Re: [PATCH 08/16] fs: add vfs_get_fscaps()
From: Christian Brauner <brauner@kernel.org>
Date: 2023-12-01 17:09:42
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linux-fsdevel, linux-unionfs, lkml
On Wed, Nov 29, 2023 at 03:50:26PM -0600, Seth Forshee (DigitalOcean) wrote:
quoted hunk ↗ jump to hunk
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(), which skips security checks for later use from the capability code. Signed-off-by: Seth Forshee (DigitalOcean) <sforshee@kernel.org> --- fs/xattr.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ include/linux/fs.h | 4 ++++ 2 files changed, 70 insertions(+)diff --git a/fs/xattr.c b/fs/xattr.c index 09d927603433..3abaf9bef0a5 100644 --- a/fs/xattr.c +++ b/fs/xattr.c@@ -181,6 +181,72 @@ 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 = NULL; + int ret; + + ret = (int)vfs_getxattr_alloc(idmap, dentry, XATTR_NAME_CAPS,
I don't think you need that case here.
+ (char **)&nscaps, 0, GFP_NOFS); + + if (ret >= 0) + ret = vfs_caps_from_xattr(idmap, i_user_ns(inode), caps, nscaps, ret); + + kfree(nscaps); + return ret; +} + +/** + * __vfs_get_fscaps - 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(struct mnt_idmap *idmap, struct dentry *dentry, + struct vfs_caps *caps)
I would rename that to vfs_get_fscaps_nosec(). We do that for vfs_getxattr_nosec() as well. It's not pretty but it's better than just slapping underscores onto it imo.