From fd7af71be54271a9f03b2e6f63e4b3ac1ecd113d Mon Sep 17 00:00:00 2001 From: Lianbo Jiang Date: Thu, 25 Jun 2020 20:29:27 -0700 Subject: kexec: do not verify the signature without the lockdown or mandatory signature Signature verification is an important security feature, to protect system from being attacked with a kernel of unknown origin. Kexec rebooting is a way to replace the running kernel, hence need be secured carefully. In the current code of handling signature verification of kexec kernel, the logic is very twisted. It mixes signature verification, IMA signature appraising and kexec lockdown. If there is no KEXEC_SIG_FORCE, kexec kernel image doesn't have one of signature, the supported crypto, and key, we don't think this is wrong, Unless kexec lockdown is executed. IMA is considered as another kind of signature appraising method. If kexec kernel image has signature/crypto/key, it has to go through the signature verification and pass. Otherwise it's seen as verification failure, and won't be loaded. Seems kexec kernel image with an unqualified signature is even worse than those w/o signature at all, this sounds very unreasonable. E.g. If people get a unsigned kernel to load, or a kernel signed with expired key, which one is more dangerous? So, here, let's simplify the logic to improve code readability. If the KEXEC_SIG_FORCE enabled or kexec lockdown enabled, signature verification is mandated. Otherwise, we lift the bar for any kernel image. Link: http://lkml.kernel.org/r/20200602045952.27487-1-lijiang@redhat.com Signed-off-by: Lianbo Jiang Reviewed-by: Jiri Bohac Acked-by: Dave Young Acked-by: Baoquan He Cc: James Morris Cc: Matthew Garrett Cc: "Eric W. Biederman" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/kexec_file.c | 34 ++++++---------------------------- 1 file changed, 6 insertions(+), 28 deletions(-) (limited to 'kernel') diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index bb05fd52de85..09cc78df53c6 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -181,34 +181,19 @@ void kimage_file_post_load_cleanup(struct kimage *image) static int kimage_validate_signature(struct kimage *image) { - const char *reason; int ret; ret = arch_kexec_kernel_verify_sig(image, image->kernel_buf, image->kernel_buf_len); - switch (ret) { - case 0: - break; + if (ret) { - /* Certain verification errors are non-fatal if we're not - * checking errors, provided we aren't mandating that there - * must be a valid signature. - */ - case -ENODATA: - reason = "kexec of unsigned image"; - goto decide; - case -ENOPKG: - reason = "kexec of image with unsupported crypto"; - goto decide; - case -ENOKEY: - reason = "kexec of image with unavailable key"; - decide: if (IS_ENABLED(CONFIG_KEXEC_SIG_FORCE)) { - pr_notice("%s rejected\n", reason); + pr_notice("Enforced kernel signature verification failed (%d).\n", ret); return ret; } - /* If IMA is guaranteed to appraise a signature on the kexec + /* + * If IMA is guaranteed to appraise a signature on the kexec * image, permit it even if the kernel is otherwise locked * down. */ @@ -216,17 +201,10 @@ kimage_validate_signature(struct kimage *image) security_locked_down(LOCKDOWN_KEXEC)) return -EPERM; - return 0; - - /* All other errors are fatal, including nomem, unparseable - * signatures and signature check failures - even if signatures - * aren't required. - */ - default: - pr_notice("kernel signature verification failed (%d).\n", ret); + pr_debug("kernel signature verification failed (%d).\n", ret); } - return ret; + return 0; } #endif -- cgit v1.2.3 From 7a0e27b2a0ce2735e27e21ebc8b777550fe0ed81 Mon Sep 17 00:00:00 2001 From: Christoph Hellwig Date: Thu, 25 Jun 2020 20:30:47 -0700 Subject: mm: remove vmalloc_exec Merge vmalloc_exec into its only caller. Note that for !CONFIG_MMU __vmalloc_node_range maps to __vmalloc, which directly clears the __GFP_HIGHMEM added by the vmalloc_exec stub anyway. Link: http://lkml.kernel.org/r/20200618064307.32739-4-hch@lst.de Signed-off-by: Christoph Hellwig Reviewed-by: David Hildenbrand Acked-by: Peter Zijlstra (Intel) Cc: Catalin Marinas Cc: Dexuan Cui Cc: Jessica Yu Cc: Vitaly Kuznetsov Cc: Wei Liu Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/vmalloc.h | 1 - kernel/module.c | 4 +++- mm/nommu.c | 17 ----------------- mm/vmalloc.c | 20 -------------------- 4 files changed, 3 insertions(+), 39 deletions(-) (limited to 'kernel') diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h index 48bb681e6c2a..0221f852a7e1 100644 --- a/include/linux/vmalloc.h +++ b/include/linux/vmalloc.h @@ -106,7 +106,6 @@ extern void *vzalloc(unsigned long size); extern void *vmalloc_user(unsigned long size); extern void *vmalloc_node(unsigned long size, int node); extern void *vzalloc_node(unsigned long size, int node); -extern void *vmalloc_exec(unsigned long size); extern void *vmalloc_32(unsigned long size); extern void *vmalloc_32_user(unsigned long size); extern void *__vmalloc(unsigned long size, gfp_t gfp_mask); diff --git a/kernel/module.c b/kernel/module.c index e8a198588f26..0c6573b98c36 100644 --- a/kernel/module.c +++ b/kernel/module.c @@ -2783,7 +2783,9 @@ static void dynamic_debug_remove(struct module *mod, struct _ddebug *debug) void * __weak module_alloc(unsigned long size) { - return vmalloc_exec(size); + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, + GFP_KERNEL, PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, + NUMA_NO_NODE, __func__); } bool __weak module_init_section(const char *name) diff --git a/mm/nommu.c b/mm/nommu.c index cdcad5d61dd1..f32a69095d50 100644 --- a/mm/nommu.c +++ b/mm/nommu.c @@ -290,23 +290,6 @@ void *vzalloc_node(unsigned long size, int node) } EXPORT_SYMBOL(vzalloc_node); -/** - * vmalloc_exec - allocate virtually contiguous, executable memory - * @size: allocation size - * - * Kernel-internal function to allocate enough pages to cover @size - * the page level allocator and map them into contiguous and - * executable kernel virtual space. - * - * For tight control over page level allocator and protection flags - * use __vmalloc() instead. - */ - -void *vmalloc_exec(unsigned long size) -{ - return __vmalloc(size, GFP_KERNEL | __GFP_HIGHMEM); -} - /** * vmalloc_32 - allocate virtually contiguous memory (32bit addressable) * @size: allocation size diff --git a/mm/vmalloc.c b/mm/vmalloc.c index 957a0be77270..5a2b55c8dd9a 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2695,26 +2695,6 @@ void *vzalloc_node(unsigned long size, int node) } EXPORT_SYMBOL(vzalloc_node); -/** - * vmalloc_exec - allocate virtually contiguous, executable memory - * @size: allocation size - * - * Kernel-internal function to allocate enough pages to cover @size - * the page level allocator and map them into contiguous and - * executable kernel virtual space. - * - * For tight control over page level allocator and protection flags - * use __vmalloc() instead. - * - * Return: pointer to the allocated memory or %NULL on error - */ -void *vmalloc_exec(unsigned long size) -{ - return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END, - GFP_KERNEL, PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, - NUMA_NO_NODE, __builtin_return_address(0)); -} - #if defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA32) #define GFP_VMALLOC32 (GFP_DMA32 | GFP_KERNEL) #elif defined(CONFIG_64BIT) && defined(CONFIG_ZONE_DMA) -- cgit v1.2.3