[pve-devel] [PATCH conntrack-tool v2 3/5] add expectation support

Mira Limbeck m.limbeck at proxmox.com
Wed Feb 3 15:25:33 CET 2021


Expectation support requires net.netfilter.nf_conntrack_helper to be set
to 1. In addition the helper modules have to be loaded as well. In the
tests nf_conntrack_ftp was used as helper.

Together with expectation support, string attribute support is also
added. Some functions which are conntrack specific are renamed to
contain 'conntrack' in their names.

Signed-off-by: Mira Limbeck <m.limbeck at proxmox.com>
---
v2:
 - mostly the same changes as for patch 1

 src/main.rs                | 249 +++++++++++++++++++++++++++++++++++--
 src/netfilter_conntrack.rs |  44 +++++++
 2 files changed, 285 insertions(+), 8 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 2137556..79779ff 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -43,20 +43,37 @@ fn main() -> Result<()> {
                 }
             }
         }
+
+        let mut exps = Vec::new();
+        socket
+            .query_expects(&mut exps)
+            .map_err(|err| format_err!("Error querying expects: {}", err))?;
+
+        for exp in exps.iter() {
+            match serde_json::to_string(exp) {
+                Ok(s) => println!("{}", s),
+                Err(err) => {
+                    eprintln!("Failed to serialize expect: {}", err);
+                    break;
+                }
+            }
+        }
     } else if args[1] == "insert" {
         for line in BufReader::new(stdin())
             .lines()
             .map(|line| line.unwrap_or_else(|_| "".to_string()))
         {
-            let ct: Conntrack = match serde_json::from_str(&line) {
-                Ok(ct) => ct,
-                Err(err) => {
-                    eprintln!("Failed to deserialize conntrack: {}", err);
-                    break;
+            if let Ok(ct) = serde_json::from_str::<Conntrack>(&line) {
+                if let Err(err) = socket.insert_conntrack(ct) {
+                    eprintln!("Error inserting conntrack: {}", err);
                 }
-            };
-            if let Err(err) = socket.insert_conntrack(ct) {
-                eprintln!("Error inserting conntrack: {}", err);
+            } else if let Ok(exp) = serde_json::from_str::<Expect>(&line) {
+                if let Err(err) = socket.insert_expect(exp) {
+                    eprintln!("Error inserting expect: {}", err);
+                }
+            } else {
+                eprintln!("Failed to deserialize input: {}", line);
+                break;
             }
         }
     } else {
@@ -92,6 +109,13 @@ const CONNTRACK_INSERT_MSG_TYPE: u16 =
     ((libc::NFNL_SUBSYS_CTNETLINK << 8) | IPCTNL_MSG_CT_NEW) as u16;
 const CONNTRACK_INSERT_FLAGS: u16 =
     (libc::NLM_F_ACK | libc::NLM_F_REQUEST | libc::NLM_F_CREATE) as u16;
+const EXPECT_QUERY_MSG_TYPE: u16 =
+    ((libc::NFNL_SUBSYS_CTNETLINK_EXP << 8) | IPCTNL_MSG_EXP_GET) as u16;
+const EXPECT_QUERY_FLAGS: u16 = (libc::NLM_F_ACK | libc::NLM_F_REQUEST | libc::NLM_F_DUMP) as u16;
+const EXPECT_INSERT_MSG_TYPE: u16 =
+    ((libc::NFNL_SUBSYS_CTNETLINK_EXP << 8) | IPCTNL_MSG_EXP_NEW) as u16;
+const EXPECT_INSERT_FLAGS: u16 =
+    (libc::NLM_F_ACK | libc::NLM_F_REQUEST | libc::NLM_F_CREATE) as u16;
 
 pub struct Socket {
     socket: NonNull<mnl_socket>,
@@ -176,6 +200,88 @@ impl Socket {
         Ok(())
     }
 
+    fn query_expects(&mut self, exps: &mut Vec<Expect>) -> Result<()> {
+        let seq = self.seq();
+        self.query_expects_impl(exps, seq, libc::AF_INET as _)?;
+        let seq = self.seq();
+        self.query_expects_impl(exps, seq, libc::AF_INET6 as _)?;
+        Ok(())
+    }
+
+    fn query_expects_impl(&mut self, exps: &mut Vec<Expect>, seq: u32, proto: u8) -> Result<()> {
+        let mut buf = [0u8; MNL_SOCKET_DUMP_SIZE as _];
+        let hdr = build_msg_header(
+            buf.as_mut_ptr() as _,
+            EXPECT_QUERY_MSG_TYPE,
+            EXPECT_QUERY_FLAGS,
+            seq,
+            proto,
+        );
+        self.send_and_receive(hdr, 0, Some(query_exp_cb), exps as *mut Vec<Expect> as _)
+    }
+
+    fn insert_expect(&mut self, exp: Expect) -> Result<()> {
+        let proto = if exp.is_ipv6() {
+            libc::AF_INET6 as u8
+        } else {
+            libc::AF_INET as u8
+        };
+
+        let mut buf = [0u8; MNL_SOCKET_BUFFER_SIZE as _];
+        let hdr = build_msg_header(
+            buf.as_mut_ptr() as _,
+            EXPECT_INSERT_MSG_TYPE,
+            EXPECT_INSERT_FLAGS,
+            self.seq(),
+            proto,
+        );
+
+        let exph = unsafe { nfexp_new() };
+        if exph.is_null() {
+            bail!("Failed to create new expect object");
+        }
+
+        let mut strings = Vec::new();
+        let mut cts = Vec::new();
+        for attr in exp.attributes {
+            match attr.value {
+                ExpectAttrValue::CT(ct) => unsafe {
+                    let (ct, mut s) = build_conntrack(ct)?;
+                    nfexp_set_attr(exph, attr.key, ct as _);
+                    strings.append(&mut s);
+                    cts.push(ct);
+                },
+                ExpectAttrValue::U8(v) => unsafe {
+                    nfexp_set_attr_u8(exph, attr.key, v);
+                },
+                ExpectAttrValue::U16(v) => unsafe {
+                    nfexp_set_attr_u16(exph, attr.key, v);
+                },
+                ExpectAttrValue::U32(v) => unsafe {
+                    nfexp_set_attr_u32(exph, attr.key, v);
+                },
+                ExpectAttrValue::String(v) => unsafe {
+                    nfexp_set_attr(exph, attr.key, v.as_ptr() as _);
+                    strings.push(v);
+                },
+            }
+        }
+
+        unsafe {
+            nfexp_nlmsg_build(hdr, exph);
+            nfexp_destroy(exph);
+        }
+        for ct in cts {
+            unsafe {
+                nfct_destroy(ct);
+            }
+        }
+
+        self.send_and_receive(hdr, 0, None, std::ptr::null_mut())?;
+
+        Ok(())
+    }
+
     fn send_and_receive(
         &mut self,
         msg: *const libc::nlmsghdr,
@@ -409,6 +515,7 @@ fn build_conntrack(ct: Conntrack) -> Result<(*mut nf_conntrack, Vec<CString>)> {
     }
     Ok((cth, strings))
 }
+
 const ALL_ATTRIBUTES: &[(CTAttr, AttrType)] = &[
     (CTAttr::ORIG_IPV4_SRC, AttrType::U32),        /* u32 bits */
     (CTAttr::ORIG_IPV4_DST, AttrType::U32),        /* u32 bits */
@@ -486,3 +593,129 @@ const ALL_ATTRIBUTES: &[(CTAttr, AttrType)] = &[
     (CTAttr::SYNPROXY_ITS, AttrType::U32),         /* u32 bits */
     (CTAttr::SYNPROXY_TSOFF, AttrType::U32),       /* u32 bits */
 ];
+
+extern "C" fn query_exp_cb(nlh: *const libc::nlmsghdr, data_ptr: *mut libc::c_void) -> libc::c_int {
+    let exp = unsafe { nfexp_new() };
+    unsafe {
+        nfexp_nlmsg_parse(nlh, exp);
+    }
+
+    let mut attributes = Vec::new();
+    for (attr, ty) in EXPECT_ALL_ATTRIBUTES {
+        if unsafe { nfexp_attr_is_set(exp, *attr) } == 0 {
+            continue;
+        }
+        match ty {
+            ExpectAttrType::CT => {
+                let ct = unsafe { nfexp_get_attr(exp, *attr) };
+                if let Some(ct) = parse_conntrack(ct as _) {
+                    attributes.push(ExpectAttr {
+                        key: *attr,
+                        value: ExpectAttrValue::CT(ct),
+                    });
+                }
+            }
+            ExpectAttrType::U8 => {
+                let val = unsafe { nfexp_get_attr_u8(exp, *attr) };
+                attributes.push(ExpectAttr {
+                    key: *attr,
+                    value: ExpectAttrValue::U8(val),
+                });
+            }
+            ExpectAttrType::U16 => {
+                let val = unsafe { nfexp_get_attr_u16(exp, *attr) };
+                attributes.push(ExpectAttr {
+                    key: *attr,
+                    value: ExpectAttrValue::U16(val),
+                });
+            }
+            ExpectAttrType::U32 => {
+                let val = unsafe { nfexp_get_attr_u32(exp, *attr) };
+                attributes.push(ExpectAttr {
+                    key: *attr,
+                    value: ExpectAttrValue::U32(val),
+                });
+            }
+            ExpectAttrType::String(Some(len)) => {
+                let ptr = unsafe { nfexp_get_attr(exp, *attr) };
+                let cstr = unsafe { std::ffi::CStr::from_ptr(ptr as _) };
+                let s = cstr.to_bytes();
+                let s =
+                    unsafe { CString::from_vec_unchecked(s[0..s.len().min((*len) as _)].to_vec()) };
+                attributes.push(ExpectAttr {
+                    key: *attr,
+                    value: ExpectAttrValue::String(s),
+                });
+            }
+            ExpectAttrType::String(None) => {
+                let ptr = unsafe { nfexp_get_attr(exp, *attr) };
+                let cstr = unsafe { std::ffi::CStr::from_ptr(ptr as _) };
+                let s = cstr.to_bytes();
+                let s = unsafe { CString::from_vec_unchecked(s.to_vec()) };
+                attributes.push(ExpectAttr {
+                    key: *attr,
+                    value: ExpectAttrValue::String(s),
+                });
+            }
+        }
+    }
+
+    let exps: &mut Vec<Expect> = unsafe { &mut *(data_ptr as *mut Vec<Expect>) };
+    exps.push(Expect { attributes });
+
+    MNL_CB_OK
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct Expect {
+    attributes: Vec<ExpectAttr>,
+}
+
+impl Expect {
+    fn is_ipv6(&self) -> bool {
+        for attr in &self.attributes {
+            if let ExpectAttrValue::CT(ct) = &attr.value {
+                return ct.is_ipv6();
+            }
+        }
+        false
+    }
+}
+
+enum ExpectAttrType {
+    CT,
+    U8,
+    U16,
+    U32,
+    String(Option<u32>),
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+enum ExpectAttrValue {
+    CT(Conntrack),
+    U8(u8),
+    U16(u16),
+    U32(u32),
+    String(CString),
+}
+
+#[derive(Debug, Serialize, Deserialize)]
+struct ExpectAttr {
+    #[serde(rename = "type")]
+    key: ExpAttr,
+    value: ExpectAttrValue,
+}
+
+const EXPECT_ALL_ATTRIBUTES: &[(ExpAttr, ExpectAttrType)] = &[
+    (ExpAttr::MASTER, ExpectAttrType::CT),   // conntrack
+    (ExpAttr::EXPECTED, ExpectAttrType::CT), // conntrack
+    (ExpAttr::MASK, ExpectAttrType::CT),     // conntrack
+    (ExpAttr::TIMEOUT, ExpectAttrType::U32), // u32 bits
+    (ExpAttr::ZONE, ExpectAttrType::U16),    // u16 bits
+    (ExpAttr::FLAGS, ExpectAttrType::U32),   // u32 bits
+    (ExpAttr::HELPER_NAME, ExpectAttrType::String(Some(16))), // string 16 bytes max
+    (ExpAttr::CLASS, ExpectAttrType::U32),   // u32 bits
+    (ExpAttr::NAT_TUPLE, ExpectAttrType::CT), // conntrack
+    (ExpAttr::NAT_DIR, ExpectAttrType::U8),  // u8 bits
+    (ExpAttr::FN, ExpectAttrType::String(None)), // string
+];
diff --git a/src/netfilter_conntrack.rs b/src/netfilter_conntrack.rs
index a9e67e4..8a56ad8 100644
--- a/src/netfilter_conntrack.rs
+++ b/src/netfilter_conntrack.rs
@@ -39,6 +39,25 @@ extern "C" {
     pub fn nfct_get_attr_u64(ct: *const nf_conntrack, type_: CTAttr) -> u64;
 
     pub fn nfct_attr_is_set(ct: *const nf_conntrack, type_: CTAttr) -> libc::c_int;
+
+    // expectation API
+    pub fn nfexp_new() -> *mut nf_expect;
+    pub fn nfexp_destroy(exp: *mut nf_expect);
+
+    pub fn nfexp_set_attr(exp: *mut nf_expect, type_: ExpAttr, value: *const libc::c_void);
+    pub fn nfexp_set_attr_u8(exp: *mut nf_expect, type_: ExpAttr, value: u8);
+    pub fn nfexp_set_attr_u16(exp: *mut nf_expect, type_: ExpAttr, value: u16);
+    pub fn nfexp_set_attr_u32(exp: *mut nf_expect, type_: ExpAttr, value: u32);
+
+    pub fn nfexp_get_attr(exp: *const nf_expect, type_: ExpAttr) -> *const libc::c_void;
+    pub fn nfexp_get_attr_u8(exp: *const nf_expect, type_: ExpAttr) -> u8;
+    pub fn nfexp_get_attr_u16(exp: *const nf_expect, type_: ExpAttr) -> u16;
+    pub fn nfexp_get_attr_u32(exp: *const nf_expect, type_: ExpAttr) -> u32;
+
+    pub fn nfexp_attr_is_set(exp: *const nf_expect, type_: ExpAttr) -> libc::c_int;
+
+    pub fn nfexp_nlmsg_parse(nlh: *const libc::nlmsghdr, exp: *mut nf_expect) -> libc::c_int;
+    pub fn nfexp_nlmsg_build(nlh: *mut libc::nlmsghdr, exp: *const nf_expect) -> libc::c_int;
 }
 
 // set option
@@ -166,3 +185,28 @@ pub enum CTAttr {
     SYNPROXY_TSOFF = 74,		/* u32 bits */
     MAX = 75,
 }
+
+#[repr(C)]
+pub struct nf_expect {
+    _private: [u8; 0],
+}
+
+#[repr(u32)]
+#[non_exhaustive]
+#[derive(Debug, Copy, Clone, PartialEq)]
+#[derive(serde::Deserialize, serde::Serialize)]
+#[allow(non_camel_case_types)]
+pub enum ExpAttr {
+    MASTER = 0,         /* pointer to conntrack object */
+    EXPECTED = 1,	/* pointer to conntrack object */
+    MASK = 2,		/* pointer to conntrack object */
+    TIMEOUT = 3,	/* u32 bits */
+    ZONE = 4,		/* u16 bits */
+    FLAGS = 5,		/* u32 bits */
+    HELPER_NAME = 6,	/* string (16 bytes max) */
+    CLASS = 7,		/* u32 bits */
+    NAT_TUPLE = 8,	/* pointer to conntrack object */
+    NAT_DIR = 9,	/* u8 bits */
+    FN = 10,		/* string */
+    MAX = 11,
+}
-- 
2.20.1





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