1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352 353 354 355 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 381 382 383 384 385 386 387 388 389 390 391 392 393 394 395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410 411 412 413 414 415 416 417 418 419 420 421 422 423 424 425 426 427 428 429 430 431 432 433 434 435 436 437 438 439 440 441 442 443 444 445 446 447 448 449 450 451 452 453 454 455 456 457 458 459 460 461 462 463 464 465 466 467 468 469 470 471 472 473 474 475 476 477 478 479 480 481 482 483 484 485 486 487 488 489 490 491 492 493 494 495 496 497 498 499 500 501 502 503 504 505 506 507 508 509 510 511 512
// Copyright 2023 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#[cfg(feature = "fs_permission_translation")]
use std::io;
#[cfg(feature = "fs_permission_translation")]
use std::str::FromStr;
use std::time::Duration;
#[cfg(feature = "fs_permission_translation")]
use libc;
#[allow(unused_imports)]
use serde::de::Error;
use serde::Deserialize;
use serde::Deserializer;
use serde::Serialize;
use serde_keyvalue::FromKeyValues;
/// The caching policy that the file system should report to the FUSE client. By default the FUSE
/// protocol uses close-to-open consistency. This means that any cached contents of the file are
/// invalidated the next time that file is opened.
#[derive(Debug, Clone, Default, Eq, PartialEq, Serialize, Deserialize, FromKeyValues)]
#[serde(rename_all = "kebab-case")]
pub enum CachePolicy {
/// The client should never cache file data and all I/O should be directly forwarded to the
/// server. This policy must be selected when file contents may change without the knowledge of
/// the FUSE client (i.e., the file system does not have exclusive access to the directory).
Never,
/// The client is free to choose when and how to cache file data. This is the default policy
/// and uses close-to-open consistency as described in the enum documentation.
#[default]
Auto,
/// The client should always cache file data. This means that the FUSE client will not
/// invalidate any cached data that was returned by the file system the last time the file was
/// opened. This policy should only be selected when the file system has exclusive access to
/// the directory.
Always,
}
const fn config_default_timeout() -> Duration {
Duration::from_secs(5)
}
const fn config_default_negative_timeout() -> Duration {
Duration::ZERO
}
const fn config_default_posix_acl() -> bool {
true
}
const fn config_default_security_ctx() -> bool {
true
}
fn deserialize_timeout<'de, D: Deserializer<'de>>(deserializer: D) -> Result<Duration, D::Error> {
let secs = u64::deserialize(deserializer)?;
Ok(Duration::from_secs(secs))
}
#[cfg(feature = "arc_quota")]
fn deserialize_privileged_quota_uids<'de, D: Deserializer<'de>>(
deserializer: D,
) -> Result<Vec<libc::uid_t>, D::Error> {
// space-separated list
let s: &str = serde::Deserialize::deserialize(deserializer)?;
s.split(" ")
.map(|s| {
s.parse::<libc::uid_t>().map_err(|e| {
<D as Deserializer>::Error::custom(format!(
"failed to parse priviledged quota uid {s}: {e}"
))
})
})
.collect()
}
/// Permission structure that is configured to map the UID-GID at runtime
#[cfg(feature = "fs_permission_translation")]
#[derive(Debug, Clone, Eq, PartialEq, Serialize)]
pub struct PermissionData {
/// UID to be set for all the files in the path inside guest.
pub guest_uid: libc::uid_t,
/// GID to be set for all the files in the path inside guest.
pub guest_gid: libc::gid_t,
/// UID to be set for all the files in the path in the host.
pub host_uid: libc::uid_t,
/// GID to be set for all the files in the path in the host.
pub host_gid: libc::gid_t,
/// umask to be set at runtime for the files in the path.
pub umask: libc::mode_t,
/// This is the absolute path from the root of the shared directory.
pub perm_path: String,
}
#[cfg(feature = "fs_runtime_ugid_map")]
fn process_ugid_map(result: Vec<Vec<String>>) -> Result<Vec<PermissionData>, io::Error> {
let mut permissions = Vec::new();
for inner_vec in result {
let guest_uid = match libc::uid_t::from_str(&inner_vec[0]) {
Ok(uid) => uid,
Err(_) => {
return Err(io::Error::from_raw_os_error(libc::EINVAL));
}
};
let guest_gid = match libc::gid_t::from_str(&inner_vec[1]) {
Ok(gid) => gid,
Err(_) => {
return Err(io::Error::from_raw_os_error(libc::EINVAL));
}
};
let host_uid = match libc::uid_t::from_str(&inner_vec[2]) {
Ok(uid) => uid,
Err(_) => {
return Err(io::Error::from_raw_os_error(libc::EINVAL));
}
};
let host_gid = match libc::gid_t::from_str(&inner_vec[3]) {
Ok(gid) => gid,
Err(_) => {
return Err(io::Error::from_raw_os_error(libc::EINVAL));
}
};
let umask = match libc::mode_t::from_str(&inner_vec[4]) {
Ok(mode) => mode,
Err(_) => {
return Err(io::Error::from_raw_os_error(libc::EINVAL));
}
};
let perm_path = inner_vec[5].clone();
// Create PermissionData and push it to the vector
permissions.push(PermissionData {
guest_uid,
guest_gid,
host_uid,
host_gid,
umask,
perm_path,
});
}
Ok(permissions)
}
#[cfg(feature = "fs_runtime_ugid_map")]
fn deserialize_ugid_map<'de, D: Deserializer<'de>>(
deserializer: D,
) -> Result<Vec<PermissionData>, D::Error> {
// space-separated list
let s: &str = serde::Deserialize::deserialize(deserializer)?;
let result: Vec<Vec<String>> = s
.split(';')
.map(|group| group.trim().split(' ').map(String::from).collect())
.collect();
// Length Validation for each inner vector
for inner_vec in &result {
if inner_vec.len() != 6 {
return Err(D::Error::custom(
"Invalid ugid_map format. Each group must have 6 elements.",
));
}
}
let permissions = match process_ugid_map(result) {
Ok(p) => p,
Err(e) => {
return Err(D::Error::custom(format!(
"Error processing uid_gid_map: {}",
e
)));
}
};
Ok(permissions)
}
/// Options that configure the behavior of the file system.
#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, FromKeyValues)]
#[serde(deny_unknown_fields, rename_all = "snake_case")]
pub struct Config {
/// How long the FUSE client should consider directory entries and file/directory attributes to
/// be valid.
/// This value corresponds to `entry_timeout` and `attr_timeout` in
/// [libfuse's `fuse_config`](https://libfuse.github.io/doxygen/structfuse__config.html), but
/// we use the same value for the two.
///
/// If the contents of a directory or the attributes of a file or directory can only be
/// modified by the FUSE client (i.e., the file system has exclusive access), then this should
/// be a large value.
/// The default value for this option is 5 seconds.
#[serde(
default = "config_default_timeout",
deserialize_with = "deserialize_timeout"
)]
pub timeout: Duration,
/// How long the FUSE client can cache negative lookup results.
/// If a file lookup fails, the client can assume the file doesn't exist until the timeout and
/// won't send lookup.
/// The value 0 means that negative lookup shouldn't be cached.
///
/// If the contents of a directory can only be modified by the FUSE client (i.e., the file
/// system has exclusive access), then this should be a large value.
/// The default value for this option is 0 seconds (= no negative cache).
#[serde(
default = "config_default_negative_timeout",
deserialize_with = "deserialize_timeout"
)]
pub negative_timeout: Duration,
/// The caching policy the file system should use. See the documentation of `CachePolicy` for
/// more details.
#[serde(default, alias = "cache")]
pub cache_policy: CachePolicy,
/// Whether the file system should enabled writeback caching. This can improve performance as
/// it allows the FUSE client to cache and coalesce multiple writes before sending them to
/// the file system. However, enabling this option can increase the risk of data corruption
/// if the file contents can change without the knowledge of the FUSE client (i.e., the
/// server does **NOT** have exclusive access). Additionally, the file system should have
/// read access to all files in the directory it is serving as the FUSE client may send
/// read requests even for files opened with `O_WRONLY`.
///
/// Therefore callers should only enable this option when they can guarantee that: 1) the file
/// system has exclusive access to the directory and 2) the file system has read permissions
/// for all files in that directory.
///
/// The default value for this option is `false`.
#[serde(default)]
pub writeback: bool,
/// Controls whether security.* xattrs (except for security.selinux) are re-written. When this
/// is set to true, the server will add a "user.virtiofs" prefix to xattrs in the security
/// namespace. Setting these xattrs requires CAP_SYS_ADMIN in the namespace where the file
/// system was mounted and since the server usually runs in an unprivileged user namespace,
/// it's unlikely to have that capability.
///
/// The default value for this option is `false`.
#[serde(default, alias = "rewrite-security-xattrs")]
pub rewrite_security_xattrs: bool,
/// Use case-insensitive lookups for directory entries (ASCII only).
///
/// The default value for this option is `false`.
#[serde(default)]
pub ascii_casefold: bool,
// UIDs which are privileged to perform quota-related operations. We cannot perform a
// CAP_FOWNER check so we consult this list when the VM tries to set the project quota and
// the process uid doesn't match the owner uid. In that case, all uids in this list are
// treated as if they have CAP_FOWNER.
#[cfg(feature = "arc_quota")]
#[serde(default, deserialize_with = "deserialize_privileged_quota_uids")]
pub privileged_quota_uids: Vec<libc::uid_t>,
/// Use DAX for shared files.
///
/// Enabling DAX can improve performance for frequently accessed files by mapping regions of
/// the file directly into the VM's memory region, allowing direct access with the cost of
/// slightly increased latency the first time the file is accessed. Additionally, since the
/// mapping is shared directly from the host kernel's file cache, enabling DAX can improve
/// performance even when the cache policy is `Never`.
///
/// The default value for this option is `false`.
#[serde(default, alias = "dax")]
pub use_dax: bool,
/// Enable support for POSIX acls.
///
/// Enable POSIX acl support for the shared directory. This requires that the underlying file
/// system also supports POSIX acls.
///
/// The default value for this option is `true`.
#[serde(default = "config_default_posix_acl")]
pub posix_acl: bool,
// Maximum number of dynamic permission paths.
//
// The dynamic permission paths are used to set specific paths certain uid/gid after virtiofs
// device is created. It is for arcvm special usage, normal device should not support
// this feature.
//
// The default value for this option is 0.
#[serde(default)]
pub max_dynamic_perm: usize,
// Maximum number of dynamic xattr paths.
//
// The dynamic xattr paths are used to set specific paths certain xattr after virtiofs
// device is created. It is for arcvm special usage, normal device should not support
// this feature.
//
// The default value for this option is 0.
#[serde(default)]
pub max_dynamic_xattr: usize,
// Controls whether fuse_security_context feature is enabled
//
// The FUSE_SECURITY_CONTEXT feature needs write data into /proc/thread-self/attr/fscreate.
// For the hosts that prohibit the write operation, the option should be set to false to
// disable the FUSE_SECURITY_CONTEXT feature. When FUSE_SECURITY_CONTEXT is disabled, the
// security context won't be passed with fuse request, which makes guest created files/dir
// having unlabeled security context or empty security context.
//
// The default value for this option is true
#[serde(default = "config_default_security_ctx")]
pub security_ctx: bool,
// Specifies run-time UID/GID mapping that works without user namespaces.
//
// The virtio-fs usually does mapping of UIDs/GIDs between host and guest with user namespace.
// In Android, however, user namespace isn't available for non-root users.
// This allows mapping UIDs and GIDs without user namespace by intercepting FUSE
// requests and translating UID/GID in virito-fs's process at runtime.
//
// The format is "guest-uid, guest-gid, host-uid, host-gid, umask, path;{repeat}"
//
// guest-uid: UID to be set for all the files in the path inside guest.
// guest-gid: GID to be set for all the files in the path inside guest.
// host-uid: UID to be set for all the files in the path in the host.
// host-gid: GID to be set for all the files in the path in the host.
// umask: umask to be set at runtime for the files in the path.
// path: This is the absolute path from the root of the shared directory.
//
// This follows similar format to ARCVM IOCTL "FS_IOC_SETPERMISSION"
#[cfg(feature = "fs_runtime_ugid_map")]
#[serde(default, deserialize_with = "deserialize_ugid_map")]
pub ugid_map: Vec<PermissionData>,
}
impl Default for Config {
fn default() -> Self {
Config {
timeout: config_default_timeout(),
negative_timeout: config_default_negative_timeout(),
cache_policy: Default::default(),
writeback: false,
rewrite_security_xattrs: false,
ascii_casefold: false,
#[cfg(feature = "arc_quota")]
privileged_quota_uids: Default::default(),
use_dax: false,
posix_acl: config_default_posix_acl(),
max_dynamic_perm: 0,
max_dynamic_xattr: 0,
security_ctx: config_default_security_ctx(),
#[cfg(feature = "fs_runtime_ugid_map")]
ugid_map: Vec::new(),
}
}
}
#[cfg(all(test, feature = "fs_runtime_ugid_map"))]
mod tests {
use super::*;
#[test]
fn test_deserialize_ugid_map_valid() {
let input_string =
"\"1000 1000 1000 1000 0022 /path/to/dir;2000 2000 2000 2000 0022 /path/to/other/dir\"";
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer).unwrap();
assert_eq!(result.len(), 2);
assert_eq!(
result,
vec![
PermissionData {
guest_uid: 1000,
guest_gid: 1000,
host_uid: 1000,
host_gid: 1000,
umask: 22,
perm_path: "/path/to/dir".to_string(),
},
PermissionData {
guest_uid: 2000,
guest_gid: 2000,
host_uid: 2000,
host_gid: 2000,
umask: 22,
perm_path: "/path/to/other/dir".to_string(),
},
]
);
}
#[test]
fn test_process_ugid_map_valid() {
let input_vec = vec![
vec![
"1000".to_string(),
"1000".to_string(),
"1000".to_string(),
"1000".to_string(),
"0022".to_string(),
"/path/to/dir".to_string(),
],
vec![
"2000".to_string(),
"2000".to_string(),
"2000".to_string(),
"2000".to_string(),
"0022".to_string(),
"/path/to/other/dir".to_string(),
],
];
let result = process_ugid_map(input_vec).unwrap();
assert_eq!(result.len(), 2);
assert_eq!(
result,
vec![
PermissionData {
guest_uid: 1000,
guest_gid: 1000,
host_uid: 1000,
host_gid: 1000,
umask: 22,
perm_path: "/path/to/dir".to_string(),
},
PermissionData {
guest_uid: 2000,
guest_gid: 2000,
host_uid: 2000,
host_gid: 2000,
umask: 22,
perm_path: "/path/to/other/dir".to_string(),
},
]
);
}
#[test]
fn test_deserialize_ugid_map_invalid_format() {
let input_string = "\"1000 1000 1000 0022 /path/to/dir\""; // Missing one element
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
#[test]
fn test_deserialize_ugid_map_invalid_guest_uid() {
let input_string = "\"invalid 1000 1000 1000 0022 /path/to/dir\""; // Invalid guest-UID
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
#[test]
fn test_deserialize_ugid_map_invalid_guest_gid() {
let input_string = "\"1000 invalid 1000 1000 0022 /path/to/dir\""; // Invalid guest-GID
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
#[test]
fn test_deserialize_ugid_map_invalid_umask() {
let input_string = "\"1000 1000 1000 1000 invalid /path/to/dir\""; // Invalid umask
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
#[test]
fn test_deserialize_ugid_map_invalid_host_uid() {
let input_string = "\"1000 1000 invalid 1000 0022 /path/to/dir\""; // Invalid host-UID
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
#[test]
fn test_deserialize_ugid_map_invalid_host_gid() {
let input_string = "\"1000 1000 1000 invalid 0022 /path/to/dir\""; // Invalid host-UID
// Create a Deserializer from the input string
let mut deserializer = serde_json::Deserializer::from_str(input_string);
let result = deserialize_ugid_map(&mut deserializer);
assert!(result.is_err());
}
}