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| author | Kees Cook <keescook@chromium.org> | 2016-06-24 08:01:26 +0300 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2016-07-07 21:09:19 +0300 |
| commit | 6c3521400c345fa2575a6f5b212c215db38c5d93 (patch) | |
| tree | da82894be96d44bc48809e6871dd096db1106f22 /drivers/misc | |
| parent | e2402b1d214e5d50e807773563d590115a161f45 (diff) | |
| download | linux-6c3521400c345fa2575a6f5b212c215db38c5d93.tar.xz | |
lkdtm: add usercopy test for blocking kernel text
The upcoming HARDENED_USERCOPY checks will also block access to the
kernel text, so provide a test for this as well.
Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'drivers/misc')
| -rw-r--r-- | drivers/misc/lkdtm_core.c | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/drivers/misc/lkdtm_core.c b/drivers/misc/lkdtm_core.c index a595a6f2615a..c915961c4df2 100644 --- a/drivers/misc/lkdtm_core.c +++ b/drivers/misc/lkdtm_core.c @@ -120,6 +120,7 @@ enum ctype { CT_USERCOPY_STACK_FRAME_TO, CT_USERCOPY_STACK_FRAME_FROM, CT_USERCOPY_STACK_BEYOND, + CT_USERCOPY_KERNEL, }; static char* cp_name[] = { @@ -171,6 +172,7 @@ static char* cp_type[] = { "USERCOPY_STACK_FRAME_TO", "USERCOPY_STACK_FRAME_FROM", "USERCOPY_STACK_BEYOND", + "USERCOPY_KERNEL", }; static struct jprobe lkdtm; @@ -495,6 +497,35 @@ free_user: vm_munmap(user_addr, PAGE_SIZE); } +static void do_usercopy_kernel(void) +{ + unsigned long user_addr; + + user_addr = vm_mmap(NULL, 0, PAGE_SIZE, + PROT_READ | PROT_WRITE | PROT_EXEC, + MAP_ANONYMOUS | MAP_PRIVATE, 0); + if (user_addr >= TASK_SIZE) { + pr_warn("Failed to allocate user memory\n"); + return; + } + + pr_info("attempting good copy_to_user from kernel rodata\n"); + if (copy_to_user((void __user *)user_addr, test_text, + sizeof(test_text))) { + pr_warn("copy_to_user failed unexpectedly?!\n"); + goto free_user; + } + + pr_info("attempting bad copy_to_user from kernel text\n"); + if (copy_to_user((void __user *)user_addr, vm_mmap, PAGE_SIZE)) { + pr_warn("copy_to_user failed, but lacked Oops\n"); + goto free_user; + } + +free_user: + vm_munmap(user_addr, PAGE_SIZE); +} + static void do_usercopy_heap_size(bool to_user) { unsigned long user_addr; @@ -957,6 +988,9 @@ static void lkdtm_do_action(enum ctype which) case CT_USERCOPY_STACK_BEYOND: do_usercopy_stack(true, false); break; + case CT_USERCOPY_KERNEL: + do_usercopy_kernel(); + break; case CT_NONE: default: break; |