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ptrace: do not audit capability check when outputing /proc/pid/stat

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Reading /proc/pid/stat of another process checks if one has ptrace permissions
on that process.  If one does have permissions it outputs some data about the
process which might have security and attack implications.  If the current
task does not have ptrace permissions the read still works, but those fields
are filled with inocuous (0) values.  Since this check and a subsequent denial
is not a violation of the security policy we should not audit such denials.

This can be quite useful to removing ptrace broadly across a system without
flooding the logs when ps is run or something which harmlessly walks proc.

Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Serge E. Hallyn <serge.hallyn@canonical.com>
This commit is contained in:
Eric Paris
2012-01-03 12:25:15 -05:00
parent f1c84dae0e
commit 69f594a389
4 changed files with 15 additions and 6 deletions
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2
fs/proc/array.c
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@@ -380,7 +380,7 @@ static int do_task_stat(struct seq_file *m, struct pid_namespace *ns,
state = *get_task_state(task);
vsize = eip = esp = 0;
permitted = ptrace_may_access(task, PTRACE_MODE_READ);
permitted = ptrace_may_access(task, PTRACE_MODE_READ | PTRACE_MODE_NOAUDIT);
mm = get_task_mm(task);
if (mm) {
vsize = task_vsize(mm);