1 files changed, 274 insertions, 0 deletions
diff --git a/security/sandbox/linux/SandboxBrokerClient.cpp b/security/sandbox/linux/SandboxBrokerClient.cpp
new file mode 100644
index 0000000000..8dd8a2f5cf
--- /dev/null
+++ b/security/sandbox/linux/SandboxBrokerClient.cpp
@@ -0,0 +1,274 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "SandboxBrokerClient.h"
+#include "SandboxInfo.h"
+#include "SandboxLogging.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "mozilla/Assertions.h"
+#include "base/strings/safe_sprintf.h"
+
+namespace mozilla {
+
+SandboxBrokerClient::SandboxBrokerClient(int aFd) : mFileDesc(aFd) {}
+
+SandboxBrokerClient::~SandboxBrokerClient() { close(mFileDesc); }
+
+int SandboxBrokerClient::DoCall(const Request* aReq, const char* aPath,
+                                const char* aPath2, void* aResponseBuff,
+                                bool expectFd) {
+  // Remap /proc/self to the actual pid, so that the broker can open
+  // it.  This happens here instead of in the broker to follow the
+  // principle of least privilege and keep the broker as simple as
+  // possible.  (Note: when pid namespaces happen, this will also need
+  // to remap the inner pid to the outer pid.)
+  // We only remap the first path.
+  static const char kProcSelf[] = "/proc/self/";
+  static const size_t kProcSelfLen = sizeof(kProcSelf) - 1;
+  const char* path = aPath;
+  // This buffer just needs to be large enough for any such path that
+  // the policy would actually allow.  sizeof("/proc/2147483647/") == 18.
+  char rewrittenPath[64];
+  if (strncmp(aPath, kProcSelf, kProcSelfLen) == 0) {
+    ssize_t len = base::strings::SafeSPrintf(rewrittenPath, "/proc/%d/%s",
+                                             getpid(), aPath + kProcSelfLen);
+    if (static_cast<size_t>(len) < sizeof(rewrittenPath)) {
+      if (SandboxInfo::Get().Test(SandboxInfo::kVerbose)) {
+        SANDBOX_LOG("rewriting %s -> %s", aPath, rewrittenPath);
+      }
+      path = rewrittenPath;
+    } else {
+      SANDBOX_LOG("not rewriting unexpectedly long path %s", aPath);
+    }
+  }
+
+  struct iovec ios[3];
+  int respFds[2];
+
+  // Set up iovecs for request + path.
+  ios[0].iov_base = const_cast<Request*>(aReq);
+  ios[0].iov_len = sizeof(*aReq);
+  ios[1].iov_base = const_cast<char*>(path);
+  ios[1].iov_len = strlen(path) + 1;
+  if (aPath2 != nullptr) {
+    ios[2].iov_base = const_cast<char*>(aPath2);
+    ios[2].iov_len = strlen(aPath2) + 1;
+  } else {
+    ios[2].iov_base = nullptr;
+    ios[2].iov_len = 0;
+  }
+  if (ios[1].iov_len > kMaxPathLen) {
+    return -ENAMETOOLONG;
+  }
+  if (ios[2].iov_len > kMaxPathLen) {
+    return -ENAMETOOLONG;
+  }
+
+  // Create response socket and send request.
+  if (socketpair(AF_UNIX, SOCK_SEQPACKET, 0, respFds) < 0) {
+    return -errno;
+  }
+  const ssize_t sent = SendWithFd(mFileDesc, ios, 3, respFds[1]);
+  const int sendErrno = errno;
+  MOZ_ASSERT(sent < 0 || static_cast<size_t>(sent) ==
+                             ios[0].iov_len + ios[1].iov_len + ios[2].iov_len);
+  close(respFds[1]);
+  if (sent < 0) {
+    close(respFds[0]);
+    return -sendErrno;
+  }
+
+  // Set up iovecs for response.
+  Response resp;
+  ios[0].iov_base = &resp;
+  ios[0].iov_len = sizeof(resp);
+  if (aResponseBuff) {
+    ios[1].iov_base = aResponseBuff;
+    ios[1].iov_len = aReq->mBufSize;
+  } else {
+    ios[1].iov_base = nullptr;
+    ios[1].iov_len = 0;
+  }
+
+  // Wait for response and return appropriately.
+  int openedFd = -1;
+  const ssize_t recvd = RecvWithFd(respFds[0], ios, aResponseBuff ? 2 : 1,
+                                   expectFd ? &openedFd : nullptr);
+  const int recvErrno = errno;
+  close(respFds[0]);
+  if (recvd < 0) {
+    return -recvErrno;
+  }
+  if (recvd == 0) {
+    SANDBOX_LOG("Unexpected EOF, op %d flags 0%o path %s", aReq->mOp,
+                aReq->mFlags, path);
+    return -EIO;
+  }
+  MOZ_ASSERT(static_cast<size_t>(recvd) <= ios[0].iov_len + ios[1].iov_len);
+  // Some calls such as readlink return a size if successful
+  if (resp.mError >= 0) {
+    // Success!
+    if (expectFd) {
+      MOZ_ASSERT(openedFd >= 0);
+      return openedFd;
+    }
+    return resp.mError;
+  }
+  if (SandboxInfo::Get().Test(SandboxInfo::kVerbose)) {
+    // Keep in mind that "rejected" files can include ones that don't
+    // actually exist, if it's something that's optional or part of a
+    // search path (e.g., shared libraries).  In those cases, this
+    // error message is expected.
+    SANDBOX_LOG("Failed errno %d op %s flags 0%o path %s", resp.mError,
+                OperationDescription[aReq->mOp], aReq->mFlags, path);
+  }
+  if (openedFd >= 0) {
+    close(openedFd);
+  }
+  return resp.mError;
+}
+
+int SandboxBrokerClient::Open(const char* aPath, int aFlags) {
+  Request req = {SANDBOX_FILE_OPEN, aFlags, 0};
+  int maybeFd = DoCall(&req, aPath, nullptr, nullptr, true);
+  if (maybeFd >= 0) {
+    // NSPR has opinions about file flags.  Fix O_CLOEXEC.
+    if ((aFlags & O_CLOEXEC) == 0) {
+      fcntl(maybeFd, F_SETFD, 0);
+    }
+  }
+  return maybeFd;
+}
+
+int SandboxBrokerClient::Access(const char* aPath, int aMode) {
+  Request req = {SANDBOX_FILE_ACCESS, aMode, 0};
+  return DoCall(&req, aPath, nullptr, nullptr, false);
+}
+
+int SandboxBrokerClient::Stat(const char* aPath, statstruct* aStat) {
+  if (!aPath || !aStat) {
+    return -EFAULT;
+  }
+
+  Request req = {SANDBOX_FILE_STAT, 0, sizeof(statstruct)};
+  return DoCall(&req, aPath, nullptr, (void*)aStat, false);
+}
+
+int SandboxBrokerClient::LStat(const char* aPath, statstruct* aStat) {
+  if (!aPath || !aStat) {
+    return -EFAULT;
+  }
+
+  Request req = {SANDBOX_FILE_STAT, O_NOFOLLOW, sizeof(statstruct)};
+  return DoCall(&req, aPath, nullptr, (void*)aStat, false);
+}
+
+int SandboxBrokerClient::Chmod(const char* aPath, int aMode) {
+  Request req = {SANDBOX_FILE_CHMOD, aMode, 0};
+  return DoCall(&req, aPath, nullptr, nullptr, false);
+}
+
+int SandboxBrokerClient::Link(const char* aOldPath, const char* aNewPath) {
+  Request req = {SANDBOX_FILE_LINK, 0, 0};
+  return DoCall(&req, aOldPath, aNewPath, nullptr, false);
+}
+
+int SandboxBrokerClient::Symlink(const char* aOldPath, const char* aNewPath) {
+  Request req = {SANDBOX_FILE_SYMLINK, 0, 0};
+  return DoCall(&req, aOldPath, aNewPath, nullptr, false);
+}
+
+int SandboxBrokerClient::Rename(const char* aOldPath, const char* aNewPath) {
+  Request req = {SANDBOX_FILE_RENAME, 0, 0};
+  return DoCall(&req, aOldPath, aNewPath, nullptr, false);
+}
+
+int SandboxBrokerClient::Mkdir(const char* aPath, int aMode) {
+  Request req = {SANDBOX_FILE_MKDIR, aMode, 0};
+  return DoCall(&req, aPath, nullptr, nullptr, false);
+}
+
+int SandboxBrokerClient::Unlink(const char* aPath) {
+  Request req = {SANDBOX_FILE_UNLINK, 0, 0};
+  return DoCall(&req, aPath, nullptr, nullptr, false);
+}
+
+int SandboxBrokerClient::Rmdir(const char* aPath) {
+  Request req = {SANDBOX_FILE_RMDIR, 0, 0};
+  return DoCall(&req, aPath, nullptr, nullptr, false);
+}
+
+int SandboxBrokerClient::Readlink(const char* aPath, void* aBuff,
+                                  size_t aSize) {
+  Request req = {SANDBOX_FILE_READLINK, 0, aSize};
+  return DoCall(&req, aPath, nullptr, aBuff, false);
+}
+
+int SandboxBrokerClient::Connect(const sockaddr_un* aAddr, size_t aLen,
+                                 int aType) {
+  static constexpr size_t maxLen = sizeof(aAddr->sun_path);
+  const char* path = aAddr->sun_path;
+  const auto addrEnd = reinterpret_cast<const char*>(aAddr) + aLen;
+  // Ensure that the length isn't impossibly small.
+  if (addrEnd <= path) {
+    return -EINVAL;
+  }
+  // Unix domain only
+  if (aAddr->sun_family != AF_UNIX) {
+    return -EAFNOSUPPORT;
+  }
+  // How much of sun_path may be accessed?
+  auto bufLen = static_cast<size_t>(addrEnd - path);
+  if (bufLen > maxLen) {
+    bufLen = maxLen;
+  }
+
+  // Try to handle abstract addresses where the address (the part
+  // after the leading null byte) resembles a pathname: a leading
+  // slash and no embedded nulls.
+  //
+  // `DoCall` expects null-terminated strings, but in this case the
+  // "path" is terminated by the sockaddr length (without a null), so
+  // we need to make a copy.
+  if (bufLen >= 2 && path[0] == '\0' && path[1] == '/' &&
+      !memchr(path + 1, '\0', bufLen - 1)) {
+    char tmpBuf[maxLen];
+    MOZ_RELEASE_ASSERT(bufLen - 1 < maxLen);
+    memcpy(tmpBuf, path + 1, bufLen - 1);
+    tmpBuf[bufLen - 1] = '\0';
+
+    const Request req = {SANDBOX_SOCKET_CONNECT_ABSTRACT, aType, 0};
+    return DoCall(&req, tmpBuf, nullptr, nullptr, true);
+  }
+
+  // Require null-termination.  (Linux doesn't require it, but
+  // applications usually null-terminate for portability, and not
+  // handling unterminated strings means we don't have to copy the path.)
+  const size_t pathLen = strnlen(path, bufLen);
+  if (pathLen == bufLen) {
+    return -ENAMETOOLONG;
+  }
+
+  // Abstract addresses are handled only in some specific case, error in others
+  if (pathLen == 0) {
+    return -ENETUNREACH;
+  }
+
+  const Request req = {SANDBOX_SOCKET_CONNECT, aType, 0};
+  return DoCall(&req, path, nullptr, nullptr, true);
+}
+
+}  // namespace mozilla