CRED: Inaugurate COW credentials

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / fs / nfsd / nfs4recover.c

diff --git a/fs/nfsd/nfs4recover.c b/fs/nfsd/nfs4recover.c
index 632a50b4b371064d8a837d71f89d7e645384d359..9371ea12d7fa459e6ff9b6f6babd148eaccfd1fb 100644 (file)
--- a/fs/nfsd/nfs4recover.c
+++ b/fs/nfsd/nfs4recover.c
@@ -54,20 +54,26 @@
 static struct path rec_dir;
 static int rec_dir_init = 0;
 
-static void
-nfs4_save_user(uid_t *saveuid, gid_t *savegid)
+static int
+nfs4_save_creds(const struct cred **original_creds)
 {
-       *saveuid = current->cred->fsuid;
-       *savegid = current->cred->fsgid;
-       current->cred->fsuid = 0;
-       current->cred->fsgid = 0;
+       struct cred *new;
+
+       new = prepare_creds();
+       if (!new)
+               return -ENOMEM;
+
+       new->fsuid = 0;
+       new->fsgid = 0;
+       *original_creds = override_creds(new);
+       put_cred(new);
+       return 0;
 }
 
 static void
-nfs4_reset_user(uid_t saveuid, gid_t savegid)
+nfs4_reset_creds(const struct cred *original)
 {
-       current->cred->fsuid = saveuid;
-       current->cred->fsgid = savegid;
+       revert_creds(original);
 }
 
 static void
@@ -129,10 +135,9 @@ nfsd4_sync_rec_dir(void)
 int
 nfsd4_create_clid_dir(struct nfs4_client *clp)
 {
+       const struct cred *original_cred;
        char *dname = clp->cl_recdir;
        struct dentry *dentry;
-       uid_t uid;
-       gid_t gid;
        int status;
 
        dprintk("NFSD: nfsd4_create_clid_dir for \"%s\"\n", dname);
@@ -140,7 +145,9 @@ nfsd4_create_clid_dir(struct nfs4_client *clp)
        if (!rec_dir_init || clp->cl_firststate)
                return 0;
 
-       nfs4_save_user(&uid, &gid);
+       status = nfs4_save_creds(&original_cred);
+       if (status < 0)
+               return status;
 
        /* lock the parent */
        mutex_lock(&rec_dir.dentry->d_inode->i_mutex);
@@ -168,7 +175,7 @@ out_unlock:
                clp->cl_firststate = 1;
                nfsd4_sync_rec_dir();
        }
-       nfs4_reset_user(uid, gid);
+       nfs4_reset_creds(original_cred);
        dprintk("NFSD: nfsd4_create_clid_dir returns %d\n", status);
        return status;
 }
@@ -211,20 +218,21 @@ nfsd4_build_dentrylist(void *arg, const char *name, int namlen,
 static int
 nfsd4_list_rec_dir(struct dentry *dir, recdir_func *f)
 {
+       const struct cred *original_cred;
        struct file *filp;
        struct dentry_list_arg dla = {
                .parent = dir,
        };
        struct list_head *dentries = &dla.dentries;
        struct dentry_list *child;
-       uid_t uid;
-       gid_t gid;
        int status;
 
        if (!rec_dir_init)
                return 0;
 
-       nfs4_save_user(&uid, &gid);
+       status = nfs4_save_creds(&original_cred);
+       if (status < 0)
+               return status;
 
        filp = dentry_open(dget(dir), mntget(rec_dir.mnt), O_RDONLY,
                           current_cred());
@@ -250,7 +258,7 @@ out:
                dput(child->dentry);
                kfree(child);
        }
-       nfs4_reset_user(uid, gid);
+       nfs4_reset_creds(original_cred);
        return status;
 }
 
@@ -312,8 +320,7 @@ out:
 void
 nfsd4_remove_clid_dir(struct nfs4_client *clp)
 {
-       uid_t uid;
-       gid_t gid;
+       const struct cred *original_cred;
        int status;
 
        if (!rec_dir_init || !clp->cl_firststate)
@@ -323,9 +330,13 @@ nfsd4_remove_clid_dir(struct nfs4_client *clp)
        if (status)
                goto out;
        clp->cl_firststate = 0;
-       nfs4_save_user(&uid, &gid);
+
+       status = nfs4_save_creds(&original_cred);
+       if (status < 0)
+               goto out;
+
        status = nfsd4_unlink_clid_dir(clp->cl_recdir, HEXDIR_LEN-1);
-       nfs4_reset_user(uid, gid);
+       nfs4_reset_creds(original_cred);
        if (status == 0)
                nfsd4_sync_rec_dir();
        mnt_drop_write(rec_dir.mnt);
@@ -402,16 +413,21 @@ nfsd4_recdir_load(void) {
 void
 nfsd4_init_recdir(char *rec_dirname)
 {
-       uid_t                   uid = 0;
-       gid_t                   gid = 0;
-       int                     status;
+       const struct cred *original_cred;
+       int status;
 
        printk("NFSD: Using %s as the NFSv4 state recovery directory\n",
                        rec_dirname);
 
        BUG_ON(rec_dir_init);
 
-       nfs4_save_user(&uid, &gid);
+       status = nfs4_save_creds(&original_cred);
+       if (status < 0) {
+               printk("NFSD: Unable to change credentials to find recovery"
+                      " directory: error %d\n",
+                      status);
+               return;
+       }
 
        status = kern_path(rec_dirname, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
                        &rec_dir);
@@ -421,7 +437,7 @@ nfsd4_init_recdir(char *rec_dirname)
 
        if (!status)
                rec_dir_init = 1;
-       nfs4_reset_user(uid, gid);
+       nfs4_reset_creds(original_cred);
 }
 
 void