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);