diff options
| author | Mathieu Desnoyers <mathieu.desnoyers@efficios.com> | 2014-03-13 05:41:30 +0400 |
|---|---|---|
| committer | Rusty Russell <rusty@rustcorp.com.au> | 2014-03-13 05:41:51 +0400 |
| commit | 66cc69e34e86a231fbe68d8918c6119e3b7549a3 (patch) | |
| tree | c1ea795511e9ed8ab83fda895f0151000b166629 /kernel/module.c | |
| parent | cff26a51da5d206d3baf871e75778da44710219d (diff) | |
| download | linux-66cc69e34e86a231fbe68d8918c6119e3b7549a3.tar.xz | |
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 <mathieu.desnoyers@efficios.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
NAKed-by: Ingo Molnar <mingo@redhat.com>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: David Howells <dhowells@redhat.com>
CC: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Diffstat (limited to 'kernel/module.c')
| -rw-r--r-- | kernel/module.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/module.c b/kernel/module.c index efa1e6031950..c1acb0c5b637 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -1013,6 +1013,8 @@ static size_t module_flags_taint(struct module *mod, char *buf) buf[l++] = 'F'; if (mod->taints & (1 << TAINT_CRAP)) buf[l++] = 'C'; + if (mod->taints & (1 << TAINT_UNSIGNED_MODULE)) + buf[l++] = 'X'; /* * TAINT_FORCED_RMMOD: could be added. * TAINT_UNSAFE_SMP, TAINT_MACHINE_CHECK, TAINT_BAD_PAGE don't @@ -3214,7 +3216,7 @@ static int load_module(struct load_info *info, const char __user *uargs, pr_notice_once("%s: module verification failed: signature " "and/or required key missing - tainting " "kernel\n", mod->name); - add_taint_module(mod, TAINT_FORCED_MODULE, LOCKDEP_STILL_OK); + add_taint_module(mod, TAINT_UNSIGNED_MODULE, LOCKDEP_STILL_OK); } #endif |