Merge remote-tracking branch 'userns/for-next'

11 files changed, 58 insertions, 17 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/namespace.c b/fs/namespace.c
index c7cb8a526c05..ce428cadd41f 100644
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -3194,6 +3194,8 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
 	down_read(&namespace_sem);
 	list_for_each_entry(mnt, &ns->list, mnt_list) {
 		struct mount *child;
+		int mnt_flags;
+
 		if (mnt->mnt.mnt_sb->s_type != type)
 			continue;
 
@@ -3203,17 +3205,30 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
 		if (mnt->mnt.mnt_root != mnt->mnt.mnt_sb->s_root)
 			continue;
 
+		/* Read the mount flags and filter out flags that
+		 * may safely be ignored.
+		 */
+		mnt_flags = mnt->mnt.mnt_flags;
+		if (mnt->mnt.mnt_sb->s_iflags & SB_I_NOEXEC)
+			mnt_flags &= ~(MNT_LOCK_NOSUID | MNT_LOCK_NOEXEC);
+
 		/* Verify the mount flags are equal to or more permissive
 		 * than the proposed new mount.
 		 */
-		if ((mnt->mnt.mnt_flags & MNT_LOCK_READONLY) &&
+		if ((mnt_flags & MNT_LOCK_READONLY) &&
 		    !(new_flags & MNT_READONLY))
 			continue;
-		if ((mnt->mnt.mnt_flags & MNT_LOCK_NODEV) &&
+		if ((mnt_flags & MNT_LOCK_NODEV) &&
 		    !(new_flags & MNT_NODEV))
 			continue;
-		if ((mnt->mnt.mnt_flags & MNT_LOCK_ATIME) &&
-		    ((mnt->mnt.mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
+		if ((mnt_flags & MNT_LOCK_NOSUID) &&
+		    !(new_flags & MNT_NOSUID))
+			continue;
+		if ((mnt_flags & MNT_LOCK_NOEXEC) &&
+		    !(new_flags & MNT_NOEXEC))
+			continue;
+		if ((mnt_flags & MNT_LOCK_ATIME) &&
+		    ((mnt_flags & MNT_ATIME_MASK) != (new_flags & MNT_ATIME_MASK)))
 			continue;
 
 		/* This mount is not fully visible if there are any
@@ -3223,16 +3238,18 @@ static bool fs_fully_visible(struct file_system_type *type, int *new_mnt_flags)
 		list_for_each_entry(child, &mnt->mnt_mounts, mnt_child) {
 			struct inode *inode = child->mnt_mountpoint->d_inode;
 			/* Only worry about locked mounts */
-			if (!(mnt->mnt.mnt_flags & MNT_LOCKED))
+			if (!(mnt_flags & MNT_LOCKED))
 				continue;
 			/* Is the directory permanetly empty? */
 			if (!is_empty_dir_inode(inode))
 				goto next;
 		}
 		/* Preserve the locked attributes */
-		*new_mnt_flags |= mnt->mnt.mnt_flags & (MNT_LOCK_READONLY | \
-							MNT_LOCK_NODEV    | \
-							MNT_LOCK_ATIME);
+		*new_mnt_flags |= mnt_flags & (MNT_LOCK_READONLY | \
+					       MNT_LOCK_NODEV    | \
+					       MNT_LOCK_NOSUID   | \
+					       MNT_LOCK_NOEXEC   | \
+					       MNT_LOCK_ATIME);
 		visible = true;
 		goto found;
 	next:	;
diff --git a/fs/nsfs.c b/fs/nsfs.c
index 99521e7c492b..e4905fbf3396 100644
--- a/fs/nsfs.c
+++ b/fs/nsfs.c
@@ -4,6 +4,7 @@
 #include <linux/proc_ns.h>
 #include <linux/magic.h>
 #include <linux/ktime.h>
+#include <linux/seq_file.h>
 
 static struct vfsmount *nsfs_mnt;
 
@@ -136,9 +137,18 @@ out_invalid:
 	return ERR_PTR(-EINVAL);
 }
 
+static int nsfs_show_path(struct seq_file *seq, struct dentry *dentry)
+{
+	struct inode *inode = d_inode(dentry);
+	const struct proc_ns_operations *ns_ops = dentry->d_fsdata;
+
+	return seq_printf(seq, "%s:[%lu]", ns_ops->name, inode->i_ino);
+}
+
 static const struct super_operations nsfs_ops = {
 	.statfs = simple_statfs,
 	.evict_inode = nsfs_evict,
+	.show_path = nsfs_show_path,
 };
 static struct dentry *nsfs_mount(struct file_system_type *fs_type,
 			int flags, const char *dev_name, void *data)
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 cc008c338f5a..bf3246512a26 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1259,6 +1259,7 @@ 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 {
@@ -3040,4 +3041,6 @@ 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);