xnu-6153.141.1.tar.gz

[apple/xnu.git] / bsd / vfs / vfs_lookup.c

diff --git a/bsd/vfs/vfs_lookup.c b/bsd/vfs/vfs_lookup.c
index aaaf2fbb1270052804fdafbbc38b2b42d7b80044..9aad31d57bc851436c038190d84ca638c906de37 100644 (file)
--- a/bsd/vfs/vfs_lookup.c
+++ b/bsd/vfs/vfs_lookup.c
@@ -183,6 +183,8 @@ namei(struct nameidata *ndp)
        int volfs_restarts = 0;
 #endif
        size_t bytes_copied = 0;
+       bool take_proc_lock = !(ndp->ni_flag & NAMEI_NOPROCLOCK);
+       bool proc_lock_taken = false;
 
        fdp = p->p_fd;
 
@@ -348,12 +350,33 @@ retry_copy:
 
        /*
         * determine the starting point for the translation.
+        *
+        * We hold the proc_dirs lock across the lookup so that the
+        * process rootdir and cwd are stable (i.e. the usecounts
+        * on them are mainatained for the duration of the lookup)
         */
-       if ((ndp->ni_rootdir = fdp->fd_rdir) == NULLVP) {
+       if (take_proc_lock) {
+               assert(proc_lock_taken == false);
+               proc_dirs_lock_shared(p);
+               proc_lock_taken = true;
+       }
+       if (!(fdp->fd_flags & FD_CHROOT)) {
+               ndp->ni_rootdir = rootvnode;
+       } else {
+               ndp->ni_rootdir = fdp->fd_rdir;
+       }
+
+       if (!ndp->ni_rootdir) {
                if (!(fdp->fd_flags & FD_CHROOT)) {
-                       ndp->ni_rootdir = rootvnode;
+                       printf("rootvnode is not set\n");
+               } else {
+                       /* This should be a panic */
+                       printf("fdp->fd_rdir is not set\n");
                }
+               error = ENOENT;
+               goto error_out;
        }
+
        cnp->cn_nameptr = cnp->cn_pnbuf;
 
        ndp->ni_usedvp = NULLVP;
@@ -372,9 +395,11 @@ retry_copy:
        }
 
        if (dp == NULLVP || (dp->v_lflag & VL_DEAD)) {
+               dp = NULLVP;
                error = ENOENT;
                goto error_out;
        }
+
        ndp->ni_dvp = NULLVP;
        ndp->ni_vp  = NULLVP;
 
@@ -393,8 +418,8 @@ retry_copy:
                        goto error_out;
                }
 #endif
-
                ndp->ni_startdir = dp;
+               dp = NULLVP;
 
                if ((error = lookup(ndp))) {
                        goto error_out;
@@ -404,6 +429,10 @@ retry_copy:
                 * Check for symbolic link
                 */
                if ((cnp->cn_flags & ISSYMLINK) == 0) {
+                       if (proc_lock_taken) {
+                               proc_dirs_unlock_shared(p);
+                               proc_lock_taken = false;
+                       }
                        return 0;
                }
 
@@ -428,6 +457,10 @@ out_drop:
                vnode_put(ndp->ni_vp);
        }
 error_out:
+       if (proc_lock_taken) {
+               proc_dirs_unlock_shared(p);
+               proc_lock_taken = false;
+       }
        if ((cnp->cn_flags & HASBUF)) {
                cnp->cn_flags &= ~HASBUF;
                FREE_ZONE(cnp->cn_pnbuf, cnp->cn_pnlen, M_NAMEI);
@@ -1121,13 +1154,15 @@ dirloop:
                        tdp = dp;
                        dp = tdp->v_mount->mnt_vnodecovered;
 
-                       vnode_put(tdp);
-
                        if ((vnode_getwithref(dp))) {
+                               vnode_put(tdp);
                                dp = NULLVP;
                                error = ENOENT;
                                goto bad;
                        }
+
+                       vnode_put(tdp);
+
                        ndp->ni_dvp = dp;
                        dp_authorized = 0;
                }