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syscalls: add _SYSCALL_VERIFY_MSG()

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Expecting stringified expressions to be completely comprehensible to end
users is wishful thinking; we really need to express what a failed
system call verification step means in human terms in most cases.

Memory buffer and kernel object checks now are implemented in terms of
_SYSCALL_VERIFY_MSG.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
This commit is contained in:
Andrew Boie 2017-10-09 15:09:29 -07:00 • committed by Andrew Boie
commit 231b95cfc0
1 changed files with 25 additions and 5 deletions
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30
kernel/include/syscall_handler.h
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@ -43,20 +43,37 @@ int _k_object_validate(void *obj, enum k_objects otype, int init);
* @brief Runtime expression check for system call arguments
*
* Used in handler functions to perform various runtime checks on arguments,
* and generate a kernel oops if anything is not expected
* and generate a kernel oops if anything is not expected, printing a custom
* message.
*
* @param expr Boolean expression to verify, a false result will trigger an
* oops
* @param ssf Syscall stack frame argument passed to the handler function
* @param fmt Printf-style format string (followed by appropriate variadic
* arguments) to print on verification failure
*/
#define _SYSCALL_VERIFY(expr, ssf) \
#define _SYSCALL_VERIFY_MSG(expr, ssf, fmt, ...) \
do { \
if (!(expr)) { \
printk("FATAL: syscall failed check: " #expr "\n"); \
printk("FATAL: syscall %s failed check: " fmt "\n", \
__func__, ##__VA_ARGS__); \
_arch_syscall_oops(ssf); \
} \
} while (0)
/**
* @brief Runtime expression check for system call arguments
*
* Used in handler functions to perform various runtime checks on arguments,
* and generate a kernel oops if anything is not expected.
*
* @param expr Boolean expression to verify, a false result will trigger an
* oops. A stringified version of this expression will be printed.
* @param ssf Syscall stack frame argument passed to the handler function
* arguments) to print on verification failure
*/
#define _SYSCALL_VERIFY(expr, ssf) _SYSCALL_VERIFY_MSG(expr, ssf, #expr)
/**
* @brief Runtime check that a user thread has proper access to a memory area
*
@ -73,7 +90,9 @@ int _k_object_validate(void *obj, enum k_objects otype, int init);
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_MEMORY(ptr, size, write, ssf) \
_SYSCALL_VERIFY(!_arch_buffer_validate((void *)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))
/**
* @brief Runtime check that a pointer is a kernel object of expected type
@ -87,7 +106,8 @@ int _k_object_validate(void *obj, enum k_objects otype, int init);
* @param ssf Syscall stack frame argument passed to the handler function
*/
#define _SYSCALL_IS_OBJ(ptr, type, init, ssf) \
_SYSCALL_VERIFY(!_k_object_validate((void *)ptr, type, init), ssf)
_SYSCALL_VERIFY_MSG(!_k_object_validate((void *)ptr, type, init), ssf, \
"object %p access denied", (void *)(ptr))
/* Convenience macros for handler implementations */
#define _SYSCALL_ARG0 ARG_UNUSED(arg1); ARG_UNUSED(arg2); ARG_UNUSED(arg3); \