On Tue, Feb 25, 2014 at 09:20:24AM +0000, AKASHI Takahiro wrote:
secure_computing() should always be called first in syscall_trace(), and if it returns non-zero, we should stop further handling. Then that system call may eventually fail, be trapped or the process itself be killed depending on loaded rules.
[...]
diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c index d4ce70e..f2a74bc 100644 --- a/arch/arm64/kernel/ptrace.c +++ b/arch/arm64/kernel/ptrace.c @@ -20,12 +20,14 @@ */ #include <linux/audit.h> +#include <linux/errno.h> #include <linux/kernel.h> #include <linux/sched.h> #include <linux/mm.h> #include <linux/smp.h> #include <linux/ptrace.h> #include <linux/user.h> +#include <linux/seccomp.h> #include <linux/security.h> #include <linux/init.h> #include <linux/signal.h> @@ -1064,6 +1066,10 @@ asmlinkage int syscall_trace(int dir, struct pt_regs *regs) { unsigned long saved_reg;
- if (!dir && secure_computing((int)regs->syscallno))
Why do you need this cast to (int)? Also, it's probably better to check for -1 explicitly here.
I'm slightly surprised that we do the secure computing check first. Doesn't this allow a debugger to change the syscall to something else after we've decided that it's ok?
Will