#ifdef __APPLE__
#include <libc.h>
#endif
#include <unistd.h>
#include <stdlib.h>
#ifdef linux
#else
#endif
/*
* The only purpose of this program is to copy the ssh authorized_keys file
* written by the web application to ${DATA_ROOT}/.ssh/authorized_keys to the
* ${GIT_HOME}/.ssh/authorized_keys file, whereby ${GIT_HOME} is the home
* directory of the user running the git service (default ~git).
*
* Thus to get it actually work, the resulting binary needs to be owned by the
* corresponding user running the git service and needs to be set suid (ssh
* accepts authorized_keys files writable the owning user, only - i.e. just
* setting the group write bit of the authorized_keys file simply doesn't work).
*
* Because suid stuff is always a "makes-me-nervous" thing, we hardcode the
* source and destination as well as the binary to call, so that it cannot be
* abused by malicious users - they would just cause a possibly redundant sync.
*
* As an alternative on a modern OS having a fine grained security model like
* Solaris one could create a web2git RBAC role, add this role to the user
* running the web service and add an appropriate entry to the exec_attr(4)
* file, which allows web2git role to run the given command with euid of the
* user running the git service and thus no suid bit is needed, e.g.:
* running scripts in a similar way is impossible, because when the related
* interpreter gets executed, it doesn't inherit the capabilities/euid/... of
* the script. Anyway, if one has a lot of time and likes really complex setups,
* get script work in a similar way. However, we don't support that, i.e. we
* leave such complex tasks to real security experts. The 3rd alternative is
* for people which do not care a lot about security: the 'StrictModes no'
* setting of the sshd_config instructs the ssh daemon to relax checks and thus
* accept group writable authorized_keys files. But this is not recommended,
* since this setting applies to ALL users and NOT ONLY to the authorized_keys
* files!
*
* Last but not least: The application expects the resulting binary in the
* .ssh directory of the ${DATA_ROOT}, which should be equal to the
* lib/authorized_keys_manager.rb for more info.
*
* Steps to do (we assume the web service is run by webservd:webservd and the
* git service is run by the user git:webservd):
* 0) edit cp_keys.c - adjust DATA_ROOT and GIT_HOME wrt. your environment
* 5) optional for paranoid people add exec restricting withdrawn POSIX ACLs:
* chacl u::r-x,g::---,o::---,u:ontohub:r-x,u:webservd:--x,m::rwx \
* 6) touch ${DATA_DIR}/.ssh/authorized_keys
* 7) chown webservd:webservd ${DATA_DIR}/.ssh/authorized_keys
* 8) chmod 0640 ${DATA_DIR}/.ssh/authorized_keys
*/
int
{
perror("execve");
}