Add syscall setdomainname

book/src/kernel/linux-compatibility/README.md

@@ -191,7 +191,7 @@ provided by Linux on x86-64 architecture.
 | 168     | swapoff                | ❌             |     |
 | 169     | reboot                 | ❌             |     |
 | 170     | sethostname            | ✅             |     |
-| 171     | setdomainname          | ❌             |     |
+| 171     | setdomainname          | ✅             |     |
 | 172     | iopl                   | ❌             |     |
 | 173     | ioperm                 | ❌             |     |
 | 174     | create_module          | ❌             |     |

kernel/src/net/uts_ns.rs

@@ -80,6 +80,22 @@ impl UtsNamespace {
         self.uts_name.write().nodename = new_host_name;
         Ok(())
     }
+
+    /// Sets a new domain name for the UTS namespace.
+    ///
+    /// This method will fail with `EPERM` if the caller does not have the SYS_ADMIN capability
+    /// in the owner user namespace.
+    pub fn set_domainname(&self, addr: Vaddr, len: usize, ctx: &Context) -> Result<()> {
+        self.owner.check_cap(CapSet::SYS_ADMIN, ctx.posix_thread)?;
+
+        let new_domain_name = copy_uts_field_from_user(addr, len as _, ctx)?;
+        debug!(
+            "set domain name: {:?}",
+            CStr::from_bytes_until_nul(new_domain_name.as_bytes()).unwrap()
+        );
+        self.uts_name.write().domainname = new_domain_name;
+        Ok(())
+    }
 }
 
 const UTS_FIELD_LEN: usize = 65;

kernel/src/syscall/arch/loongarch.rs

@@ -113,6 +113,7 @@ use super::{
     set_priority::sys_set_priority,
     set_robust_list::sys_set_robust_list,
     set_tid_address::sys_set_tid_address,
+    setdomainname::sys_setdomainname,
     setfsgid::sys_setfsgid,
     setfsuid::sys_setfsuid,
     setgid::sys_setgid,
@@ -285,6 +286,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_SETGROUPS = 159              => sys_setgroups(args[..2]);
     SYS_NEWUNAME = 160               => sys_uname(args[..1]);
     SYS_SETHOSTNAME = 161            => sys_sethostname(args[..2]);
+    SYS_SETDOMAINNAME = 162          => sys_setdomainname(args[..2]);
     SYS_GETRUSAGE = 165              => sys_getrusage(args[..2]);
     SYS_UMASK = 166                  => sys_umask(args[..1]);
     SYS_PRCTL = 167                  => sys_prctl(args[..5]);

kernel/src/syscall/arch/riscv.rs

@@ -113,6 +113,7 @@ use super::{
     set_priority::sys_set_priority,
     set_robust_list::sys_set_robust_list,
     set_tid_address::sys_set_tid_address,
+    setdomainname::sys_setdomainname,
     setfsgid::sys_setfsgid,
     setfsuid::sys_setfsuid,
     setgid::sys_setgid,
@@ -285,6 +286,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_SETGROUPS = 159              => sys_setgroups(args[..2]);
     SYS_NEWUNAME = 160               => sys_uname(args[..1]);
     SYS_SETHOSTNAME = 161            => sys_sethostname(args[..2]);
+    SYS_SETDOMAINNAME = 162          => sys_setdomainname(args[..2]);
     SYS_GETRLIMIT = 163              => sys_getrlimit(args[..2]);
     SYS_SETRLIMIT = 164              => sys_setrlimit(args[..2]);
     SYS_GETRUSAGE = 165              => sys_getrusage(args[..2]);

kernel/src/syscall/arch/x86.rs

@@ -124,6 +124,7 @@ use super::{
     set_priority::sys_set_priority,
     set_robust_list::sys_set_robust_list,
     set_tid_address::sys_set_tid_address,
+    setdomainname::sys_setdomainname,
     setfsgid::sys_setfsgid,
     setfsuid::sys_setfsuid,
     setgid::sys_setgid,
@@ -309,6 +310,7 @@ impl_syscall_nums_and_dispatch_fn! {
     SYS_MOUNT = 165            => sys_mount(args[..5]);
     SYS_UMOUNT2 = 166          => sys_umount(args[..2]);
     SYS_SETHOSTNAME = 170      => sys_sethostname(args[..2]);
+    SYS_SETDOMAINNAME = 171    => sys_setdomainname(args[..2]);
     SYS_GETTID = 186           => sys_gettid(args[..0]);
     SYS_SETXATTR = 188         => sys_setxattr(args[..5]);
     SYS_LSETXATTR = 189        => sys_lsetxattr(args[..5]);

kernel/src/syscall/mod.rs

@@ -140,6 +140,7 @@ mod set_ioprio;
 mod set_priority;
 mod set_robust_list;
 mod set_tid_address;
+mod setdomainname;
 mod setfsgid;
 mod setfsuid;
 mod setgid;

kernel/src/syscall/setdomainname.rs

@@ -0,0 +1,10 @@
+// SPDX-License-Identifier: MPL-2.0
+
+use crate::{prelude::*, syscall::SyscallReturn};
+
+pub fn sys_setdomainname(addr: Vaddr, len: usize, ctx: &Context) -> Result<SyscallReturn> {
+    let ns_proxy_ref = ctx.thread_local.borrow_ns_proxy();
+    let ns_proxy = ns_proxy_ref.unwrap();
+    ns_proxy.uts_ns().set_domainname(addr, len, ctx)?;
+    Ok(SyscallReturn::Return(0))
+}

test/src/syscall/ltp/testcases/all.txt

@@ -1340,8 +1340,9 @@ set_robust_list01
 # set_thread_area01
 # set_tid_address01
 
-# setdomainname01
-# setdomainname02
+setdomainname01
+setdomainname02
+# TODO: Drop capabilities on UID changes, so that setdomainname() will fail with EPERM.
 # setdomainname03
 
 # setfsgid01