From 6a3981af3fd97fec57f2c5eeca213cbf5216a3c0 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 16 Aug 2022 12:14:54 -0700 Subject: [PATCH 1/2] LoadPin: Return EFAULT on copy_from_user() failures The copy_from_user() function returns the number of bytes remaining to be copied on a failure. Such failures should return -EFAULT to high levels. Reported-by: kernel test robot Reported-by: Dan Carpenter Fixes: 3f805f8cc23b ("LoadPin: Enable loading from trusted dm-verity devices") Cc: Matthias Kaehlcke Cc: James Morris Cc: "Serge E. Hallyn" Cc: linux-security-module@vger.kernel.org Signed-off-by: Kees Cook --- security/loadpin/loadpin.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/security/loadpin/loadpin.c b/security/loadpin/loadpin.c index 6ab5f2bbf41f..44521582dcba 100644 --- a/security/loadpin/loadpin.c +++ b/security/loadpin/loadpin.c @@ -356,13 +356,11 @@ static long dm_verity_ioctl(struct file *filp, unsigned int cmd, unsigned long a { void __user *uarg = (void __user *)arg; unsigned int fd; - int rc; switch (cmd) { case LOADPIN_IOC_SET_TRUSTED_VERITY_DIGESTS: - rc = copy_from_user(&fd, uarg, sizeof(fd)); - if (rc) - return rc; + if (copy_from_user(&fd, uarg, sizeof(fd))) + return -EFAULT; return read_trusted_verity_root_digests(fd); From 012e8d2034f1bda8863435cd589636e618d6a659 Mon Sep 17 00:00:00 2001 From: Andrew Donnellan Date: Tue, 16 Aug 2022 15:17:20 +1000 Subject: [PATCH 2/2] gcc-plugins: Undefine LATENT_ENTROPY_PLUGIN when plugin disabled for a file Commit 36d4b36b6959 ("lib/nodemask: inline next_node_in() and node_random()") refactored some code by moving node_random() from lib/nodemask.c to include/linux/nodemask.h, thus requiring nodemask.h to include random.h, which conditionally defines add_latent_entropy() depending on whether the macro LATENT_ENTROPY_PLUGIN is defined. This broke the build on powerpc, where nodemask.h is indirectly included in arch/powerpc/kernel/prom_init.c, part of the early boot machinery that is excluded from the latent entropy plugin using DISABLE_LATENT_ENTROPY_PLUGIN. It turns out that while we add a gcc flag to disable the actual plugin, we don't undefine LATENT_ENTROPY_PLUGIN. This leads to the following: CC arch/powerpc/kernel/prom_init.o In file included from ./include/linux/nodemask.h:97, from ./include/linux/mmzone.h:17, from ./include/linux/gfp.h:7, from ./include/linux/xarray.h:15, from ./include/linux/radix-tree.h:21, from ./include/linux/idr.h:15, from ./include/linux/kernfs.h:12, from ./include/linux/sysfs.h:16, from ./include/linux/kobject.h:20, from ./include/linux/pci.h:35, from arch/powerpc/kernel/prom_init.c:24: ./include/linux/random.h: In function 'add_latent_entropy': ./include/linux/random.h:25:46: error: 'latent_entropy' undeclared (first use in this function); did you mean 'add_latent_entropy'? 25 | add_device_randomness((const void *)&latent_entropy, sizeof(latent_entropy)); | ^~~~~~~~~~~~~~ | add_latent_entropy ./include/linux/random.h:25:46: note: each undeclared identifier is reported only once for each function it appears in make[2]: *** [scripts/Makefile.build:249: arch/powerpc/kernel/prom_init.o] Fehler 1 make[1]: *** [scripts/Makefile.build:465: arch/powerpc/kernel] Fehler 2 make: *** [Makefile:1855: arch/powerpc] Error 2 Change the DISABLE_LATENT_ENTROPY_PLUGIN flags to undefine LATENT_ENTROPY_PLUGIN for files where the plugin is disabled. Cc: Yury Norov Fixes: 38addce8b600 ("gcc-plugins: Add latent_entropy plugin") Link: https://bugzilla.kernel.org/show_bug.cgi?id=216367 Link: https://lore.kernel.org/linuxppc-dev/alpine.DEB.2.22.394.2208152006320.289321@ramsan.of.borg/ Reported-by: Erhard Furtner Signed-off-by: Andrew Donnellan Reviewed-by: Yury Norov Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20220816051720.44108-1-ajd@linux.ibm.com --- scripts/Makefile.gcc-plugins | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/scripts/Makefile.gcc-plugins b/scripts/Makefile.gcc-plugins index 692d64a70542..e4deaf5fa571 100644 --- a/scripts/Makefile.gcc-plugins +++ b/scripts/Makefile.gcc-plugins @@ -4,7 +4,7 @@ gcc-plugin-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) += latent_entropy_plugin.so gcc-plugin-cflags-$(CONFIG_GCC_PLUGIN_LATENT_ENTROPY) \ += -DLATENT_ENTROPY_PLUGIN ifdef CONFIG_GCC_PLUGIN_LATENT_ENTROPY - DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable + DISABLE_LATENT_ENTROPY_PLUGIN += -fplugin-arg-latent_entropy_plugin-disable -ULATENT_ENTROPY_PLUGIN endif export DISABLE_LATENT_ENTROPY_PLUGIN