9 files changed, 23 insertions, 9 deletions

diff --git a/fs/exec.c b/fs/exec.c
index 1977c2a553ac..b06623a9347f 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -98,6 +98,12 @@ static inline void put_binfmt(struct linux_binfmt * fmt)
         module_put(fmt->module);
 }
 
+bool path_noexec(const struct path *path)
+{
+        return (path->mnt->mnt_flags & MNT_NOEXEC) ||
+               (path->mnt->mnt_sb->s_iflags & SB_I_NOEXEC);
+}
+
 #ifdef CONFIG_USELIB
 /*
  * Note that a shared library must be both readable and executable due to
@@ -132,7 +138,7 @@ SYSCALL_DEFINE1(uselib, const char __user *, library)
                 goto exit;
 
         error = -EACCES;
-        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+        if (path_noexec(&file->f_path))
                 goto exit;
 
         fsnotify_open(file);
@@ -777,7 +783,7 @@ static struct file *do_open_execat(int fd, struct filename *name, int flags)
         if (!S_ISREG(file_inode(file)->i_mode))
                 goto exit;
 
-        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+        if (path_noexec(&file->f_path))
                 goto exit;
 
         err = deny_write_access(file);
diff --git a/fs/open.c b/fs/open.c
index e33dab287fa0..b6f1e96a7c0b 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -377,7 +377,7 @@ retry:
                  * with the "noexec" flag.
                  */
                 res = -EACCES;
-                if (path.mnt->mnt_flags & MNT_NOEXEC)
+                if (path_noexec(&path))
                         goto out_path_release;
         }
 
diff --git a/fs/proc/root.c b/fs/proc/root.c
index 68feb0f70e63..361ab4ee42fc 100644
--- a/fs/proc/root.c
+++ b/fs/proc/root.c
@@ -134,6 +134,8 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
                 }
 
                 sb->s_flags |= MS_ACTIVE;
+                /* User space would break if executables appear on proc */
+                sb->s_iflags |= SB_I_NOEXEC;
         }
 
         return dget(sb->s_root);
diff --git a/fs/sysfs/mount.c b/fs/sysfs/mount.c
index 1c6ac6fcee9f..f3db82071cfb 100644
--- a/fs/sysfs/mount.c
+++ b/fs/sysfs/mount.c
@@ -40,6 +40,10 @@ static struct dentry *sysfs_mount(struct file_system_type *fs_type,
                                 SYSFS_MAGIC, &new_sb, ns);
         if (IS_ERR(root) || !new_sb)
                 kobj_ns_drop(KOBJ_NS_TYPE_NET, ns);
+        else if (new_sb)
+                /* Userspace would break if executables appear on sysfs */
+                root->d_sb->s_iflags |= SB_I_NOEXEC;
+
         return root;
 }
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index a0653e560c26..42912f8d286e 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1244,6 +1244,7 @@ struct mm_struct;
 
 /* sb->s_iflags */
 #define SB_I_CGROUPWB   0x00000001      /* cgroup-aware writeback enabled */
+#define SB_I_NOEXEC     0x00000002      /* Ignore executables on this fs */
 
 /* Possible states of 'frozen' field */
 enum {
@@ -3030,4 +3031,6 @@ static inline bool dir_relax(struct inode *inode)
         return !IS_DEADDIR(inode);
 }
 
+extern bool path_noexec(const struct path *path);
+
 #endif /* _LINUX_FS_H */
diff --git a/kernel/sys.c b/kernel/sys.c
index 259fda25eb6b..fa2f2f671a5c 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1668,8 +1668,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
          * overall picture.
          */
         err = -EACCES;
-        if (!S_ISREG(inode->i_mode)     ||
-            exe.file->f_path.mnt->mnt_flags & MNT_NOEXEC)
+        if (!S_ISREG(inode->i_mode) || path_noexec(&exe.file->f_path))
                 goto exit;
 
         err = inode_permission(inode, MAY_EXEC);
diff --git a/mm/mmap.c b/mm/mmap.c
index aa632ade2be7..f126923ce683 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -1268,7 +1268,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
          *  mounted, in which case we dont add PROT_EXEC.)
          */
         if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC))
-                if (!(file && (file->f_path.mnt->mnt_flags & MNT_NOEXEC)))
+                if (!(file && path_noexec(&file->f_path)))
                         prot |= PROT_EXEC;
 
         if (!(flags & MAP_FIXED))
@@ -1337,7 +1337,7 @@ unsigned long do_mmap_pgoff(struct file *file, unsigned long addr,
                 case MAP_PRIVATE:
                         if (!(file->f_mode & FMODE_READ))
                                 return -EACCES;
-                        if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
+                        if (path_noexec(&file->f_path)) {
                                 if (vm_flags & VM_EXEC)
                                         return -EPERM;
                                 vm_flags &= ~VM_MAYEXEC;
diff --git a/mm/nommu.c b/mm/nommu.c
index 58ea3643b9e9..ce17abf087ff 100644
--- a/mm/nommu.c
+++ b/mm/nommu.c
@@ -1035,7 +1035,7 @@ static int validate_mmap_request(struct file *file,
 
                 /* handle executable mappings and implied executable
                  * mappings */
-                if (file->f_path.mnt->mnt_flags & MNT_NOEXEC) {
+                if (path_noexec(&file->f_path)) {
                         if (prot & PROT_EXEC)
                                 return -EPERM;
                 } else if ((prot & PROT_READ) && !(prot & PROT_EXEC)) {
diff --git a/security/security.c b/security/security.c
index 595fffab48b0..062f3c997fdc 100644
--- a/security/security.c
+++ b/security/security.c
@@ -776,7 +776,7 @@ static inline unsigned long mmap_prot(struct file *file, unsigned long prot)
          * ditto if it's not on noexec mount, except that on !MMU we need
          * NOMMU_MAP_EXEC (== VM_MAYEXEC) in this case
          */
-        if (!(file->f_path.mnt->mnt_flags & MNT_NOEXEC)) {
+        if (!path_noexec(&file->f_path)) {
 #ifndef CONFIG_MMU
                 if (file->f_op->mmap_capabilities) {
                         unsigned caps = file->f_op->mmap_capabilities(file);