip/smp/core kees/for-next/execve linus/master v6.11-rc7]
[cannot apply to akpm-mm/mm-everything next-20240913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Deepak-Gupta/mm-Introduce-ARCH_HAS_USER_SHADOW_STACK/20240913-072124
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
patch link:    https://lore.kernel.org/r/20240912231650.3740732-17-debug%40rivosinc.com
patch subject: [PATCH v4 16/30] riscv/shstk: If needed allocate a new shadow stack on clone
config: riscv-randconfig-001-20240914 (https://download.01.org/0day-ci/archive/20240914/202409141059.SDUgpQw4-lkp@intel.com/config)
compiler: clang version 14.0.6 (https://github.com/llvm/llvm-project f28c006a5895fc0e329fe15fead81e37457cb1d1)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240914/202409141059.SDUgpQw4-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409141059.SDUgpQw4-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

>> clang diag: arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
--
   In file included from drivers/gpu/drm/drm_plane.c:23:
   In file included from include/linux/slab.h:16:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:8:
   In file included from include/linux/spinlock.h:56:
   In file included from include/linux/preempt.h:79:
   In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
   In file included from include/asm-generic/preempt.h:5:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/riscv/include/asm/thread_info.h:37:
   In file included from arch/riscv/include/asm/processor.h:17:
>> arch/riscv/include/asm/usercfi.h:44:15: error: no previous prototype for function 'get_shstk_base' [-Werror,-Wmissing-prototypes]
   unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
                 ^
   arch/riscv/include/asm/usercfi.h:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
   ^
   static 
   1 error generated.
--
   In file included from arch/riscv/kernel/asm-offsets.c:10:
   In file included from include/linux/mm.h:7:
   In file included from include/linux/gfp.h:7:
   In file included from include/linux/mmzone.h:8:
   In file included from include/linux/spinlock.h:56:
   In file included from include/linux/preempt.h:79:
   In file included from ./arch/riscv/include/generated/asm/preempt.h:1:
   In file included from include/asm-generic/preempt.h:5:
   In file included from include/linux/thread_info.h:60:
   In file included from arch/riscv/include/asm/thread_info.h:37:
   In file included from arch/riscv/include/asm/processor.h:17:
   arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
   unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
                 ^
   arch/riscv/include/asm/usercfi.h:44:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
   ^
   static 
   1 warning generated.
>> clang diag: arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]
>> clang diag: arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for function 'get_shstk_base' [-Wmissing-prototypes]


vim +/get_shstk_base +44 arch/riscv/include/asm/usercfi.h

    43	
  > 44	unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
    45	{
    46		return 0;
    47	}
    48
kernel test robot Sept. 14, 2024, 3:26 a.m. UTC | #3 
Hi Deepak,

kernel test robot noticed the following build errors:

[auto build test ERROR on shuah-kselftest/next]
[also build test ERROR on shuah-kselftest/fixes tip/x86/core robh/for-next arnd-asm-generic/master tip/smp/core kees/for-next/execve linus/master v6.11-rc7]
[cannot apply to akpm-mm/mm-everything next-20240913]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Deepak-Gupta/mm-Introduce-ARCH_HAS_USER_SHADOW_STACK/20240913-072124
base:   https://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest.git next
patch link:    https://lore.kernel.org/r/20240912231650.3740732-17-debug%40rivosinc.com
patch subject: [PATCH v4 16/30] riscv/shstk: If needed allocate a new shadow stack on clone
config: riscv-randconfig-r071-20240914 (https://download.01.org/0day-ci/archive/20240914/202409141139.mn5fTYCl-lkp@intel.com/config)
compiler: riscv64-linux-gcc (GCC) 14.1.0
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240914/202409141139.mn5fTYCl-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202409141139.mn5fTYCl-lkp@intel.com/

All error/warnings (new ones prefixed by >>):

   In file included from arch/riscv/include/asm/processor.h:17,
                    from arch/riscv/include/asm/thread_info.h:37,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/riscv/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:79,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/mm.h:7,
                    from arch/riscv/kernel/asm-offsets.c:10:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/sched.h:13,
                    from kernel/ptrace.c:13:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   In file included from include/linux/string.h:374,
                    from include/linux/bitmap.h:13,
                    from include/linux/cpumask.h:12,
                    from arch/riscv/include/asm/processor.h:79:
   In function 'fortify_memcpy_chk',
       inlined from 'syscall_get_arguments.isra' at arch/riscv/include/asm/syscall.h:66:2:
   include/linux/fortify-string.h:580:25: warning: call to '__read_overflow2_field' declared with attribute warning: detected read beyond size of field (2nd parameter); maybe use struct_group()? [-Wattribute-warning]
     580 |                         __read_overflow2_field(q_size_field, size);
         |                         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/mutex.h:19,
                    from include/linux/notifier.h:14,
                    from include/linux/clk.h:14,
                    from lib/vsprintf.c:22:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   lib/vsprintf.c: In function 'va_format':
   lib/vsprintf.c:1683:9: warning: function 'va_format' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
    1683 |         buf += vsnprintf(buf, end > buf ? end - buf : 0, va_fmt->fmt, va);
         |         ^~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/sched.h:13,
                    from include/linux/ratelimit.h:6,
                    from include/linux/dev_printk.h:16,
                    from include/linux/device.h:15,
                    from lib/string_helpers.c:13:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   lib/string_helpers.c: In function 'string_get_size':
   lib/string_helpers.c:124:46: warning: '%03u' directive output may be truncated writing between 3 and 10 bytes into a region of size 7 [-Wformat-truncation=]
     124 |                 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
         |                                              ^~~~
   lib/string_helpers.c:124:44: note: directive argument in the range [0, 4294966295]
     124 |                 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
         |                                            ^~~~~~~
   lib/string_helpers.c:124:17: note: 'snprintf' output between 5 and 12 bytes into a destination of size 8
     124 |                 snprintf(tmp, sizeof(tmp), ".%03u", remainder);
         |                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from arch/riscv/include/asm/thread_info.h:37,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/riscv/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:79,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/umh.h:4,
                    from include/linux/kmod.h:9,
                    from include/linux/module.h:17,
                    from lib/test_bitops.c:10:
>> arch/riscv/include/asm/usercfi.h:44:15: error: no previous prototype for 'get_shstk_base' [-Werror=missing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   cc1: all warnings being treated as errors
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/mutex.h:19,
                    from kernel/locking/lockdep.c:30:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   In file included from kernel/locking/lockdep.c:62:
   kernel/locking/lockdep_internals.h:69:28: warning: 'LOCKF_USED_IN_IRQ_READ' defined but not used [-Wunused-const-variable=]
      69 | static const unsigned long LOCKF_USED_IN_IRQ_READ =
         |                            ^~~~~~~~~~~~~~~~~~~~~~
   kernel/locking/lockdep_internals.h:63:28: warning: 'LOCKF_ENABLED_IRQ_READ' defined but not used [-Wunused-const-variable=]
      63 | static const unsigned long LOCKF_ENABLED_IRQ_READ =
         |                            ^~~~~~~~~~~~~~~~~~~~~~
   kernel/locking/lockdep_internals.h:57:28: warning: 'LOCKF_USED_IN_IRQ' defined but not used [-Wunused-const-variable=]
      57 | static const unsigned long LOCKF_USED_IN_IRQ =
         |                            ^~~~~~~~~~~~~~~~~
   kernel/locking/lockdep_internals.h:51:28: warning: 'LOCKF_ENABLED_IRQ' defined but not used [-Wunused-const-variable=]
      51 | static const unsigned long LOCKF_ENABLED_IRQ =
         |                            ^~~~~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from arch/riscv/include/asm/thread_info.h:37,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/riscv/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:79,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/umh.h:4,
                    from include/linux/kmod.h:9,
                    from include/linux/module.h:17,
                    from net/sunrpc/clnt.c:22:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   net/sunrpc/clnt.c: In function 'rpc_create':
   net/sunrpc/clnt.c:582:75: warning: '%s' directive output may be truncated writing up to 107 bytes into a region of size 48 [-Wformat-truncation=]
     582 |                                 snprintf(servername, sizeof(servername), "%s",
         |                                                                           ^~
   net/sunrpc/clnt.c:582:33: note: 'snprintf' output between 1 and 108 bytes into a destination of size 48
     582 |                                 snprintf(servername, sizeof(servername), "%s",
         |                                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
     583 |                                          sun->sun_path);
         |                                          ~~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from arch/riscv/include/asm/thread_info.h:37,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/riscv/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:79,
                    from include/linux/spinlock.h:56,
                    from include/linux/mmzone.h:8,
                    from include/linux/gfp.h:7,
                    from include/linux/umh.h:4,
                    from include/linux/kmod.h:9,
                    from include/linux/module.h:17,
                    from drivers/clk/clkdev.c:9:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   drivers/clk/clkdev.c: In function 'vclkdev_alloc':
   drivers/clk/clkdev.c:185:17: warning: function 'vclkdev_alloc' might be a candidate for 'gnu_printf' format attribute [-Wsuggest-attribute=format]
     185 |                 res = vsnprintf(cla->dev_id, sizeof(cla->dev_id), dev_fmt, ap);
         |                 ^~~
--
   riscv64-linux-ld: net/dns_resolver/dns_query.o: in function `get_shstk_base':
>> arch/riscv/include/asm/usercfi.h:45: multiple definition of `get_shstk_base'; net/dns_resolver/dns_key.o:arch/riscv/include/asm/usercfi.h:45: first defined here
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/sched.h:13,
                    from include/linux/ratelimit.h:6,
                    from include/linux/dev_printk.h:16,
                    from include/linux/device.h:15,
                    from include/linux/miscdevice.h:7,
                    from drivers/misc/xilinx_sdfec.c:13:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   drivers/misc/xilinx_sdfec.c: In function 'xsdfec_probe':
   drivers/misc/xilinx_sdfec.c:1404:57: warning: '%d' directive output may be truncated writing between 1 and 10 bytes into a region of size 6 [-Wformat-truncation=]
    1404 |         snprintf(xsdfec->dev_name, DEV_NAME_LEN, "xsdfec%d", xsdfec->dev_id);
         |                                                         ^~
   drivers/misc/xilinx_sdfec.c:1404:50: note: directive argument in the range [0, 2147483647]
    1404 |         snprintf(xsdfec->dev_name, DEV_NAME_LEN, "xsdfec%d", xsdfec->dev_id);
         |                                                  ^~~~~~~~~~
   drivers/misc/xilinx_sdfec.c:1404:9: note: 'snprintf' output between 8 and 17 bytes into a destination of size 12
    1404 |         snprintf(xsdfec->dev_name, DEV_NAME_LEN, "xsdfec%d", xsdfec->dev_id);
         |         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
--
   In file included from arch/riscv/include/asm/processor.h:17,
                    from include/linux/sched.h:13,
                    from include/linux/ratelimit.h:6,
                    from include/linux/dev_printk.h:16,
                    from include/linux/device.h:15,
                    from include/linux/node.h:18,
                    from include/linux/cpu.h:17,
                    from kernel/time/hrtimer.c:25:
>> arch/riscv/include/asm/usercfi.h:44:15: warning: no previous prototype for 'get_shstk_base' [-Wmissing-prototypes]
      44 | unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
         |               ^~~~~~~~~~~~~~
   kernel/time/hrtimer.c:121:35: warning: initialized field overwritten [-Woverride-init]
     121 |         [CLOCK_REALTIME]        = HRTIMER_BASE_REALTIME,
         |                                   ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:121:35: note: (near initialization for 'hrtimer_clock_to_base_table[0]')
   kernel/time/hrtimer.c:122:35: warning: initialized field overwritten [-Woverride-init]
     122 |         [CLOCK_MONOTONIC]       = HRTIMER_BASE_MONOTONIC,
         |                                   ^~~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:122:35: note: (near initialization for 'hrtimer_clock_to_base_table[1]')
   kernel/time/hrtimer.c:123:35: warning: initialized field overwritten [-Woverride-init]
     123 |         [CLOCK_BOOTTIME]        = HRTIMER_BASE_BOOTTIME,
         |                                   ^~~~~~~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:123:35: note: (near initialization for 'hrtimer_clock_to_base_table[7]')
   kernel/time/hrtimer.c:124:35: warning: initialized field overwritten [-Woverride-init]
     124 |         [CLOCK_TAI]             = HRTIMER_BASE_TAI,
         |                                   ^~~~~~~~~~~~~~~~
   kernel/time/hrtimer.c:124:35: note: (near initialization for 'hrtimer_clock_to_base_table[11]')
..


vim +/get_shstk_base +44 arch/riscv/include/asm/usercfi.h

    43	
  > 44	unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
  > 45	{
    46		return 0;
    47	}
    48
diff mbox series

Patch

diff --git a/arch/riscv/include/asm/usercfi.h b/arch/riscv/include/asm/usercfi.h
index 4fa201b4fc4e..a6974307ca6c 100644
--- a/arch/riscv/include/asm/usercfi.h
+++ b/arch/riscv/include/asm/usercfi.h
@@ -8,6 +8,9 @@ 
 #ifndef __ASSEMBLY__
 #include <linux/types.h>
 
+struct task_struct;
+struct kernel_clone_args;
+
 #ifdef CONFIG_RISCV_USER_CFI
 struct cfi_status {
 	unsigned long ubcfi_en : 1; /* Enable for backward cfi. */
@@ -17,6 +20,48 @@  struct cfi_status {
 	unsigned long shdw_stk_size; /* size of shadow stack */
 };
 
+unsigned long shstk_alloc_thread_stack(struct task_struct *tsk,
+							const struct kernel_clone_args *args);
+void shstk_release(struct task_struct *tsk);
+void set_shstk_base(struct task_struct *task, unsigned long shstk_addr, unsigned long size);
+unsigned long get_shstk_base(struct task_struct *task, unsigned long *size);
+void set_active_shstk(struct task_struct *task, unsigned long shstk_addr);
+bool is_shstk_enabled(struct task_struct *task);
+
+#else
+
+static inline unsigned long shstk_alloc_thread_stack(struct task_struct *tsk,
+					   const struct kernel_clone_args *args)
+{
+	return 0;
+}
+
+static inline void shstk_release(struct task_struct *tsk)
+{
+
+}
+
+unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
+{
+	return 0;
+}
+
+static inline void set_shstk_base(struct task_struct *task, unsigned long shstk_addr,
+								unsigned long size)
+{
+
+}
+
+static inline void set_active_shstk(struct task_struct *task, unsigned long shstk_addr)
+{
+
+}
+
+static inline bool is_shstk_enabled(struct task_struct *task)
+{
+	return false;
+}
+
 #endif /* CONFIG_RISCV_USER_CFI */
 
 #endif /* __ASSEMBLY__ */
diff --git a/arch/riscv/kernel/process.c b/arch/riscv/kernel/process.c
index 9b66dc07c3d2..6747db72435a 100644
--- a/arch/riscv/kernel/process.c
+++ b/arch/riscv/kernel/process.c
@@ -26,6 +26,7 @@ 
 #include <asm/cpuidle.h>
 #include <asm/vector.h>
 #include <asm/cpufeature.h>
+#include <asm/usercfi.h>
 
 #if defined(CONFIG_STACKPROTECTOR) && !defined(CONFIG_STACKPROTECTOR_PER_TASK)
 #include <linux/stackprotector.h>
@@ -194,7 +195,8 @@  int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src)
 
 void exit_thread(struct task_struct *tsk)
 {
-
+	if (IS_ENABLED(CONFIG_RISCV_USER_CFI))
+		shstk_release(tsk);
 }
 
 int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
@@ -202,6 +204,7 @@  int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 	unsigned long clone_flags = args->flags;
 	unsigned long usp = args->stack;
 	unsigned long tls = args->tls;
+	unsigned long ssp = 0;
 	struct pt_regs *childregs = task_pt_regs(p);
 
 	memset(&p->thread.s, 0, sizeof(p->thread.s));
@@ -216,11 +219,18 @@  int copy_thread(struct task_struct *p, const struct kernel_clone_args *args)
 		p->thread.s[0] = (unsigned long)args->fn;
 		p->thread.s[1] = (unsigned long)args->fn_arg;
 	} else {
+		/* allocate new shadow stack if needed. In case of CLONE_VM we have to */
+		ssp = shstk_alloc_thread_stack(p, args);
+		if (IS_ERR_VALUE(ssp))
+			return PTR_ERR((void *)ssp);
+
 		*childregs = *(current_pt_regs());
 		/* Turn off status.VS */
 		riscv_v_vstate_off(childregs);
 		if (usp) /* User fork */
 			childregs->sp = usp;
+		if (ssp) /* if needed, set new ssp */
+			set_active_shstk(p, ssp);
 		if (clone_flags & CLONE_SETTLS)
 			childregs->tp = tls;
 		childregs->a0 = 0; /* Return value of fork() */
diff --git a/arch/riscv/kernel/usercfi.c b/arch/riscv/kernel/usercfi.c
index ce002eabbdc1..7a7f0b57b2d4 100644
--- a/arch/riscv/kernel/usercfi.c
+++ b/arch/riscv/kernel/usercfi.c
@@ -19,6 +19,41 @@ 
 
 #define SHSTK_ENTRY_SIZE sizeof(void *)
 
+bool is_shstk_enabled(struct task_struct *task)
+{
+	return task->thread_info.user_cfi_state.ubcfi_en ? true : false;
+}
+
+void set_shstk_base(struct task_struct *task, unsigned long shstk_addr, unsigned long size)
+{
+	task->thread_info.user_cfi_state.shdw_stk_base = shstk_addr;
+	task->thread_info.user_cfi_state.shdw_stk_size = size;
+}
+
+unsigned long get_shstk_base(struct task_struct *task, unsigned long *size)
+{
+	if (size)
+		*size = task->thread_info.user_cfi_state.shdw_stk_size;
+	return task->thread_info.user_cfi_state.shdw_stk_base;
+}
+
+void set_active_shstk(struct task_struct *task, unsigned long shstk_addr)
+{
+	task->thread_info.user_cfi_state.user_shdw_stk = shstk_addr;
+}
+
+/*
+ * If size is 0, then to be compatible with regular stack we want it to be as big as
+ * regular stack. Else PAGE_ALIGN it and return back
+ */
+static unsigned long calc_shstk_size(unsigned long size)
+{
+	if (size)
+		return PAGE_ALIGN(size);
+
+	return PAGE_ALIGN(min_t(unsigned long long, rlimit(RLIMIT_STACK), SZ_4G));
+}
+
 /*
  * Writes on shadow stack can either be `sspush` or `ssamoswap`. `sspush` can happen
  * implicitly on current shadow stack pointed to by CSR_SSP. `ssamoswap` takes pointer to
@@ -143,3 +178,89 @@  SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsi
 
 	return allocate_shadow_stack(addr, aligned_size, size, set_tok);
 }
+
+/*
+ * This gets called during clone/clone3/fork. And is needed to allocate a shadow stack for
+ * cases where CLONE_VM is specified and thus a different stack is specified by user. We
+ * thus need a separate shadow stack too. How does separate shadow stack is specified by
+ * user is still being debated. Once that's settled, remove this part of the comment.
+ * This function simply returns 0 if shadow stack are not supported or if separate shadow
+ * stack allocation is not needed (like in case of !CLONE_VM)
+ */
+unsigned long shstk_alloc_thread_stack(struct task_struct *tsk,
+					   const struct kernel_clone_args *args)
+{
+	unsigned long addr, size;
+
+	/* If shadow stack is not supported, return 0 */
+	if (!cpu_supports_shadow_stack())
+		return 0;
+
+	/*
+	 * If shadow stack is not enabled on the new thread, skip any
+	 * switch to a new shadow stack.
+	 */
+	if (is_shstk_enabled(tsk))
+		return 0;
+
+	/*
+	 * For CLONE_VFORK the child will share the parents shadow stack.
+	 * Set base = 0 and size = 0, this is special means to track this state
+	 * so the freeing logic run for child knows to leave it alone.
+	 */
+	if (args->flags & CLONE_VFORK) {
+		set_shstk_base(tsk, 0, 0);
+		return 0;
+	}
+
+	/*
+	 * For !CLONE_VM the child will use a copy of the parents shadow
+	 * stack.
+	 */
+	if (!(args->flags & CLONE_VM))
+		return 0;
+
+	/*
+	 * reaching here means, CLONE_VM was specified and thus a separate shadow
+	 * stack is needed for new cloned thread. Note: below allocation is happening
+	 * using current mm.
+	 */
+	size = calc_shstk_size(args->stack_size);
+	addr = allocate_shadow_stack(0, size, 0, false);
+	if (IS_ERR_VALUE(addr))
+		return addr;
+
+	set_shstk_base(tsk, addr, size);
+
+	return addr + size;
+}
+
+void shstk_release(struct task_struct *tsk)
+{
+	unsigned long base = 0, size = 0;
+	/* If shadow stack is not supported or not enabled, nothing to release */
+	if (!cpu_supports_shadow_stack() ||
+		!is_shstk_enabled(tsk))
+		return;
+
+	/*
+	 * When fork() with CLONE_VM fails, the child (tsk) already has a
+	 * shadow stack allocated, and exit_thread() calls this function to
+	 * free it.  In this case the parent (current) and the child share
+	 * the same mm struct. Move forward only when they're same.
+	 */
+	if (!tsk->mm || tsk->mm != current->mm)
+		return;
+
+	/*
+	 * We know shadow stack is enabled but if base is NULL, then
+	 * this task is not managing its own shadow stack (CLONE_VFORK). So
+	 * skip freeing it.
+	 */
+	base = get_shstk_base(tsk, &size);
+	if (!base)
+		return;
+
+	vm_munmap(base, size);
+	set_shstk_base(tsk, 0, 0);
+}