Provide a type-safe interface for retrieving filesystem capabilities and a generic implementation suitable for most filesystems. Also add an internal interface, vfs_get_fscaps_nosec(), which skips security checks for later use from the capability code.
Signed-off-by: Seth Forshee (DigitalOcean) <[email protected]> --- fs/xattr.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 4 ++++ 2 files changed, 68 insertions(+) diff --git a/fs/xattr.c b/fs/xattr.c index 06290e4ebc03..10d1b1f78fc2 100644 --- a/fs/xattr.c +++ b/fs/xattr.c @@ -181,6 +181,70 @@ xattr_supports_user_prefix(struct inode *inode) } EXPORT_SYMBOL(xattr_supports_user_prefix); +static int generic_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + struct inode *inode = d_inode(dentry); + struct vfs_ns_cap_data nscaps; + int ret; + + ret = __vfs_getxattr(dentry, inode, XATTR_NAME_CAPS, &nscaps, sizeof(nscaps)); + + if (ret >= 0) + ret = vfs_caps_from_xattr(idmap, i_user_ns(inode), caps, &nscaps, ret); + + return ret; +} + +/** + * vfs_get_fscaps_nosec - get filesystem capabilities without security checks + * @idmap: idmap of the mount the inode was found from + * @dentry: the dentry from which to get filesystem capabilities + * @caps: storage in which to return the filesystem capabilities + * + * This function gets the filesystem capabilities for the dentry and returns + * them in @caps. It does not perform security checks. + * + * Return: 0 on success, a negative errno on error. + */ +int vfs_get_fscaps_nosec(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + struct inode *inode = d_inode(dentry); + + if (inode->i_op->get_fscaps) + return inode->i_op->get_fscaps(idmap, dentry, caps); + return generic_get_fscaps(idmap, dentry, caps); +} + +/** + * vfs_get_fscaps - get filesystem capabilities + * @idmap: idmap of the mount the inode was found from + * @dentry: the dentry from which to get filesystem capabilities + * @caps: storage in which to return the filesystem capabilities + * + * This function gets the filesystem capabilities for the dentry and returns + * them in @caps. + * + * Return: 0 on success, a negative errno on error. + */ +int vfs_get_fscaps(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps) +{ + int error; + + /* + * The VFS has no restrictions on reading security.* xattrs, so + * xattr_permission() isn't needed. Only LSMs get a say. + */ + error = security_inode_get_fscaps(idmap, dentry); + if (error) + return error; + + return vfs_get_fscaps_nosec(idmap, dentry, caps); +} +EXPORT_SYMBOL(vfs_get_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 89163e0f7aad..d7cd2467e1ea 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2116,6 +2116,10 @@ extern int vfs_dedupe_file_range(struct file *file, extern loff_t vfs_dedupe_file_range_one(struct file *src_file, loff_t src_pos, struct file *dst_file, loff_t dst_pos, loff_t len, unsigned int remap_flags); +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); /** * enum freeze_holder - holder of the freeze -- 2.43.0
