Commit b394d468 authored by Kees Cook's avatar Kees Cook

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: default avatarKees Cook <keescook@chromium.org>
parent 4f5e8386
...@@ -273,4 +273,10 @@ extern long strncpy_from_unsafe(char *dst, const void *unsafe_addr, long count); ...@@ -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) #define unsafe_put_user(x, ptr, err) do { if (unlikely(__put_user(x, ptr))) goto err; } while (0)
#endif #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__ */ #endif /* __LINUX_UACCESS_H__ */
...@@ -58,11 +58,25 @@ static noinline int check_stack_object(const void *obj, unsigned long len) ...@@ -58,11 +58,25 @@ static noinline int check_stack_object(const void *obj, unsigned long len)
return GOOD_STACK; 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", pr_emerg("Kernel memory %s attempt detected %s %s%s%s%s (offset %lu, size %lu)!\n",
to_user ? "exposure" : "overwrite", to_user ? "exposure" : "overwrite",
to_user ? "from" : "to", type ? : "unknown", len); to_user ? "from" : "to",
name ? : "unknown?!",
detail ? " '" : "", detail ? : "", detail ? "'" : "",
offset, len);
/* /*
* For greater effect, it would be nice to do do_group_exit(), * For greater effect, it would be nice to do do_group_exit(),
* but BUG() actually hooks all the lock-breaking and per-arch * 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) ...@@ -260,6 +274,6 @@ void __check_object_size(const void *ptr, unsigned long n, bool to_user)
return; return;
report: report:
report_usercopy(n, to_user, err); usercopy_abort(err, NULL, to_user, 0, n);
} }
EXPORT_SYMBOL(__check_object_size); EXPORT_SYMBOL(__check_object_size);
...@@ -138,6 +138,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func, ...@@ -138,6 +138,7 @@ static int __dead_end_function(struct objtool_file *file, struct symbol *func,
"__reiserfs_panic", "__reiserfs_panic",
"lbug_with_loc", "lbug_with_loc",
"fortify_panic", "fortify_panic",
"usercopy_abort",
}; };
if (func->bind == STB_WEAK) if (func->bind == STB_WEAK)
......
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