diff options
| author | Kees Cook <keescook@chromium.org> | 2018-01-10 14:22:38 -0800 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2018-01-15 12:07:44 -0800 |
| commit | b394d468e7d75637e682a9be4a1181b27186c593 (patch) | |
| tree | 1c0894b3aafc06a4ee6bfc6facc81d192781de66 | |
| parent | 4f5e838605c264fcf16c3ff9495bd83da99acc6a (diff) | |
usercopy: Enhance and rename report_usercopy()
In preparation for refactoring the usercopy checks to pass offset to
the hardened usercopy report, this renames report_usercopy() to the
more accurate usercopy_abort(), marks it as noreturn because it is,
adds a hopefully helpful comment for anyone investigating such reports,
makes the function available to the slab allocators, and adds new "detail"
and "offset" arguments.
Signed-off-by: Kees Cook <keescook@chromium.org>
| -rw-r--r-- | include/linux/uaccess.h | 6 | ||||
| -rw-r--r-- | mm/usercopy.c | 24 | ||||
| -rw-r--r-- | tools/objtool/check.c | 1 |
3 files changed, 26 insertions, 5 deletions
diff --git a/include/linux/uaccess.h b/include/linux/uaccess.h index 251e655d407f..38b6442dc569 100644 --- a/include/linux/uaccess.h +++ b/include/linux/uaccess.h @@ -273,4 +273,10 @@ extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); #define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0) #endif +#ifdef CONFIG_HARDENED_USERCOPY +void __noreturn usercopy_abort(const char *name, const char *detail, + bool to_user, unsigned long offset, + unsigned long len); +#endif + #endif /* __LINUX_UACCESS_H__ */ diff --git a/mm/usercopy.c b/mm/usercopy.c index 5df1e68d4585..8006baa4caac 100644 --- a/mm/usercopy.c +++ b/mm/usercopy.c @@ -58,11 +58,25 @@ static noinline int check_stack_object(const void *obj, unsigned long len) return GOOD_STACK; } -static void report_usercopy(unsigned long len, bool to_user, const char *type) +/* + * If this function is reached, then CONFIG_HARDENED_USERCOPY has found an + * unexpected state during a copy_from_user() or copy_to_user() call. + * There are several checks being performed on the buffer by the + * __check_object_size() function. Normal stack buffer usage should never + * trip the checks, and kernel text addressing will always trip the check. + * For cache objects, copies must be within the object size. + */ +void __noreturn usercopy_abort(const char *name, const char *detail, + bool to_user, unsigned long offset, + unsigned long len) { - pr_emerg("kernel memory %s attempt detected %s '%s' (%lu bytes)\n", - to_user ? "exposure" : "overwrite", - to_user ? "from" : "to", type ? : "unknown", len); + pr_emerg("Kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)!\n", + to_user ? "exposure" : "overwrite", + to_user ? "from" : "to", + name ? : "unknown?!", + detail ? " '" : "", detail ? : "", detail ? "'" : "", + offset, len); + /* * For greater effect, it would be nice to do do_group_exit(), * but BUG() actually hooks all the lock-breaking and per-arch @@ -260,6 +274,6 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user) return; report: - report_usercopy(n, to_user, err); + usercopy_abort(err, NULL, to_user, 0, n); } EXPORT_SYMBOL(__check_object_size); diff --git a/tools/objtool/check.c b/tools/objtool/check.c index 9b341584eb1b..ae39444896d4 100644 --- a/tools/objtool/check.c +++ b/tools/objtool/check.c @@ -138,6 +138,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func, "__reiserfs_panic", "lbug_with_loc", "fortify_panic", + "usercopy_abort", }; if (func->bind == STB_WEAK) |