| Message ID | 20221203003606.6838-40-rick.p.edgecombe@intel.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | Shadow stacks for userspace | expand |
On Fri, Dec 02, 2022 at 04:36:06PM -0800, Rick Edgecombe wrote: > CRIU and GDB need to get the current shadow stack and WRSS enablement > status. This information is already available via /proc/pid/status, but > this is incovienent for CRIU because it involves parsing the text output > in an area of the code where this is difficult. Provide a status > arch_prctl(), ARCH_SHSTK_STATUS for retrieving the status. Have arg2 be a > userspace address, and make the new arch_prctl simply copy the features > out to userspace. > > Tested-by: Pengfei Xu <pengfei.xu@intel.com> > Requested-by: Mike Rapoport <rppt@kernel.org> > Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com> > --- > > v4: > - New patch > > Documentation/x86/shstk.rst | 6 ++++++ > arch/x86/include/asm/shstk.h | 4 ++-- > arch/x86/include/uapi/asm/prctl.h | 1 + > arch/x86/kernel/process_64.c | 1 + > arch/x86/kernel/shstk.c | 8 +++++++- > 5 files changed, 17 insertions(+), 3 deletions(-) > > diff --git a/Documentation/x86/shstk.rst b/Documentation/x86/shstk.rst > index 0d7d1ccfff06..b3eb87046c27 100644 > --- a/Documentation/x86/shstk.rst > +++ b/Documentation/x86/shstk.rst > @@ -77,6 +77,11 @@ arch_prctl(ARCH_SHSTK_UNLOCK, unsigned long features) > Unlock features. 'features' is a mask of all features to unlock. All > bits set are processed, unset bits are ignored. Only works via ptrace. > > +arch_prctl(ARCH_SHSTK_STATUS, unsigned long addr) > + Copy the currently enabled features to the address passed in addr. The > + features are described using the bits passed into the others in > + 'features'. > + > The return values are as following: > On success, return 0. On error, errno can be:: > > @@ -84,6 +89,7 @@ The return values are as following: > -EOPNOTSUPP if the feature is not supported by the hardware or > disabled by kernel parameter. > -EINVAL arguments (non existing feature, etc) > + -EFAULT if could not copy information back to userspace > > The feature's bits supported are:: > > diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h > index c82f22fd5e6d..23bfb63c597d 100644 > --- a/arch/x86/include/asm/shstk.h > +++ b/arch/x86/include/asm/shstk.h > @@ -15,7 +15,7 @@ struct thread_shstk { > u64 size; > }; > > -long shstk_prctl(struct task_struct *task, int option, unsigned long features); > +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2); > void reset_thread_features(void); > int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags, > unsigned long stack_size, > @@ -31,7 +31,7 @@ static inline bool shstk_enabled(void) > } > #else > static inline long shstk_prctl(struct task_struct *task, int option, > - unsigned long features) { return -EINVAL; } > + unsigned long arg2) { return -EINVAL; } > static inline void reset_thread_features(void) {} > static inline int shstk_alloc_thread_stack(struct task_struct *p, > unsigned long clone_flags, > diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h > index 0c95688cf58e..abe3fe6db6d2 100644 > --- a/arch/x86/include/uapi/asm/prctl.h > +++ b/arch/x86/include/uapi/asm/prctl.h > @@ -31,6 +31,7 @@ > #define ARCH_SHSTK_DISABLE 0x5002 > #define ARCH_SHSTK_LOCK 0x5003 > #define ARCH_SHSTK_UNLOCK 0x5004 > +#define ARCH_SHSTK_STATUS 0x5005 > > /* ARCH_SHSTK_ features bits */ > #define ARCH_SHSTK_SHSTK (1ULL << 0) > diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c > index 2be6e01fb144..5dcf5426241b 100644 > --- a/arch/x86/kernel/process_64.c > +++ b/arch/x86/kernel/process_64.c > @@ -922,6 +922,7 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) > case ARCH_SHSTK_DISABLE: > case ARCH_SHSTK_LOCK: > case ARCH_SHSTK_UNLOCK: > + case ARCH_SHSTK_STATUS: > return shstk_prctl(task, option, arg2); > default: > ret = -EINVAL; > diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c > index 95579f7bace3..05f8dcc19dbc 100644 > --- a/arch/x86/kernel/shstk.c > +++ b/arch/x86/kernel/shstk.c > @@ -448,8 +448,14 @@ SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsi > return alloc_shstk(addr, aligned_size, size, set_tok); > } > > -long shstk_prctl(struct task_struct *task, int option, unsigned long features) > +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2) > { > + unsigned long features = arg2; > + > + if (option == ARCH_SHSTK_STATUS) { > + return put_user(task->thread.features, (unsigned long __user *)arg2); > + } Doesn't need the braces, but that's fine by me. Reviewed-by: Kees Cook <keescook@chromium.org> > + > if (option == ARCH_SHSTK_LOCK) { > task->thread.features_locked |= features; > return 0; > -- > 2.17.1 >
diff --git a/Documentation/x86/shstk.rst b/Documentation/x86/shstk.rst index 0d7d1ccfff06..b3eb87046c27 100644 --- a/Documentation/x86/shstk.rst +++ b/Documentation/x86/shstk.rst @@ -77,6 +77,11 @@ arch_prctl(ARCH_SHSTK_UNLOCK, unsigned long features) Unlock features. 'features' is a mask of all features to unlock. All bits set are processed, unset bits are ignored. Only works via ptrace. +arch_prctl(ARCH_SHSTK_STATUS, unsigned long addr) + Copy the currently enabled features to the address passed in addr. The + features are described using the bits passed into the others in + 'features'. + The return values are as following: On success, return 0. On error, errno can be:: @@ -84,6 +89,7 @@ The return values are as following: -EOPNOTSUPP if the feature is not supported by the hardware or disabled by kernel parameter. -EINVAL arguments (non existing feature, etc) + -EFAULT if could not copy information back to userspace The feature's bits supported are:: diff --git a/arch/x86/include/asm/shstk.h b/arch/x86/include/asm/shstk.h index c82f22fd5e6d..23bfb63c597d 100644 --- a/arch/x86/include/asm/shstk.h +++ b/arch/x86/include/asm/shstk.h @@ -15,7 +15,7 @@ struct thread_shstk { u64 size; }; -long shstk_prctl(struct task_struct *task, int option, unsigned long features); +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2); void reset_thread_features(void); int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags, unsigned long stack_size, @@ -31,7 +31,7 @@ static inline bool shstk_enabled(void) } #else static inline long shstk_prctl(struct task_struct *task, int option, - unsigned long features) { return -EINVAL; } + unsigned long arg2) { return -EINVAL; } static inline void reset_thread_features(void) {} static inline int shstk_alloc_thread_stack(struct task_struct *p, unsigned long clone_flags, diff --git a/arch/x86/include/uapi/asm/prctl.h b/arch/x86/include/uapi/asm/prctl.h index 0c95688cf58e..abe3fe6db6d2 100644 --- a/arch/x86/include/uapi/asm/prctl.h +++ b/arch/x86/include/uapi/asm/prctl.h @@ -31,6 +31,7 @@ #define ARCH_SHSTK_DISABLE 0x5002 #define ARCH_SHSTK_LOCK 0x5003 #define ARCH_SHSTK_UNLOCK 0x5004 +#define ARCH_SHSTK_STATUS 0x5005 /* ARCH_SHSTK_ features bits */ #define ARCH_SHSTK_SHSTK (1ULL << 0) diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c index 2be6e01fb144..5dcf5426241b 100644 --- a/arch/x86/kernel/process_64.c +++ b/arch/x86/kernel/process_64.c @@ -922,6 +922,7 @@ long do_arch_prctl_64(struct task_struct *task, int option, unsigned long arg2) case ARCH_SHSTK_DISABLE: case ARCH_SHSTK_LOCK: case ARCH_SHSTK_UNLOCK: + case ARCH_SHSTK_STATUS: return shstk_prctl(task, option, arg2); default: ret = -EINVAL; diff --git a/arch/x86/kernel/shstk.c b/arch/x86/kernel/shstk.c index 95579f7bace3..05f8dcc19dbc 100644 --- a/arch/x86/kernel/shstk.c +++ b/arch/x86/kernel/shstk.c @@ -448,8 +448,14 @@ SYSCALL_DEFINE3(map_shadow_stack, unsigned long, addr, unsigned long, size, unsi return alloc_shstk(addr, aligned_size, size, set_tok); } -long shstk_prctl(struct task_struct *task, int option, unsigned long features) +long shstk_prctl(struct task_struct *task, int option, unsigned long arg2) { + unsigned long features = arg2; + + if (option == ARCH_SHSTK_STATUS) { + return put_user(task->thread.features, (unsigned long __user *)arg2); + } + if (option == ARCH_SHSTK_LOCK) { task->thread.features_locked |= features; return 0;