* Document apt-key finger and adv commands (thanks to Stefan Schmidt, closes: #350575)

[apt.git] / cmdline / apt-key

diff --git a/cmdline/apt-key b/cmdline/apt-key
index 3bd1a92d9c838ed847a4a086afb448fbba5eed1b..51a0bc2d156b7d3c8d487e48e13129c0ab248148 100755 (executable)
--- a/cmdline/apt-key
+++ b/cmdline/apt-key
@@ -5,13 +5,76 @@ set -e
 # We don't use a secret keyring, of course, but gpg panics and
 # implodes if there isn't one available
 
-GPG_CMD="gpg --no-options --no-default-keyring --secret-keyring /etc/apt/secring.gpg --trustdb-name /etc/apt/trustdb.gpg"
+GPG_CMD="gpg --ignore-time-conflict --no-options --no-default-keyring --secret-keyring /etc/apt/secring.gpg --trustdb-name /etc/apt/trustdb.gpg"
 GPG="$GPG_CMD --keyring /etc/apt/trusted.gpg"
 
 
+MASTER_KEYRING=""
+ARCHIVE_KEYRING_URI=""
+#MASTER_KEYRING=/usr/share/keyrings/debian-master-keyring.gpg
+#ARCHIVE_KEYRING_URI=http://ftp.debian.org/debian/debian-archive-keyring.gpg
+
 ARCHIVE_KEYRING=/usr/share/keyrings/debian-archive-keyring.gpg
 REMOVED_KEYS=/usr/share/keyrings/debian-archive-removed-keys.gpg
 
+add_keys_with_verify_against_master_keyring() {
+    ADD_KEYRING=$1
+    MASTER=$2
+    
+    if [ ! -f "$ADD_KEYRING" ]; then
+       echo "ERROR: '$ADD_KEYRING' not found"
+       return
+    fi 
+    if [ ! -f "$MASTER" ]; then
+       echo "ERROR: '$MASTER' not found"
+       return
+    fi
+
+    # when adding new keys, make sure that the archive-master-keyring
+    # is honored. so:
+    #   all keys that are exported must have a valid signature
+    #   from a key in the $distro-master-keyring
+    add_keys=`$GPG_CMD --keyring $ADD_KEYRING --with-colons --list-keys | grep ^pub | cut -d: -f5`
+    master_keys=`$GPG_CMD --keyring $MASTER --with-colons --list-keys | grep ^pub | cut -d: -f5`
+    for add_key in $add_keys; do
+       ADDED=0
+       for master_key in $master_keys; do
+           if $GPG_CMD --keyring $ADD_KEYRING --list-sigs --with-colons $add_key | grep ^sig | cut -d: -f5 | grep -q $master_key; then
+               $GPG_CMD --quiet --batch --keyring $ADD_KEYRING --export $add_key | $GPG --import
+               ADDED=1
+           fi
+       done
+       if [ $ADDED = 0 ]; then
+           echo >&2 "Key '$add_key' not added. It is not signed with a master key"
+       fi
+    done
+}
+
+# update the current archive signing keyring from a network URI
+# the archive-keyring keys needs to be signed with the master key
+# (otherwise it does not make sense from a security POV)
+net_update() {
+    if [ -z "$ARCHIVE_KEYRING_URI" ]; then
+       echo "ERROR: no location for the archive-keyring given" 
+    fi
+    if [ ! -d /var/lib/apt/keyrings ]; then
+       mkdir -p /var/lib/apt/keyrings
+    fi
+    keyring=/var/lib/apt/keyrings/$(basename $ARCHIVE_KEYRING)
+    old_mtime=0
+    if [ -e $keyring ]; then
+       old_mtime=$(stat -c %Y $keyring)
+    fi
+    (cd  /var/lib/apt/keyrings; wget -q -N $ARCHIVE_KEYRING_URI)
+    if [ ! -e $keyring ]; then
+       return
+    fi
+    new_mtime=$(stat -c %Y $keyring)
+    if [ $new_mtime -ne $old_mtime ]; then
+       echo "Checking for new archive signing keys now"
+       add_keys_with_verify_against_master_keyring $keyring $MASTER_KEYRING
+    fi
+}
 
 update() {
     if [ ! -f $ARCHIVE_KEYRING ]; then
@@ -20,10 +83,16 @@ update() {
        exit 1
     fi
 
-    # add new keys
-    $GPG_CMD --quiet --batch --keyring $ARCHIVE_KEYRING --export | $GPG --ignore-time-conflict --import
+    # add new keys from the package;
+
+    # we do not use add_keys_with_verify_against_master_keyring here,
+    # because "update" is run on regular package updates.  A
+    # attacker might as well replace the master-archive-keyring file
+    # in the package and add his own keys. so this check wouldn't
+    # add any security. we *need* this check on net-update though
+    $GPG_CMD --quiet --batch --keyring $ARCHIVE_KEYRING --export | $GPG --import
 
-    # remove no-longer used keys
+    # remove no-longer supported/used keys
     keys=`$GPG_CMD --keyring $REMOVED_KEYS --with-colons --list-keys | grep ^pub | cut -d: -f5`
     for key in $keys; do
        if $GPG --list-keys --with-colons | grep ^pub | cut -d: -f5 | grep -q $key; then
@@ -32,6 +101,7 @@ update() {
     done
 }
 
+
 usage() {
     echo "Usage: apt-key [command] [arguments]"
     echo
@@ -42,7 +112,10 @@ usage() {
     echo "  apt-key export <keyid>      - output the key <keyid>"
     echo "  apt-key exportall           - output all trusted keys"
     echo "  apt-key update              - update keys using the keyring package"
+    echo "  apt-key net-update          - update keys using the network"
     echo "  apt-key list                - list keys"
+    echo "  apt-key finger              - list fingerprints"
+    echo "  apt-key adv                 - pass advanced options to gpg (download key)"
     echo
 }
 
@@ -71,6 +144,9 @@ case "$command" in
     update)
        update
        ;;
+    net-update)
+       net_update
+       ;;
     list)
         $GPG --batch --list-keys
         ;;