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#!/bin/bash
## Note that the shebang is not used, but it's the login shell that
## will execute this command.
exname=$(basename "$0")
mkdir -p /var/log/rsync
LOG="/var/log/rsync/$exname.log"
ssh_connection=(${SSH_CONNECTION})
SSH_SOURCE_IP="${ssh_connection[0]}:${ssh_connection[1]}"
log() {
printf "%s [%s] %s - %s\n" \
"$(date --rfc-3339=seconds)" "$$" "$SSH_SOURCE_IP" "$*" \
>> "$LOG"
}
log "NEW ADMIN CONNECTION"
if [ -z "$1" ] || ! [[ "$1" =~ ^[a-zA-Z0-9._-]+$ ]]; then
log "INVALID SETUP, ARG IS: '$1'"
echo "Your command has been rejected. Contact administrator."
exit 1
fi
label="$1"
reject() {
log "REJECTED: $SSH_ORIGINAL_COMMAND"
# echo "ORIG: $SSH_ORIGINAL_COMMAND" >&2
echo "Your command has been rejected and reported to sys admin." >&2
exit 1
}
if [[ "$SSH_ORIGINAL_COMMAND" =~ [\&\(\{\;\<\>\`\$\}] ]]; then
log "BAD CHARS DETECTED"
# echo "Bad chars: $SSH_ORIGINAL_COMMAND" >&2
reject
fi
if [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key add ssh-rsa "[a-zA-Z0-9/+]+" "[a-zA-Z0-9._-]+"@"[a-zA-Z0-9._-]+""$ ]]; then
log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
## Interpret \ to allow passing spaces (want to avoid possible issue with \n)
#read -a ssh_args <<< "${SSH_ORIGINAL_COMMAND}"
ssh_args=(${SSH_ORIGINAL_COMMAND})
# echo "Would accept: $SSH_ORIGINAL_COMMAND" >&2
exec sudo /usr/local/sbin/ssh-key add "$label" "${ssh_args[@]:2}"
elif [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key ls"$ ]]; then
log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
## Interpret \ to allow passing spaces (want to avoid possible issue with \n)
#read -a ssh_args <<< "${SSH_ORIGINAL_COMMAND}"
ssh_args=(${SSH_ORIGINAL_COMMAND})
# echo "Would accept: $SSH_ORIGINAL_COMMAND" >&2
exec /usr/local/sbin/ssh-key ls "$label" "${ssh_args[@]:2}"
elif [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key rm "[a-zA-Z0-9._-]+$ ]]; then
log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
## Interpret \ to allow passing spaces (want to avoid possible issue with \n)
#read -a ssh_args <<< "${SSH_ORIGINAL_COMMAND}"
ssh_args=(${SSH_ORIGINAL_COMMAND})
# echo "Would accept: $SSH_ORIGINAL_COMMAND" >&2
exec sudo /usr/local/sbin/ssh-key rm "$label" "${ssh_args[@]:2}"
elif [[ "$SSH_ORIGINAL_COMMAND" =~ ^"ssh-key get-type "[a-zA-Z0-9._-]+$ ]]; then
log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
## Interpret \ to allow passing spaces (want to avoid possible issue with \n)
#read -a ssh_args <<< "${SSH_ORIGINAL_COMMAND}"
ssh_args=(${SSH_ORIGINAL_COMMAND})
# echo "Would accept: $SSH_ORIGINAL_COMMAND" >&2
exec sudo /usr/local/sbin/ssh-key get-type "$label" "${ssh_args[@]:2}"
elif [[ "$SSH_ORIGINAL_COMMAND" =~ ^"request-recovery-key "[a-zA-Z0-9._-]+$ ]]; then
log "ACCEPTED: $SSH_ORIGINAL_COMMAND"
## Interpret \ to allow passing spaces (want to avoid possible issue with \n)
#read -a ssh_args <<< "${SSH_ORIGINAL_COMMAND}"
ssh_args=(${SSH_ORIGINAL_COMMAND})
# echo "Would accept: $SSH_ORIGINAL_COMMAND" >&2
exec sudo /usr/local/sbin/request-recovery-key "$label" "${ssh_args[@]:1}"
else
log "NOT MATCHING ANY ALLOWED COMMAND"
reject
fi
## For other commands, like `find` or `md5`, that could be used to
## challenge the backups and check that archive is actually
## functional, I would suggest to write a simple command that takes no
## arguments, so as to prevent allowing wildcards or suspicious
## contents. Letting `find` go through is dangerous for instance
## because of the `-exec`. And path traversal can be done also when
## allowing /my/path/* by using '..'. This is why a fixed purpose
## embedded executable will be much simpler to handle, and to be honest
## we don't need much more.