refactor boot selection algorithm

citadel-mount/src/boot_select.rs

@@ -1,140 +0,0 @@
-
-use libcitadel::{Partition,Result,ImageHeader};
-
-pub struct BootSelection {
-    partitions: Vec<Partition>,
-}
-
-impl BootSelection {
-    pub fn choose_install_partition() -> Result<Partition> {
-        let bs = BootSelection::load_partitions()?;
-        match bs._choose_install_partition() {
-            Some(p) => Ok(p.clone()),
-            None => bail!("no partition found for installation"),
-        }
-    }
-
-    pub fn choose_boot_partition() -> Result<Partition> {
-        let bs = BootSelection::load_partitions()?;
-        match bs._choose_boot_partition() {
-            Some(p) => Ok(p.clone()),
-            None => bail!("no partition found to boot from"),
-        }
-    }
-
-    fn load_partitions() -> Result<BootSelection> {
-        let partitions = Partition::rootfs_partitions()
-            .map_err(|e| format_err!("Could not load rootfs partition info: {}", e))?;
-
-        Ok(BootSelection {
-            partitions
-        })
-    }
-
-    fn _choose_install_partition(&self) -> Option<&Partition> {
-        self.choose(|p| {
-            // first pass, if there is a partition which is not mounted and 
-            // not initialized use that one
-            !p.is_mounted() && !p.is_initialized()
-        }).or_else(|| self.choose(|p| {
-            // second pass, just find one that's not mounted
-            !p.is_mounted()
-        }))
-    }
-
-    fn choose<F>(&self, pred: F) -> Option<&Partition> 
-        where F: Sized + Fn(&&Partition) -> bool
-    {
-        self.partitions.iter().find(pred)
-    }
-
-    /// Find the best rootfs partition to boot from
-    fn _choose_boot_partition(&self) -> Option<&Partition> {
-        let mut best: Option<&Partition> = None;
-
-        for p in &self.partitions {
-            if is_better(&best, p) {
-                best = Some(p);
-            }
-        }
-        best
-    }
-
-
-    /// Perform checks for error states at boot time.
-    pub fn scan_boot_partitions(&mut self) -> Result<()> {
-        for mut p in &mut self.partitions {
-            if let Err(e) = boot_scan_partition(&mut p) {
-                warn!("error in bootscan of partition {}: {}", p.path().display(), e);
-            }
-        }
-        Ok(())
-    }
-}
-
-/// Called at boot to perform various checks and possibly
-/// update the status field to an error state.
-///
-/// Mark `STATUS_TRY_BOOT` partition as `STATUS_FAILED`.
-///
-/// If metainfo cannot be parsed, mark as `STATUS_BAD_META`.
-///
-/// Verify metainfo signature and mark `STATUS_BAD_SIG` if
-/// signature verification fails.
-///
-fn boot_scan_partition(p: &mut Partition) -> Result<()> {
-    if !p.is_initialized() {
-        return Ok(())
-    }
-    if p.header().status() == ImageHeader::STATUS_TRY_BOOT {
-        warn!("Partition {} has STATUS_TRY_BOOT, assuming it failed boot attempt and marking STATUS_FAILED", p.path().display());
-        p.write_status(ImageHeader::STATUS_FAILED)?;
-    }
-    p.header().verify_signature()?;
-    Ok(())
-}
-
-fn is_better<'a>(current_best: &Option<&'a Partition>, other: &'a Partition) -> bool {
-
-    if !other.is_initialized() {
-        return false;
-    }
-
-    // Only consider partitions in state NEW or state GOOD
-    if !other.is_good() && !other.is_new() {
-        return false;
-    }
-    // If metainfo is broken, then no, it's not better
-    //if !other.metainfo().is_ok() {
-    //    return false;
-    //}
-
-    let best = match *current_best {
-        Some(p) => p,
-        // No current 'best', so 'other' is better, whatever it is.
-        None => return true,
-    };
-
-    // First parition with PREFER flag trumps everything else
-    if best.is_preferred() {
-        return false;
-    }
-
-    let best_version = best.metainfo().version();
-    let other_version = other.metainfo().version();
-
-    if best_version > other_version {
-        return false;
-    }
-
-    if other_version > best_version {
-        return true;
-    }
-
-    // choose NEW over GOOD if versions are the same 
-    if other.is_new() && best.is_good() {
-        return true;
-    }
-    // ... but if all things otherwise match, return first match
-    false
-}

citadel-mount/src/main.rs

@@ -10,11 +10,7 @@ use std::fs;
 use libcitadel::{Result,CommandLine,set_verbose,format_error,ResourceImage,util};
 
 
-mod boot_select;
 mod rootfs;
-pub use boot_select::BootSelection;
-use rootfs::Rootfs;
-
 
 /// mount command supports 4 subcommands
 ///
@@ -27,7 +23,7 @@ use rootfs::Rootfs;
 ///
 /// 'kernel' mounts a resource bundle containing kernel modules
 /// 'extra' mounts a resource bundle containing extra files
-///
+/// 'overlay' mounts a tmpfs overlay over rootfs filesystem only if citadel.overlay is set
 ///
 
 fn main() {
@@ -54,8 +50,7 @@ fn main() {
 
 fn mount_rootfs() -> Result<()> {
     info!("citadel-mount rootfs");
-    let rootfs = Rootfs::new();
+    rootfs::setup_rootfs()
-    rootfs.setup()
 }
 
 fn mount_kernel() -> Result<()> {

citadel-mount/src/rootfs.rs

@@ -1,78 +1,75 @@
 use std::process::Command;
 
-use libcitadel::{BlockDev,CommandLine,Partition,Result,verity};
+use libcitadel::{BlockDev,CommandLine,ImageHeader,Partition,Result,verity};
 use std::path::Path;
 use std::process::Stdio;
-use BootSelection;
 use ResourceImage;
 
-pub struct Rootfs {
+pub fn setup_rootfs() -> Result<()> {
-}
-
-impl Rootfs {
-    pub fn new() -> Rootfs {
-        Rootfs {}
-    }
-
-    pub fn setup(&self) -> Result<()> {
     if CommandLine::install_mode() || CommandLine::live_mode() {
-            self.setup_rootfs_resource()
+        setup_rootfs_resource()
     } else {
-            let partition = BootSelection::choose_boot_partition()?;
+        let p = choose_boot_partiton(true)?;
-            self.setup_partition(partition)
+        setup_partition(p)
     }
 }
 
-    fn setup_partition(&self, partition: Partition) -> Result<()> {
+fn setup_partition(mut p: Partition) -> Result<()> {
     if CommandLine::noverity() {
-            self.setup_partition_unverified(&partition)
+        setup_partition_unverified(&p)
     } else {
-            self.setup_partition_verified(&partition)
+        setup_partition_verified(&mut p)
     }
 }
 
-    fn setup_rootfs_resource(&self) -> Result<()> {
+fn setup_rootfs_resource() -> Result<()> {
     info!("Searching for rootfs resource image");
 
     let img = ResourceImage::find_rootfs()?;
 
     if CommandLine::noverity() {
-            self.setup_resource_unverified(&img)
+        setup_resource_unverified(&img)
     } else {
-            self.setup_resource_verified(&img)
+        setup_resource_verified(&img)
     }
 }
 
-    fn setup_resource_unverified(&self, img: &ResourceImage) -> Result<()> {
+fn setup_resource_unverified(img: &ResourceImage) -> Result<()> {
     if img.is_compressed() {
         img.decompress()?;
     }
     let loopdev = img.create_loopdev()?;
     info!("Loop device created: {}", loopdev.display());
-        self.setup_linear_mapping(&loopdev)
+    setup_linear_mapping(&loopdev)
 }
 
-    fn setup_resource_verified(&self, img: &ResourceImage) -> Result<()> {
+fn setup_resource_verified(img: &ResourceImage) -> Result<()> {
     let _ = img.setup_verity_device()?;
     Ok(())
 }
 
-    fn setup_partition_unverified(&self, partition: &Partition) -> Result<()> {
+fn setup_partition_unverified(p: &Partition) -> Result<()> {
     info!("Creating /dev/mapper/rootfs device with linear device mapping of partition (no verity)");
-        self.setup_linear_mapping(partition.path())
+    setup_linear_mapping(p.path())
 }
 
-    fn setup_partition_verified(&self, partition: &Partition) -> Result<()> {
+fn setup_partition_verified(p: &mut Partition) -> Result<()> {
     info!("Creating /dev/mapper/rootfs dm-verity device");
     if !CommandLine::nosignatures() {
-            partition.header().verify_signature()?;
+        if !p.has_public_key() {
-            info!("Image signature is valid for channel {}", partition.metainfo().channel());
+            bail!("No public key available for channel {}", p.metainfo().channel())
         }
-        verity::setup_partition_device(partition)?;
+        if !p.is_signature_valid() {
+            p.write_status(ImageHeader::STATUS_BAD_SIG)?;
+            bail!("Signature verification failed on partition");
+        }
+        info!("Image signature is valid for channel {}", p.metainfo().channel());
+    }
+    verity::setup_partition_device(p)?;
     Ok(())
 }
 
-    fn setup_linear_mapping(&self, blockdev: &Path) -> Result<()> {
+fn setup_linear_mapping(blockdev: &Path) -> Result<()> {
     let dev = BlockDev::open_ro(blockdev)?;
     let table = format!("0 {} linear {} 0", dev.nsectors()?, blockdev.display());
 
@@ -90,4 +87,88 @@ impl Rootfs {
     }
     Ok(())
 }
+
+fn choose_boot_partiton(scan: bool) -> Result<Partition> {
+    let mut partitions = Partition::rootfs_partitions()?;
+
+    if scan {
+        for p in &mut partitions {
+            p.boot_scan()?;
+        }
+    }
+
+    let mut best = None;
+    for p in partitions {
+        best = compare_boot_partitions(best, p);
+    }
+    best.ok_or(format_err!("No partition found to boot from"))
+}
+
+fn compare_boot_partitions(a: Option<Partition>, b: Partition) -> Option<Partition> {
+    if !is_bootable(&b) {
+        return a;
+    }
+
+    // b is bootable, so if a is None, then just return b
+    let a = match a {
+        Some(partition) => partition,
+        None => return Some(b),
+    };
+
+    // First partition with FLAG_PREFER_BOOT trumps everything
+    if a.is_preferred() {
+        return Some(a);
+    }
+
+    if b.is_preferred() {
+        return Some(b);
+    }
+
+    // Compare versions and channels
+    let a_v = a.metainfo().version();
+    let b_v = b.metainfo().version();
+
+    // Compare versions only if channels match
+    if a.metainfo().channel() == b.metainfo().channel() {
+        if a_v > b_v {
+            return Some(a);
+        } else if b_v > a_v {
+            return Some(b);
+        }
+    }
+
+    // choose NEW over GOOD if versions are the same or
+    // if versions cannot be compared because channels differ
+    if b.is_new() && a.is_good() {
+        return Some(b);
+    }
+
+    Some(a)
+}
+
+fn is_bootable(p: &Partition) -> bool {
+    if !p.is_initialized() {
+        return false;
+    }
+
+    // signatures enabled so not bootable without pubkey
+    if signatures_enabled() && !p.has_public_key() {
+        return false;
+    }
+
+    if p.is_new() || p.is_good() {
+        return true;
+    }
+
+    // If signatures are disabled then don't disqualify an
+    // image which failed a prior signature verification
+    if !signatures_enabled() && p.is_sig_failed() {
+        return true;
+    }
+
+    false
+}
+
+fn signatures_enabled() -> bool {
+    !(CommandLine::nosignatures() || CommandLine::noverity())
 }