[PATCH v4 04/15] fs/fuse: support idmapped FUSE_EXT_GROUPS

Alexander Mikhalitsyn
2024-09-03T15:16:59Z

We don't need to remap parent_gid, but have to adjust
group membership checks and take idmapping into account.

Cc: Christian Brauner <brauner@kernel.org>
Cc: Seth Forshee <sforshee@kernel.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Bernd Schubert <bschubert@ddn.com>
Cc: <linux-fsdevel@vger.kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
---
v4:
- this commit added
---
fs/fuse/dir.c | 19 ++++++++++++-------
1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/fs/fuse/dir.c b/fs/fuse/dir.c
index 2a8344776350..b0b57f383889 100644
--- a/fs/fuse/dir.c
+++ b/fs/fuse/dir.c
@@ -545,17 +545,21 @@ static u32 fuse_ext_size(size_t size)
/*
* This adds just a single supplementary group that matches the parent's group.
*/
-static int get_create_supp_group(struct inode *dir, struct fuse_in_arg *ext)
+static int get_create_supp_group(struct mnt_idmap *idmap,
+ struct inode *dir,
+ struct fuse_in_arg *ext)
{
struct fuse_conn *fc = get_fuse_conn(dir);
struct fuse_ext_header *xh;
struct fuse_supp_groups *sg;
kgid_t kgid = dir->i_gid;
+ vfsgid_t vfsgid = make_vfsgid(idmap, fc->user_ns, kgid);
gid_t parent_gid = from_kgid(fc->user_ns, kgid);
+
u32 sg_len = fuse_ext_size(sizeof(*sg) + sizeof(sg->groups[0]));

- if (parent_gid == (gid_t) -1 || gid_eq(kgid, current_fsgid()) ||
- !in_group_p(kgid))
+ if (parent_gid == (gid_t) -1 || vfsgid_eq_kgid(vfsgid, current_fsgid()) ||
+ !vfsgid_in_group_p(vfsgid))
return 0;

xh = extend_arg(ext, sg_len);
@@ -572,7 +576,8 @@ static int get_create_supp_group(struct inode *dir, struct fuse_in_arg *ext)
return 0;
}

-static int get_create_ext(struct fuse_args *args,
+static int get_create_ext(struct mnt_idmap *idmap,
+ struct fuse_args *args,
struct inode *dir, struct dentry *dentry,
umode_t mode)
{
@@ -583,7 +588,7 @@ static int get_create_ext(struct fuse_args *args,
if (fc->init_security)
err = get_security_context(dentry, mode, &ext);
if (!err && fc->create_supp_group)
- err = get_create_supp_group(dir, &ext);
+ err = get_create_supp_group(idmap, dir, &ext);

if (!err && ext.size) {
WARN_ON(args->in_numargs >= ARRAY_SIZE(args->in_args));
@@ -668,7 +673,7 @@ static int fuse_create_open(struct inode *dir, struct dentry *entry,
args.out_args[1].size = sizeof(*outopenp);
args.out_args[1].value = outopenp;

- err = get_create_ext(&args, dir, entry, mode);
+ err = get_create_ext(&nop_mnt_idmap, &args, dir, entry, mode);
if (err)
goto out_put_forget_req;

@@ -798,7 +803,7 @@ static int create_new_entry(struct fuse_mount *fm, struct fuse_args *args,
args->out_args[0].value = &outarg;

if (args->opcode != FUSE_LINK) {
- err = get_create_ext(args, dir, entry, mode);
+ err = get_create_ext(&nop_mnt_idmap, args, dir, entry, mode);
if (err)
goto out_put_forget_req;
}
--
2.34.1