diff options
Diffstat (limited to 'drivers/misc/lkdtm.c')
| -rw-r--r-- | drivers/misc/lkdtm.c | 111 |
1 files changed, 108 insertions, 3 deletions
diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index 11fdadc68e53..8e06e1020ad9 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -47,11 +47,18 @@ #include <linux/vmalloc.h> #include <linux/mman.h> #include <asm/cacheflush.h> +#include <linux/list.h> +#include <linux/sched.h> +#include <linux/uaccess.h> #ifdef CONFIG_IDE #include <linux/ide.h> #endif +struct lkdtm_list { + struct list_head node; +}; + /* * Make sure our attempts to over run the kernel stack doesn't trigger * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we @@ -88,6 +95,9 @@ enum ctype { CT_EXCEPTION, CT_LOOP, CT_OVERFLOW, + CT_CORRUPT_LIST_ADD, + CT_CORRUPT_LIST_DEL, + CT_CORRUPT_USER_DS, CT_CORRUPT_STACK, CT_UNALIGNED_LOAD_STORE_WRITE, CT_OVERWRITE_ALLOCATION, @@ -103,6 +113,7 @@ enum ctype { CT_EXEC_USERSPACE, CT_ACCESS_USERSPACE, CT_WRITE_RO, + CT_WRITE_RO_AFTER_INIT, CT_WRITE_KERN, }; @@ -125,6 +136,9 @@ static char* cp_type[] = { "EXCEPTION", "LOOP", "OVERFLOW", + "CORRUPT_LIST_ADD", + "CORRUPT_LIST_DEL", + "CORRUPT_USER_DS", "CORRUPT_STACK", "UNALIGNED_LOAD_STORE_WRITE", "OVERWRITE_ALLOCATION", @@ -140,6 +154,7 @@ static char* cp_type[] = { "EXEC_USERSPACE", "ACCESS_USERSPACE", "WRITE_RO", + "WRITE_RO_AFTER_INIT", "WRITE_KERN", }; @@ -162,6 +177,7 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; static const unsigned long rodata = 0xAA55AA55; +static unsigned long ro_after_init __ro_after_init = 0x55AA5500; module_param(recur_count, int, 0644); MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); @@ -503,11 +519,28 @@ static void lkdtm_do_action(enum ctype which) break; } case CT_WRITE_RO: { - unsigned long *ptr; + /* Explicitly cast away "const" for the test. */ + unsigned long *ptr = (unsigned long *)&rodata; - ptr = (unsigned long *)&rodata; + pr_info("attempting bad rodata write at %p\n", ptr); + *ptr ^= 0xabcd1234; - pr_info("attempting bad write at %p\n", ptr); + break; + } + case CT_WRITE_RO_AFTER_INIT: { + unsigned long *ptr = &ro_after_init; + + /* + * Verify we were written to during init. Since an Oops + * is considered a "success", a failure is to just skip the + * real test. + */ + if ((*ptr & 0xAA) != 0xAA) { + pr_info("%p was NOT written during init!?\n", ptr); + break; + } + + pr_info("attempting bad ro_after_init write at %p\n", ptr); *ptr ^= 0xabcd1234; break; @@ -528,6 +561,75 @@ static void lkdtm_do_action(enum ctype which) do_overwritten(); break; } + case CT_CORRUPT_LIST_ADD: { + /* + * Initially, an empty list via LIST_HEAD: + * test_head.next = &test_head + * test_head.prev = &test_head + */ + LIST_HEAD(test_head); + struct lkdtm_list good, bad; + void *target[2] = { }; + void *redirection = ⌖ + + pr_info("attempting good list addition\n"); + + /* + * Adding to the list performs these actions: + * test_head.next->prev = &good.node + * good.node.next = test_head.next + * good.node.prev = test_head + * test_head.next = good.node + */ + list_add(&good.node, &test_head); + + pr_info("attempting corrupted list addition\n"); + /* + * In simulating this "write what where" primitive, the "what" is + * the address of &bad.node, and the "where" is the address held + * by "redirection". + */ + test_head.next = redirection; + list_add(&bad.node, &test_head); + + if (target[0] == NULL && target[1] == NULL) + pr_err("Overwrite did not happen, but no BUG?!\n"); + else + pr_err("list_add() corruption not detected!\n"); + break; + } + case CT_CORRUPT_LIST_DEL: { + LIST_HEAD(test_head); + struct lkdtm_list item; + void *target[2] = { }; + void *redirection = ⌖ + + list_add(&item.node, &test_head); + + pr_info("attempting good list removal\n"); + list_del(&item.node); + + pr_info("attempting corrupted list removal\n"); + list_add(&item.node, &test_head); + + /* As with the list_add() test above, this corrupts "next". */ + item.node.next = redirection; + list_del(&item.node); + + if (target[0] == NULL && target[1] == NULL) + pr_err("Overwrite did not happen, but no BUG?!\n"); + else + pr_err("list_del() corruption not detected!\n"); + break; + } + case CT_CORRUPT_USER_DS: { + pr_info("setting bad task size limit\n"); + set_fs(KERNEL_DS); + + /* Make sure we do not keep running with a KERNEL_DS! */ + force_sig(SIGKILL, current); + break; + } case CT_NONE: default: break; @@ -817,6 +919,9 @@ static int __init lkdtm_module_init(void) int n_debugfs_entries = 1; /* Assume only the direct entry */ int i; + /* Make sure we can write to __ro_after_init values during __init */ + ro_after_init |= 0xAA; + /* Register debugfs interface */ lkdtm_debugfs_root = debugfs_create_dir("provoke-crash", NULL); if (!lkdtm_debugfs_root) { |