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authorMicah Morton <mortonm@chromium.org>2019-01-22 14:42:09 -0800
committerJames Morris <james.morris@microsoft.com>2019-01-25 11:22:43 -0800
commit40852275a94afb3e836be9248399e036982d1a79 (patch)
tree97db7b5d7dfae0ecd678b57bc861e60e949afe44 /kernel/capability.c
parent4b42564181d683d767b495d7041b1f229468042f (diff)
downloadlwn-40852275a94afb3e836be9248399e036982d1a79.tar.gz
lwn-40852275a94afb3e836be9248399e036982d1a79.zip
LSM: add SafeSetID module that gates setid calls
This change ensures that the set*uid family of syscalls in kernel/sys.c (setreuid, setuid, setresuid, setfsuid) all call ns_capable_common with the CAP_OPT_INSETID flag, so capability checks in the security_capable hook can know whether they are being called from within a set*uid syscall. This change is a no-op by itself, but is needed for the proposed SafeSetID LSM. Signed-off-by: Micah Morton <mortonm@chromium.org> Acked-by: Kees Cook <keescook@chromium.org> Signed-off-by: James Morris <james.morris@microsoft.com>
Diffstat (limited to 'kernel/capability.c')
-rw-r--r--kernel/capability.c19
1 files changed, 19 insertions, 0 deletions
diff --git a/kernel/capability.c b/kernel/capability.c
index cfbbcb68e11e..1444f3954d75 100644
--- a/kernel/capability.c
+++ b/kernel/capability.c
@@ -416,6 +416,25 @@ bool ns_capable_noaudit(struct user_namespace *ns, int cap)
EXPORT_SYMBOL(ns_capable_noaudit);
/**
+ * ns_capable_setid - Determine if the current task has a superior capability
+ * in effect, while signalling that this check is being done from within a
+ * setid syscall.
+ * @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_setid(struct user_namespace *ns, int cap)
+{
+ return ns_capable_common(ns, cap, CAP_OPT_INSETID);
+}
+EXPORT_SYMBOL(ns_capable_setid);
+
+/**
* capable - Determine if the current task has a superior capability in effect
* @cap: The capability to be tested for
*