Add fallback to mount syscall (#1349)

userspace/ksud/Cargo.lock

@@ -121,25 +121,6 @@ version = "1.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8c3c1a368f70d6cf7302d78f8f7093da241fb8e8807c05cc9e51a125895a6d5b"
 
-[[package]]
-name = "bindgen"
-version = "0.60.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "062dddbc1ba4aca46de6338e2bf87771414c335f7b2f2036e8f3e9befebf88e6"
-dependencies = [
- "bitflags 1.3.2",
- "cexpr",
- "clang-sys",
- "lazy_static",
- "lazycell",
- "peeking_take_while",
- "proc-macro2",
- "quote",
- "regex",
- "rustc-hash",
- "shlex",
-]
-
 [[package]]
 name = "bitflags"
 version = "1.3.2"
@@ -209,15 +190,6 @@ dependencies = [
  "jobserver",
 ]
 
-[[package]]
-name = "cexpr"
-version = "0.6.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6fac387a98bb7c37292057cffc56d62ecb629900026402633ae9160df93a8766"
-dependencies = [
- "nom",
-]
-
 [[package]]
 name = "cfg-if"
 version = "0.1.10"
@@ -254,17 +226,6 @@ dependencies = [
  "generic-array",
 ]
 
-[[package]]
-name = "clang-sys"
-version = "1.7.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "67523a3b4be3ce1989d607a828d036249522dd9c1c8de7f4dd2dae43a37369d1"
-dependencies = [
- "glob",
- "libc",
- "libloading",
-]
-
 [[package]]
 name = "clap"
 version = "4.1.4"
@@ -618,12 +579,6 @@ version = "0.27.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "b6c80984affa11d98d1b88b66ac8853f143217b399d3c74116778ff8fdb4ed2e"
 
-[[package]]
-name = "glob"
-version = "0.3.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d2fabcfbdc87f4758337ca535fb41a6d701b65693ce38287d856d1674551ec9b"
-
 [[package]]
 name = "heck"
 version = "0.4.1"
@@ -875,12 +830,6 @@ version = "1.4.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "e2abad23fbc42b3700f2f279844dc832adb2b2eb069b2df918f455c4e18cc646"
 
-[[package]]
-name = "lazycell"
-version = "1.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"
-
 [[package]]
 name = "libc"
 version = "0.2.152"
@@ -907,16 +856,6 @@ dependencies = [
  "rle-decode-fast",
 ]
 
-[[package]]
-name = "libloading"
-version = "0.8.1"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c571b676ddfc9a8c12f1f3d3085a7b163966a8fd8098a90640953ce5f6170161"
-dependencies = [
- "cfg-if 1.0.0",
- "windows-sys 0.48.0",
-]
-
 [[package]]
 name = "libm"
 version = "0.2.6"
@@ -953,9 +892,8 @@ checksum = "b5e6163cb8c49088c2c36f57875e58ccd8c87c7427f7fbd50ea6710b2f3f2e8f"
 [[package]]
 name = "loopdev"
 version = "0.5.0"
-source = "git+https://github.com/tiann/loopdev?branch=loopfix#b6ca5e3ea163f66239f6a835874fe231b2a9286f"
+source = "git+https://github.com/Kernel-SU/loopdev#7a921f8d966477a645b1188732fac486c71a68ef"
 dependencies = [
- "bindgen",
  "errno 0.2.8",
  "libc",
 ]
@@ -1080,12 +1018,6 @@ dependencies = [
  "sha2",
 ]
 
-[[package]]
-name = "peeking_take_while"
-version = "0.1.2"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "19b17cddbe7ec3f8bc800887bab5e717348c95ea2ca0b1bf0837fb964dc67099"
-
 [[package]]
 name = "pin-project-lite"
 version = "0.2.9"
@@ -1349,12 +1281,6 @@ version = "0.1.23"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d626bb9dae77e28219937af045c257c28bfd3f69333c512553507f5f9798cb76"
 
-[[package]]
-name = "rustc-hash"
-version = "1.1.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "08d43f7aa6b08d49f382cde6a7982047c3426db949b1424bc4b7ec9ae12c6ce2"
-
 [[package]]
 name = "rustix"
 version = "0.36.7"
@@ -1469,12 +1395,6 @@ dependencies = [
  "tokio",
 ]
 
-[[package]]
-name = "shlex"
-version = "1.3.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0fda2ff0d084019ba4d7c6f371c95d8fd75ce3524c3cb8fb653a3023f6323e64"
-
 [[package]]
 name = "strsim"
 version = "0.10.0"

userspace/ksud/Cargo.toml

@@ -43,7 +43,7 @@ rustix = { git = "https://github.com/Kernel-SU/rustix.git", branch = "main", fea
 # some android specific dependencies which compiles under unix are also listed here for convenience of coding
 android-properties = { version = "0.2.2", features = ["bionic-deprecated"] }
 procfs = "0.16"
-loopdev = { git = "https://github.com/tiann/loopdev", branch = "loopfix" }
+loopdev = { git = "https://github.com/Kernel-SU/loopdev" }
 
 [target.'cfg(target_os = "android")'.dependencies]
 android_logger = "0.13"

userspace/ksud/src/mount.rs

@@ -59,7 +59,7 @@ pub fn mount_ext4(source: impl AsRef<Path>, target: impl AsRef<Path>) -> Result<
     let new_loopback = loopdev::LoopControl::open()?.next_free()?;
     new_loopback.with().attach(source)?;
     let lo = new_loopback.path().ok_or(anyhow!("no loop"))?;
-    let fs = fsopen("ext4", FsOpenFlags::FSOPEN_CLOEXEC)?;
+    if let Result::Ok(fs) = fsopen("ext4", FsOpenFlags::FSOPEN_CLOEXEC) {
         let fs = fs.as_fd();
         fsconfig_set_string(fs, "source", lo)?;
         fsconfig_create(fs)?;
@@ -71,6 +71,9 @@ pub fn mount_ext4(source: impl AsRef<Path>, target: impl AsRef<Path>) -> Result<
             target.as_ref(),
             MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
         )?;
+    } else {
+        mount(lo, target.as_ref(), "ext4", MountFlags::empty(), "")?;
+    }
     Ok(())
 }
 
@@ -102,7 +105,7 @@ pub fn mount_overlayfs(
         upperdir,
         workdir
     );
-    let fs = fsopen("overlay", FsOpenFlags::FSOPEN_CLOEXEC)?;
+    if let Result::Ok(fs) = fsopen("overlay", FsOpenFlags::FSOPEN_CLOEXEC) {
         let fs = fs.as_fd();
         fsconfig_set_string(fs, "lowerdir", lowerdir_config)?;
         if let (Some(upperdir), Some(workdir)) = (upperdir, workdir) {
@@ -121,13 +124,32 @@ pub fn mount_overlayfs(
             dest.as_ref(),
             MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
         )?;
+    } else {
+        let mut data = format!("lowerdir={lowerdir_config}");
+        if let (Some(upperdir), Some(workdir)) = (upperdir, workdir) {
+            if upperdir.exists() && workdir.exists() {
+                data = format!(
+                    "{data},upperdir={},workdir={}",
+                    upperdir.display(),
+                    workdir.display()
+                );
+            }
+        }
+        mount(
+            KSU_OVERLAY_SOURCE,
+            dest.as_ref(),
+            "overlay",
+            MountFlags::empty(),
+            data,
+        )?;
+    }
     Ok(())
 }
 
 #[cfg(any(target_os = "linux", target_os = "android"))]
 pub fn mount_tmpfs(dest: impl AsRef<Path>) -> Result<()> {
     info!("mount tmpfs on {}", dest.as_ref().display());
-    let fs = fsopen("tmpfs", FsOpenFlags::FSOPEN_CLOEXEC)?;
+    if let Result::Ok(fs) = fsopen("tmpfs", FsOpenFlags::FSOPEN_CLOEXEC) {
         let fs = fs.as_fd();
         fsconfig_set_string(fs, "source", KSU_OVERLAY_SOURCE)?;
         fsconfig_create(fs)?;
@@ -139,6 +161,15 @@ pub fn mount_tmpfs(dest: impl AsRef<Path>) -> Result<()> {
             dest.as_ref(),
             MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
         )?;
+    } else {
+        mount(
+            KSU_OVERLAY_SOURCE,
+            dest.as_ref(),
+            "tmpfs",
+            MountFlags::empty(),
+            "",
+        )?;
+    }
     Ok(())
 }
 
@@ -149,13 +180,13 @@ fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
         from.as_ref().display(),
         to.as_ref().display()
     );
-    let tree = open_tree(
+    if let Result::Ok(tree) = open_tree(
         CWD,
         from.as_ref(),
         OpenTreeFlags::OPEN_TREE_CLOEXEC
             | OpenTreeFlags::OPEN_TREE_CLONE
             | OpenTreeFlags::AT_RECURSIVE,
-    )?;
+    ) {
         move_mount(
             tree.as_fd(),
             "",
@@ -163,6 +194,15 @@ fn bind_mount(from: impl AsRef<Path>, to: impl AsRef<Path>) -> Result<()> {
             to.as_ref(),
             MoveMountFlags::MOVE_MOUNT_F_EMPTY_PATH,
         )?;
+    } else {
+        mount(
+            from.as_ref(),
+            to.as_ref(),
+            "",
+            MountFlags::BIND | MountFlags::REC,
+            "",
+        )?;
+    }
     Ok(())
 }