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 --- kernel/panic.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 6d6300375090..0e25fe10871e 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -210,6 +210,7 @@ static const struct tnt tnts[] = { { TAINT_CRAP, 'C', ' ' }, { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, { TAINT_OOT_MODULE, 'O', ' ' }, + { TAINT_UNSIGNED_MODULE, 'X', ' ' }, }; /** @@ -228,6 +229,7 @@ static const struct tnt tnts[] = { * 'C' - modules from drivers/staging are loaded. * 'I' - Working around severe firmware bug. * 'O' - Out-of-tree module has been loaded. + * 'X' - Unsigned module has been loaded. * * The string is overwritten by the next call to print_tainted(). */ -- cgit From 57673c2b0baa900dddae3b9eb3d7748ebf550eb3 Mon Sep 17 00:00:00 2001 From: Rusty Russell Date: Mon, 31 Mar 2014 14:39:57 +1030 Subject: Use 'E' instead of 'X' for unsigned module taint flag. Takashi Iwai says: > The letter 'X' has been already used for SUSE kernels for very long > time, to indicate the external supported modules. Can the new flag be > changed to another letter for avoiding conflict...? > (BTW, we also use 'N' for "no support", too.) Note: this code should be cleaned up, so we don't have such maps in three places! Signed-off-by: Rusty Russell --- kernel/panic.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'kernel/panic.c') diff --git a/kernel/panic.c b/kernel/panic.c index 0e25fe10871e..02b6c9f0171b 100644 --- a/kernel/panic.c +++ b/kernel/panic.c @@ -210,7 +210,7 @@ static const struct tnt tnts[] = { { TAINT_CRAP, 'C', ' ' }, { TAINT_FIRMWARE_WORKAROUND, 'I', ' ' }, { TAINT_OOT_MODULE, 'O', ' ' }, - { TAINT_UNSIGNED_MODULE, 'X', ' ' }, + { TAINT_UNSIGNED_MODULE, 'E', ' ' }, }; /** @@ -229,7 +229,7 @@ static const struct tnt tnts[] = { * 'C' - modules from drivers/staging are loaded. * 'I' - Working around severe firmware bug. * 'O' - Out-of-tree module has been loaded. - * 'X' - Unsigned module has been loaded. + * 'E' - Unsigned module has been loaded. * * The string is overwritten by the next call to print_tainted(). */ -- cgit