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>
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@ -54,12 +54,12 @@ struct linux_binprm;
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/*
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* ptrace report for syscall entry and exit looks identical.
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*/
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static inline void ptrace_report_syscall(struct pt_regs *regs)
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static inline int ptrace_report_syscall(struct pt_regs *regs)
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{
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int ptrace = current->ptrace;
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if (!(ptrace & PT_PTRACED))
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return;
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return 0;
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ptrace_notify(SIGTRAP | ((ptrace & PT_TRACESYSGOOD) ? 0x80 : 0));
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@ -72,6 +72,8 @@ static inline void ptrace_report_syscall(struct pt_regs *regs)
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send_sig(current->exit_code, current, 1);
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current->exit_code = 0;
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}
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return fatal_signal_pending(current);
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}
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/**
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@ -96,8 +98,7 @@ static inline void ptrace_report_syscall(struct pt_regs *regs)
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static inline __must_check int tracehook_report_syscall_entry(
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struct pt_regs *regs)
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{
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ptrace_report_syscall(regs);
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return 0;
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return ptrace_report_syscall(regs);
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}
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/**
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