[PATCH 5.10 195/770] fs: add file and path permissions helpers

[PATCH 5.10 195/770] fs: add file and path permissions helpers

[Greg Kroah-Hartman]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christian Brauner <christian.brauner@ubuntu.com>

[ Upstream commit 02f92b3868a1b34ab98464e76b0e4e060474ba10 ]

Add two simple helpers to check permissions on a file and path
respectively and convert over some callers. It simplifies quite a few
codepaths and also reduces the churn in later patches quite a bit.
Christoph also correctly points out that this makes codepaths (e.g.
ioctls) way easier to follow that would otherwise have to do more
complex argument passing than necessary.

Link: https://lore.kernel.org/r/20210121131959.646623-4-christian.brauner@ubuntu.com
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Suggested-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: James Morris <jamorris@linux.microsoft.com>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/init.c                          | 6 +++---
 fs/notify/fanotify/fanotify_user.c | 2 +-
 fs/notify/inotify/inotify_user.c   | 2 +-
 fs/open.c                          | 6 +++---
 fs/udf/file.c                      | 2 +-
 fs/verity/enable.c                 | 2 +-
 include/linux/fs.h                 | 8 ++++++++
 kernel/bpf/inode.c                 | 2 +-
 kernel/sys.c                       | 2 +-
 mm/madvise.c                       | 2 +-
 mm/memcontrol.c                    | 2 +-
 mm/mincore.c                       | 2 +-
 net/unix/af_unix.c                 | 2 +-
 13 files changed, 24 insertions(+), 16 deletions(-)

diff --git a/fs/init.c b/fs/init.c
index e9c320a48cf15..02723bea84990 100644
--- a/fs/init.c
+++ b/fs/init.c
@@ -49,7 +49,7 @@ int __init init_chdir(const char *filename)
 	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
 	if (error)
 		return error;
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 	if (!error)
 		set_fs_pwd(current->fs, &path);
 	path_put(&path);
@@ -64,7 +64,7 @@ int __init init_chroot(const char *filename)
 	error = kern_path(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY, &path);
 	if (error)
 		return error;
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;
 	error = -EPERM;
@@ -118,7 +118,7 @@ int __init init_eaccess(const char *filename)
 	error = kern_path(filename, LOOKUP_FOLLOW, &path);
 	if (error)
 		return error;
-	error = inode_permission(d_inode(path.dentry), MAY_ACCESS);
+	error = path_permission(&path, MAY_ACCESS);
 	path_put(&path);
 	return error;
 }
diff --git a/fs/notify/fanotify/fanotify_user.c b/fs/notify/fanotify/fanotify_user.c
index 3e905b2e1b9c3..829ead2792dfb 100644
--- a/fs/notify/fanotify/fanotify_user.c
+++ b/fs/notify/fanotify/fanotify_user.c
@@ -702,7 +702,7 @@ static int fanotify_find_path(int dfd, const char __user *filename,
 	}
 
 	/* you can only watch an inode if you have read permissions on it */
-	ret = inode_permission(path->dentry->d_inode, MAY_READ);
+	ret = path_permission(path, MAY_READ);
 	if (ret) {
 		path_put(path);
 		goto out;
diff --git a/fs/notify/inotify/inotify_user.c b/fs/notify/inotify/inotify_user.c
index ad8fb4bca6dc1..82fc0cf86a7c3 100644
--- a/fs/notify/inotify/inotify_user.c
+++ b/fs/notify/inotify/inotify_user.c
@@ -352,7 +352,7 @@ static int inotify_find_inode(const char __user *dirname, struct path *path,
 	if (error)
 		return error;
 	/* you can only watch an inode if you have read permissions on it */
-	error = inode_permission(path->dentry->d_inode, MAY_READ);
+	error = path_permission(path, MAY_READ);
 	if (error) {
 		path_put(path);
 		return error;
diff --git a/fs/open.c b/fs/open.c
index 48933cbb75391..9f56ebacfbefe 100644
--- a/fs/open.c
+++ b/fs/open.c
@@ -492,7 +492,7 @@ SYSCALL_DEFINE1(chdir, const char __user *, filename)
 	if (error)
 		goto out;
 
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;
 
@@ -521,7 +521,7 @@ SYSCALL_DEFINE1(fchdir, unsigned int, fd)
 	if (!d_can_lookup(f.file->f_path.dentry))
 		goto out_putf;
 
-	error = inode_permission(file_inode(f.file), MAY_EXEC | MAY_CHDIR);
+	error = file_permission(f.file, MAY_EXEC | MAY_CHDIR);
 	if (!error)
 		set_fs_pwd(current->fs, &f.file->f_path);
 out_putf:
@@ -540,7 +540,7 @@ SYSCALL_DEFINE1(chroot, const char __user *, filename)
 	if (error)
 		goto out;
 
-	error = inode_permission(path.dentry->d_inode, MAY_EXEC | MAY_CHDIR);
+	error = path_permission(&path, MAY_EXEC | MAY_CHDIR);
 	if (error)
 		goto dput_and_out;
 
diff --git a/fs/udf/file.c b/fs/udf/file.c
index e283a62701b83..25f7c915f22b7 100644
--- a/fs/udf/file.c
+++ b/fs/udf/file.c
@@ -181,7 +181,7 @@ long udf_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	long old_block, new_block;
 	int result;
 
-	if (inode_permission(inode, MAY_READ) != 0) {
+	if (file_permission(filp, MAY_READ) != 0) {
 		udf_debug("no permission to access inode %lu\n", inode->i_ino);
 		return -EPERM;
 	}
diff --git a/fs/verity/enable.c b/fs/verity/enable.c
index 5ceae66e1ae02..29becb66d0d88 100644
--- a/fs/verity/enable.c
+++ b/fs/verity/enable.c
@@ -369,7 +369,7 @@ int fsverity_ioctl_enable(struct file *filp, const void __user *uarg)
 	 * has verity enabled, and to stabilize the data being hashed.
 	 */
 
-	err = inode_permission(inode, MAY_WRITE);
+	err = file_permission(filp, MAY_WRITE);
 	if (err)
 		return err;
 
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 6de70634e5471..0974e8160f50c 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -2824,6 +2824,14 @@ static inline int bmap(struct inode *inode,  sector_t *block)
 extern int notify_change(struct dentry *, struct iattr *, struct inode **);
 extern int inode_permission(struct inode *, int);
 extern int generic_permission(struct inode *, int);
+static inline int file_permission(struct file *file, int mask)
+{
+	return inode_permission(file_inode(file), mask);
+}
+static inline int path_permission(const struct path *path, int mask)
+{
+	return inode_permission(d_inode(path->dentry), mask);
+}
 extern int __check_sticky(struct inode *dir, struct inode *inode);
 
 static inline bool execute_ok(struct inode *inode)
diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c
index 6b14b4c4068cc..5966013bc788b 100644
--- a/kernel/bpf/inode.c
+++ b/kernel/bpf/inode.c
@@ -507,7 +507,7 @@ static void *bpf_obj_do_get(const char __user *pathname,
 		return ERR_PTR(ret);
 
 	inode = d_backing_inode(path.dentry);
-	ret = inode_permission(inode, ACC_MODE(flags));
+	ret = path_permission(&path, ACC_MODE(flags));
 	if (ret)
 		goto out;
 
diff --git a/kernel/sys.c b/kernel/sys.c
index efc213ae4c5ad..7a2cfb57fa9e7 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1873,7 +1873,7 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm, unsigned int fd)
 	if (!S_ISREG(inode->i_mode) || path_noexec(&exe.file->f_path))
 		goto exit;
 
-	err = inode_permission(inode, MAY_EXEC);
+	err = file_permission(exe.file, MAY_EXEC);
 	if (err)
 		goto exit;
 
diff --git a/mm/madvise.c b/mm/madvise.c
index f71fc88f0b331..a63aa04ec7fa3 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -543,7 +543,7 @@ static inline bool can_do_pageout(struct vm_area_struct *vma)
 	 * opens a side channel.
 	 */
 	return inode_owner_or_capable(file_inode(vma->vm_file)) ||
-		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
+	       file_permission(vma->vm_file, MAY_WRITE) == 0;
 }
 
 static long madvise_pageout(struct vm_area_struct *vma,
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ddc8ed096deca..186ae9dba0fd5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4918,7 +4918,7 @@ static ssize_t memcg_write_event_control(struct kernfs_open_file *of,
 
 	/* the process need read permission on control file */
 	/* AV: shouldn't we check that it's been opened for read instead? */
-	ret = inode_permission(file_inode(cfile.file), MAY_READ);
+	ret = file_permission(cfile.file, MAY_READ);
 	if (ret < 0)
 		goto out_put_cfile;
 
diff --git a/mm/mincore.c b/mm/mincore.c
index 02db1a834021b..7bdb4673f776a 100644
--- a/mm/mincore.c
+++ b/mm/mincore.c
@@ -167,7 +167,7 @@ static inline bool can_do_mincore(struct vm_area_struct *vma)
 	 * mappings, which opens a side channel.
 	 */
 	return inode_owner_or_capable(file_inode(vma->vm_file)) ||
-		inode_permission(file_inode(vma->vm_file), MAY_WRITE) == 0;
+	       file_permission(vma->vm_file, MAY_WRITE) == 0;
 }
 
 static const struct mm_walk_ops mincore_walk_ops = {
diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c
index 3ab726a668e8a..405bf3e6eb796 100644
--- a/net/unix/af_unix.c
+++ b/net/unix/af_unix.c
@@ -959,7 +959,7 @@ static struct sock *unix_find_other(struct net *net,
 		if (err)
 			goto fail;
 		inode = d_backing_inode(path.dentry);
-		err = inode_permission(inode, MAY_WRITE);
+		err = path_permission(&path, MAY_WRITE);
 		if (err)
 			goto put_fail;
 
-- 
2.43.0

[PATCH 5.10 196/770] namei: introduce struct renamedata

[Greg Kroah-Hartman]

5.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Christian Brauner <christian.brauner@ubuntu.com>

[ Upstream commit 9fe61450972d3900bffb1dc26a17ebb9cdd92db2 ]

In order to handle idmapped mounts we will extend the vfs rename helper
to take two new arguments in follow up patches. Since this operations
already takes a bunch of arguments add a simple struct renamedata and
make the current helper use it before we extend it.

Link: https://lore.kernel.org/r/20210121131959.646623-14-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
[ cel: backported to 5.10.y, prior to idmapped mounts ]
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/cachefiles/namei.c    |  9 +++++++--
 fs/ecryptfs/inode.c      | 10 +++++++---
 fs/namei.c               | 21 +++++++++++++++------
 fs/nfsd/vfs.c            |  8 +++++++-
 fs/overlayfs/overlayfs.h |  9 ++++++++-
 include/linux/fs.h       | 12 +++++++++++-
 6 files changed, 55 insertions(+), 14 deletions(-)

diff --git a/fs/cachefiles/namei.c b/fs/cachefiles/namei.c
index ecc8ecbbfa5ac..7b987de0babe8 100644
--- a/fs/cachefiles/namei.c
+++ b/fs/cachefiles/namei.c
@@ -412,9 +412,14 @@ static int cachefiles_bury_object(struct cachefiles_cache *cache,
 	if (ret < 0) {
 		cachefiles_io_error(cache, "Rename security error %d", ret);
 	} else {
+		struct renamedata rd = {
+			.old_dir	= d_inode(dir),
+			.old_dentry	= rep,
+			.new_dir	= d_inode(cache->graveyard),
+			.new_dentry	= grave,
+		};
 		trace_cachefiles_rename(object, rep, grave, why);
-		ret = vfs_rename(d_inode(dir), rep,
-				 d_inode(cache->graveyard), grave, NULL, 0);
+		ret = vfs_rename(&rd);
 		if (ret != 0 && ret != -ENOMEM)
 			cachefiles_io_error(cache,
 					    "Rename failed with error %d", ret);
diff --git a/fs/ecryptfs/inode.c b/fs/ecryptfs/inode.c
index c867a0d62f360..1dbe0c3ff38ea 100644
--- a/fs/ecryptfs/inode.c
+++ b/fs/ecryptfs/inode.c
@@ -598,6 +598,7 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 	struct dentry *lower_new_dir_dentry;
 	struct dentry *trap;
 	struct inode *target_inode;
+	struct renamedata rd = {};
 
 	if (flags)
 		return -EINVAL;
@@ -627,9 +628,12 @@ ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 		rc = -ENOTEMPTY;
 		goto out_lock;
 	}
-	rc = vfs_rename(d_inode(lower_old_dir_dentry), lower_old_dentry,
-			d_inode(lower_new_dir_dentry), lower_new_dentry,
-			NULL, 0);
+
+	rd.old_dir	= d_inode(lower_old_dir_dentry);
+	rd.old_dentry	= lower_old_dentry;
+	rd.new_dir	= d_inode(lower_new_dir_dentry);
+	rd.new_dentry	= lower_new_dentry;
+	rc = vfs_rename(&rd);
 	if (rc)
 		goto out_lock;
 	if (target_inode)
diff --git a/fs/namei.c b/fs/namei.c
index cb37d7c477e0b..72521a614514b 100644
--- a/fs/namei.c
+++ b/fs/namei.c
@@ -4277,11 +4277,14 @@ SYSCALL_DEFINE2(link, const char __user *, oldname, const char __user *, newname
  *	   ->i_mutex on parents, which works but leads to some truly excessive
  *	   locking].
  */
-int vfs_rename(struct inode *old_dir, struct dentry *old_dentry,
-	       struct inode *new_dir, struct dentry *new_dentry,
-	       struct inode **delegated_inode, unsigned int flags)
+int vfs_rename(struct renamedata *rd)
 {
 	int error;
+	struct inode *old_dir = rd->old_dir, *new_dir = rd->new_dir;
+	struct dentry *old_dentry = rd->old_dentry;
+	struct dentry *new_dentry = rd->new_dentry;
+	struct inode **delegated_inode = rd->delegated_inode;
+	unsigned int flags = rd->flags;
 	bool is_dir = d_is_dir(old_dentry);
 	struct inode *source = old_dentry->d_inode;
 	struct inode *target = new_dentry->d_inode;
@@ -4429,6 +4432,7 @@ EXPORT_SYMBOL(vfs_rename);
 int do_renameat2(int olddfd, struct filename *from, int newdfd,
 		 struct filename *to, unsigned int flags)
 {
+	struct renamedata rd;
 	struct dentry *old_dentry, *new_dentry;
 	struct dentry *trap;
 	struct path old_path, new_path;
@@ -4532,9 +4536,14 @@ int do_renameat2(int olddfd, struct filename *from, int newdfd,
 				     &new_path, new_dentry, flags);
 	if (error)
 		goto exit5;
-	error = vfs_rename(old_path.dentry->d_inode, old_dentry,
-			   new_path.dentry->d_inode, new_dentry,
-			   &delegated_inode, flags);
+
+	rd.old_dir	   = old_path.dentry->d_inode;
+	rd.old_dentry	   = old_dentry;
+	rd.new_dir	   = new_path.dentry->d_inode;
+	rd.new_dentry	   = new_dentry;
+	rd.delegated_inode = &delegated_inode;
+	rd.flags	   = flags;
+	error = vfs_rename(&rd);
 exit5:
 	dput(new_dentry);
 exit4:
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 3e30788e0046b..d12c3e71ca10e 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -1812,7 +1812,13 @@ nfsd_rename(struct svc_rqst *rqstp, struct svc_fh *ffhp, char *fname, int flen,
 		close_cached = true;
 		goto out_dput_old;
 	} else {
-		host_err = vfs_rename(fdir, odentry, tdir, ndentry, NULL, 0);
+		struct renamedata rd = {
+			.old_dir	= fdir,
+			.old_dentry	= odentry,
+			.new_dir	= tdir,
+			.new_dentry	= ndentry,
+		};
+		host_err = vfs_rename(&rd);
 		if (!host_err) {
 			host_err = commit_metadata(tfhp);
 			if (!host_err)
diff --git a/fs/overlayfs/overlayfs.h b/fs/overlayfs/overlayfs.h
index 26f91868fbdaf..87b7a4a74f4ed 100644
--- a/fs/overlayfs/overlayfs.h
+++ b/fs/overlayfs/overlayfs.h
@@ -212,9 +212,16 @@ static inline int ovl_do_rename(struct inode *olddir, struct dentry *olddentry,
 				unsigned int flags)
 {
 	int err;
+	struct renamedata rd = {
+		.old_dir 	= olddir,
+		.old_dentry 	= olddentry,
+		.new_dir 	= newdir,
+		.new_dentry 	= newdentry,
+		.flags 		= flags,
+	};
 
 	pr_debug("rename(%pd2, %pd2, 0x%x)\n", olddentry, newdentry, flags);
-	err = vfs_rename(olddir, olddentry, newdir, newdentry, NULL, flags);
+	err = vfs_rename(&rd);
 	if (err) {
 		pr_debug("...rename(%pd2, %pd2, ...) = %i\n",
 			 olddentry, newdentry, err);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 0974e8160f50c..cc3b6ddf58223 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -1780,7 +1780,17 @@ extern int vfs_symlink(struct inode *, struct dentry *, const char *);
 extern int vfs_link(struct dentry *, struct inode *, struct dentry *, struct inode **);
 extern int vfs_rmdir(struct inode *, struct dentry *);
 extern int vfs_unlink(struct inode *, struct dentry *, struct inode **);
-extern int vfs_rename(struct inode *, struct dentry *, struct inode *, struct dentry *, struct inode **, unsigned int);
+
+struct renamedata {
+	struct inode *old_dir;
+	struct dentry *old_dentry;
+	struct inode *new_dir;
+	struct dentry *new_dentry;
+	struct inode **delegated_inode;
+	unsigned int flags;
+} __randomize_layout;
+
+int vfs_rename(struct renamedata *);
 
 static inline int vfs_whiteout(struct inode *dir, struct dentry *dentry)
 {
-- 
2.43.0