syscall_handler: introduce new macros

Instead of boolean arguments to indicate memory read/write
permissions, or init/non-init APIs, new macros are introduced
which bake the semantics directly into the name of the macro.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2017-10-10 12:25:55 -07:00 committed by Andrew Boie
commit 32a08a81ab

View file

@ -74,14 +74,20 @@ int _k_object_validate(void *obj, enum k_objects otype, int init);
*/
#define _SYSCALL_VERIFY(expr, ssf) _SYSCALL_VERIFY_MSG(expr, ssf, #expr)
#define _SYSCALL_MEMORY(ptr, size, write, ssf) \
_SYSCALL_VERIFY_MSG(!_arch_buffer_validate((void *)ptr, size, write), \
ssf, "Memory region %p (size %u) %s access denied", \
(void *)(ptr), (u32_t)(size), \
write ? "write" : "read")
/**
* @brief Runtime check that a user thread has proper access to a memory area
* @brief Runtime check that a user thread has read permission to a memory area
*
* Checks that the particular memory area is readable or writable by the
* currently running thread if the CPU was in user mode, and generates a kernel
* oops if it wasn't. Prevents userspace from getting the kernel to read or
* modify memory the thread does not have access to, or passing in garbage
* pointers that would crash/pagefault the kernel if accessed.
* Checks that the particular memory area is readable by the currently running
* thread if the CPU was in user mode, and generates a kernel oops if it
* wasn't. Prevents userspace from getting the kernel to read memory the thread
* does not have access to, or passing in garbage pointers that would
* crash/pagefault the kernel if dereferenced.
*
* @param ptr Memory area to examine
* @param size Size of the memory area
@ -89,26 +95,60 @@ int _k_object_validate(void *obj, enum k_objects otype, int init);
* read it
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_MEMORY(ptr, size, write, ssf) \
_SYSCALL_VERIFY_MSG(!_arch_buffer_validate((void *)ptr, size, write), \
ssf, "Memory region %p (size %u) has incorrect permissions", \
(void *)(ptr), (u32_t)(size))
#define _SYSCALL_MEMORY_READ(ptr, size, ssf) \
_SYSCALL_MEMORY(ptr, size, 0, ssf)
/**
* @brief Runtime check that a pointer is a kernel object of expected type
* @brief Runtime check that a user thread has write permission to a memory area
*
* Passes along arguments to _k_object_validate() and triggers a kernel oops
* if the object wasn't valid or had incorrect permissions.
* Checks that the particular memory area is readable and writable by the
* currently running thread if the CPU was in user mode, and generates a kernel
* oops if it wasn't. Prevents userspace from getting the kernel to read or
* modify memory the thread does not have access to, or passing in garbage
* pointers that would crash/pagefault the kernel if dereferenced.
*
* @param ptr Untrusted kernel object pointer
* @param type Expected kernel object type
* @param init Whether this is an init function handler
* @param ptr Memory area to examine
* @param size Size of the memory area
* @param write If the thread should be able to write to this memory, not just
* read it
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_MEMORY_WRITE(ptr, size, ssf) \
_SYSCALL_MEMORY(ptr, size, 1, ssf)
#define _SYSCALL_IS_OBJ(ptr, type, init, ssf) \
_SYSCALL_VERIFY_MSG(!_k_object_validate((void *)ptr, type, init), ssf, \
"object %p access denied", (void *)(ptr))
/**
* @brief Runtime check kernel object pointer for non-init functions
*
* Calls _k_object_validate and triggers a kernel oops if the check files.
* For use in system call handlers which are not init functions; a check
* enforcing that an object is initialized* will not occur.
*
* @param ptr Untrusted kernel object pointer
* @param type Expected kernel object type
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_OBJ(ptr, type, ssf) \
_SYSCALL_IS_OBJ(ptr, type, 0, ssf)
/**
* @brief Runtime check kernel object pointer for non-init functions
*
* See description of _SYSCALL_IS_OBJ. For use in system call handlers which
* are not init functions; a check enforcing that an object is initialized
* will not occur.
*
* @param ptr Untrusted kernel object pointer
* @param type Expected kernel object type
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_OBJ_INIT(ptr, type, ssf) \
_SYSCALL_IS_OBJ(ptr, type, 1, ssf)
/* Convenience macros for handler implementations */
#define _SYSCALL_ARG0 ARG_UNUSED(arg1); ARG_UNUSED(arg2); ARG_UNUSED(arg3); \
ARG_UNUSED(arg4); ARG_UNUSED(arg5); ARG_UNUSED(arg6)