kprobes: Blacklist symbols in arch-defined prohibited area

BugLink: https://bugs.launchpad.net/bugs/1855787
[ Upstream commit fb1a59fae8baa3f3c69b72a87ff94fc4fa5683ec ]

Blacklist symbols in arch-defined probe-prohibited areas.
With this change, user can see all symbols which are prohibited
to probe in debugfs.

All archtectures which have custom prohibit areas should define
its own arch_populate_kprobe_blacklist() function, but unless that,
all symbols marked __kprobes are blacklisted.

Reported-by: Andrea Righi <righi.andrea@gmail.com>
Tested-by: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: David S. Miller <davem@davemloft.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Yonghong Song <yhs@fb.com>
Link: http://lkml.kernel.org/r/154503485491.26176.15823229545155174796.stgit@devbox
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 55122b2c924cd61c212c8eba41d3030f444dcd84..fe4cbb0ffe73865057ce058c2f8c1888658520e4 100644 (file)
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -268,10 +268,13 @@ extern int arch_init_kprobes(void);
 extern void show_registers(struct pt_regs *regs);
 extern void kprobes_inc_nmissed_count(struct kprobe *p);
 extern bool arch_within_kprobe_blacklist(unsigned long addr);
+extern int arch_populate_kprobe_blacklist(void);
 extern bool arch_kprobe_on_func_entry(unsigned long offset);
 extern bool kprobe_on_func_entry(kprobe_opcode_t *addr, const char *sym, unsigned long offset);
 
 extern bool within_kprobe_blacklist(unsigned long addr);
+extern int kprobe_add_ksym_blacklist(unsigned long entry);
+extern int kprobe_add_area_blacklist(unsigned long start, unsigned long end);
 
 struct kprobe_insn_cache {
        struct mutex mutex;

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 6ede02bb05ac406090301aceeadc63cf1e6425a7..cd1d7d1ec87cf9d6c0c282dd341a0a5235d7d72b 100644 (file)
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2149,6 +2149,47 @@ void dump_kprobe(struct kprobe *kp)
 }
 NOKPROBE_SYMBOL(dump_kprobe);
 
+int kprobe_add_ksym_blacklist(unsigned long entry)
+{
+       struct kprobe_blacklist_entry *ent;
+       unsigned long offset = 0, size = 0;
+
+       if (!kernel_text_address(entry) ||
+           !kallsyms_lookup_size_offset(entry, &size, &offset))
+               return -EINVAL;
+
+       ent = kmalloc(sizeof(*ent), GFP_KERNEL);
+       if (!ent)
+               return -ENOMEM;
+       ent->start_addr = entry;
+       ent->end_addr = entry + size;
+       INIT_LIST_HEAD(&ent->list);
+       list_add_tail(&ent->list, &kprobe_blacklist);
+
+       return (int)size;
+}
+
+/* Add all symbols in given area into kprobe blacklist */
+int kprobe_add_area_blacklist(unsigned long start, unsigned long end)
+{
+       unsigned long entry;
+       int ret = 0;
+
+       for (entry = start; entry < end; entry += ret) {
+               ret = kprobe_add_ksym_blacklist(entry);
+               if (ret < 0)
+                       return ret;
+               if (ret == 0)   /* In case of alias symbol */
+                       ret = 1;
+       }
+       return 0;
+}
+
+int __init __weak arch_populate_kprobe_blacklist(void)
+{
+       return 0;
+}
+
 /*
  * Lookup and populate the kprobe_blacklist.
  *
@@ -2160,26 +2201,24 @@ NOKPROBE_SYMBOL(dump_kprobe);
 static int __init populate_kprobe_blacklist(unsigned long *start,
                                             unsigned long *end)
 {
+       unsigned long entry;
        unsigned long *iter;
-       struct kprobe_blacklist_entry *ent;
-       unsigned long entry, offset = 0, size = 0;
+       int ret;
 
        for (iter = start; iter < end; iter++) {
                entry = arch_deref_entry_point((void *)*iter);
-
-               if (!kernel_text_address(entry) ||
-                   !kallsyms_lookup_size_offset(entry, &size, &offset))
+               ret = kprobe_add_ksym_blacklist(entry);
+               if (ret == -EINVAL)
                        continue;
-
-               ent = kmalloc(sizeof(*ent), GFP_KERNEL);
-               if (!ent)
-                       return -ENOMEM;
-               ent->start_addr = entry;
-               ent->end_addr = entry + size;
-               INIT_LIST_HEAD(&ent->list);
-               list_add_tail(&ent->list, &kprobe_blacklist);
+               if (ret < 0)
+                       return ret;
        }
-       return 0;
+
+       /* Symbols in __kprobes_text are blacklisted */
+       ret = kprobe_add_area_blacklist((unsigned long)__kprobes_text_start,
+                                       (unsigned long)__kprobes_text_end);
+
+       return ret ? : arch_populate_kprobe_blacklist();
 }
 
 /* Module notifier call back, checking kprobes on the module */