On Mon, Nov 21, 2016 at 4:54 PM, Steven Rostedt <[email protected]> wrote: > On Wed, 16 Nov 2016 17:37:01 +0000 > [email protected] wrote: > >> This is a simple way to be able to verify syscall parameters before the >> call to the actual syscall, and also verify the return value after the >> call. >> >> Signed-off-by: Sasha Levin <[email protected]> >> --- >> include/linux/syscalls.h | 7 ++++++- >> kernel/Makefile | 2 ++ >> kernel/abi_spec.c | 15 +++++++++++++++ >> 3 files changed, 23 insertions(+), 1 deletion(-) >> create mode 100644 kernel/abi_spec.c >> >> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >> index 91a740f..6aa3228 100644 >> --- a/include/linux/syscalls.h >> +++ b/include/linux/syscalls.h >> @@ -79,6 +79,7 @@ union bpf_attr; >> #include <linux/quota.h> >> #include <linux/key.h> >> #include <trace/syscall.h> >> +#include <linux/abi_spec.h> >> >> /* >> * __MAP - apply a macro to syscall arguments >> @@ -192,13 +193,17 @@ extern struct trace_event_functions >> exit_syscall_print_funcs; >> >> #define __PROTECT(...) asmlinkage_protect(__VA_ARGS__) >> #define __SYSCALL_DEFINEx(x, name, ...) >> \ >> + extern const struct syscall_spec syscall_spec##name; \ >> asmlinkage long sys##name(__MAP(x,__SC_DECL,__VA_ARGS__)) \ >> __attribute__((alias(__stringify(SyS##name)))); \ >> static inline long SYSC##name(__MAP(x,__SC_DECL,__VA_ARGS__)); \ >> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)); \ >> asmlinkage long SyS##name(__MAP(x,__SC_LONG,__VA_ARGS__)) \ >> { \ >> - long ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ >> + long ret; \ >> + abispec_check_pre(&syscall_spec##name, >> __MAP(x,__SC_CAST,__VA_ARGS__)); \ >> + ret = SYSC##name(__MAP(x,__SC_CAST,__VA_ARGS__)); \ >> + abispec_check_post(&syscall_spec##name, ret, >> __MAP(x,__SC_CAST,__VA_ARGS__)); \ > > Do you want this for DEFINE0() too? Or does this not care about system > calls with no arguments?
This should care about syscalls without args: - we still may want to check return values - something like debug tracing would like to print them - there may also be some side effects (or absence of side effects) that we may want to check >> __MAP(x,__SC_TEST,__VA_ARGS__); \ >> __PROTECT(x, ret,__MAP(x,__SC_ARGS,__VA_ARGS__)); \ >> return ret; \ >
