kprobes: Introduce NOKPROBE_SYMBOL() macro to maintain kprobes blacklist

[firefly-linux-kernel-4.4.55.git] / kernel / kprobes.c

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 5b5ac76671e7c3e9edaf28ea73de4fdc5d709cf1..5ffc6875d2a7d4f55914df322615f8ddad91bbbe 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -86,18 +86,8 @@ static raw_spinlock_t *kretprobe_table_lock_ptr(unsigned long hash)
        return &(kretprobe_table_locks[hash].lock);
 }
 
-/*
- * Normally, functions that we'd want to prohibit kprobes in, are marked
- * __kprobes. But, there are cases where such functions already belong to
- * a different section (__sched for preempt_schedule)
- *
- * For such cases, we now have a blacklist
- */
-static struct kprobe_blackpoint kprobe_blacklist[] = {
-       {"preempt_schedule",},
-       {"native_get_debugreg",},
-       {NULL}    /* Terminator */
-};
+/* Blacklist -- list of struct kprobe_blacklist_entry */
+static LIST_HEAD(kprobe_blacklist);
 
 #ifdef __ARCH_WANT_KPROBES_INSN_SLOT
 /*
@@ -1328,24 +1318,22 @@ bool __weak arch_within_kprobe_blacklist(unsigned long addr)
               addr < (unsigned long)__kprobes_text_end;
 }
 
-static int __kprobes in_kprobes_functions(unsigned long addr)
+static bool __kprobes within_kprobe_blacklist(unsigned long addr)
 {
-       struct kprobe_blackpoint *kb;
+       struct kprobe_blacklist_entry *ent;
 
        if (arch_within_kprobe_blacklist(addr))
-               return -EINVAL;
+               return true;
        /*
         * If there exists a kprobe_blacklist, verify and
         * fail any probe registration in the prohibited area
         */
-       for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
-               if (kb->start_addr) {
-                       if (addr >= kb->start_addr &&
-                           addr < (kb->start_addr + kb->range))
-                               return -EINVAL;
-               }
+       list_for_each_entry(ent, &kprobe_blacklist, list) {
+               if (addr >= ent->start_addr && addr < ent->end_addr)
+                       return true;
        }
-       return 0;
+
+       return false;
 }
 
 /*
@@ -1436,7 +1424,7 @@ static __kprobes int check_kprobe_address_safe(struct kprobe *p,
 
        /* Ensure it is not in reserved area nor out of text */
        if (!kernel_text_address((unsigned long) p->addr) ||
-           in_kprobes_functions((unsigned long) p->addr) ||
+           within_kprobe_blacklist((unsigned long) p->addr) ||
            jump_label_text_reserved(p->addr, p->addr)) {
                ret = -EINVAL;
                goto out;
@@ -2022,6 +2010,38 @@ void __kprobes dump_kprobe(struct kprobe *kp)
               kp->symbol_name, kp->addr, kp->offset);
 }
 
+/*
+ * Lookup and populate the kprobe_blacklist.
+ *
+ * Unlike the kretprobe blacklist, we'll need to determine
+ * the range of addresses that belong to the said functions,
+ * since a kprobe need not necessarily be at the beginning
+ * of a function.
+ */
+static int __init populate_kprobe_blacklist(unsigned long *start,
+                                            unsigned long *end)
+{
+       unsigned long *iter;
+       struct kprobe_blacklist_entry *ent;
+       unsigned long offset = 0, size = 0;
+
+       for (iter = start; iter < end; iter++) {
+               if (!kallsyms_lookup_size_offset(*iter, &size, &offset)) {
+                       pr_err("Failed to find blacklist %p\n", (void *)*iter);
+                       continue;
+               }
+
+               ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+               if (!ent)
+                       return -ENOMEM;
+               ent->start_addr = *iter;
+               ent->end_addr = *iter + size;
+               INIT_LIST_HEAD(&ent->list);
+               list_add_tail(&ent->list, &kprobe_blacklist);
+       }
+       return 0;
+}
+
 /* Module notifier call back, checking kprobes on the module */
 static int __kprobes kprobes_module_callback(struct notifier_block *nb,
                                             unsigned long val, void *data)
@@ -2065,14 +2085,13 @@ static struct notifier_block kprobe_module_nb = {
        .priority = 0
 };
 
+/* Markers of _kprobe_blacklist section */
+extern unsigned long __start_kprobe_blacklist[];
+extern unsigned long __stop_kprobe_blacklist[];
+
 static int __init init_kprobes(void)
 {
        int i, err = 0;
-       unsigned long offset = 0, size = 0;
-       char *modname, namebuf[KSYM_NAME_LEN];
-       const char *symbol_name;
-       void *addr;
-       struct kprobe_blackpoint *kb;
 
        /* FIXME allocate the probe table, currently defined statically */
        /* initialize all list heads */
@@ -2082,26 +2101,11 @@ static int __init init_kprobes(void)
                raw_spin_lock_init(&(kretprobe_table_locks[i].lock));
        }
 
-       /*
-        * Lookup and populate the kprobe_blacklist.
-        *
-        * Unlike the kretprobe blacklist, we'll need to determine
-        * the range of addresses that belong to the said functions,
-        * since a kprobe need not necessarily be at the beginning
-        * of a function.
-        */
-       for (kb = kprobe_blacklist; kb->name != NULL; kb++) {
-               kprobe_lookup_name(kb->name, addr);
-               if (!addr)
-                       continue;
-
-               kb->start_addr = (unsigned long)addr;
-               symbol_name = kallsyms_lookup(kb->start_addr,
-                               &size, &offset, &modname, namebuf);
-               if (!symbol_name)
-                       kb->range = 0;
-               else
-                       kb->range = size;
+       err = populate_kprobe_blacklist(__start_kprobe_blacklist,
+                                       __stop_kprobe_blacklist);
+       if (err) {
+               pr_err("kprobes: failed to populate blacklist: %d\n", err);
+               pr_err("Please take care of using kprobes.\n");
        }
 
        if (kretprobe_blacklist_size) {