From f1c84dae0ecc51aa35c81f19a0ebcd6c0921ddcb Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 3 Jan 2012 12:25:15 -0500 Subject: capabilities: remove task_ns_* functions task_ in the front of a function, in the security subsystem anyway, means to me at least, that we are operating with that task as the subject of the security decision. In this case what it means is that we are using current as the subject but we use the task to get the right namespace. Who in the world would ever realize that's what task_ns_capability means just by the name? This patch eliminates the task_ns functions entirely and uses the has_ns_capability function instead. This means we explicitly open code the ns in question in the caller. I think it makes the caller a LOT more clear what is going on. Signed-off-by: Eric Paris Acked-by: Serge E. Hallyn --- kernel/ptrace.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/ptrace.c') diff --git a/kernel/ptrace.c b/kernel/ptrace.c index a70d2a5d8c7b..210bbf045ee9 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -196,7 +196,7 @@ ok: smp_rmb(); if (task->mm) dumpable = get_dumpable(task->mm); - if (!dumpable && !task_ns_capable(task, CAP_SYS_PTRACE)) + if (!dumpable && !ns_capable(task_user_ns(task), CAP_SYS_PTRACE)) return -EPERM; return security_ptrace_access_check(task, mode); @@ -266,7 +266,7 @@ static int ptrace_attach(struct task_struct *task, long request, task->ptrace = PT_PTRACED; if (seize) task->ptrace |= PT_SEIZED; - if (task_ns_capable(task, CAP_SYS_PTRACE)) + if (ns_capable(task_user_ns(task), CAP_SYS_PTRACE)) task->ptrace |= PT_PTRACE_CAP; __ptrace_link(task, current); -- cgit From 69f594a38967f4540ce7a29b3fd214e68a8330bd Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Tue, 3 Jan 2012 12:25:15 -0500 Subject: ptrace: do not audit capability check when outputing /proc/pid/stat 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 Acked-by: Serge E. Hallyn --- kernel/ptrace.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) (limited to 'kernel/ptrace.c') diff --git a/kernel/ptrace.c b/kernel/ptrace.c index 210bbf045ee9..c890ac9a7962 100644 --- a/kernel/ptrace.c +++ b/kernel/ptrace.c @@ -161,6 +161,14 @@ int ptrace_check_attach(struct task_struct *child, bool ignore_state) return ret; } +static int ptrace_has_cap(struct user_namespace *ns, unsigned int mode) +{ + if (mode & PTRACE_MODE_NOAUDIT) + return has_ns_capability_noaudit(current, ns, CAP_SYS_PTRACE); + else + return has_ns_capability(current, ns, CAP_SYS_PTRACE); +} + int __ptrace_may_access(struct task_struct *task, unsigned int mode) { const struct cred *cred = current_cred(), *tcred; @@ -187,7 +195,7 @@ int __ptrace_may_access(struct task_struct *task, unsigned int mode) cred->gid == tcred->sgid && cred->gid == tcred->gid)) goto ok; - if (ns_capable(tcred->user->user_ns, CAP_SYS_PTRACE)) + if (ptrace_has_cap(tcred->user->user_ns, mode)) goto ok; rcu_read_unlock(); return -EPERM; @@ -196,7 +204,7 @@ ok: smp_rmb(); if (task->mm) dumpable = get_dumpable(task->mm); - if (!dumpable && !ns_capable(task_user_ns(task), CAP_SYS_PTRACE)) + if (!dumpable && !ptrace_has_cap(task_user_ns(task), mode)) return -EPERM; return security_ptrace_access_check(task, mode); -- cgit