Commit 15cab952 authored Mar 23, 2012 by Oleg Nesterov Committed by Linus Torvalds Mar 23, 2012

ptrace: the killed tracee should not enter the syscall



Another old/known problem.  If the tracee is killed after it reports
syscall_entry, it starts the syscall and debugger can't control this.
This confuses the users and this creates the security problems for
ptrace jailers.

Change tracehook_report_syscall_entry() to return non-zero if killed,
this instructs syscall_trace_enter() to abort the syscall.

Reported-by: Chris Evans <scarybeasts@gmail.com>
Tested-by: Indan Zupancic <indan@nul.nu>
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <vda.linux@googlemail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Pedro Alves <palves@redhat.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d533df07

include/linux/tracehook.h

+5 −4

Original line number	Diff line number	Diff line
		@@ -54,12 +54,12 @@ struct linux_binprm;
		/*
		* ptrace report for syscall entry and exit looks identical.
		*/
		static inline void ptrace_report_syscall(struct pt_regs *regs)
		static inline int ptrace_report_syscall(struct pt_regs *regs)
		{
		int ptrace = current->ptrace;

		if (!(ptrace & PT_PTRACED))
		return;
		return 0;

		ptrace_notify(SIGTRAP \| ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));

		@@ -72,6 +72,8 @@ static inline void ptrace_report_syscall(struct pt_regs *regs)
		send_sig(current->exit_code, current, 1);
		current->exit_code = 0;
		}

		return fatal_signal_pending(current);
		}

		/**
		@@ -96,8 +98,7 @@ static inline void ptrace_report_syscall(struct pt_regs *regs)
		static inline __must_check int tracehook_report_syscall_entry(
		struct pt_regs *regs)
		{
		ptrace_report_syscall(regs);
		return 0;
		return ptrace_report_syscall(regs);
		}

		/**