diff options
Diffstat (limited to 'fs/namei.c')
| -rw-r--r-- | fs/namei.c | 48 |
1 files changed, 33 insertions, 15 deletions
@@ -238,7 +238,8 @@ int generic_permission(struct inode *inode, int mask, unsigned int flags, /* * Read/write DACs are always overridable. - * Executable DACs are overridable if at least one exec bit is set. + * Executable DACs are overridable for all directories and + * for non-directories that have least one exec bit set. */ if (!(mask & MAY_EXEC) || execute_ok(inode)) if (ns_capable(inode_userns(inode), CAP_DAC_OVERRIDE)) @@ -432,6 +433,8 @@ static int unlazy_walk(struct nameidata *nd, struct dentry *dentry) goto err_parent; BUG_ON(nd->inode != parent->d_inode); } else { + if (dentry->d_parent != parent) + goto err_parent; spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); if (!__d_rcu_to_refcount(dentry, nd->seq)) goto err_child; @@ -812,6 +815,11 @@ static int follow_automount(struct path *path, unsigned flags, if (!mnt) /* mount collision */ return 0; + if (!*need_mntput) { + /* lock_mount() may release path->mnt on error */ + mntget(path->mnt); + *need_mntput = true; + } err = finish_automount(mnt, path); switch (err) { @@ -819,12 +827,9 @@ static int follow_automount(struct path *path, unsigned flags, /* Someone else made a mount here whilst we were busy */ return 0; case 0: - dput(path->dentry); - if (*need_mntput) - mntput(path->mnt); + path_put(path); path->mnt = mnt; path->dentry = dget(mnt->mnt_root); - *need_mntput = true; return 0; default: return err; @@ -844,9 +849,10 @@ static int follow_automount(struct path *path, unsigned flags, */ static int follow_managed(struct path *path, unsigned flags) { + struct vfsmount *mnt = path->mnt; /* held by caller, must be left alone */ unsigned managed; bool need_mntput = false; - int ret; + int ret = 0; /* Given that we're not holding a lock here, we retain the value in a * local variable for each dentry as we look at it so that we don't see @@ -861,7 +867,7 @@ static int follow_managed(struct path *path, unsigned flags) BUG_ON(!path->dentry->d_op->d_manage); ret = path->dentry->d_op->d_manage(path->dentry, false); if (ret < 0) - return ret == -EISDIR ? 0 : ret; + break; } /* Transit to a mounted filesystem. */ @@ -887,14 +893,19 @@ static int follow_managed(struct path *path, unsigned flags) if (managed & DCACHE_NEED_AUTOMOUNT) { ret = follow_automount(path, flags, &need_mntput); if (ret < 0) - return ret == -EISDIR ? 0 : ret; + break; continue; } /* We didn't change the current path point */ break; } - return 0; + + if (need_mntput && path->mnt == mnt) + mntput(path->mnt); + if (ret == -EISDIR) + ret = 0; + return ret; } int follow_down_one(struct path *path) @@ -931,7 +942,6 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, * Don't forget we might have a non-mountpoint managed dentry * that wants to block transit. */ - *inode = path->dentry->d_inode; if (unlikely(managed_dentry_might_block(path->dentry))) return false; @@ -944,6 +954,12 @@ static bool __follow_mount_rcu(struct nameidata *nd, struct path *path, path->mnt = mounted; path->dentry = mounted->mnt_root; nd->seq = read_seqcount_begin(&path->dentry->d_seq); + /* + * Update the inode too. We don't need to re-check the + * dentry sequence number here after this d_inode read, + * because a mount-point is always pinned. + */ + *inode = path->dentry->d_inode; } return true; } @@ -1003,9 +1019,6 @@ failed: * Follow down to the covering mount currently visible to userspace. At each * point, the filesystem owning that dentry may be queried as to whether the * caller is permitted to proceed or not. - * - * Care must be taken as namespace_sem may be held (indicated by mounting_here - * being true). */ int follow_down(struct path *path) { @@ -2624,6 +2637,10 @@ static long do_rmdir(int dfd, const char __user *pathname) error = PTR_ERR(dentry); if (IS_ERR(dentry)) goto exit2; + if (!dentry->d_inode) { + error = -ENOENT; + goto exit3; + } error = mnt_want_write(nd.path.mnt); if (error) goto exit3; @@ -2712,8 +2729,9 @@ static long do_unlinkat(int dfd, const char __user *pathname) if (nd.last.name[nd.last.len]) goto slashes; inode = dentry->d_inode; - if (inode) - ihold(inode); + if (!inode) + goto slashes; + ihold(inode); error = mnt_want_write(nd.path.mnt); if (error) goto exit2; |
