NFSD: Server implementation of MAC Labeling

Implement labeled NFS on the server: encoding and decoding, and writing
and reading, of file labels.

Enabled with CONFIG_NFSD_V4_SECURITY_LABEL.

Signed-off-by: Matthew N. Dodd <Matthew.Dodd@sparta.com>
Signed-off-by: Miguel Rodel Felipe <Rodel_FM@dsi.a-star.edu.sg>
Signed-off-by: Phua Eu Gene <PHUA_Eu_Gene@dsi.a-star.edu.sg>
Signed-off-by: Khin Mi Mi Aung <Mi_Mi_AUNG@dsi.a-star.edu.sg>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

7 files changed, 207 insertions, 10 deletions

diff --git a/fs/nfsd/Kconfig b/fs/nfsd/Kconfig
index 430b6872806f..dc8f1ef665ce 100644
--- a/fs/nfsd/Kconfig
+++ b/fs/nfsd/Kconfig
@@ -81,6 +81,22 @@ config NFSD_V4
 
           If unsure, say N.
 
+config NFSD_V4_SECURITY_LABEL
+        bool "Provide Security Label support for NFSv4 server"
+        depends on NFSD_V4 && SECURITY
+        help
+
+        Say Y here if you want enable fine-grained security label attribute
+        support for NFS version 4.  Security labels allow security modules like
+        SELinux and Smack to label files to facilitate enforcement of their policies.
+        Without this an NFSv4 mount will have the same label on each file.
+
+        If you do not wish to enable fine-grained security labels SELinux or
+        Smack policies on NFSv4 files, say N.
+
+        WARNING: there is still a chance of backwards-incompatible protocol changes.
+        For now we recommend "Y" only for developers and testers."
+
 config NFSD_FAULT_INJECTION
         bool "NFS server manual fault injection"
         depends on NFSD_V4 && DEBUG_KERNEL
diff --git a/fs/nfsd/nfs4proc.c b/fs/nfsd/nfs4proc.c
index 27d74a294515..1a1ff247bc59 100644
--- a/fs/nfsd/nfs4proc.c
+++ b/fs/nfsd/nfs4proc.c
@@ -42,6 +42,36 @@
 #include "current_stateid.h"
 #include "netns.h"
 
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+#include <linux/security.h>
+
+static inline void
+nfsd4_security_inode_setsecctx(struct svc_fh *resfh, struct xdr_netobj *label, u32 *bmval)
+{
+        struct inode *inode = resfh->fh_dentry->d_inode;
+        int status;
+
+        mutex_lock(&inode->i_mutex);
+        status = security_inode_setsecctx(resfh->fh_dentry,
+                label->data, label->len);
+        mutex_unlock(&inode->i_mutex);
+
+        if (status)
+                /*
+                 * XXX: We should really fail the whole open, but we may
+                 * already have created a new file, so it may be too
+                 * late.  For now this seems the least of evils:
+                 */
+                bmval[2] &= ~FATTR4_WORD2_SECURITY_LABEL;
+
+        return;
+}
+#else
+static inline void
+nfsd4_security_inode_setsecctx(struct svc_fh *resfh, struct xdr_netobj *label, u32 *bmval)
+{ }
+#endif
+
 #define NFSDDBG_FACILITY                NFSDDBG_PROC
 
 static u32 nfsd_attrmask[] = {
@@ -239,6 +269,9 @@ do_open_lookup(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate, stru
                                         (u32 *)open->op_verf.data,
                                         &open->op_truncate, &open->op_created);
 
+                if (!status && open->op_label.len)
+                        nfsd4_security_inode_setsecctx(resfh, &open->op_label, open->op_bmval);
+
                 /*
                  * Following rfc 3530 14.2.16, use the returned bitmask
                  * to indicate which attributes we used to store the
@@ -637,6 +670,9 @@ nfsd4_create(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
         if (status)
                 goto out;
 
+        if (create->cr_label.len)
+                nfsd4_security_inode_setsecctx(&resfh, &create->cr_label, create->cr_bmval);
+
         if (create->cr_acl != NULL)
                 do_set_nfs4_acl(rqstp, &resfh, create->cr_acl,
                                 create->cr_bmval);
@@ -916,6 +952,11 @@ nfsd4_setattr(struct svc_rqst *rqstp, struct nfsd4_compound_state *cstate,
                                             setattr->sa_acl);
         if (status)
                 goto out;
+        if (setattr->sa_label.len)
+                status = nfsd4_set_nfs4_label(rqstp, &cstate->current_fh,
+                                &setattr->sa_label);
+        if (status)
+                goto out;
         status = nfsd_setattr(rqstp, &cstate->current_fh, &setattr->sa_iattr,
                                 0, (time_t)0);
 out:
diff --git a/fs/nfsd/nfs4xdr.c b/fs/nfsd/nfs4xdr.c
index 9aeacddafa3f..dfca5121de53 100644
--- a/fs/nfsd/nfs4xdr.c
+++ b/fs/nfsd/nfs4xdr.c
@@ -55,6 +55,11 @@
 #include "cache.h"
 #include "netns.h"
 
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+#include <linux/security.h>
+#endif
+
+
 #define NFSDDBG_FACILITY                NFSDDBG_XDR
 
 /*
@@ -242,7 +247,8 @@ nfsd4_decode_bitmap(struct nfsd4_compoundargs *argp, u32 *bmval)
 
 static __be32
 nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
-                   struct iattr *iattr, struct nfs4_acl **acl)
+                   struct iattr *iattr, struct nfs4_acl **acl,
+                   struct xdr_netobj *label)
 {
         int expected_len, len = 0;
         u32 dummy32;
@@ -380,6 +386,32 @@ nfsd4_decode_fattr(struct nfsd4_compoundargs *argp, u32 *bmval,
                         goto xdr_error;
                 }
         }
+
+        label->len = 0;
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+        if (bmval[2] & FATTR4_WORD2_SECURITY_LABEL) {
+                READ_BUF(4);
+                len += 4;
+                READ32(dummy32); /* lfs: we don't use it */
+                READ_BUF(4);
+                len += 4;
+                READ32(dummy32); /* pi: we don't use it either */
+                READ_BUF(4);
+                len += 4;
+                READ32(dummy32);
+                READ_BUF(dummy32);
+                if (dummy32 > NFSD4_MAX_SEC_LABEL_LEN)
+                        return nfserr_badlabel;
+                len += (XDR_QUADLEN(dummy32) << 2);
+                READMEM(buf, dummy32);
+                label->data = kzalloc(dummy32 + 1, GFP_KERNEL);
+                if (!label->data)
+                        return nfserr_jukebox;
+                defer_free(argp, kfree, label->data);
+                memcpy(label->data, buf, dummy32);
+        }
+#endif
+
         if (bmval[0] & ~NFSD_WRITEABLE_ATTRS_WORD0
             || bmval[1] & ~NFSD_WRITEABLE_ATTRS_WORD1
             || bmval[2] & ~NFSD_WRITEABLE_ATTRS_WORD2)
@@ -576,7 +608,7 @@ nfsd4_decode_create(struct nfsd4_compoundargs *argp, struct nfsd4_create *create
                 return status;
 
         status = nfsd4_decode_fattr(argp, create->cr_bmval, &create->cr_iattr,
-                                    &create->cr_acl);
+                                    &create->cr_acl, &create->cr_label);
         if (status)
                 goto out;
 
@@ -827,7 +859,7 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
                 case NFS4_CREATE_UNCHECKED:
                 case NFS4_CREATE_GUARDED:
                         status = nfsd4_decode_fattr(argp, open->op_bmval,
-                                &open->op_iattr, &open->op_acl);
+                                &open->op_iattr, &open->op_acl, &open->op_label);
                         if (status)
                                 goto out;
                         break;
@@ -841,7 +873,7 @@ nfsd4_decode_open(struct nfsd4_compoundargs *argp, struct nfsd4_open *open)
                         READ_BUF(NFS4_VERIFIER_SIZE);
                         COPYMEM(open->op_verf.data, NFS4_VERIFIER_SIZE);
                         status = nfsd4_decode_fattr(argp, open->op_bmval,
-                                &open->op_iattr, &open->op_acl);
+                                &open->op_iattr, &open->op_acl, &open->op_label);
                         if (status)
                                 goto out;
                         break;
@@ -1063,7 +1095,7 @@ nfsd4_decode_setattr(struct nfsd4_compoundargs *argp, struct nfsd4_setattr *seta
         if (status)
                 return status;
         return nfsd4_decode_fattr(argp, setattr->sa_bmval, &setattr->sa_iattr,
-                                  &setattr->sa_acl);
+                                  &setattr->sa_acl, &setattr->sa_label);
 }
 
 static __be32
@@ -1954,6 +1986,36 @@ nfsd4_encode_aclname(struct svc_rqst *rqstp, struct nfs4_ace *ace,
                               FATTR4_WORD0_RDATTR_ERROR)
 #define WORD1_ABSENT_FS_ATTRS FATTR4_WORD1_MOUNTED_ON_FILEID
 
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+static inline __be32
+nfsd4_encode_security_label(struct svc_rqst *rqstp, void *context, int len, __be32 **pp, int *buflen)
+{
+        __be32 *p = *pp;
+
+        if (*buflen < ((XDR_QUADLEN(len) << 2) + 4 + 4 + 4))
+                return nfserr_resource;
+
+        /*
+         * For now we use a 0 here to indicate the null translation; in
+         * the future we may place a call to translation code here.
+         */
+        if ((*buflen -= 8) < 0)
+                return nfserr_resource;
+
+        WRITE32(0); /* lfs */
+        WRITE32(0); /* pi */
+        p = xdr_encode_opaque(p, context, len);
+        *buflen -= (XDR_QUADLEN(len) << 2) + 4;
+
+        *pp = p;
+        return 0;
+}
+#else
+static inline __be32
+nfsd4_encode_security_label(struct svc_rqst *rqstp, struct dentry *dentry, __be32 **pp, int *buflen)
+{ return 0; }
+#endif
+
 static __be32 fattr_handle_absent_fs(u32 *bmval0, u32 *bmval1, u32 *rdattr_err)
 {
         /* As per referral draft:  */
@@ -2013,6 +2075,9 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
         int err;
         int aclsupport = 0;
         struct nfs4_acl *acl = NULL;
+        void *context = NULL;
+        int contextlen;
+        bool contextsupport = false;
         struct nfsd4_compoundres *resp = rqstp->rq_resp;
         u32 minorversion = resp->cstate.minorversion;
         struct path path = {
@@ -2066,6 +2131,21 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
                 }
         }
 
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+        if ((bmval[2] & FATTR4_WORD2_SECURITY_LABEL) ||
+                        bmval[0] & FATTR4_WORD0_SUPPORTED_ATTRS) {
+                err = security_inode_getsecctx(dentry->d_inode,
+                                                &context, &contextlen);
+                contextsupport = (err == 0);
+                if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
+                        if (err == -EOPNOTSUPP)
+                                bmval2 &= ~FATTR4_WORD2_SECURITY_LABEL;
+                        else if (err)
+                                goto out_nfserr;
+                }
+        }
+#endif /* CONFIG_NFSD_V4_SECURITY_LABEL */
+
         if (bmval2) {
                 if ((buflen -= 16) < 0)
                         goto out_resource;
@@ -2094,6 +2174,8 @@ nfsd4_encode_fattr(struct svc_fh *fhp, struct svc_export *exp,
 
                 if (!aclsupport)
                         word0 &= ~FATTR4_WORD0_ACL;
+                if (!contextsupport)
+                        word2 &= ~FATTR4_WORD2_SECURITY_LABEL;
                 if (!word2) {
                         if ((buflen -= 12) < 0)
                                 goto out_resource;
@@ -2401,6 +2483,12 @@ out_acl:
                         get_parent_attributes(exp, &stat);
                 WRITE64(stat.ino);
         }
+        if (bmval2 & FATTR4_WORD2_SECURITY_LABEL) {
+                status = nfsd4_encode_security_label(rqstp, context,
+                                contextlen, &p, &buflen);
+                if (status)
+                        goto out;
+        }
         if (bmval2 & FATTR4_WORD2_SUPPATTR_EXCLCREAT) {
                 WRITE32(3);
                 WRITE32(NFSD_SUPPATTR_EXCLCREAT_WORD0);
@@ -2413,6 +2501,8 @@ out_acl:
         status = nfs_ok;
 
 out:
+        if (context)
+                security_release_secctx(context, contextlen);
         kfree(acl);
         if (fhp == &tempfh)
                 fh_put(&tempfh);
@@ -3177,16 +3267,18 @@ nfsd4_encode_setattr(struct nfsd4_compoundres *resp, __be32 nfserr, struct nfsd4
 {
         __be32 *p;
 
-        RESERVE_SPACE(12);
+        RESERVE_SPACE(16);
         if (nfserr) {
-                WRITE32(2);
+                WRITE32(3);
+                WRITE32(0);
                 WRITE32(0);
                 WRITE32(0);
         }
         else {
-                WRITE32(2);
+                WRITE32(3);
                 WRITE32(setattr->sa_bmval[0]);
                 WRITE32(setattr->sa_bmval[1]);
+                WRITE32(setattr->sa_bmval[2]);
         }
         ADJUST_ARGS();
         return nfserr;
diff --git a/fs/nfsd/nfsd.h b/fs/nfsd/nfsd.h
index 15e7e1d531f0..2bbd94e51efc 100644
--- a/fs/nfsd/nfsd.h
+++ b/fs/nfsd/nfsd.h
@@ -328,6 +328,13 @@ void		nfsd_lockd_shutdown(void);
 #define NFSD4_1_SUPPORTED_ATTRS_WORD2 \
         (NFSD4_SUPPORTED_ATTRS_WORD2 | FATTR4_WORD2_SUPPATTR_EXCLCREAT)
 
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+#define NFSD4_2_SUPPORTED_ATTRS_WORD2 \
+        (NFSD4_1_SUPPORTED_ATTRS_WORD2 | FATTR4_WORD2_SECURITY_LABEL)
+#else
+#define NFSD4_2_SUPPORTED_ATTRS_WORD2 0
+#endif
+
 static inline u32 nfsd_suppattrs0(u32 minorversion)
 {
         return minorversion ? NFSD4_1_SUPPORTED_ATTRS_WORD0
@@ -342,8 +349,11 @@ static inline u32 nfsd_suppattrs1(u32 minorversion)
 
 static inline u32 nfsd_suppattrs2(u32 minorversion)
 {
-        return minorversion ? NFSD4_1_SUPPORTED_ATTRS_WORD2
-                            : NFSD4_SUPPORTED_ATTRS_WORD2;
+        switch (minorversion) {
+        default: return NFSD4_2_SUPPORTED_ATTRS_WORD2;
+        case 1:  return NFSD4_1_SUPPORTED_ATTRS_WORD2;
+        case 0:  return NFSD4_SUPPORTED_ATTRS_WORD2;
+        }
 }
 
 /* These will return ERR_INVAL if specified in GETATTR or READDIR. */
@@ -356,7 +366,11 @@ static inline u32 nfsd_suppattrs2(u32 minorversion)
 #define NFSD_WRITEABLE_ATTRS_WORD1 \
         (FATTR4_WORD1_MODE | FATTR4_WORD1_OWNER | FATTR4_WORD1_OWNER_GROUP \
         | FATTR4_WORD1_TIME_ACCESS_SET | FATTR4_WORD1_TIME_MODIFY_SET)
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+#define NFSD_WRITEABLE_ATTRS_WORD2 FATTR4_WORD2_SECURITY_LABEL
+#else
 #define NFSD_WRITEABLE_ATTRS_WORD2 0
+#endif
 
 #define NFSD_SUPPATTR_EXCLCREAT_WORD0 \
         NFSD_WRITEABLE_ATTRS_WORD0
diff --git a/fs/nfsd/vfs.c b/fs/nfsd/vfs.c
index 84ce601d8063..1e757fa45c40 100644
--- a/fs/nfsd/vfs.c
+++ b/fs/nfsd/vfs.c
@@ -28,6 +28,7 @@
 #include <asm/uaccess.h>
 #include <linux/exportfs.h>
 #include <linux/writeback.h>
+#include <linux/security.h>
 
 #ifdef CONFIG_NFSD_V3
 #include "xdr3.h"
@@ -621,6 +622,33 @@ int nfsd4_is_junction(struct dentry *dentry)
                 return 0;
         return 1;
 }
+#ifdef CONFIG_NFSD_V4_SECURITY_LABEL
+__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                struct xdr_netobj *label)
+{
+        __be32 error;
+        int host_error;
+        struct dentry *dentry;
+
+        error = fh_verify(rqstp, fhp, 0 /* S_IFREG */, NFSD_MAY_SATTR);
+        if (error)
+                return error;
+
+        dentry = fhp->fh_dentry;
+
+        mutex_lock(&dentry->d_inode->i_mutex);
+        host_error = security_inode_setsecctx(dentry, label->data, label->len);
+        mutex_unlock(&dentry->d_inode->i_mutex);
+        return nfserrno(host_error);
+}
+#else
+__be32 nfsd4_set_nfs4_label(struct svc_rqst *rqstp, struct svc_fh *fhp,
+                struct xdr_netobj *label)
+{
+        return nfserr_notsupp;
+}
+#endif
+
 #endif /* defined(CONFIG_NFSD_V4) */
 
 #ifdef CONFIG_NFSD_V3
diff --git a/fs/nfsd/vfs.h b/fs/nfsd/vfs.h
index 8d2b40d71669..a4be2e389670 100644
--- a/fs/nfsd/vfs.h
+++ b/fs/nfsd/vfs.h
@@ -55,6 +55,8 @@ int nfsd_mountpoint(struct dentry *, struct svc_export *);
 __be32          nfsd4_set_nfs4_acl(struct svc_rqst *, struct svc_fh *,
                     struct nfs4_acl *);
 int             nfsd4_get_nfs4_acl(struct svc_rqst *, struct dentry *, struct nfs4_acl **);
+__be32          nfsd4_set_nfs4_label(struct svc_rqst *, struct svc_fh *,
+                    struct xdr_netobj *);
 #endif /* CONFIG_NFSD_V4 */
 __be32          nfsd_create(struct svc_rqst *, struct svc_fh *,
                                 char *name, int len, struct iattr *attrs,
diff --git a/fs/nfsd/xdr4.h b/fs/nfsd/xdr4.h
index 3b271d2092b6..b3ed6446ed8e 100644
--- a/fs/nfsd/xdr4.h
+++ b/fs/nfsd/xdr4.h
@@ -40,6 +40,7 @@
 #include "state.h"
 #include "nfsd.h"
 
+#define NFSD4_MAX_SEC_LABEL_LEN 2048
 #define NFSD4_MAX_TAGLEN        128
 #define XDR_LEN(n)                     (((n) + 3) & ~3)
 
@@ -118,6 +119,7 @@ struct nfsd4_create {
         struct iattr    cr_iattr;           /* request */
         struct nfsd4_change_info  cr_cinfo; /* response */
         struct nfs4_acl *cr_acl;
+        struct xdr_netobj cr_label;
 };
 #define cr_linklen      u.link.namelen
 #define cr_linkname     u.link.name
@@ -246,6 +248,7 @@ struct nfsd4_open {
         struct nfs4_file *op_file;          /* used during processing */
         struct nfs4_ol_stateid *op_stp;     /* used during processing */
         struct nfs4_acl *op_acl;
+        struct xdr_netobj op_label;
 };
 #define op_iattr        iattr
 
@@ -330,6 +333,7 @@ struct nfsd4_setattr {
         u32             sa_bmval[3];        /* request */
         struct iattr    sa_iattr;           /* request */
         struct nfs4_acl *sa_acl;
+        struct xdr_netobj sa_label;
 };
 
 struct nfsd4_setclientid {