Merge remote-tracking branch 'remotes/dgilbert-gitlab/tags/pull-virtiofs-20200303' into staging

Virtiofsd pull 2020-03-03

xattr fixes from Misono.

# gpg: Signature made Tue 03 Mar 2020 15:15:04 GMT
# gpg:                using RSA key 45F5C71B4A0CB7FB977A9FA90516331EBC5BFDE7
# gpg: Good signature from "Dr. David Alan Gilbert (RH2) <dgilbert@redhat.com>" [full]
# Primary key fingerprint: 45F5 C71B 4A0C B7FB 977A  9FA9 0516 331E BC5B FDE7

* remotes/dgilbert-gitlab/tags/pull-virtiofs-20200303:
  virtiofsd: Fix xattr operations
  virtiofsd: passthrough_ll: cleanup getxattr/listxattr

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

3 files changed, 89 insertions, 69 deletions

diff --git a/tools/virtiofsd/fuse_virtio.c b/tools/virtiofsd/fuse_virtio.c
index dd1c605dbf..3b6d16a041 100644
--- a/tools/virtiofsd/fuse_virtio.c
+++ b/tools/virtiofsd/fuse_virtio.c
@@ -426,6 +426,8 @@ err:
     return ret;
 }
 
+static __thread bool clone_fs_called;
+
 /* Process one FVRequest in a thread pool */
 static void fv_queue_worker(gpointer data, gpointer user_data)
 {
@@ -441,6 +443,17 @@ static void fv_queue_worker(gpointer data, gpointer user_data)
 
     assert(se->bufsize > sizeof(struct fuse_in_header));
 
+    if (!clone_fs_called) {
+        int ret;
+
+        /* unshare FS for xattr operation */
+        ret = unshare(CLONE_FS);
+        /* should not fail */
+        assert(ret == 0);
+
+        clone_fs_called = true;
+    }
+
     /*
      * An element contains one request and the space to send our response
      * They're spread over multiple descriptors in a scatter/gather set
diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c
index 02ff01fad0..4f259aac70 100644
--- a/tools/virtiofsd/passthrough_ll.c
+++ b/tools/virtiofsd/passthrough_ll.c
@@ -123,7 +123,7 @@ struct lo_inode {
     pthread_mutex_t plock_mutex;
     GHashTable *posix_locks; /* protected by lo_inode->plock_mutex */
 
-    bool is_symlink;
+    mode_t filetype;
 };
 
 struct lo_cred {
@@ -695,7 +695,7 @@ static int utimensat_empty(struct lo_data *lo, struct lo_inode *inode,
     struct lo_inode *parent;
     char path[PATH_MAX];
 
-    if (inode->is_symlink) {
+    if (S_ISLNK(inode->filetype)) {
         res = utimensat(inode->fd, "", tv, AT_EMPTY_PATH);
         if (res == -1 && errno == EINVAL) {
             /* Sorry, no race free way to set times on symlink. */
@@ -928,7 +928,8 @@ static int lo_do_lookup(fuse_req_t req, fuse_ino_t parent, const char *name,
             goto out_err;
         }
 
-        inode->is_symlink = S_ISLNK(e->attr.st_mode);
+        /* cache only filetype */
+        inode->filetype = (e->attr.st_mode & S_IFMT);
 
         /*
          * One for the caller and one for nlookup (released in
@@ -1135,7 +1136,7 @@ static int linkat_empty_nofollow(struct lo_data *lo, struct lo_inode *inode,
     struct lo_inode *parent;
     char path[PATH_MAX];
 
-    if (inode->is_symlink) {
+    if (S_ISLNK(inode->filetype)) {
         res = linkat(inode->fd, "", dfd, name, AT_EMPTY_PATH);
         if (res == -1 && (errno == ENOENT || errno == EINVAL)) {
             /* Sorry, no race free way to hard-link a symlink. */
@@ -2189,40 +2190,43 @@ static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
     fuse_log(FUSE_LOG_DEBUG, "lo_getxattr(ino=%" PRIu64 ", name=%s size=%zd)\n",
              ino, name, size);
 
-    if (inode->is_symlink) {
-        /* Sorry, no race free way to getxattr on symlink. */
-        saverr = EPERM;
-        goto out;
-    }
-
-    sprintf(procname, "%i", inode->fd);
-    fd = openat(lo->proc_self_fd, procname, O_RDONLY);
-    if (fd < 0) {
-        goto out_err;
-    }
-
     if (size) {
         value = malloc(size);
         if (!value) {
             goto out_err;
         }
+    }
 
-        ret = fgetxattr(fd, name, value, size);
-        if (ret == -1) {
+    sprintf(procname, "%i", inode->fd);
+    /*
+     * It is not safe to open() non-regular/non-dir files in file server
+     * unless O_PATH is used, so use that method for regular files/dir
+     * only (as it seems giving less performance overhead).
+     * Otherwise, call fchdir() to avoid open().
+     */
+    if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+        fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+        if (fd < 0) {
             goto out_err;
         }
+        ret = fgetxattr(fd, name, value, size);
+    } else {
+        /* fchdir should not fail here */
+        assert(fchdir(lo->proc_self_fd) == 0);
+        ret = getxattr(procname, name, value, size);
+        assert(fchdir(lo->root.fd) == 0);
+    }
+
+    if (ret == -1) {
+        goto out_err;
+    }
+    if (size) {
         saverr = 0;
         if (ret == 0) {
             goto out;
         }
-
         fuse_reply_buf(req, value, ret);
     } else {
-        ret = fgetxattr(fd, name, NULL, 0);
-        if (ret == -1) {
-            goto out_err;
-        }
-
         fuse_reply_xattr(req, ret);
     }
 out_free:
@@ -2238,7 +2242,6 @@ out_free:
 out_err:
     saverr = errno;
 out:
-    lo_inode_put(lo, &inode);
     fuse_reply_err(req, saverr);
     goto out_free;
 }
@@ -2267,40 +2270,37 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size)
     fuse_log(FUSE_LOG_DEBUG, "lo_listxattr(ino=%" PRIu64 ", size=%zd)\n", ino,
              size);
 
-    if (inode->is_symlink) {
-        /* Sorry, no race free way to listxattr on symlink. */
-        saverr = EPERM;
-        goto out;
-    }
-
-    sprintf(procname, "%i", inode->fd);
-    fd = openat(lo->proc_self_fd, procname, O_RDONLY);
-    if (fd < 0) {
-        goto out_err;
-    }
-
     if (size) {
         value = malloc(size);
         if (!value) {
             goto out_err;
         }
+    }
 
-        ret = flistxattr(fd, value, size);
-        if (ret == -1) {
+    sprintf(procname, "%i", inode->fd);
+    if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+        fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+        if (fd < 0) {
             goto out_err;
         }
+        ret = flistxattr(fd, value, size);
+    } else {
+        /* fchdir should not fail here */
+        assert(fchdir(lo->proc_self_fd) == 0);
+        ret = listxattr(procname, value, size);
+        assert(fchdir(lo->root.fd) == 0);
+    }
+
+    if (ret == -1) {
+        goto out_err;
+    }
+    if (size) {
         saverr = 0;
         if (ret == 0) {
             goto out;
         }
-
         fuse_reply_buf(req, value, ret);
     } else {
-        ret = flistxattr(fd, NULL, 0);
-        if (ret == -1) {
-            goto out_err;
-        }
-
         fuse_reply_xattr(req, ret);
     }
 out_free:
@@ -2316,7 +2316,6 @@ out_free:
 out_err:
     saverr = errno;
 out:
-    lo_inode_put(lo, &inode);
     fuse_reply_err(req, saverr);
     goto out_free;
 }
@@ -2345,20 +2344,21 @@ static void lo_setxattr(fuse_req_t req, fuse_ino_t ino, const char *name,
     fuse_log(FUSE_LOG_DEBUG, "lo_setxattr(ino=%" PRIu64
              ", name=%s value=%s size=%zd)\n", ino, name, value, size);
 
-    if (inode->is_symlink) {
-        /* Sorry, no race free way to setxattr on symlink. */
-        saverr = EPERM;
-        goto out;
-    }
-
     sprintf(procname, "%i", inode->fd);
-    fd = openat(lo->proc_self_fd, procname, O_RDWR);
-    if (fd < 0) {
-        saverr = errno;
-        goto out;
+    if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+        fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+        if (fd < 0) {
+            saverr = errno;
+            goto out;
+        }
+        ret = fsetxattr(fd, name, value, size, flags);
+    } else {
+        /* fchdir should not fail here */
+        assert(fchdir(lo->proc_self_fd) == 0);
+        ret = setxattr(procname, name, value, size, flags);
+        assert(fchdir(lo->root.fd) == 0);
     }
 
-    ret = fsetxattr(fd, name, value, size, flags);
     saverr = ret == -1 ? errno : 0;
 
 out:
@@ -2393,20 +2393,21 @@ static void lo_removexattr(fuse_req_t req, fuse_ino_t ino, const char *name)
     fuse_log(FUSE_LOG_DEBUG, "lo_removexattr(ino=%" PRIu64 ", name=%s)\n", ino,
              name);
 
-    if (inode->is_symlink) {
-        /* Sorry, no race free way to setxattr on symlink. */
-        saverr = EPERM;
-        goto out;
-    }
-
     sprintf(procname, "%i", inode->fd);
-    fd = openat(lo->proc_self_fd, procname, O_RDWR);
-    if (fd < 0) {
-        saverr = errno;
-        goto out;
+    if (S_ISREG(inode->filetype) || S_ISDIR(inode->filetype)) {
+        fd = openat(lo->proc_self_fd, procname, O_RDONLY);
+        if (fd < 0) {
+            saverr = errno;
+            goto out;
+        }
+        ret = fremovexattr(fd, name);
+    } else {
+        /* fchdir should not fail here */
+        assert(fchdir(lo->proc_self_fd) == 0);
+        ret = removexattr(procname, name);
+        assert(fchdir(lo->root.fd) == 0);
     }
 
-    ret = fremovexattr(fd, name);
     saverr = ret == -1 ? errno : 0;
 
 out:
@@ -2806,7 +2807,7 @@ static void setup_root(struct lo_data *lo, struct lo_inode *root)
         exit(1);
     }
 
-    root->is_symlink = false;
+    root->filetype = S_IFDIR;
     root->fd = fd;
     root->key.ino = stat.st_ino;
     root->key.dev = stat.st_dev;
diff --git a/tools/virtiofsd/seccomp.c b/tools/virtiofsd/seccomp.c
index 2d9d4a7ec0..bd9e7b083c 100644
--- a/tools/virtiofsd/seccomp.c
+++ b/tools/virtiofsd/seccomp.c
@@ -41,6 +41,7 @@ static const int syscall_whitelist[] = {
     SCMP_SYS(exit),
     SCMP_SYS(exit_group),
     SCMP_SYS(fallocate),
+    SCMP_SYS(fchdir),
     SCMP_SYS(fchmodat),
     SCMP_SYS(fchownat),
     SCMP_SYS(fcntl),
@@ -62,7 +63,9 @@ static const int syscall_whitelist[] = {
     SCMP_SYS(getpid),
     SCMP_SYS(gettid),
     SCMP_SYS(gettimeofday),
+    SCMP_SYS(getxattr),
     SCMP_SYS(linkat),
+    SCMP_SYS(listxattr),
     SCMP_SYS(lseek),
     SCMP_SYS(madvise),
     SCMP_SYS(mkdirat),
@@ -85,6 +88,7 @@ static const int syscall_whitelist[] = {
     SCMP_SYS(recvmsg),
     SCMP_SYS(renameat),
     SCMP_SYS(renameat2),
+    SCMP_SYS(removexattr),
     SCMP_SYS(rt_sigaction),
     SCMP_SYS(rt_sigprocmask),
     SCMP_SYS(rt_sigreturn),
@@ -98,10 +102,12 @@ static const int syscall_whitelist[] = {
     SCMP_SYS(setresuid32),
 #endif
     SCMP_SYS(set_robust_list),
+    SCMP_SYS(setxattr),
     SCMP_SYS(symlinkat),
     SCMP_SYS(time), /* Rarely needed, except on static builds */
     SCMP_SYS(tgkill),
     SCMP_SYS(unlinkat),
+    SCMP_SYS(unshare),
     SCMP_SYS(utimensat),
     SCMP_SYS(write),
     SCMP_SYS(writev),