| Message ID | 20170212233140.10606-3-ewk@edkovsky.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Sun, Feb 12, 2017 at 3:31 PM, Eddie Kovsky <ewk@edkovsky.org> wrote: > Provide a mechanism to check if the address of a variable is > const or ro_after_init. It mimics the existing functions that test if an > address is inside the kernel's text section. > > Signed-off-by: Eddie Kovsky <ewk@edkovsky.org> > --- > include/linux/kernel.h | 2 ++ > kernel/extable.c | 31 +++++++++++++++++++++++++++++++ > 2 files changed, 33 insertions(+) > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > index 4c26dc3a8295..51beea39e6c4 100644 > --- a/include/linux/kernel.h > +++ b/include/linux/kernel.h > @@ -444,6 +444,8 @@ extern int core_kernel_data(unsigned long addr); > extern int __kernel_text_address(unsigned long addr); > extern int kernel_text_address(unsigned long addr); > extern int func_ptr_is_kernel_text(void *ptr); > +extern int core_kernel_ro_data(unsigned long addr); > +extern int kernel_ro_address(unsigned long addr); > > unsigned long int_sqrt(unsigned long); > > diff --git a/kernel/extable.c b/kernel/extable.c > index 6b0d09051efb..f5a29c4ae391 100644 > --- a/kernel/extable.c > +++ b/kernel/extable.c > @@ -149,3 +149,34 @@ int func_ptr_is_kernel_text(void *ptr) > return 1; > return is_module_text_address(addr); > } > + > +/** > + * core_kernel_ro_data - Verify address points to read-only section > + * @addr: address to test > + * > + */ > +int core_kernel_ro_data(unsigned long addr) > +{ > + if (addr >= (unsigned long)__start_rodata && > + addr < (unsigned long)__end_rodata) > + return 1; > + > + if (addr >= (unsigned long)__start_data_ro_after_init && > + addr < (unsigned long)__end_data_ro_after_init) > + return 1; > + > + return 0; > +} > + > +/* Verify that address is const or ro_after_init. */ > +int kernel_ro_address(unsigned long addr) > +{ > + if (core_kernel_ro_data(addr)) > + return 1; > + if (is_module_ro_address(addr)) > + return 1; > + if (is_ftrace_trampoline(addr)) > + return 1; Why the trampoline test here? > + > + return 0; > +} > -- > 2.11.1 Otherwise looks exactly like what I had in mind; nice! -Kees
On 02/13/17, Kees Cook wrote: > On Sun, Feb 12, 2017 at 3:31 PM, Eddie Kovsky <ewk@edkovsky.org> wrote: > > Provide a mechanism to check if the address of a variable is > > const or ro_after_init. It mimics the existing functions that test if an > > address is inside the kernel's text section. > > > > Signed-off-by: Eddie Kovsky <ewk@edkovsky.org> > > --- > > include/linux/kernel.h | 2 ++ > > kernel/extable.c | 31 +++++++++++++++++++++++++++++++ > > 2 files changed, 33 insertions(+) > > > > diff --git a/include/linux/kernel.h b/include/linux/kernel.h > > index 4c26dc3a8295..51beea39e6c4 100644 > > --- a/include/linux/kernel.h > > +++ b/include/linux/kernel.h > > @@ -444,6 +444,8 @@ extern int core_kernel_data(unsigned long addr); > > extern int __kernel_text_address(unsigned long addr); > > extern int kernel_text_address(unsigned long addr); > > extern int func_ptr_is_kernel_text(void *ptr); > > +extern int core_kernel_ro_data(unsigned long addr); > > +extern int kernel_ro_address(unsigned long addr); > > > > unsigned long int_sqrt(unsigned long); > > > > diff --git a/kernel/extable.c b/kernel/extable.c > > index 6b0d09051efb..f5a29c4ae391 100644 > > --- a/kernel/extable.c > > +++ b/kernel/extable.c > > @@ -149,3 +149,34 @@ int func_ptr_is_kernel_text(void *ptr) > > return 1; > > return is_module_text_address(addr); > > } > > + > > +/** > > + * core_kernel_ro_data - Verify address points to read-only section > > + * @addr: address to test > > + * > > + */ > > +int core_kernel_ro_data(unsigned long addr) > > +{ > > + if (addr >= (unsigned long)__start_rodata && > > + addr < (unsigned long)__end_rodata) > > + return 1; > > + > > + if (addr >= (unsigned long)__start_data_ro_after_init && > > + addr < (unsigned long)__end_data_ro_after_init) > > + return 1; > > + > > + return 0; > > +} > > + > > +/* Verify that address is const or ro_after_init. */ > > +int kernel_ro_address(unsigned long addr) > > +{ > > + if (core_kernel_ro_data(addr)) > > + return 1; > > + if (is_module_ro_address(addr)) > > + return 1; > > + if (is_ftrace_trampoline(addr)) > > + return 1; > > Why the trampoline test here? > I wasn't certain if we needed to keep that as a fall through. I'll take it out when I send version 2. > > + > > + return 0; > > +} > > -- > > 2.11.1 > > Otherwise looks exactly like what I had in mind; nice! > > -Kees > > -- > Kees Cook > Pixel Security
diff --git a/include/linux/kernel.h b/include/linux/kernel.h index 4c26dc3a8295..51beea39e6c4 100644 --- a/include/linux/kernel.h +++ b/include/linux/kernel.h @@ -444,6 +444,8 @@ extern int core_kernel_data(unsigned long addr); extern int __kernel_text_address(unsigned long addr); extern int kernel_text_address(unsigned long addr); extern int func_ptr_is_kernel_text(void *ptr); +extern int core_kernel_ro_data(unsigned long addr); +extern int kernel_ro_address(unsigned long addr); unsigned long int_sqrt(unsigned long); diff --git a/kernel/extable.c b/kernel/extable.c index 6b0d09051efb..f5a29c4ae391 100644 --- a/kernel/extable.c +++ b/kernel/extable.c @@ -149,3 +149,34 @@ int func_ptr_is_kernel_text(void *ptr) return 1; return is_module_text_address(addr); } + +/** + * core_kernel_ro_data - Verify address points to read-only section + * @addr: address to test + * + */ +int core_kernel_ro_data(unsigned long addr) +{ + if (addr >= (unsigned long)__start_rodata && + addr < (unsigned long)__end_rodata) + return 1; + + if (addr >= (unsigned long)__start_data_ro_after_init && + addr < (unsigned long)__end_data_ro_after_init) + return 1; + + return 0; +} + +/* Verify that address is const or ro_after_init. */ +int kernel_ro_address(unsigned long addr) +{ + if (core_kernel_ro_data(addr)) + return 1; + if (is_module_ro_address(addr)) + return 1; + if (is_ftrace_trampoline(addr)) + return 1; + + return 0; +}
Provide a mechanism to check if the address of a variable is const or ro_after_init. It mimics the existing functions that test if an address is inside the kernel's text section. Signed-off-by: Eddie Kovsky <ewk@edkovsky.org> --- include/linux/kernel.h | 2 ++ kernel/extable.c | 31 +++++++++++++++++++++++++++++++ 2 files changed, 33 insertions(+) -- 2.11.1