From ad7c1399b7d0c6788b8f5fdb5c274110f3ce6017 Mon Sep 17 00:00:00 2001 From: Tyler Hicks Date: Thu, 2 Jun 2016 23:43:21 -0500 Subject: [PATCH] kernel: Add noaudit variant of ns_capable() commit 98f368e9e2630a3ce3e80fb10fb2e02038cf9578 upstream. When checking the current cred for a capability in a specific user namespace, it isn't always desirable to have the LSMs audit the check. This patch adds a noaudit variant of ns_capable() for when those situations arise. The common logic between ns_capable() and the new ns_capable_noaudit() is moved into a single, shared function to keep duplicated code to a minimum and ease maintainability. Signed-off-by: Tyler Hicks Acked-by: Serge E. Hallyn Signed-off-by: James Morris Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- include/linux/capability.h | 5 +++++ kernel/capability.c | 46 +++++++++++++++++++++++++++++--------- 2 files changed, 41 insertions(+), 10 deletions(-) diff --git a/include/linux/capability.h b/include/linux/capability.h index af9f0b9e80e6..5f8249d378a2 100644 --- a/include/linux/capability.h +++ b/include/linux/capability.h @@ -214,6 +214,7 @@ extern bool has_ns_capability_noaudit(struct task_struct *t, struct user_namespace *ns, int cap); extern bool capable(int cap); extern bool ns_capable(struct user_namespace *ns, int cap); +extern bool ns_capable_noaudit(struct user_namespace *ns, int cap); #else static inline bool has_capability(struct task_struct *t, int cap) { @@ -241,6 +242,10 @@ static inline bool ns_capable(struct user_namespace *ns, int cap) { return true; } +static inline bool ns_capable_noaudit(struct user_namespace *ns, int cap) +{ + return true; +} #endif /* CONFIG_MULTIUSER */ extern bool capable_wrt_inode_uidgid(const struct inode *inode, int cap); extern bool file_ns_capable(const struct file *file, struct user_namespace *ns, int cap); diff --git a/kernel/capability.c b/kernel/capability.c index 45432b54d5c6..00411c82dac5 100644 --- a/kernel/capability.c +++ b/kernel/capability.c @@ -361,6 +361,24 @@ bool has_capability_noaudit(struct task_struct *t, int cap) return has_ns_capability_noaudit(t, &init_user_ns, cap); } +static bool ns_capable_common(struct user_namespace *ns, int cap, bool audit) +{ + int capable; + + if (unlikely(!cap_valid(cap))) { + pr_crit("capable() called with invalid cap=%u\n", cap); + BUG(); + } + + capable = audit ? security_capable(current_cred(), ns, cap) : + security_capable_noaudit(current_cred(), ns, cap); + if (capable == 0) { + current->flags |= PF_SUPERPRIV; + return true; + } + return false; +} + /** * ns_capable - Determine if the current task has a superior capability in effect * @ns: The usernamespace we want the capability in @@ -374,19 +392,27 @@ bool has_capability_noaudit(struct task_struct *t, int cap) */ bool ns_capable(struct user_namespace *ns, int cap) { - if (unlikely(!cap_valid(cap))) { - pr_crit("capable() called with invalid cap=%u\n", cap); - BUG(); - } - - if (security_capable(current_cred(), ns, cap) == 0) { - current->flags |= PF_SUPERPRIV; - return true; - } - return false; + return ns_capable_common(ns, cap, true); } EXPORT_SYMBOL(ns_capable); +/** + * ns_capable_noaudit - Determine if the current task has a superior capability + * (unaudited) in effect + * @ns: The usernamespace we want the capability in + * @cap: The capability to be tested for + * + * Return true if the current task has the given superior capability currently + * available for use, false if not. + * + * This sets PF_SUPERPRIV on the task if the capability is available on the + * assumption that it's about to be used. + */ +bool ns_capable_noaudit(struct user_namespace *ns, int cap) +{ + return ns_capable_common(ns, cap, false); +} +EXPORT_SYMBOL(ns_capable_noaudit); /** * capable - Determine if the current task has a superior capability in effect -- 2.34.1