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1 #!/usr/bin/env bash
2 #
3 # Mkinitramfs creates a basic init ram fs with encryption support.
4 # Copyright (C) 2016 Aaron Ball <nullspoon@oper.io>
5 #
6 # This program is free software: you can redistribute it and/or modify
7 # it under the terms of the GNU General Public License as published by
8 # the Free Software Foundation, either version 3 of the License, or
9 # (at your option) any later version.
10 #
11 # This program is distributed in the hope that it will be useful,
12 # but WITHOUT ANY WARRANTY; without even the implied warranty of
13 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 # GNU General Public License for more details.
15 #
16 # You should have received a copy of the GNU General Public License
17 # along with this program. If not, see <http://www.gnu.org/licenses/>.
18 #
19
20
21 # Hash of fully-qualified binaries
22 declare -a fqbins
23
24
25 #
26 # Searches PATH for all binaries listed as function arguments. Each found
27 # binary is then put into the global "bins" array.
28 #
29 # This function also serves to ensure all specified binaries are present and
30 # in PATH. It will exit code 1 with an error message if any binaries are not
31 # found.
32 #
33 # Note: To use this function, insert "declare -a fqbins" at top of script).
34 #
35 # @param bins All function arguments are the names of binaries to locate.
36 #
37 function resolve_bins {
38 local args=${@}
39
40 for i in ${args[@]}; do
41 local path=$(which ${i} 2>/dev/null)
42
43 if [[ $? -gt 0 ]]; then
44 echo "Could not find binary ${i}. Is it installed?"
45 exit 1
46 fi
47
48 echo "Located ${i} at ${path}"
49 fqbins+=("${path}")
50 done
51 }
52
53
54 #
55 # Gets first path locatable in a string
56 #
57 function get_first_path {
58 local str=${1}
59
60 local out=''
61 local cursor=''
62
63 for ((i=0; i<${#str}; i++)); do
64 if [[ ${str:$i:1} == '/' ]]; then
65 cursor=${i}
66 break
67 fi
68 done
69
70 # Exit if no path found
71 [[ ${cursor} == '' ]] && return
72
73 while [[ ${str:$cursor:1} != ' ' ]] && [[ ${cursor} -lt ${#str} ]]; do
74 out="${out}${str:$cursor:1}"
75 cursor=$((${cursor} + 1))
76 done
77
78 echo "${out}"
79 }
80
81
82 function get_deps {
83 local bin=${1}
84
85 for dep in $(ldd ${bin}); do
86 get_first_path "${dep}"
87 done
88 }
89
90
91 #
92 # Creates cpio file for specified initrd cache directory.
93 # Outputs to /boot/initrd-${version}.
94 #
95 # @param cache Path to the uncompressed source directory to be archived
96 # @param version Version of initrd archive
97 #
98 function mkcpio {
99 [[ -z ${1} ]] && echo "Initramfs cache path required." && exit 1
100 [[ -z ${2} ]] && echo "Kernel version required." && exit 1
101
102 local cache=${1}
103 local version=${2}
104
105 cd ${cache}
106 fspath="/boot/initrd-${version}"
107
108 # Notify user of initrd overwriting
109 [[ -f ${fspath} ]] && echo -e "\n\n${fspath} exists. Overwriting.\n"
110
111 # Create the initrd
112 echo "Building initrd to ${fspath}"
113 find . -print0 | cpio --null -o --format=newc | xz -C crc32 -9 -c > ${fspath}
114 }
115
116
117 #
118 # Sets up cache dir for later writing to an archive (via cpio).
119 # Performs simple operations like creating a basic directory structure,
120 #
121 # @param cache Path to the cache directory. Will be created if not exists
122 #
123 function cache_dir_setup {
124 [[ -z ${1} ]] && echo "Please specify a cache dir." && exit 1
125 local cache=${1}
126
127 # Clean the cache so we start fresh
128 rm -rf ${cache} && mkdir ${cache}
129
130 local dirs=(bin dev etc lib lib32 lib64 mnt/root proc root run sbin sys usr)
131
132 # Create the temporary directory structure
133 for i in ${dirs[*]}; do
134 mkdir -p ${cache}/${i}
135 done
136 }
137
138
139 #
140 # Checks installed kernel modules for the specified version to see if the
141 # corresponding kernel has encryption support statically compiled in.
142 #
143 # @param version Version of kernel modules to check
144 #
145 function check_crypto_support {
146 [[ -z ${1} ]] && echo "Kernel version required." && exit 1
147 local version=${1}
148
149 builtinpath=/lib/modules/${version}/modules.builtin
150
151 # Check for encryption support
152 if [[ ! $(grep dm-crypt ${builtinpath}) ]]; then
153 echo -e "\n\nWarning: Static encryption support not found."
154 echo " Module dm-crypt not found in modules.builtin."
155 echo "Press enter to continue, or Ctrl+c to exit and resolve."
156 read
157 fi
158 }
159
160
161 #
162 # Checks to see if kernel modules for the specified version have been
163 # installed.
164 #
165 # @param version Version to check for installation status
166 #
167 function check_kernel_version {
168 [[ -z ${1} ]] && echo "Kernel version required." && exit 1
169 local version=${1}
170
171 modulespath=/lib/modules/${version}
172 if [[ ! -d ${modulespath} ]]; then
173 echo "Error: Could not find ${modulespath}."
174 echo "Has kernel version ${version} been comiled?"
175 exit 1
176 fi
177 }
178
179
180 function main {
181 [[ -z ${1} ]] && echo "Please specify a kernel version" && exit 1
182
183 local version=${1}
184
185 check_kernel_version ${version}
186
187 local cache='/tmp/initrd'
188 local res_path=/usr/share/mkinitramfs/
189
190 # List of binaries to exist in the new initramfs
191 resolve_bins \
192 bash cat echo ls cryptsetup chmod chown mount sleep umount clear cut \
193 grep less tr which blkid reboot shutdown switch_root
194
195
196 # Set up the archive source dir.
197 cache_dir_setup ${cache}
198
199 # Ensure static crypto support exists in kernel
200 check_crypto_support ${version}
201
202 # Copy binary and dependencies to cache dir
203 for bin in ${fqbins[@]}; do
204 # Copy the binary of interest
205 install -D "${bin}" "${cache}/${bin}"
206
207 local deps=$(get_deps ${bin})
208 # Copy each of the binary's deps
209 for dep in ${deps[@]}; do
210 install -D ${dep} "${cache}/${dep}"
211 done
212 done
213
214 # Copy in message file
215 [[ -f ${res_path}/msg ]] && install -D ${res_path}/msg ${cache}/etc/msg
216 # Copy in init script and add execute
217 install -D -m 755 ${res_path}/init ${cache}/init
218 # Copy in the system shell profile
219 install -D /etc/profile ${cache}/etc/profile
220
221 # Create archive image
222 mkcpio ${cache} ${version}
223 }
224
225
226 main ${@}
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