add position header if -pie

Author: bradjc

src/convert.rs

@@ -443,6 +443,23 @@ pub fn elf_to_tbf(
         }
     }
 
+    // Check if the _pie symbol is defined meaning this app uses -pie for
+    // position independence.
+    let position_configuration = if let Ok(Some((symtab, sym_strtab))) = elf_file.symbol_table() {
+        if let Some(_) = symtab.iter().find(|sym| {
+            let name = sym_strtab
+                .get(sym.st_name as usize)
+                .expect("Failed to parse symbol name");
+            name == "_pie"
+        }) {
+            Some(header::PositionConfiguration::Pie)
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
     // Now we can create the first pass TBF header. This is mostly to get the
     // size of the header since we have to fill in some of the offsets later.
     let mut tbfheader = header::TbfHeader::new();
@@ -463,6 +480,7 @@ pub fn elf_to_tbf(
         storage_ids,
         kernel_version,
         short_id,
+        position_configuration,
         disabled,
     );
 

src/header.rs

@@ -20,6 +20,7 @@ pub enum TbfHeaderTypes {
     KernelVersion = 8,
     Program = 9,
     ShortId = 10,
+    Position = 11,
 
     Credentials = 128,
 }
@@ -132,6 +133,18 @@ struct TbfHeaderShortId {
     short_id: u32,
 }
 
+pub enum PositionConfiguration {
+    RopiRwpi = 0,
+    Pie = 1,
+}
+
+#[repr(C)]
+#[derive(Clone, Copy, Debug)]
+struct TbfHeaderPosition {
+    base: TbfHeaderTlv,
+    configuration: u32,
+}
+
 #[repr(C)]
 #[derive(Debug)]
 pub struct TbfFooterCredentials {
@@ -285,7 +298,6 @@ impl fmt::Display for TbfHeaderKernelVersion {
 
 impl fmt::Display for TbfHeaderShortId {
     fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
-        // ^x.y means >= x.y, < (x+1).0
         writeln!(
             f,
             "
@@ -295,6 +307,17 @@ impl fmt::Display for TbfHeaderShortId {
     }
 }
 
+impl fmt::Display for TbfHeaderPosition {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        writeln!(
+            f,
+            "
+               Position Independent: {}",
+            self.configuration
+        )
+    }
+}
+
 const FLAGS_ENABLE: u32 = 0x0000_0001;
 
 pub struct TbfHeader {
@@ -308,6 +331,7 @@ pub struct TbfHeader {
     hdr_persistent: Option<TbfHeaderPersistentAcl>,
     hdr_kernel_version: Option<TbfHeaderKernelVersion>,
     hdr_short_id: Option<TbfHeaderShortId>,
+    hdr_position: Option<TbfHeaderPosition>,
     package_name: String,
     package_name_pad: usize,
 }
@@ -340,6 +364,7 @@ impl TbfHeader {
             hdr_persistent: None,
             hdr_kernel_version: None,
             hdr_short_id: None,
+            hdr_position: None,
             package_name: String::new(),
             package_name_pad: 0,
         }
@@ -363,6 +388,7 @@ impl TbfHeader {
         storage_ids: (Option<u32>, Option<Vec<u32>>, Option<Vec<u32>>),
         kernel_version: Option<(u16, u16)>,
         short_id: Option<u32>,
+        position_configuration: Option<PositionConfiguration>,
         disabled: bool,
     ) -> usize {
         // Need to calculate lengths ahead of time. Need the base and the
@@ -573,6 +599,17 @@ impl TbfHeader {
             });
         }
 
+        // If the position configuration is set, include that header.
+        if let Some(position_configuration) = position_configuration {
+            self.hdr_position = Some(TbfHeaderPosition {
+                base: TbfHeaderTlv {
+                    tipe: TbfHeaderTypes::Position,
+                    length: 4,
+                },
+                configuration: position_configuration as u32,
+            })
+        }
+
         // Return the length by generating the header and seeing how long it is.
         self.generate()
             .expect("No header was generated")