fs: make helpers idmap mount aware

Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-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>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>

4 files changed, 24 insertions, 15 deletions

diff --git a/fs/coda/coda_linux.h b/fs/coda/coda_linux.h
index d5ebd36fb2cc..e7b27754ce78 100644
--- a/fs/coda/coda_linux.h
+++ b/fs/coda/coda_linux.h
@@ -46,10 +46,12 @@ extern const struct file_operations coda_ioctl_operations;
 /* operations shared over more than one file */
 int coda_open(struct inode *i, struct file *f);
 int coda_release(struct inode *i, struct file *f);
-int coda_permission(struct inode *inode, int mask);
+int coda_permission(struct user_namespace *mnt_userns, struct inode *inode,
+		    int mask);
 int coda_revalidate_inode(struct inode *);
-int coda_getattr(const struct path *, struct kstat *, u32, unsigned int);
-int coda_setattr(struct dentry *, struct iattr *);
+int coda_getattr(struct user_namespace *, const struct path *, struct kstat *,
+		 u32, unsigned int);
+int coda_setattr(struct user_namespace *, struct dentry *, struct iattr *);
 
 /* this file:  heloers */
 char *coda_f2s(struct CodaFid *f);
diff --git a/fs/coda/dir.c b/fs/coda/dir.c
index ca40c2556ba6..d69989c1bac3 100644
--- a/fs/coda/dir.c
+++ b/fs/coda/dir.c
@@ -73,7 +73,8 @@ static struct dentry *coda_lookup(struct inode *dir, struct dentry *entry, unsig
 }
 
 
-int coda_permission(struct inode *inode, int mask)
+int coda_permission(struct user_namespace *mnt_userns, struct inode *inode,
+		    int mask)
 {
 	int error;
 
@@ -132,7 +133,8 @@ static inline void coda_dir_drop_nlink(struct inode *dir)
 }
 
 /* creation routines: create, mknod, mkdir, link, symlink */
-static int coda_create(struct inode *dir, struct dentry *de, umode_t mode, bool excl)
+static int coda_create(struct user_namespace *mnt_userns, struct inode *dir,
+		       struct dentry *de, umode_t mode, bool excl)
 {
 	int error;
 	const char *name=de->d_name.name;
@@ -164,7 +166,8 @@ err_out:
 	return error;
 }
 
-static int coda_mkdir(struct inode *dir, struct dentry *de, umode_t mode)
+static int coda_mkdir(struct user_namespace *mnt_userns, struct inode *dir,
+		      struct dentry *de, umode_t mode)
 {
 	struct inode *inode;
 	struct coda_vattr attrs;
@@ -225,7 +228,8 @@ static int coda_link(struct dentry *source_de, struct inode *dir_inode,
 }
 
 
-static int coda_symlink(struct inode *dir_inode, struct dentry *de,
+static int coda_symlink(struct user_namespace *mnt_userns,
+			struct inode *dir_inode, struct dentry *de,
 			const char *symname)
 {
 	const char *name = de->d_name.name;
@@ -291,9 +295,9 @@ static int coda_rmdir(struct inode *dir, struct dentry *de)
 }
 
 /* rename */
-static int coda_rename(struct inode *old_dir, struct dentry *old_dentry,
-		       struct inode *new_dir, struct dentry *new_dentry,
-		       unsigned int flags)
+static int coda_rename(struct user_namespace *mnt_userns, struct inode *old_dir,
+		       struct dentry *old_dentry, struct inode *new_dir,
+		       struct dentry *new_dentry, unsigned int flags)
 {
 	const char *old_name = old_dentry->d_name.name;
 	const char *new_name = new_dentry->d_name.name;
diff --git a/fs/coda/inode.c b/fs/coda/inode.c
index 4d113e191cb8..d9f1bd7153df 100644
--- a/fs/coda/inode.c
+++ b/fs/coda/inode.c
@@ -251,8 +251,8 @@ static void coda_evict_inode(struct inode *inode)
 	coda_cache_clear_inode(inode);
 }
 
-int coda_getattr(const struct path *path, struct kstat *stat,
-		 u32 request_mask, unsigned int flags)
+int coda_getattr(struct user_namespace *mnt_userns, const struct path *path,
+		 struct kstat *stat, u32 request_mask, unsigned int flags)
 {
 	int err = coda_revalidate_inode(d_inode(path->dentry));
 	if (!err)
@@ -260,7 +260,8 @@ int coda_getattr(const struct path *path, struct kstat *stat,
 	return err;
 }
 
-int coda_setattr(struct dentry *de, struct iattr *iattr)
+int coda_setattr(struct user_namespace *mnt_userns, struct dentry *de,
+		 struct iattr *iattr)
 {
 	struct inode *inode = d_inode(de);
 	struct coda_vattr vattr;
diff --git a/fs/coda/pioctl.c b/fs/coda/pioctl.c
index 3aec27e5eb82..cb9fd59a688c 100644
--- a/fs/coda/pioctl.c
+++ b/fs/coda/pioctl.c
@@ -24,7 +24,8 @@
 #include "coda_linux.h"
 
 /* pioctl ops */
-static int coda_ioctl_permission(struct inode *inode, int mask);
+static int coda_ioctl_permission(struct user_namespace *mnt_userns,
+				 struct inode *inode, int mask);
 static long coda_pioctl(struct file *filp, unsigned int cmd,
 			unsigned long user_data);
 
@@ -40,7 +41,8 @@ const struct file_operations coda_ioctl_operations = {
 };
 
 /* the coda pioctl inode ops */
-static int coda_ioctl_permission(struct inode *inode, int mask)
+static int coda_ioctl_permission(struct user_namespace *mnt_userns,
+				 struct inode *inode, int mask)
 {
 	return (mask & MAY_EXEC) ? -EACCES : 0;
 }