# HG changeset patch
# User Julien Cristau <jcristau@mozilla.com>
# Date 1599423639 0
# Node ID 8ecb82a2f65cf6082d50d1e00453fbeba97633fb
# Parent  0ce38d3c2aa2357df4a8fcc5fd39d3af05fce7e1
Bug 1660901 - ignore AT_NO_AUTOMOUNT in fstatat system call. r=jld, a=RyanVM

Per the manpage "Both stat() and lstat() act as though AT_NO_AUTOMOUNT
was set.", so don't bail if it's set in a call to fstatat.

Differential Revision: https://phabricator.services.mozilla.com/D89121

diff --git a/security/sandbox/linux/SandboxFilter.cpp b/security/sandbox/linux/SandboxFilter.cpp
--- a/security/sandbox/linux/SandboxFilter.cpp
+++ b/security/sandbox/linux/SandboxFilter.cpp
@@ -249,19 +249,20 @@ class SandboxPolicyCommon : public Sandb
       return ConvertError(fstatsyscall(fd, buf));
     }
 
     if (fd != AT_FDCWD && path[0] != '/') {
       SANDBOX_LOG_ERROR("unsupported fd-relative fstatat(%d, \"%s\", %p, %d)",
                         fd, path, buf, flags);
       return BlockedSyscallTrap(aArgs, nullptr);
     }
-    if ((flags & ~AT_SYMLINK_NOFOLLOW) != 0) {
+    if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)) != 0) {
       SANDBOX_LOG_ERROR("unsupported flags %d in fstatat(%d, \"%s\", %p, %d)",
-                        (flags & ~AT_SYMLINK_NOFOLLOW), fd, path, buf, flags);
+                        (flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT)), fd,
+                        path, buf, flags);
       return BlockedSyscallTrap(aArgs, nullptr);
     }
     return (flags & AT_SYMLINK_NOFOLLOW) == 0 ? broker->Stat(path, buf)
                                               : broker->LStat(path, buf);
   }
 
   static intptr_t ChmodTrap(ArgsRef aArgs, void* aux) {
     auto broker = static_cast<SandboxBrokerClient*>(aux);