Re: [AppArmor 32/45] Enable LSM hooks to distinguish operations on file descriptors from operations on pathnames

Miklos Szeredi
2007-10-26T11:44:47Z

On Fri, 2007-10-26 at 13:30 +0200, Miklos Szeredi wrote:

> So I think the correct solution (which was suggested by Trond and
> others) is to define an f_op->fsetattr() method, which interested
> filesystems can define.
>

And here's the patch, which applies on top of the f_op->fgetattr()
patch, recently posted on -fsdevel.

(First time I'm trying to post a patch from this account, hope evolution
doesn't mess it up)

Miklos
---

Subject: VFS: new fsetattr() file operation

From: Miklos Szeredi <mszeredi@suse.cz>

Add a new file operation: f_op->fsetattr(), that is invoked by
ftruncate, fchmod, fchown and utimensat. Fall back to i_op->setattr()
if it is not defined.

For the reasons why we need this, see patch adding fgetattr().

ftruncate() already passed the open file to the filesystem via the
ia_file member of struct iattr. However it is cleaner to have a
separate file operation for this, so remove ia_file, ATTR_FILE and
convert existing users: fuse and AFS.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> ---

Index: linux/fs/afs/dir.c
===================================================================
--- linux.orig/fs/afs/dir.c 2007-10-23 11:14:07.000000000 +0200
+++ linux/fs/afs/dir.c 2007-10-26 13:39:22.000000000 +0200
@@ -45,6 +45,7 @@ const struct file_operations afs_dir_fil
.release = afs_release,
.readdir = afs_readdir,
.lock = afs_lock,
+ .fsetattr = afs_fsetattr,
};

const struct inode_operations afs_dir_inode_operations = {
Index: linux/fs/afs/file.c
===================================================================
--- linux.orig/fs/afs/file.c 2007-10-09 22:31:38.000000000 +0200
+++ linux/fs/afs/file.c 2007-10-26 13:39:22.000000000 +0200
@@ -36,6 +36,7 @@ const struct file_operations afs_file_op
.fsync = afs_fsync,
.lock = afs_lock,
.flock = afs_flock,
+ .fsetattr = afs_fsetattr,
};

const struct inode_operations afs_file_inode_operations = {
Index: linux/fs/afs/inode.c
===================================================================
--- linux.orig/fs/afs/inode.c 2007-10-23 11:14:07.000000000 +0200
+++ linux/fs/afs/inode.c 2007-10-26 13:39:22.000000000 +0200
@@ -361,7 +361,8 @@ void afs_clear_inode(struct inode *inode
/*
* set the attributes of an inode
*/
-int afs_setattr(struct dentry *dentry, struct iattr *attr)
+static int afs_do_setattr(struct dentry *dentry, struct iattr *attr,
+ struct file *file)
{
struct afs_vnode *vnode = AFS_FS_I(dentry->d_inode);
struct key *key;
@@ -383,8 +384,8 @@ int afs_setattr(struct dentry *dentry, s
afs_writeback_all(vnode);
}

- if (attr->ia_valid & ATTR_FILE) {
- key = attr->ia_file->private_data;
+ if (file) {
+ key = file->private_data;
} else {
key = afs_request_key(vnode->volume->cell);
if (IS_ERR(key)) {
@@ -394,10 +395,20 @@ int afs_setattr(struct dentry *dentry, s
}

ret = afs_vnode_setattr(vnode, key, attr);
- if (!(attr->ia_valid & ATTR_FILE))
+ if (!file)
key_put(key);

error:
_leave(" = %d", ret);
return ret;
}
+
+int afs_setattr(struct dentry *dentry, struct iattr *attr)
+{
+ return afs_do_setattr(dentry, attr, NULL);
+}
+
+int afs_fsetattr(struct file *file, struct iattr *attr)
+{
+ return afs_do_setattr(file->f_path.dentry, attr, file);
+}
Index: linux/fs/afs/internal.h
===================================================================
--- linux.orig/fs/afs/internal.h 2007-10-23 11:14:07.000000000 +0200
+++ linux/fs/afs/internal.h 2007-10-26 13:39:22.000000000 +0200
@@ -550,6 +550,7 @@ extern void afs_zap_data(struct afs_vnod
extern int afs_validate(struct afs_vnode *, struct key *);
extern int afs_getattr(struct vfsmount *, struct dentry *, struct kstat *);
extern int afs_setattr(struct dentry *, struct iattr *);
+extern int afs_fsetattr(struct file *, struct iattr *);
extern void afs_clear_inode(struct inode *);

/*
Index: linux/fs/attr.c
===================================================================
--- linux.orig/fs/attr.c 2007-10-23 11:14:07.000000000 +0200
+++ linux/fs/attr.c 2007-10-26 13:39:22.000000000 +0200
@@ -100,7 +100,7 @@ int inode_setattr(struct inode * inode,
}
EXPORT_SYMBOL(inode_setattr);

-int notify_change(struct dentry * dentry, struct iattr * attr)
+int fnotify_change(struct dentry *dentry, struct iattr *attr, struct file *file)
{
struct inode *inode = dentry->d_inode;
mode_t mode = inode->i_mode;
@@ -159,8 +159,12 @@ int notify_change(struct dentry * dentry

if (inode->i_op && inode->i_op->setattr) {
error = security_inode_setattr(dentry, attr);
- if (!error)
- error = inode->i_op->setattr(dentry, attr);
+ if (!error) {
+ if (file && file->f_op && file->f_op->fsetattr)
+ error = file->f_op->fsetattr(file, attr);
+ else
+ error = inode->i_op->setattr(dentry, attr);
+ }
} else {
error = inode_change_ok(inode, attr);
if (!error)
@@ -183,4 +187,9 @@ int notify_change(struct dentry * dentry
return error;
}

+int notify_change(struct dentry *dentry, struct iattr *attr)
+{
+ return fnotify_change(dentry, attr, NULL);
+}
+
EXPORT_SYMBOL(notify_change);
Index: linux/fs/open.c
===================================================================
--- linux.orig/fs/open.c 2007-10-23 11:14:22.000000000 +0200
+++ linux/fs/open.c 2007-10-26 13:39:22.000000000 +0200
@@ -206,16 +206,12 @@ int do_truncate(struct dentry *dentry, l

newattrs.ia_size = length;
newattrs.ia_valid = ATTR_SIZE | time_attrs;
- if (filp) {
- newattrs.ia_file = filp;
- newattrs.ia_valid |= ATTR_FILE;
- }

/* Remove suid/sgid on truncate too */
newattrs.ia_valid |= should_remove_suid(dentry);

mutex_lock(&dentry->d_inode->i_mutex);
- err = notify_change(dentry, &newattrs);
+ err = fnotify_change(dentry, &newattrs, filp);
mutex_unlock(&dentry->d_inode->i_mutex);
return err;
}
@@ -593,7 +589,7 @@ asmlinkage long sys_fchmod(unsigned int
mode = inode->i_mode;
newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
- err = notify_change(dentry, &newattrs);
+ err = fnotify_change(dentry, &newattrs, file);
mutex_unlock(&inode->i_mutex);

out_drop_write:
@@ -646,7 +642,8 @@ asmlinkage long sys_chmod(const char __u
return sys_fchmodat(AT_FDCWD, filename, mode);
}

-static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
+static int chown_common(struct dentry * dentry, uid_t user, gid_t group,
+ struct file *file)
{
struct inode * inode;
int error;
@@ -673,7 +670,7 @@ static int chown_common(struct dentry *
newattrs.ia_valid |=
ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
mutex_lock(&inode->i_mutex);
- error = notify_change(dentry, &newattrs);
+ error = fnotify_change(dentry, &newattrs, file);
mutex_unlock(&inode->i_mutex);
out:
return error;
@@ -690,7 +687,7 @@ asmlinkage long sys_chown(const char __u
error = mnt_want_write(nd.mnt);
if (error)
goto out_release;
- error = chown_common(nd.dentry, user, group);
+ error = chown_common(nd.dentry, user, group, NULL);
mnt_drop_write(nd.mnt);
out_release:
path_release(&nd);
@@ -715,7 +712,7 @@ asmlinkage long sys_fchownat(int dfd, co
error = mnt_want_write(nd.mnt);
if (error)
goto out_release;
- error = chown_common(nd.dentry, user, group);
+ error = chown_common(nd.dentry, user, group, NULL);
mnt_drop_write(nd.mnt);
out_release:
path_release(&nd);
@@ -734,7 +731,7 @@ asmlinkage long sys_lchown(const char __
error = mnt_want_write(nd.mnt);
if (error)
goto out_release;
- error = chown_common(nd.dentry, user, group);
+ error = chown_common(nd.dentry, user, group, NULL);
mnt_drop_write(nd.mnt);
out_release:
path_release(&nd);
@@ -758,7 +755,7 @@ asmlinkage long sys_fchown(unsigned int
goto out_fput;
dentry = file->f_path.dentry;
audit_inode(NULL, dentry);
- error = chown_common(dentry, user, group);
+ error = chown_common(dentry, user, group, file);
mnt_drop_write(file->f_vfsmnt);
out_fput:
fput(file);
Index: linux/include/linux/fs.h
===================================================================
--- linux.orig/include/linux/fs.h 2007-10-26 13:37:30.000000000 +0200
+++ linux/include/linux/fs.h 2007-10-26 13:39:22.000000000 +0200
@@ -335,7 +335,6 @@ typedef void (dio_iodone_t)(struct kiocb
#define ATTR_ATTR_FLAG 1024
#define ATTR_KILL_SUID 2048
#define ATTR_KILL_SGID 4096
-#define ATTR_FILE 8192
#define ATTR_KILL_PRIV 16384
#define ATTR_OPEN 32768 /* Truncating from open(O_TRUNC) */

@@ -357,13 +356,6 @@ struct iattr {
struct timespec ia_atime;
struct timespec ia_mtime;
struct timespec ia_ctime;
-
- /*
- * Not an attribute, but an auxilary info for filesystems wanting to
- * implement an ftruncate() like method. NOTE: filesystem should
- * check for (ia_valid & ATTR_FILE), and not for (ia_file != NULL).
- */
- struct file *ia_file;
};

/*
@@ -1196,6 +1188,7 @@ struct file_operations {
int (*setlease)(struct file *, long, struct file_lock **);
int (*revoke)(struct file *, struct address_space *);
int (*fgetattr)(struct file *, struct kstat *);
+ int (*fsetattr)(struct file *, struct iattr *);
};

struct inode_operations {
@@ -1703,6 +1696,7 @@ extern int do_remount_sb(struct super_bl
extern sector_t bmap(struct inode *, sector_t);
#endif
extern int notify_change(struct dentry *, struct iattr *);
+extern int fnotify_change(struct dentry *, struct iattr *, struct file *);
extern int permission(struct inode *, int, struct nameidata *);
extern int generic_permission(struct inode *, int,
int (*check_acl)(struct inode *, int));
Index: linux/fs/utimes.c
===================================================================
--- linux.orig/fs/utimes.c 2007-10-23 11:14:23.000000000 +0200
+++ linux/fs/utimes.c 2007-10-26 13:39:22.000000000 +0200
@@ -135,7 +135,7 @@ long do_utimes(int dfd, char __user *fil
}
}
mutex_lock(&inode->i_mutex);
- error = notify_change(dentry, &newattrs);
+ error = fnotify_change(dentry, &newattrs, f);
mutex_unlock(&inode->i_mutex);
mnt_drop_write_and_out:
mnt_drop_write(mnt);
Index: linux/fs/fuse/dir.c
===================================================================
--- linux.orig/fs/fuse/dir.c 2007-10-25 21:48:16.000000000 +0200
+++ linux/fs/fuse/dir.c 2007-10-26 13:39:22.000000000 +0200
@@ -1060,21 +1060,22 @@ static int fuse_dir_fsync(struct file *f
return file ? fuse_fsync_common(file, de, datasync, 1) : 0;
}

-static bool update_mtime(unsigned ivalid)
+static bool update_mtime(unsigned ivalid, bool have_file)
{
/* Always update if mtime is explicitly set */
if (ivalid & ATTR_MTIME_SET)
return true;

/* If it's an open(O_TRUNC) or an ftruncate(), don't update */
- if ((ivalid & ATTR_SIZE) && (ivalid & (ATTR_OPEN | ATTR_FILE)))
+ if ((ivalid & ATTR_SIZE) && ((ivalid & ATTR_OPEN) || have_file))
return false;

/* In all other cases update */
return true;
}

-static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg)
+static void iattr_to_fattr(struct iattr *iattr, struct fuse_setattr_in *arg,
+ bool have_file)
{
unsigned ivalid = iattr->ia_valid;

@@ -1093,7 +1094,7 @@ static void iattr_to_fattr(struct iattr
if (!(ivalid & ATTR_ATIME_SET))
arg->valid |= FATTR_ATIME_NOW;
}
- if ((ivalid & ATTR_MTIME) && update_mtime(ivalid)) {
+ if ((ivalid & ATTR_MTIME) && update_mtime(ivalid, have_file)) {
arg->valid |= FATTR_MTIME;
arg->mtime = iattr->ia_mtime.tv_sec;
arg->mtimensec = iattr->ia_mtime.tv_nsec;
@@ -1110,8 +1111,8 @@ static void iattr_to_fattr(struct iattr
* vmtruncate() doesn't allow for this case, so do the rlimit checking
* and the actual truncation by hand.
*/
-static int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
- struct file *file)
+int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
+ struct file *file)
{
struct inode *inode = entry->d_inode;
struct fuse_conn *fc = get_fuse_conn(inode);
@@ -1149,7 +1150,7 @@ static int fuse_do_setattr(struct dentry

memset(&inarg, 0, sizeof(inarg));
memset(&outarg, 0, sizeof(outarg));
- iattr_to_fattr(attr, &inarg);
+ iattr_to_fattr(attr, &inarg, file != NULL);
if (file) {
struct fuse_file *ff = file->private_data;
inarg.valid |= FATTR_FH;
@@ -1191,10 +1192,7 @@ static int fuse_do_setattr(struct dentry

static int fuse_setattr(struct dentry *entry, struct iattr *attr)
{
- if (attr->ia_valid & ATTR_FILE)
- return fuse_do_setattr(entry, attr, attr->ia_file);
- else
- return fuse_do_setattr(entry, attr, NULL);
+ return fuse_do_setattr(entry, attr, NULL);
}

static int fuse_getattr(struct vfsmount *mnt, struct dentry *entry,
Index: linux/fs/fuse/file.c
===================================================================
--- linux.orig/fs/fuse/file.c 2007-10-26 13:37:30.000000000 +0200
+++ linux/fs/fuse/file.c 2007-10-26 13:39:22.000000000 +0200
@@ -918,6 +918,11 @@ static sector_t fuse_bmap(struct address
return err ? 0 : outarg.block;
}

+static int fuse_fsetattr(struct file *file, struct iattr *attr)
+{
+ return fuse_do_setattr(file->f_path.dentry, attr, file);
+}
+
static const struct file_operations fuse_file_operations = {
.llseek = generic_file_llseek,
.read = do_sync_read,
@@ -932,6 +937,7 @@ static const struct file_operations fuse
.lock = fuse_file_lock,
.flock = fuse_file_flock,
.fgetattr = fuse_file_fgetattr,
+ .fsetattr = fuse_fsetattr,
.splice_read = generic_file_splice_read,
};

@@ -946,6 +952,7 @@ static const struct file_operations fuse
.lock = fuse_file_lock,
.flock = fuse_file_flock,
.fgetattr = fuse_file_fgetattr,
+ .fsetattr = fuse_fsetattr,
/* no mmap and splice_read */
};

Index: linux/fs/fuse/fuse_i.h
===================================================================
--- linux.orig/fs/fuse/fuse_i.h 2007-10-26 13:36:47.000000000 +0200
+++ linux/fs/fuse/fuse_i.h 2007-10-26 13:39:22.000000000 +0200
@@ -505,6 +505,10 @@ void fuse_change_attributes(struct inode
*/
int fuse_dev_init(void);

+
+int fuse_do_setattr(struct dentry *entry, struct iattr *attr,
+ struct file *file);
+
/**
* Cleanup the client device
*/