Add resolv-conf parser

.gitmodules

@@ -22,3 +22,6 @@
 [submodule "deps/ringbuf"]
 	path = deps/ringbuf
 	url = https://github.com/agerasev/ringbuf.git
+[submodule "deps/resolv-conf"]
+	path = deps/resolv-conf
+	url = https://github.com/tailhook/resolv-conf.git

Makefile

@@ -35,6 +35,7 @@ submodule: githooks
 	@# Try to apply the patches. If failed, check if the patches are already applied
 	cd deps/serde-json-sgx && git apply ../serde-json-sgx.patch >/dev/null 2>&1 || git apply ../serde-json-sgx.patch -R --check
 	cd deps/ringbuf && git apply ../ringbuf.patch >/dev/null 2>&1 || git apply ../ringbuf.patch -R --check
+	cd deps/resolv-conf && git apply ../resolv-conf.patch >/dev/null 2>&1 || git apply ../resolv-conf.patch -R --check
 
 	@# Enclaves used by tools are running in simulation mode by default to run faster.
 	@rm -rf build build_sim

demos/grpc/run_client_on_occlum.sh

@@ -24,7 +24,6 @@ then
 fi
 
 mkdir -p image/etc
-cp /etc/resolv.conf image/etc
 cp ../greeter_client image/bin
 cp $INSTALL_DIR/lib/libprotobuf.so.3.10.0.0 image/lib
 cp $INSTALL_DIR/lib/libcares.so.2 image/lib

demos/grpc/run_server_on_occlum.sh

@@ -23,7 +23,6 @@ then
 fi
 
 mkdir -p image/etc
-cp /etc/resolv.conf image/etc
 cp ../greeter_server image/bin
 cp $INSTALL_DIR/lib/libprotobuf.so.3.10.0.0 image/lib
 cp $INSTALL_DIR/lib/libcares.so.2 image/lib

deps/resolv-conf

@@ -0,0 +1 @@
+Subproject commit c0752810e748d496c2df161a2a90c3c229b65531

deps/resolv-conf.patch

@@ -0,0 +1,80 @@
+From 9faee3943a31e359e76c5dfce23918c35fd8f317 Mon Sep 17 00:00:00 2001
+From: ClawSeven <zehuan97@gmail.com>
+Date: Fri, 9 Jul 2021 13:28:42 +0800
+Subject: [PATCH] Transplant resolv-conf into sgx-world
+
+---
+ Cargo.toml     | 3 ++-
+ src/config.rs  | 2 ++
+ src/grammar.rs | 1 +
+ src/ip.rs      | 1 +
+ src/lib.rs     | 3 +++
+ 5 files changed, 9 insertions(+), 1 deletion(-)
+
+diff --git a/Cargo.toml b/Cargo.toml
+index 0022252..617e319 100644
+--- a/Cargo.toml
++++ b/Cargo.toml
+@@ -14,7 +14,8 @@ version = "0.7.0"
+ authors = ["paul@colomiets.name"]
+ 
+ [dependencies]
+-quick-error = "1.0.0"
++quick-error = {  git = "https://github.com/mesalock-linux/quick-error-sgx.git"  }
++sgx_tstd = { git = "https://github.com/apache/teaclave-sgx-sdk.git" }
+ hostname = { version = "^0.3", optional = true }
+ 
+ [features]
+diff --git a/src/config.rs b/src/config.rs
+index b6b6460..8389064 100644
+--- a/src/config.rs
++++ b/src/config.rs
+@@ -3,6 +3,8 @@ use std::iter::{IntoIterator, Iterator};
+ use std::slice::Iter;
+ use {grammar, Network, ParseError, ScopedIp};
+ use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
++use std::vec::Vec;
++use std::string::String;
+ 
+ const NAMESERVER_LIMIT:usize = 3;
+ const SEARCH_LIMIT:usize = 6;
+diff --git a/src/grammar.rs b/src/grammar.rs
+index 9a274a8..be85081 100644
+--- a/src/grammar.rs
++++ b/src/grammar.rs
+@@ -1,5 +1,6 @@
+ use std::net::{Ipv4Addr, Ipv6Addr};
+ use std::str::{Utf8Error, from_utf8};
++use std::string::ToString;
+ 
+ use {AddrParseError, Config, Network, Lookup, Family};
+ 
+diff --git a/src/ip.rs b/src/ip.rs
+index c9cfa59..4b4bca2 100644
+--- a/src/ip.rs
++++ b/src/ip.rs
+@@ -2,6 +2,7 @@ use std::error::Error;
+ use std::fmt;
+ use std::net::{IpAddr, Ipv4Addr, Ipv6Addr};
+ use std::str::FromStr;
++use std::string::{String, ToString};
+ 
+ /// A network, that is an IP address and a mask
+ #[derive(Clone, Debug, PartialEq, Eq)]
+diff --git a/src/lib.rs b/src/lib.rs
+index a55a9d7..094a35a 100644
+--- a/src/lib.rs
++++ b/src/lib.rs
+@@ -91,6 +91,9 @@
+ #![warn(missing_debug_implementations)]
+ #![warn(missing_docs)]
+ 
++#![no_std]
++#[macro_use]
++extern crate sgx_tstd as std;
+ #[macro_use]
+ extern crate quick_error;
+ #[cfg(feature = "system")]
+-- 
+2.17.1
+

src/Enclave.edl

@@ -42,7 +42,7 @@ enclave {
          *      EEXIST - The LibOS has already been initialized.
          *      EINVAL - The value of an argument are invalid.
          */
-        public int occlum_ecall_init([in, string] const char* log_level, [in, string] const char* instance_dir);
+        public int occlum_ecall_init([in, string] const char* log_level, [in, string] const char* instance_dir, [in, string] const char* resolv_conf_ptr);
 
         /*
          * Create a new LibOS process to do the task specified by the given 

src/libos/Cargo.toml

@@ -22,6 +22,7 @@ rcore-fs-ramfs = { path = "../../deps/sefs/rcore-fs-ramfs" }
 rcore-fs-mountfs = { path = "../../deps/sefs/rcore-fs-mountfs" }
 rcore-fs-unionfs = { path = "../../deps/sefs/rcore-fs-unionfs" }
 rcore-fs-devfs = { path = "../../deps/sefs/rcore-fs-devfs" }
+resolv-conf = { path = "../../deps/resolv-conf" }
 serde = { path = "../../deps/serde-sgx/serde", features = ["derive"] }
 serde_json = { path = "../../deps/serde-json-sgx" }
 memoffset = "0.6.1"

src/libos/src/entry.rs

@@ -12,6 +12,7 @@ use crate::signal::SigNum;
 use crate::time::up_time::init;
 use crate::util::log::LevelFilter;
 use crate::util::mem_util::from_untrusted::*;
+use crate::util::resolv_conf_util::{parse_resolv_conf, write_resolv_conf};
 use crate::util::sgx::allow_debug as sgx_allow_debug;
 use sgx_tse::*;
 
@@ -23,6 +24,7 @@ lazy_static! {
     static ref HAS_INIT: AtomicBool = AtomicBool::new(false);
     pub static ref ENTRY_POINTS: RwLock<Vec<PathBuf>> =
         RwLock::new(config::LIBOS_CONFIG.entry_points.clone());
+    pub static ref RESOLV_CONF_STR: RwLock<Option<String>> = RwLock::new(None);
 }
 
 macro_rules! ecall_errno {
@@ -33,7 +35,11 @@ macro_rules! ecall_errno {
 }
 
 #[no_mangle]
-pub extern "C" fn occlum_ecall_init(log_level: *const c_char, instance_dir: *const c_char) -> i32 {
+pub extern "C" fn occlum_ecall_init(
+    log_level: *const c_char,
+    instance_dir: *const c_char,
+    resolv_conf_ptr: *const c_char,
+) -> i32 {
     if HAS_INIT.load(Ordering::SeqCst) == true {
         return ecall_errno!(EEXIST);
     }
@@ -87,6 +93,18 @@ pub extern "C" fn occlum_ecall_init(log_level: *const c_char, instance_dir: *con
         unsafe { backtrace::enable_backtrace(&ENCLAVE_PATH, PrintFormat::Short) };
     });
 
+    match parse_resolv_conf(resolv_conf_ptr) {
+        Err(e) => {
+            error!("failed to parse /etc/resolv.conf: {}", e.backtrace());
+        }
+        Ok(resolv_conf_str) => {
+            *RESOLV_CONF_STR.write().unwrap() = Some(resolv_conf_str);
+            if let Err(e) = write_resolv_conf() {
+                error!("failed to write /etc/resolv.conf: {}", e.backtrace());
+            }
+        }
+    }
+
     0
 }
 

src/libos/src/fs/fs_ops/mount.rs

@@ -1,4 +1,5 @@
 use std::sync::Once;
+use util::resolv_conf_util::write_resolv_conf;
 
 use super::rootfs::{mount_nonroot_fs_according_to, open_root_fs_according_to};
 use super::*;
@@ -27,5 +28,9 @@ pub fn do_mount_rootfs(
         *root_inode = new_root_inode;
         *ENTRY_POINTS.write().unwrap() = user_config.entry_points.to_owned();
     });
+    // Write resolv.conf file into mounted file system
+    write_resolv_conf()?;
+    *RESOLV_CONF_STR.write().unwrap() = None;
+
     Ok(())
 }

src/libos/src/lib.rs

@@ -53,6 +53,7 @@ extern crate serde;
 extern crate serde_json;
 #[macro_use]
 extern crate memoffset;
+extern crate resolv_conf;
 
 use sgx_trts::libc;
 use sgx_types::*;

src/libos/src/util/mod.rs

@@ -5,5 +5,6 @@ pub mod log;
 pub mod mem_util;
 pub mod mpx_util;
 pub mod random;
+pub mod resolv_conf_util;
 pub mod sgx;
 pub mod sync;

src/libos/src/util/resolv_conf_util.rs

@@ -0,0 +1,37 @@
+use super::*;
+use crate::fs::{AccessMode, CreationFlags, FsView};
+use resolv_conf::*;
+use std::ffi::CStr;
+use std::str;
+
+pub fn write_resolv_conf() -> Result<()> {
+    const RESOLV_CONF_PATH: &'static str = "/etc/resolv.conf";
+    let fs_view = FsView::new();
+    // overwrite /etc/resolv.conf if existed
+    let resolv_conf_file = fs_view.open_file(
+        RESOLV_CONF_PATH,
+        AccessMode::O_RDWR as u32 | CreationFlags::O_CREAT.bits() | CreationFlags::O_TRUNC.bits(),
+        0o666,
+    )?;
+    let resolv_conf_str = RESOLV_CONF_STR.read().unwrap();
+    match &*resolv_conf_str {
+        Some(str) => {
+            resolv_conf_file.write(str.as_bytes());
+        }
+        None => {}
+    }
+    Ok(())
+}
+
+pub fn parse_resolv_conf(resolv_conf_ptr: *const c_char) -> Result<String> {
+    // Read resolv.conf file from host
+    let resolv_conf_bytes = unsafe { CStr::from_ptr(resolv_conf_ptr).to_bytes() };
+    let resolv_conf_str = str::from_utf8(resolv_conf_bytes)
+        .map_err(|_| errno!(EINVAL, "/etc/resolv.conf contains non UTF-8 characters"))?;
+
+    // Parse and inspect resolv.conf file
+    if let Err(_) = resolv_conf::Config::parse(resolv_conf_bytes) {
+        return_errno!(EINVAL, "malformated host /etc/resolv.conf");
+    }
+    Ok(resolv_conf_str.to_string())
+}

src/pal/src/pal_api.c

@@ -2,6 +2,7 @@
 #include "Enclave_u.h"
 #include "pal_enclave.h"
 #include "pal_error.h"
+#include "pal_load_resolv_conf.h"
 #include "pal_interrupt_thread.h"
 #include "pal_log.h"
 #include "pal_sig_handler.h"
@@ -103,8 +104,11 @@ int occlum_pal_init(const struct occlum_pal_attr *attr) {
     eid = pal_get_enclave_id();
 
     int ecall_ret = 0;
+    const char *resolv_conf_ptr = pal_load_resolv_conf();
     sgx_status_t ecall_status = occlum_ecall_init(eid, &ecall_ret, attr->log_level,
-                                resolved_path);
+                                resolved_path, resolv_conf_ptr);
+    free((void *)resolv_conf_ptr);
+    resolv_conf_ptr = NULL;
     if (ecall_status != SGX_SUCCESS) {
         const char *sgx_err = pal_get_sgx_error_msg(ecall_status);
         PAL_ERROR("Failed to do ECall with error code 0x%x: %s", ecall_status, sgx_err);

src/pal/src/pal_load_resolv_conf.c

@@ -0,0 +1,24 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "pal_log.h"
+
+char *pal_load_resolv_conf(void) {
+    FILE *fp = fopen("/etc/resolv.conf", "rb");
+
+    if (fp == NULL) {
+        PAL_WARN("Warning: Failed to open /etc/resolv.conf file");
+        return NULL;
+    }
+    fseek(fp, 0, SEEK_END);
+    long fsize = ftell(fp);
+    fseek(fp, 0, SEEK_SET);
+    char *resolv_conf_buffer = malloc(fsize + 1);
+    if (resolv_conf_buffer == NULL) {
+        PAL_WARN("Warning: Failed to malloc for /etc/resolv.conf buffer");
+        return NULL;
+    }
+    fread(resolv_conf_buffer, 1, fsize, fp);
+    resolv_conf_buffer[fsize] = 0;
+    fclose(fp);
+    return resolv_conf_buffer;
+}

src/pal/src/pal_load_resolv_conf.h

@@ -0,0 +1,6 @@
+#ifndef __PAL_LOAD_RESOLV_CONF_H__
+#define __PAL_LOAD_RESOLV_CONF_H__
+
+char *pal_load_resolv_conf(void);
+
+#endif /* __PAL_LOAD_RESOLV_CONF_H__ */

test/Makefile

@@ -16,7 +16,7 @@ FAIL_LOG = $(BUILD_DIR)/test/.fail
 TEST_DEPS := client data_sink naughty_child
 # Tests: need to be compiled and run by test-% target
 TESTS ?= env empty hello_world malloc mmap file fs_perms getpid spawn sched pipe time timerfd \
-	truncate readdir mkdir open stat link symlink chmod chown tls pthread system_info rlimit \
+	truncate readdir mkdir open stat link symlink chmod chown tls pthread system_info resolv_conf rlimit \
 	server server_epoll unix_socket cout hostfs cpuid rdtsc device sleep exit_group \
 	ioctl fcntl eventfd emulate_syscall access signal sysinfo prctl rename procfs wait \
 	spawn_attribute exec statfs

test/resolv_conf/Makefile

@@ -0,0 +1,5 @@
+include ../test_common.mk
+
+EXTRA_C_FLAGS :=
+EXTRA_LINK_FLAGS :=
+BIN_ARGS :=

test/resolv_conf/main.c

@@ -0,0 +1,48 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "test.h"
+
+// ============================================================================
+// Helper functions
+// ============================================================================
+char *read_resolv_conf(void) {
+    FILE *fp = fopen("/etc/resolv.conf", "rb");
+    fseek(fp, 0, SEEK_END);
+    long fsize = ftell(fp);
+    fseek(fp, 0, SEEK_SET);
+    char *resolv_conf_buffer = malloc(fsize + 1);
+    if (resolv_conf_buffer == NULL) {
+        printf("ERROR: Failed to malloc for /etc/resolv.conf buffer");
+        return NULL;
+    }
+    fread(resolv_conf_buffer, 1, fsize, fp);
+    fclose(fp);
+    return resolv_conf_buffer;
+}
+
+// ============================================================================
+// Test cases for resolv.conf file
+// ============================================================================
+
+int test_resolv_conf() {
+    char *buffer = read_resolv_conf();
+    if (buffer == NULL) {
+        THROW_ERROR("failed to read resolv.conf");
+    }
+    printf("%s", buffer);
+    free(buffer);
+    buffer = NULL;
+    return 0;
+}
+
+static test_case_t test_cases[] = {
+    TEST_CASE(test_resolv_conf),
+};
+
+// ============================================================================
+// Test suite main
+// ============================================================================
+
+int main() {
+    return test_suite_run(test_cases, ARRAY_SIZE(test_cases));
+}