223 lines
6.8 KiB
Bash
223 lines
6.8 KiB
Bash
# shellcheck shell=bash
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#
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# Putting face unlock in front of sudo, polkit's admin prompts and the lock
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# screens of Hyprland and Niri, and taking it out again.
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#
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# The lock screens of Plasma and GNOME do not go through this at all: the
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# agent opens them (see src/agent/lockcontroller.h). hyprlock, swaylock and
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# the others are programs of their own that only open themselves, so the face
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# goes into their password check, and pressing Enter on the empty field is
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# how a scan starts. The login screen stays with the password: logging in is
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# what unlocks the wallet, and a face has no password to hand it.
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#
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# The line that goes in:
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#
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# -auth sufficient /usr/lib/security/pam_face_unlock.so
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#
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# with "lockscreen" after it for a lock screen (see the PAM module).
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#
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# "sufficient": a match lets the person in, anything else falls through to the
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# lines below as if this one were not there. The dash makes PAM skip it
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# quietly if the module ever goes missing, say because the package was removed
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# without turning this off first. sudo keeps working either way.
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#
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# Where the service's file is:
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# - /etc/pam.d/<service> exists: the line goes in before its first auth
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# line, with a comment saying where it came from.
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# - only the distribution's copy in /usr/lib/pam.d exists (Arch keeps
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# polkit-1 there): a small /etc/pam.d/<service> is written that puts the
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# line first and includes the distribution's file for everything else, so
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# an update to that file still counts.
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# Undoing takes out exactly those lines, or that file.
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FU_PAM_MARK="# face-unlock: the face first, the password if that does not work"
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FU_PAM_WRAPPER_MARK="# Written by face-unlock."
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FU_PAM_SERVICES=(sudo polkit-1)
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# Lock screens with a PAM file of their own. One that uses "login" or
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# "system-auth" directly is left alone: those also let people log in.
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FU_PAM_LOCKERS=(hyprlock swaylock gtklock waylock)
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# Overridable for the tests only; the root side never takes them from the
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# environment (see the top of face-unlock).
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FU_PAM_ETC_DIR="${FU_PAM_ETC_DIR:-/etc/pam.d}"
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read -r -a FU_PAM_VENDOR_DIRS <<< "${FU_PAM_VENDOR_DIRS:-/usr/lib/pam.d /usr/share/pam.d /lib/pam.d}"
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fu_pam_etc() {
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printf '%s/%s\n' "$FU_PAM_ETC_DIR" "$1"
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}
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# fu_pam_vendor <service>
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# The distribution's own copy, when it keeps one outside /etc.
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fu_pam_vendor() {
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local dir
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for dir in "${FU_PAM_VENDOR_DIRS[@]}"; do
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if [[ -f $dir/$1 ]]; then
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printf '%s\n' "$dir/$1"
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return 0
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fi
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done
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return 1
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}
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# fu_pam_is_locker <service>
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fu_pam_is_locker() {
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local s
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for s in "${FU_PAM_LOCKERS[@]}"; do
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[[ $s == "$1" ]] && return 0
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done
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return 1
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}
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# fu_pam_line <service>
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fu_pam_line() {
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if fu_pam_is_locker "$1"; then
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printf -- '-auth sufficient %s lockscreen\n' "$FU_PAM_MODULE"
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else
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printf -- '-auth sufficient %s\n' "$FU_PAM_MODULE"
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fi
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}
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# fu_pam_lockers
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# The lock screens installed here, one per line.
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fu_pam_lockers() {
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local s
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for s in "${FU_PAM_LOCKERS[@]}"; do
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if [[ -f $(fu_pam_etc "$s") ]] || fu_pam_vendor "$s" > /dev/null; then
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printf '%s\n' "$s"
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fi
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done
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}
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# fu_pam_lockers_list
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# The same, for people: "hyprlock, swaylock".
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fu_pam_lockers_list() {
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local list
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list="$(fu_pam_lockers | paste -sd ',')"
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printf '%s\n' "${list//,/, }"
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}
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# fu_pam_lockers_here
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# Whether this desktop's lock screen is a program of its own (Hyprland,
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# Niri and the like), and one with a PAM file is installed.
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fu_pam_lockers_here() {
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[[ $FU_DESKTOP != plasma && $FU_DESKTOP != gnome && -n $(fu_pam_lockers) ]]
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}
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# fu_pam_lockers_enabled
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# Whether every lock screen installed here takes the face, and there is one.
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fu_pam_lockers_enabled() {
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local s found=0
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while IFS= read -r s; do
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found=1
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fu_pam_enabled "$s" || return 1
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done < <(fu_pam_lockers)
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(( found ))
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}
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# fu_pam_enabled <service>
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fu_pam_enabled() {
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local file
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file="$(fu_pam_etc "$1")"
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[[ -r $file ]] && grep -q 'pam_face_unlock\.so' "$file"
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}
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# fu_pam_insert <file> <service>
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# Prints the file with the line added before its first auth line. Debian and
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# Ubuntu have none in sudo's file, only "@include common-auth", and that
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# counts as one: after it the password has already been asked for. A file
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# with neither (which would be odd for either service) gets it at the end.
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fu_pam_insert() {
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awk -v mark="$FU_PAM_MARK" -v line="$(fu_pam_line "$2")" '
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!done && ($0 ~ /^[[:space:]]*-?auth[[:space:]]/ || $0 ~ /^[[:space:]]*@include[[:space:]]+common-auth([[:space:]]|$)/) {
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print mark
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print line
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done = 1
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}
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{ print }
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END {
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if (!done) {
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print mark
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print line
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}
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}
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' "$1"
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}
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# fu_pam_remove_lines <file>
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# Prints the file without our comment and our line.
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fu_pam_remove_lines() {
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awk -v mark="$FU_PAM_MARK" '
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$0 == mark { next }
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/pam_face_unlock\.so/ { next }
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{ print }
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' "$1"
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}
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# fu_pam_wrapper <vendor file> <service>
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fu_pam_wrapper() {
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local vendor="$1"
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printf '#%%PAM-1.0\n'
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printf '%s The face first, then everything\n' "$FU_PAM_WRAPPER_MARK"
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printf '# %s does for this service. Removed again by\n' "$vendor"
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printf '# "face-unlock disable" or from its settings.\n\n'
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fu_pam_line "$2"
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printf 'auth include %s\n' "$vendor"
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printf 'account include %s\n' "$vendor"
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printf 'password include %s\n' "$vendor"
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printf 'session include %s\n' "$vendor"
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}
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# _fu_pam_replace <file> <content>
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# Writes the new file next to the old one and swaps it in, with the old one's
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# owner and mode. A half-written PAM file is a locked-out machine.
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_fu_pam_replace() {
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local file="$1" content="$2" tmp
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tmp="$(mktemp "${file}.fu.XXXXXX")" || return 1
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printf '%s\n' "$content" > "$tmp" || { rm -f "$tmp"; return 1; }
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if [[ -e $file ]]; then
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chown --reference="$file" "$tmp" 2>/dev/null
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chmod --reference="$file" "$tmp" 2>/dev/null
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else
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chmod 0644 "$tmp"
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fi
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mv -f "$tmp" "$file"
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}
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# fu_pam_enable <service> (root)
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fu_pam_enable() {
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local service="$1" file vendor content
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file="$(fu_pam_etc "$service")"
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[[ -e $FU_PAM_MODULE ]] || { fu_bad "$(fu_msg "The PAM module is not installed at %s." "$FU_PAM_MODULE")"; return 1; }
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fu_pam_enabled "$service" && return 0
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if [[ -f $file ]]; then
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content="$(fu_pam_insert "$file" "$service")" || return 1
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elif vendor="$(fu_pam_vendor "$service")"; then
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content="$(fu_pam_wrapper "$vendor" "$service")"
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else
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fu_bad "$(fu_msg "There is no PAM configuration for %s on this system." "$service")"
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return 1
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fi
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_fu_pam_replace "$file" "$content"
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}
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# fu_pam_disable <service> (root)
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fu_pam_disable() {
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local service="$1" file content
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file="$(fu_pam_etc "$service")"
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fu_pam_enabled "$service" || return 0
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if head -n 3 "$file" | grep -qF "$FU_PAM_WRAPPER_MARK"; then
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# Ours from the first line to the last. Without it the distribution's
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# own copy is in charge again.
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rm -f -- "$file"
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return
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fi
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content="$(fu_pam_remove_lines "$file")" || return 1
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_fu_pam_replace "$file" "$content"
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}
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