1 // SPDX-License-Identifier: GPL-2.0-only
2
3 #include "dev.h"
4 #include "fuse_i.h"
5
fuse_fill_creds(struct fuse_mount * fm,struct fuse_args * args,const struct mnt_idmap * idmap)6 static int fuse_fill_creds(struct fuse_mount *fm, struct fuse_args *args,
7 const struct mnt_idmap *idmap)
8 {
9 struct fuse_conn *fc = fm->fc;
10 bool no_idmap = !fm->sb || (fm->sb->s_iflags & SB_I_NOIDMAP);
11 kuid_t fsuid = mapped_fsuid(idmap, fc->user_ns);
12 kgid_t fsgid = mapped_fsgid(idmap, fc->user_ns);
13
14 args->pid = pid_nr_ns(task_pid(current), fc->pid_ns);
15
16 if (args->force) {
17 if (args->nocreds)
18 return 0;
19
20 if (no_idmap) {
21 args->uid = from_kuid_munged(fc->user_ns, current_fsuid());
22 args->gid = from_kgid_munged(fc->user_ns, current_fsgid());
23 } else {
24 args->uid = FUSE_INVALID_UIDGID;
25 args->gid = FUSE_INVALID_UIDGID;
26 }
27 return 0;
28 }
29
30 WARN_ON(args->nocreds);
31 /*
32 * Keep the old behavior when idmappings support was not
33 * declared by a FUSE server.
34 *
35 * For those FUSE servers who support idmapped mounts, we send UID/GID
36 * only along with "inode creation" fuse requests, otherwise idmap ==
37 * &invalid_mnt_idmap and req->in.h.{u,g}id will be equal to
38 * FUSE_INVALID_UIDGID.
39 */
40 if (no_idmap) {
41 fsuid = current_fsuid();
42 fsgid = current_fsgid();
43 }
44 args->uid = from_kuid(fc->user_ns, fsuid);
45 args->gid = from_kgid(fc->user_ns, fsgid);
46
47 if (no_idmap && unlikely(args->uid == ((uid_t)-1) || args->gid == ((gid_t)-1)))
48 return -EOVERFLOW;
49
50 return 0;
51 }
52
fuse_req_prep(struct fuse_mount * fm,struct fuse_args * args,const struct mnt_idmap * idmap)53 static int fuse_req_prep(struct fuse_mount *fm, struct fuse_args *args,
54 const struct mnt_idmap *idmap)
55 {
56 if (!args->force && fm->fc->conn_error)
57 return -ECONNREFUSED;
58
59 return fuse_fill_creds(fm, args, idmap);
60 }
61
__fuse_simple_request(const struct mnt_idmap * idmap,struct fuse_mount * fm,struct fuse_args * args)62 ssize_t __fuse_simple_request(const struct mnt_idmap *idmap, struct fuse_mount *fm,
63 struct fuse_args *args)
64 {
65 struct fuse_conn *fc = fm->fc;
66 int err = fuse_req_prep(fm, args, idmap);
67
68 if (err)
69 return err;
70
71 return fuse_chan_send(fc->chan, args);
72 }
73
fuse_simple_background(struct fuse_mount * fm,struct fuse_args * args,gfp_t gfp_flags)74 int fuse_simple_background(struct fuse_mount *fm, struct fuse_args *args, gfp_t gfp_flags)
75 {
76 struct fuse_conn *fc = fm->fc;
77 int err;
78
79 WARN_ON(args->force && !args->nocreds);
80
81 err = fuse_req_prep(fm, args, &invalid_mnt_idmap);
82 if (err)
83 return err;
84
85 return fuse_chan_send_bg(fc->chan, args, gfp_flags);
86 }
87 EXPORT_SYMBOL_GPL(fuse_simple_background);
88
fuse_simple_notify_reply(struct fuse_mount * fm,struct fuse_args * args,u64 unique)89 int fuse_simple_notify_reply(struct fuse_mount *fm, struct fuse_args *args, u64 unique)
90 {
91 struct fuse_conn *fc = fm->fc;
92 int err;
93
94 WARN_ON(args->force && !args->nocreds);
95
96 err = fuse_req_prep(fm, args, &invalid_mnt_idmap);
97 if (err)
98 return err;
99
100 return fuse_chan_send_notify_reply(fc->chan, args, unique);
101 }
102