Files
linux/fs
Kees Cook 0fd338b2d2 exec: move path_noexec() check earlier
The path_noexec() check, like the regular file check, was happening too
late, letting LSMs see impossible execve()s.  Check it earlier as well in
may_open() and collect the redundant fs/exec.c path_noexec() test under
the same robustness comment as the S_ISREG() check.

My notes on the call path, and related arguments, checks, etc:

do_open_execat()
    struct open_flags open_exec_flags = {
        .open_flag = O_LARGEFILE | O_RDONLY | __FMODE_EXEC,
        .acc_mode = MAY_EXEC,
        ...
    do_filp_open(dfd, filename, open_flags)
        path_openat(nameidata, open_flags, flags)
            file = alloc_empty_file(open_flags, current_cred());
            do_open(nameidata, file, open_flags)
                may_open(path, acc_mode, open_flag)
                    /* new location of MAY_EXEC vs path_noexec() test */
                    inode_permission(inode, MAY_OPEN | acc_mode)
                        security_inode_permission(inode, acc_mode)
                vfs_open(path, file)
                    do_dentry_open(file, path->dentry->d_inode, open)
                        security_file_open(f)
                        open()
    /* old location of path_noexec() test */

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Aleksa Sarai <cyphar@cyphar.com>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers3@gmail.com>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Link: http://lkml.kernel.org/r/20200605160013.3954297-4-keescook@chromium.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2020-08-12 10:58:01 -07:00
..
2020-03-27 09:29:56 +00:00
2020-07-08 08:27:56 +02:00
2020-07-27 14:29:23 -04:00
2020-08-12 10:58:01 -07:00
2020-05-14 16:44:25 +02:00
2020-02-07 14:48:35 -05:00
2020-08-04 21:02:38 -04:00
2020-07-25 09:47:44 -06:00
2020-07-31 08:16:01 +02:00
2020-08-07 11:33:24 -07:00
2020-07-31 08:17:51 +02:00
2020-05-14 16:44:24 +02:00
2020-08-12 10:58:01 -07:00
2020-08-12 10:58:01 -07:00
2020-07-31 08:16:00 +02:00
2020-07-31 08:16:01 +02:00