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sys_util: Add wrappers for fchmod and fchown.

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This wrappers allow for permissions and ownership changes that are less
sensitive to time-of-check-time-of-use vulnerabilities.

BUG=None
TEST=CQ passes

Change-Id: I6d5e4809a0b0113f3a95b0395d3cfb82431a3fd8
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/3049330
Auto-Submit: Allen Webb <allenwebb@google.com>
Tested-by: kokoro <noreply+kokoro@google.com>
Commit-Queue: Allen Webb <allenwebb@google.com>
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
This commit is contained in:
Allen Webb 2021-07-23 09:48:00 -05:00 committed by Commit Bot
parent 8bf5dcade3
commit 87b96033b7
1 changed files with 15 additions and 0 deletions
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15
sys_util/src/lib.rs
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@ -112,6 +112,7 @@ use libc::{
pub type Pid = libc::pid_t; pub type Pid = libc::pid_t;
pub type Uid = libc::uid_t; pub type Uid = libc::uid_t;
pub type Gid = libc::gid_t; pub type Gid = libc::gid_t;
pub type Mode = libc::mode_t;
/// Used to mark types as !Sync. /// Used to mark types as !Sync.
pub type UnsyncMarker = std::marker::PhantomData<Cell<usize>>; pub type UnsyncMarker = std::marker::PhantomData<Cell<usize>>;
@ -195,6 +196,20 @@ pub fn chown(path: &CStr, uid: Uid, gid: Gid) -> Result<()> {
syscall!(unsafe { libc::chown(path.as_ptr(), uid, gid) }).map(|_| ()) syscall!(unsafe { libc::chown(path.as_ptr(), uid, gid) }).map(|_| ())
} }
/// Safe wrapper for fchmod(2).
#[inline(always)]
pub fn fchmod<A: AsRawFd>(fd: &A, mode: Mode) -> Result<()> {
// Safe since the function does not operate on pointers and check the return value.
syscall!(unsafe { libc::fchmod(fd.as_raw_fd(), mode) }).map(|_| ())
}
/// Safe wrapper for fchown(2).
#[inline(always)]
pub fn fchown<A: AsRawFd>(fd: &A, uid: Uid, gid: Gid) -> Result<()> {
// Safe since the function does not operate on pointers and check the return value.
syscall!(unsafe { libc::fchown(fd.as_raw_fd(), uid, gid) }).map(|_| ())
}
/// The operation to perform with `flock`. /// The operation to perform with `flock`.
pub enum FlockOperation { pub enum FlockOperation {
LockShared, LockShared,