Merge commit '5bc66170dc486556a1e36fd384463536573f4b82' into x86/urgent

From Borislav Petkov <bp@amd64.org>:

Below is a RAS fix which reverts the addition of a sysfs attribute
which we agreed is not needed, post-factum. And this should go in now
because that sysfs attribute is going to end up in 3.7 otherwise and
thus exposed to userspace; removing it then would be a lot harder.

This is done as a merge rather than a simple patch/cherry-pick since
the baseline for this patch was not in the previous x86/urgent.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>

1 files changed, 20 insertions, 55 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 6c77f63c7591..61a53367d029 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -2088,15 +2088,19 @@ static int selinux_bprm_secureexec(struct linux_binprm *bprm)
         return (atsecure || cap_bprm_secureexec(bprm));
 }
 
+static int match_file(const void *p, struct file *file, unsigned fd)
+{
+        return file_has_perm(p, file, file_to_av(file)) ? fd + 1 : 0;
+}
+
 /* Derived from fs/exec.c:flush_old_files. */
 static inline void flush_unauthorized_files(const struct cred *cred,
                                             struct files_struct *files)
 {
         struct file *file, *devnull = NULL;
         struct tty_struct *tty;
-        struct fdtable *fdt;
-        long j = -1;
         int drop_tty = 0;
+        unsigned n;
 
         tty = get_current_tty();
         if (tty) {
@@ -2123,58 +2127,19 @@ static inline void flush_unauthorized_files(const struct cred *cred,
                 no_tty();
 
         /* Revalidate access to inherited open files. */
-        spin_lock(&files->file_lock);
-        for (;;) {
-                unsigned long set, i;
-                int fd;
-
-                j++;
-                i = j * BITS_PER_LONG;
-                fdt = files_fdtable(files);
-                if (i >= fdt->max_fds)
-                        break;
-                set = fdt->open_fds[j];
-                if (!set)
-                        continue;
-                spin_unlock(&files->file_lock);
-                for ( ; set ; i++, set >>= 1) {
-                        if (set & 1) {
-                                file = fget(i);
-                                if (!file)
-                                        continue;
-                                if (file_has_perm(cred,
-                                                  file,
-                                                  file_to_av(file))) {
-                                        sys_close(i);
-                                        fd = get_unused_fd();
-                                        if (fd != i) {
-                                                if (fd >= 0)
-                                                        put_unused_fd(fd);
-                                                fput(file);
-                                                continue;
-                                        }
-                                        if (devnull) {
-                                                get_file(devnull);
-                                        } else {
-                                                devnull = dentry_open(
-                                                        &selinux_null,
-                                                        O_RDWR, cred);
-                                                if (IS_ERR(devnull)) {
-                                                        devnull = NULL;
-                                                        put_unused_fd(fd);
-                                                        fput(file);
-                                                        continue;
-                                                }
-                                        }
-                                        fd_install(fd, devnull);
-                                }
-                                fput(file);
-                        }
-                }
-                spin_lock(&files->file_lock);
+        n = iterate_fd(files, 0, match_file, cred);
+        if (!n) /* none found? */
+                return;
 
-        }
-        spin_unlock(&files->file_lock);
+        devnull = dentry_open(&selinux_null, O_RDWR, cred);
+        if (IS_ERR(devnull))
+                devnull = NULL;
+        /* replace all the matching ones with this */
+        do {
+                replace_fd(n - 1, devnull, 0);
+        } while ((n = iterate_fd(files, n, match_file, cred)) != 0);
+        if (devnull)
+                fput(devnull);
 }
 
 /*
@@ -2483,9 +2448,9 @@ static int selinux_sb_statfs(struct dentry *dentry)
         return superblock_has_perm(cred, dentry->d_sb, FILESYSTEM__GETATTR, &ad);
 }
 
-static int selinux_mount(char *dev_name,
+static int selinux_mount(const char *dev_name,
                          struct path *path,
-                         char *type,
+                         const char *type,
                          unsigned long flags,
                          void *data)
 {