| Message ID | 20240221-idmap-fscap-refactor-v2-18-3039364623bd@kernel.org (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | fs: use type-safe uid representation for filesystem capabilities | expand |
On Wed, Feb 21, 2024 at 03:24:49PM -0600, Seth Forshee (DigitalOcean) wrote: > Provide a type-safe interface for setting filesystem capabilities and a > generic implementation suitable for most filesystems. > > Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org> > --- > fs/xattr.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ > include/linux/fs.h | 2 ++ > 2 files changed, 81 insertions(+) > > diff --git a/fs/xattr.c b/fs/xattr.c > index 10d1b1f78fc2..96de43928a51 100644 > --- a/fs/xattr.c > +++ b/fs/xattr.c > @@ -245,6 +245,85 @@ int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > } > EXPORT_SYMBOL(vfs_get_fscaps); > > +static int generic_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > + const struct vfs_caps *caps, int setxattr_flags) > +{ > + struct inode *inode = d_inode(dentry); > + struct vfs_ns_cap_data nscaps; > + int size; ssize_t, I believe. > + > + size = vfs_caps_to_xattr(idmap, i_user_ns(inode), caps, > + &nscaps, sizeof(nscaps)); > + if (size < 0) > + return size; > + > + return __vfs_setxattr_noperm(idmap, dentry, XATTR_NAME_CAPS, > + &nscaps, size, setxattr_flags); > +} > + > +/** > + * vfs_set_fscaps - set filesystem capabilities > + * @idmap: idmap of the mount the inode was found from > + * @dentry: the dentry on which to set filesystem capabilities > + * @caps: the filesystem capabilities to be written > + * @setxattr_flags: setxattr flags to use when writing the capabilities xattr > + * > + * This function writes the supplied filesystem capabilities to the dentry. > + * > + * Return: 0 on success, a negative errno on error. > + */ > +int vfs_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > + const struct vfs_caps *caps, int setxattr_flags) > +{ > + struct inode *inode = d_inode(dentry); > + struct inode *delegated_inode = NULL; > + int error; > + > +retry_deleg: > + inode_lock(inode); > + > + error = xattr_permission(idmap, inode, XATTR_NAME_CAPS, MAY_WRITE); > + if (error) > + goto out_inode_unlock; I think this should be /* * We only care about restrictions the inode struct itself places upon * us otherwise fscaps aren't subject to any VFS restrictions. */ error = may_write_xattr(idmap, inode); if (error) goto out_inode_unlock; which is a 1:1 copy of what POSIX ACLs do? > + error = security_inode_set_fscaps(idmap, dentry, caps, setxattr_flags); > + if (error) > + goto out_inode_unlock; > + > + error = try_break_deleg(inode, &delegated_inode); > + if (error) > + goto out_inode_unlock; > + > + if (inode->i_opflags & IOP_XATTR) { Fwiw, I think that if we move fscaps off of xattr handlers completely this can go away and we can simply rely on ->{g,s}et_fscaps() being implemented. But again, that can be in a follow-up series. > + if (inode->i_op->set_fscaps) > + error = inode->i_op->set_fscaps(idmap, dentry, caps, > + setxattr_flags); > + else > + error = generic_set_fscaps(idmap, dentry, caps, > + setxattr_flags); > + if (!error) { > + fsnotify_xattr(dentry); > + security_inode_post_set_fscaps(idmap, dentry, caps, > + setxattr_flags); > + } > + } else if (unlikely(is_bad_inode(inode))) { > + error = -EIO; > + } else { > + error = -EOPNOTSUPP; > + } > + > +out_inode_unlock: > + inode_unlock(inode); > + > + if (delegated_inode) { > + error = break_deleg_wait(&delegated_inode); > + if (!error) > + goto retry_deleg; > + } > + > + return error; > +} > +EXPORT_SYMBOL(vfs_set_fscaps); > + > int > __vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, > struct inode *inode, const char *name, const void *value, > diff --git a/include/linux/fs.h b/include/linux/fs.h > index d7cd2467e1ea..4f5d7ed44644 100644 > --- a/include/linux/fs.h > +++ b/include/linux/fs.h > @@ -2120,6 +2120,8 @@ extern int vfs_get_fscaps_nosec(struct mnt_idmap *idmap, struct dentry *dentry, > struct vfs_caps *caps); > extern int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > struct vfs_caps *caps); > +extern int vfs_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, > + const struct vfs_caps *caps, int setxattr_flags); Please drop the extern.
diff --git a/fs/xattr.c b/fs/xattr.c index 10d1b1f78fc2..96de43928a51 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -245,6 +245,85 @@ int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, } EXPORT_SYMBOL(vfs_get_fscaps); +static int generic_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + const struct vfs_caps *caps, int setxattr_flags) +{ + struct inode *inode = d_inode(dentry); + struct vfs_ns_cap_data nscaps; + int size; + + size = vfs_caps_to_xattr(idmap, i_user_ns(inode), caps, + &nscaps, sizeof(nscaps)); + if (size < 0) + return size; + + return __vfs_setxattr_noperm(idmap, dentry, XATTR_NAME_CAPS, + &nscaps, size, setxattr_flags); +} + +/** + * vfs_set_fscaps - set filesystem capabilities + * @idmap: idmap of the mount the inode was found from + * @dentry: the dentry on which to set filesystem capabilities + * @caps: the filesystem capabilities to be written + * @setxattr_flags: setxattr flags to use when writing the capabilities xattr + * + * This function writes the supplied filesystem capabilities to the dentry. + * + * Return: 0 on success, a negative errno on error. + */ +int vfs_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + const struct vfs_caps *caps, int setxattr_flags) +{ + struct inode *inode = d_inode(dentry); + struct inode *delegated_inode = NULL; + int error; + +retry_deleg: + inode_lock(inode); + + error = xattr_permission(idmap, inode, XATTR_NAME_CAPS, MAY_WRITE); + if (error) + goto out_inode_unlock; + error = security_inode_set_fscaps(idmap, dentry, caps, setxattr_flags); + if (error) + goto out_inode_unlock; + + error = try_break_deleg(inode, &delegated_inode); + if (error) + goto out_inode_unlock; + + if (inode->i_opflags & IOP_XATTR) { + if (inode->i_op->set_fscaps) + error = inode->i_op->set_fscaps(idmap, dentry, caps, + setxattr_flags); + else + error = generic_set_fscaps(idmap, dentry, caps, + setxattr_flags); + if (!error) { + fsnotify_xattr(dentry); + security_inode_post_set_fscaps(idmap, dentry, caps, + setxattr_flags); + } + } else if (unlikely(is_bad_inode(inode))) { + error = -EIO; + } else { + error = -EOPNOTSUPP; + } + +out_inode_unlock: + inode_unlock(inode); + + if (delegated_inode) { + error = break_deleg_wait(&delegated_inode); + if (!error) + goto retry_deleg; + } + + return error; +} +EXPORT_SYMBOL(vfs_set_fscaps); + int __vfs_setxattr(struct mnt_idmap *idmap, struct dentry *dentry, struct inode *inode, const char *name, const void *value, diff --git a/include/linux/fs.h b/include/linux/fs.h index d7cd2467e1ea..4f5d7ed44644 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2120,6 +2120,8 @@ extern int vfs_get_fscaps_nosec(struct mnt_idmap *idmap, struct dentry *dentry, struct vfs_caps *caps); extern int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, struct vfs_caps *caps); +extern int vfs_set_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + const struct vfs_caps *caps, int setxattr_flags); /** * enum freeze_holder - holder of the freeze
Provide a type-safe interface for setting filesystem capabilities and a generic implementation suitable for most filesystems. Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org> --- fs/xattr.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 2 ++ 2 files changed, 81 insertions(+)