ceph: handle idmapped mounts in create_request_message()

Inode operations that create a new filesystem object such as ->mknod, ->create, ->mkdir() and others don't take a {g,u}id argument explicitly. Instead the caller's fs{g,u}id is used for the {g,u}id of the new filesystem object. In order to ensure that the correct {g,u}id is used map the caller's fs{g,u}id for creation requests. This doesn't require complex changes. It suffices to pass in the relevant idmapping recorded in the request message. If this request message was triggered from an inode operation that creates filesystem objects it will have passed down the relevant idmaping. If this is a request message that was triggered from an inode operation that doens't need to take idmappings into account the initial idmapping is passed down which is an identity mapping. This change uses a new cephfs protocol extension CEPHFS_FEATURE_HAS_OWNER_UIDGID which adds two new fields (owner_{u,g}id) to the request head structure. So, we need to ensure that MDS supports it otherwise we need to fail any IO that comes through an idmapped mount because we can't process it in a proper way. MDS server without such an extension will use caller_{u,g}id fields to set a new inode owner UID/GID which is incorrect because caller_{u,g}id values are unmapped. At the same time we can't map these fields with an idmapping as it can break UID/GID-based permission checks logic on the MDS side. This problem was described with a lot of details at [1], [2]. [1] https://lore.kernel.org/lkml/CAEivzxfw1fHO2TFA4dx3u23ZKK6Q+EThfzuibrhA3RKM=ZOYLg@mail.gmail.com/ [2] https://lore.kernel.org/all/20220104140414.155198-3-brauner@kernel.org/

Christian Brauner committed 3 years ago

Commit 5ccd8531 parent 9c2df223 files · +65 −6Browse files

Unified · Split

3 files

fs/ceph/mds_client.c +52 −4
fs/ceph/mds_client.h +4 −1
include/linux/ceph/ceph_fs.h +9 −1

fs/ceph/mds_client.c+52−4

@@ -2881,6 +2881,17 @@ static void encode_mclientrequest_tail(void **p, · 2880 unmodified lines
2881	2881	}
2882	2882	}
2883	2883
	2884	+static inline u16 mds_supported_head_version(struct ceph_mds_session *session)
	2885	+{
	2886	+ if (!test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD, &session->s_features))
	2887	+ return 1;
	2888	+
	2889	+ if (!test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, &session->s_features))
	2890	+ return 2;
	2891	+
	2892	+ return CEPH_MDS_REQUEST_HEAD_VERSION;
	2893	+}
	2894	+
2884	2895	static struct ceph_mds_request_head_legacy *
2885	2896	find_legacy_request_head(void *p, u64 features)
2886	2897	{
@@ -2902,6 +2913,7 @@ static struct ceph_msg create_request_message(struct ceph_mds_session session, · 15 unmodified lines
2902	2913	{
2903	2914	int mds = session->s_mds;
2904	2915	struct ceph_mds_client *mdsc = session->s_mdsc;
	2916	+ struct ceph_client *cl = mdsc->fsc->client;
2905	2917	struct ceph_msg *msg;
2906	2918	struct ceph_mds_request_head_legacy *lhead;
2907	2919	const char *path1 = NULL;
@@ -2915,8 +2927,7 @@ static struct ceph_msg create_request_message(struct ceph_mds_session session, · 7 unmodified lines
2915	2927	void p, end;
2916	2928	int ret;
2917	2929	bool legacy = !(session->s_con.peer_features & CEPH_FEATURE_FS_BTIME);
2918		− bool old_version = !test_bit(CEPHFS_FEATURE_32BITS_RETRY_FWD,
2919		− &session->s_features);
	2930	+ u16 request_head_version = mds_supported_head_version(session);
2920	2931
2921	2932	ret = set_request_path_attr(mdsc, req->r_inode, req->r_dentry,
2922	2933	req->r_parent, req->r_path1, req->r_ino1.ino,
@@ -2957,8 +2968,10 @@ static struct ceph_msg create_request_message(struct ceph_mds_session session, · 34 unmodified lines
2957	2968	*/
2958	2969	if (legacy)
2959	2970	len = sizeof(struct ceph_mds_request_head_legacy);
2960		− else if (old_version)
	2971	+ else if (request_head_version == 1)
2961	2972	len = sizeof(struct ceph_mds_request_head_old);
	2973	+ else if (request_head_version == 2)
	2974	+ len = offsetofend(struct ceph_mds_request_head, ext_num_fwd);
2962	2975	else
2963	2976	len = sizeof(struct ceph_mds_request_head);
2964	2977
@@ -3008,6 +3021,18 @@ static struct ceph_msg create_request_message(struct ceph_mds_session session, · 43 unmodified lines
3008	3021	lhead = find_legacy_request_head(msg->front.iov_base,
3009	3022	session->s_con.peer_features);
3010	3023
	3024	+ if ((req->r_mnt_idmap != &nop_mnt_idmap) &&
	3025	+ !test_bit(CEPHFS_FEATURE_HAS_OWNER_UIDGID, &session->s_features)) {
	3026	+ WARN_ON_ONCE(!IS_CEPH_MDS_OP_NEWINODE(req->r_op));
	3027	+
	3028	+ pr_err_ratelimited_client(cl,
	3029	+ "idmapped mount is used and CEPHFS_FEATURE_HAS_OWNER_UIDGID"
	3030	+ " is not supported by MDS. Fail request with -EIO.\n");
	3031	+
	3032	+ ret = -EIO;
	3033	+ goto out_err;
	3034	+ }
	3035	+
3011	3036	/*
3012	3037	* The ceph_mds_request_head_legacy didn't contain a version field, and
3013	3038	* one was added when we moved the message version from 3->4.
@@ -3015,17 +3040,40 @@ static struct ceph_msg create_request_message(struct ceph_mds_session session, · 1 unmodified line
3015	3040	if (legacy) {
3016	3041	msg->hdr.version = cpu_to_le16(3);
3017	3042	p = msg->front.iov_base + sizeof(*lhead);
3018		− } else if (old_version) {
	3043	+ } else if (request_head_version == 1) {
3019	3044	struct ceph_mds_request_head_old *ohead = msg->front.iov_base;
3020	3045
3021	3046	msg->hdr.version = cpu_to_le16(4);
3022	3047	ohead->version = cpu_to_le16(1);
3023	3048	p = msg->front.iov_base + sizeof(*ohead);
	3049	+ } else if (request_head_version == 2) {
	3050	+ struct ceph_mds_request_head *nhead = msg->front.iov_base;
	3051	+
	3052	+ msg->hdr.version = cpu_to_le16(6);
	3053	+ nhead->version = cpu_to_le16(2);
	3054	+
	3055	+ p = msg->front.iov_base + offsetofend(struct ceph_mds_request_head, ext_num_fwd);
3024	3056	} else {
3025	3057	struct ceph_mds_request_head *nhead = msg->front.iov_base;
	3058	+ kuid_t owner_fsuid;
	3059	+ kgid_t owner_fsgid;
3026	3060
3027	3061	msg->hdr.version = cpu_to_le16(6);
3028	3062	nhead->version = cpu_to_le16(CEPH_MDS_REQUEST_HEAD_VERSION);
	3063	+ nhead->struct_len = cpu_to_le32(sizeof(struct ceph_mds_request_head));
	3064	+
	3065	+ if (IS_CEPH_MDS_OP_NEWINODE(req->r_op)) {
	3066	+ owner_fsuid = from_vfsuid(req->r_mnt_idmap, &init_user_ns,
	3067	+ VFSUIDT_INIT(req->r_cred->fsuid));
	3068	+ owner_fsgid = from_vfsgid(req->r_mnt_idmap, &init_user_ns,
	3069	+ VFSGIDT_INIT(req->r_cred->fsgid));
	3070	+ nhead->owner_uid = cpu_to_le32(from_kuid(&init_user_ns, owner_fsuid));
	3071	+ nhead->owner_gid = cpu_to_le32(from_kgid(&init_user_ns, owner_fsgid));
	3072	+ } else {
	3073	+ nhead->owner_uid = cpu_to_le32(-1);
	3074	+ nhead->owner_gid = cpu_to_le32(-1);
	3075	+ }
	3076	+
3029	3077	p = msg->front.iov_base + sizeof(*nhead);
3030	3078	}
3031	3079

fs/ceph/mds_client.h+4−1

@@ -33,8 +33,10 @@ enum ceph_feature_type { · 32 unmodified lines
33	33	CEPHFS_FEATURE_NOTIFY_SESSION_STATE,
34	34	CEPHFS_FEATURE_OP_GETVXATTR,
35	35	CEPHFS_FEATURE_32BITS_RETRY_FWD,
	36	+ CEPHFS_FEATURE_NEW_SNAPREALM_INFO,
	37	+ CEPHFS_FEATURE_HAS_OWNER_UIDGID,
36	38
37		− CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_32BITS_RETRY_FWD,
	39	+ CEPHFS_FEATURE_MAX = CEPHFS_FEATURE_HAS_OWNER_UIDGID,
38	40	};
39	41
40	42	#define CEPHFS_FEATURES_CLIENT_SUPPORTED { \
@@ -49,6 +51,7 @@ enum ceph_feature_type { · 8 unmodified lines
49	51	CEPHFS_FEATURE_NOTIFY_SESSION_STATE, \
50	52	CEPHFS_FEATURE_OP_GETVXATTR, \
51	53	CEPHFS_FEATURE_32BITS_RETRY_FWD, \
	54	+ CEPHFS_FEATURE_HAS_OWNER_UIDGID, \
52	55	}
53	56
54	57	/*

include/linux/ceph/ceph_fs.h+9−1

@@ -357,6 +357,11 @@ enum { · 356 unmodified lines
357	357	CEPH_MDS_OP_RENAMESNAP = 0x01403,
358	358	};
359	359
	360	+#define IS_CEPH_MDS_OP_NEWINODE(op) (op == CEPH_MDS_OP_CREATE \|\| \
	361	+ op == CEPH_MDS_OP_MKNOD \|\| \
	362	+ op == CEPH_MDS_OP_MKDIR \|\| \
	363	+ op == CEPH_MDS_OP_SYMLINK)
	364	+
360	365	extern const char *ceph_mds_op_name(int op);
361	366
362	367	#define CEPH_SETATTR_MODE (1 << 0)
@@ -497,7 +502,7 @@ struct ceph_mds_request_head_legacy { · 134 unmodified lines
497	502	union ceph_mds_request_args args;
498	503	} __attribute__ ((packed));
499	504
500		−#define CEPH_MDS_REQUEST_HEAD_VERSION 2
	505	+#define CEPH_MDS_REQUEST_HEAD_VERSION 3
501	506
502	507	struct ceph_mds_request_head_old {
503	508	__le16 version; /* struct version */
@@ -528,6 +533,9 @@ struct ceph_mds_request_head { · 24 unmodified lines
528	533
529	534	__le32 ext_num_retry; /* new count retry attempts */
530	535	__le32 ext_num_fwd; /* new count fwd attempts */
	536	+
	537	+ __le32 struct_len; /* to store size of struct ceph_mds_request_head */
	538	+ __le32 owner_uid, owner_gid; /* used for OPs which create inodes */
531	539	} __attribute__ ((packed));
532	540
533	541	/* cap/lease release record */

ceph: handle idmapped mounts in create_request_message()

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