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authorBodo Stroesser <bstroesser@fujitsu-siemens.com>2005-09-03 15:57:21 -0700
committerLinus Torvalds <torvalds@evo.osdl.org>2005-09-05 00:06:20 -0700
commitab1c23c24471c760c573f4fb0dd78e166ddfd844 (patch)
treefad0953ece8710b58a14a2a9eed1b1f83fb47f4b
parent1b38f0064e4e0b9ec626e39f0740b1cf2e295743 (diff)
downloadblackbird-op-linux-ab1c23c24471c760c573f4fb0dd78e166ddfd844.tar.gz
blackbird-op-linux-ab1c23c24471c760c573f4fb0dd78e166ddfd844.zip
[PATCH] SYSEMU: fix sysaudit / singlestep interaction
Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> This is simply an adjustment for "Ptrace - i386: fix Syscall Audit interaction with singlestep" to work on top of SYSEMU patches, too. On this patch, I have some doubts: I wonder why we need to alter that way ptrace_disable(). I left the patch this way because it has been extensively tested, but I don't understand the reason. The current PTRACE_DETACH handling simply clears child->ptrace; actually this is not enough because entry.S just looks at the thread_flags; actually, do_syscall_trace checks current->ptrace but I don't think depending on that is good, at least for performance, so I think the clearing is done elsewhere. For instance, on PTRACE_CONT it's done, but doing PTRACE_DETACH without PTRACE_CONT is possible (and happens when gdb crashes and one kills it manually). Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it> CC: Roland McGrath <roland@redhat.com> Cc: Jeff Dike <jdike@addtoit.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/i386/kernel/ptrace.c23
1 files changed, 20 insertions, 3 deletions
diff --git a/arch/i386/kernel/ptrace.c b/arch/i386/kernel/ptrace.c
index 3196ba50fcd5..340980203b09 100644
--- a/arch/i386/kernel/ptrace.c
+++ b/arch/i386/kernel/ptrace.c
@@ -271,6 +271,8 @@ static void clear_singlestep(struct task_struct *child)
void ptrace_disable(struct task_struct *child)
{
clear_singlestep(child);
+ clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE);
+ clear_tsk_thread_flag(child, TIF_SYSCALL_EMU);
}
/*
@@ -693,14 +695,29 @@ __attribute__((regparm(3)))
int do_syscall_trace(struct pt_regs *regs, int entryexit)
{
int is_sysemu = test_thread_flag(TIF_SYSCALL_EMU), ret = 0;
- /* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP */
+ /* With TIF_SYSCALL_EMU set we want to ignore TIF_SINGLESTEP for syscall
+ * interception. */
int is_singlestep = !is_sysemu && test_thread_flag(TIF_SINGLESTEP);
/* do the secure computing check first */
secure_computing(regs->orig_eax);
- if (unlikely(current->audit_context) && entryexit)
- audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+ if (unlikely(current->audit_context)) {
+ if (entryexit)
+ audit_syscall_exit(current, AUDITSC_RESULT(regs->eax), regs->eax);
+ /* Debug traps, when using PTRACE_SINGLESTEP, must be sent only
+ * on the syscall exit path. Normally, when TIF_SYSCALL_AUDIT is
+ * not used, entry.S will call us only on syscall exit, not
+ * entry; so when TIF_SYSCALL_AUDIT is used we must avoid
+ * calling send_sigtrap() on syscall entry.
+ *
+ * Note that when PTRACE_SYSEMU_SINGLESTEP is used,
+ * is_singlestep is false, despite his name, so we will still do
+ * the correct thing.
+ */
+ else if (is_singlestep)
+ goto out;
+ }
if (!(current->ptrace & PT_PTRACED))
goto out;
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