From 66cc69e34e86a231fbe68d8918c6119e3b7549a3 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 13 Mar 2014 12:11:30 +1030 Subject: Fix: module signature vs tracepoints: add new TAINT_UNSIGNED_MODULE Users have reported being unable to trace non-signed modules loaded within a kernel supporting module signature. This is caused by tracepoint.c:tracepoint_module_coming() refusing to take into account tracepoints sitting within force-loaded modules (TAINT_FORCED_MODULE). The reason for this check, in the first place, is that a force-loaded module may have a struct module incompatible with the layout expected by the kernel, and can thus cause a kernel crash upon forced load of that module on a kernel with CONFIG_TRACEPOINTS=y. Tracepoints, however, specifically accept TAINT_OOT_MODULE and TAINT_CRAP, since those modules do not lead to the "very likely system crash" issue cited above for force-loaded modules. With kernels having CONFIG_MODULE_SIG=y (signed modules), a non-signed module is tainted re-using the TAINT_FORCED_MODULE taint flag. Unfortunately, this means that Tracepoints treat that module as a force-loaded module, and thus silently refuse to consider any tracepoint within this module. Since an unsigned module does not fit within the "very likely system crash" category of tainting, add a new TAINT_UNSIGNED_MODULE taint flag to specifically address this taint behavior, and accept those modules within Tracepoints. We use the letter 'X' as a taint flag character for a module being loaded that doesn't know how to sign its name (proposed by Steven Rostedt). Also add the missing 'O' entry to trace event show_module_flags() list for the sake of completeness. Signed-off-by: Mathieu Desnoyers Acked-by: Steven Rostedt NAKed-by: Ingo Molnar CC: Thomas Gleixner CC: David Howells CC: Greg Kroah-Hartman Signed-off-by: Rusty Russell --- Documentation/oops-tracing.txt | 3 +++ 1 file changed, 3 insertions(+) (limited to 'Documentation/oops-tracing.txt') diff --git a/Documentation/oops-tracing.txt b/Documentation/oops-tracing.txt index 13032c0140d4..879abe289523 100644 --- a/Documentation/oops-tracing.txt +++ b/Documentation/oops-tracing.txt @@ -265,6 +265,9 @@ characters, each representing a particular tainted value. 13: 'O' if an externally-built ("out-of-tree") module has been loaded. + 14: 'X' if an unsigned module has been loaded in a kernel supporting + module signature. + The primary reason for the 'Tainted: ' string is to tell kernel debuggers if this is a clean kernel or if anything unusual has occurred. Tainting is permanent: even if an offending module is -- cgit v1.2.3-59-g8ed1b