From: Thomas Gleixner <[email protected]> This prepares for changing the return types of syscall_enter_from_user_mode[_work]() to bool, which in turn separates the decision of invoking the syscall from the syscall number, which might have been changed in the call by ptrace, seccomp, tracing.
Signed-off-by: Thomas Gleixner <[email protected]> --- include/linux/entry-common.h | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) --- a/include/linux/entry-common.h +++ b/include/linux/entry-common.h @@ -72,7 +72,7 @@ static __always_inline long syscall_trac */ if (work & SYSCALL_WORK_SYSCALL_USER_DISPATCH) { if (syscall_user_dispatch(regs)) - return -1L; + return false; } /* @@ -87,13 +87,13 @@ static __always_inline long syscall_trac if (work & (SYSCALL_WORK_SYSCALL_TRACE | SYSCALL_WORK_SYSCALL_EMU)) { if (!arch_ptrace_report_syscall_permit_entry(regs) || (work & SYSCALL_WORK_SYSCALL_EMU)) - return -1L; + return false; } /* Do seccomp after ptrace, to catch any tracer changes. */ if (work & SYSCALL_WORK_SECCOMP) { if (!__seccomp_permit_syscall()) - return -1L; + return false; } if (unlikely(work & SYSCALL_WORK_SYSCALL_TRACEPOINT)) @@ -102,8 +102,7 @@ static __always_inline long syscall_trac if (unlikely(audit_context())) syscall_enter_audit(regs); - /* Either of the above might have changed the syscall number */ - return syscall_get_nr(current, regs); + return true; } /** @@ -133,8 +132,13 @@ static __always_inline long syscall_ente { unsigned long work = READ_ONCE(current_thread_info()->syscall_work); - if (work & SYSCALL_WORK_ENTER) - syscall = syscall_trace_enter(regs, work, syscall); + if (work & SYSCALL_WORK_ENTER) { + if (!syscall_trace_enter(regs, work, syscall)) + return -1L; + + /* Reread the syscall number as it might have been modified */ + syscall = syscall_get_nr(current, regs); + } return syscall; }
