Merge pull request #62 from ntegan/54-xsdt-v2

dlrobertson · web-flow · commit 95da2c95f1b1 · 2020-06-12T12:32:22.000-04:00
acpi: add support for the xsdt
diff --git a/mythril_core/src/acpi/rsdp.rs b/mythril_core/src/acpi/rsdp.rs
@@ -30,8 +30,6 @@ mod offsets {
     pub const REVISION: usize = 15;
     /// 32-bit physical address of the RSDT.
     pub const RSDT_ADDR: Range<usize> = 16..20;
-    /// Length of the XSDT table in bytes (ACPI 2.0 only).
-    pub const LENGTH: Range<usize> = 20..24;
     /// 64-bit physical address of the XSDT (ACPI 2.0 only).
     pub const XSDT_ADDR: Range<usize> = 24..32;
     /// Checksum of entire structure (ACPI 2.0 only).
@@ -60,12 +58,10 @@ pub enum RSDP {
     V2 {
         /// OEM Supplied string.
         oemid: [u8; 6],
-        /// 32-bit physical address of the RSDT.
-        rsdt_addr: u32,
-        /// Length of the XSDT table in bytes.
-        length: u32,
         /// 64-bit physical address of the XSDT.
         xsdt_addr: u64,
+        //  TODO(ntegan) multiboot2 doesn't give us a length for rsdpv2tag,
+        //      so we can't calculate the rsdp checksum
     },
 }
 
@@ -75,15 +71,9 @@ impl fmt::Debug for RSDP {
             &RSDP::V1 { rsdt_addr, .. } => {
                 write!(f, "RSDP: revision=1.0 rsdt=0x{:x}", rsdt_addr)
             }
-            &RSDP::V2 {
-                rsdt_addr,
-                xsdt_addr,
-                ..
-            } => write!(
-                f,
-                "RSDP: revision=2.0 rsdt=0x{:x} xsdt_addr=0x{:x}",
-                rsdt_addr, xsdt_addr
-            ),
+            &RSDP::V2 { xsdt_addr, .. } => {
+                write!(f, "RSDP: revision=2.0 xsdt_addr=0x{:x}", xsdt_addr)
+            }
         }
     }
 }
@@ -125,8 +115,6 @@ impl RSDP {
             // This is ACPI 2.0. Extract the addrss and length of the XSDT.
             2 => RSDP::V2 {
                 oemid,
-                rsdt_addr,
-                length: NativeEndian::read_u32(&bytes[offsets::LENGTH]),
                 xsdt_addr: NativeEndian::read_u64(&bytes[offsets::XSDT_ADDR]),
             },
             _ => {
@@ -202,8 +190,8 @@ impl RSDP {
     /// Return the RSDT pointed to by this structure.
     pub fn rsdt(&self) -> Result<RSDT> {
         match self {
-            &RSDP::V1 { rsdt_addr, .. } => RSDT::new(rsdt_addr),
-            &RSDP::V2 { .. } => Err(Error::NotSupported),
+            &RSDP::V1 { rsdt_addr, .. } => RSDT::new_rsdt(rsdt_addr as usize),
+            &RSDP::V2 { xsdt_addr, .. } => RSDT::new_xsdt(xsdt_addr as usize),
         }
     }
 }
diff --git a/mythril_core/src/acpi/rsdt.rs b/mythril_core/src/acpi/rsdt.rs
@@ -101,27 +101,45 @@ impl<'a> SDT<'a> {
     }
 }
 
-/// The Root System Descriptor Table.
-pub struct RSDT<'a>(SDT<'a>);
+/// The Root System Description Table.
+/// Two variants to support 32 bit RSDT and 64 bit XSDT.
+pub enum RSDT<'a> {
+    /// Root System Description Table.
+    RSDT(SDT<'a>),
+    /// Extended System Description Table.
+    XSDT(SDT<'a>),
+}
 
 impl<'a> RSDT<'a> {
-    /// Create a new SDT.
-    pub fn new(rsdt_addr: u32) -> Result<RSDT<'a>> {
+    /// Create a new RSDT.
+    pub fn new_rsdt(rsdt_addr: usize) -> Result<RSDT<'a>> {
         let sdt = unsafe { SDT::new(rsdt_addr as *const u8)? };
-        Ok(RSDT(sdt))
+        Ok(RSDT::RSDT(sdt))
+    }
+
+    /// Create a new XSDT.
+    pub fn new_xsdt(xsdt_addr: usize) -> Result<RSDT<'a>> {
+        let sdt = unsafe { SDT::new(xsdt_addr as *const u8)? };
+        Ok(RSDT::XSDT(sdt))
     }
 
     /// Return the number of entries in the table.
     ///
     /// Note: This is not the same as the length value of the header.
     /// the the length value _includes_ the header.
     pub fn num_entries(&self) -> usize {
-        self.0.len() / 4
+        match self {
+            RSDT::XSDT(sdt) => sdt.len() / 8,
+            RSDT::RSDT(sdt) => sdt.len() / 4,
+        }
     }
 
     /// Return an iterator for the SDT entries.
     pub fn entries(&self) -> RSDTIterator<'a> {
-        RSDTIterator::new(self.0.table)
+        match self {
+            RSDT::RSDT(sdt) => RSDTIterator::new_rsdt(sdt.table),
+            RSDT::XSDT(sdt) => RSDTIterator::new_xsdt(sdt.table),
+        }
     }
 
     /// Returns the first matching SDT for a given signature.
@@ -137,41 +155,77 @@ impl<'a> RSDT<'a> {
 
 impl<'a> fmt::Debug for RSDT<'a> {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        write!(f, "{:?}", self.0)
+        let my_sdt = match self {
+            RSDT::RSDT(the_sdt) => the_sdt,
+            RSDT::XSDT(the_sdt) => the_sdt,
+        };
+        write!(f, "{:?}", my_sdt)
     }
 }
 
-/// Iterator for the SDT entries found in the RSDT.
-pub struct RSDTIterator<'a> {
-    table: &'a [u8],
-    offset: usize,
+/// Iterator for the SDT entries found in the RSDT/XSDT.
+pub enum RSDTIterator<'a> {
+    /// Iterates through 32 bit RSDT.
+    RSDTIterator {
+        /// Table of 32 bit SDT pointers.
+        table: &'a [u8],
+        /// Current offset to keep track of iteration.
+        offset: usize,
+    },
+    /// Iterates through 64 bit XSDT.
+    XSDTIterator {
+        /// Table of 64 bit SDT pointers.
+        table: &'a [u8],
+        /// Current offset to keep track of iteration.
+        offset: usize,
+    },
 }
 
 impl<'a> RSDTIterator<'a> {
     /// Create an iterator for the SDT entries in an RSDT.
-    pub fn new<'b: 'a>(table: &'b [u8]) -> RSDTIterator<'a> {
-        RSDTIterator { table, offset: 0 }
+    pub fn new_rsdt<'b: 'a>(table: &'b [u8]) -> RSDTIterator<'a> {
+        RSDTIterator::RSDTIterator { table, offset: 0 }
+    }
+
+    /// Create an iterator for the SDT entries in an XSDT.
+    pub fn new_xsdt<'b: 'a>(table: &'b [u8]) -> RSDTIterator<'a> {
+        RSDTIterator::XSDTIterator { table, offset: 0 }
     }
 }
 
 impl<'a> Iterator for RSDTIterator<'a> {
     type Item = Result<SDT<'a>>;
 
     fn next(&mut self) -> Option<Self::Item> {
-        let next = self.offset + 4;
-        if next <= self.table.len() {
-            let item = unsafe {
-                // TODO(dlrobertson): We currently only support the 32-bit RSDT.
-                // When we support the 64-bit XSDT, the table may point to an
-                // array of 64-bit pointers.
-                let ptr =
-                    NativeEndian::read_u32(&self.table[self.offset..next]);
-                self.offset = next;
-                SDT::new(ptr as *const u8)
-            };
-            Some(item)
-        } else {
-            None
+        match self {
+            RSDTIterator::RSDTIterator { table, offset } => {
+                let next = *offset + 4usize;
+                if next <= table.len() {
+                    let item = unsafe {
+                        let ptr = NativeEndian::read_u32(&table[*offset..next])
+                            as usize;
+                        *offset = next;
+                        SDT::new(ptr as *const u8)
+                    };
+                    Some(item)
+                } else {
+                    None
+                }
+            }
+            RSDTIterator::XSDTIterator { table, offset } => {
+                let next = *offset + 8usize;
+                if next <= table.len() {
+                    let item = unsafe {
+                        let ptr = NativeEndian::read_u64(&table[*offset..next])
+                            as usize;
+                        *offset = next;
+                        SDT::new(ptr as *const u8)
+                    };
+                    Some(item)
+                } else {
+                    None
+                }
+            }
         }
     }
 }
diff --git a/mythril_multiboot2/src/services.rs b/mythril_multiboot2/src/services.rs
@@ -35,19 +35,30 @@ impl VmServices for Multiboot2Services {
     }
 
     fn rsdp(&self) -> Result<acpi::rsdp::RSDP> {
-        // Get a v1 tag if possible
-        self.info
-            .rsdp_v1_tag()
-            .map(|tag| {
-                // use empty string if no OEM id provided
-                let id = tag.oem_id().unwrap_or("      ").as_bytes();
+        let mut arr: [u8; 6] = [0; 6];
+        self.info.rsdp_v2_tag().map_or_else(
+            || {
+                self.info.rsdp_v1_tag().map_or_else(
+                    || Err(Error::NotFound),
+                    move |tag_v1| {
+                        let id = tag_v1.oem_id().unwrap_or("      ").as_bytes();
+                        arr.copy_from_slice(&id[0..6]);
+                        Ok(acpi::rsdp::RSDP::V1 {
+                            oemid: arr,
+                            rsdt_addr: tag_v1.rsdt_address() as u32,
+                        })
+                    },
+                )
+            },
+            move |tag_v2| {
+                let id = tag_v2.oem_id().unwrap_or("      ").as_bytes();
                 let mut arr: [u8; 6] = [0; 6];
                 arr.copy_from_slice(&id[0..6]);
-                acpi::rsdp::RSDP::V1 {
+                Ok(acpi::rsdp::RSDP::V2 {
                     oemid: arr,
-                    rsdt_addr: tag.rsdt_address() as u32,
-                }
-            })
-            .ok_or(Error::NotFound)
+                    xsdt_addr: tag_v2.xsdt_address() as u64,
+                })
+            },
+        )
     }
 }
diff --git a/scripts/grub.cfg b/scripts/grub.cfg
@@ -3,9 +3,10 @@ set timeout=0
 
 menuentry 'Mythril' {
    echo	'Loading Mythril'
+   acpi -2
    multiboot2 /boot/mythril.bin
    module2 /boot/seabios.bin seabios.bin
    module2 /boot/linuxboot_dma.bin linuxboot_dma.bin
    module2 /boot/vmlinuz kernel
    module2 /boot/initramfs initramfs
-}
+}
