From bbbebca9ba2bdd285ee24c14c9799dc61406ec0f Mon Sep 17 00:00:00 2001 From: Jeremy Lin Date: Mon, 15 Sep 2014 21:16:46 -0700 Subject: [PATCH] ssh: improve key file search For private keys, use the first match from: user-specified key file (if provided), ~/.ssh/id_rsa, ~/.ssh/id_dsa, ./id_rsa, ./id_dsa Note that the previous code only looked for id_dsa files. id_rsa is now generally preferred, as it supports larger key sizes. For public keys, use the user-specified key file, if provided. Otherwise, try to extract the public key from the private key file. This means that passing --pubkey is typically no longer required, and makes the key-handling behavior more like OpenSSH. --- docs/MANUAL | 26 +++++++++++++++------- docs/curl.1 | 8 ++++++- lib/ssh.c | 74 +++++++++++++++++++++++++++++++++++++++---------------------- 3 files changed, 72 insertions(+), 36 deletions(-) diff --git a/docs/MANUAL b/docs/MANUAL index 06b3abe..18fecf6 100644 --- a/docs/MANUAL +++ b/docs/MANUAL @@ -41,12 +41,19 @@ SIMPLE USAGE Get a file from an SSH server using SFTP: - curl -u username sftp://shell.example.com/etc/issue + curl -u username sftp://example.com/etc/issue - Get a file from an SSH server using SCP using a private key to authenticate: + Get a file from an SSH server using SCP using a private key + (not password-protected) to authenticate: - curl -u username: --key ~/.ssh/id_dsa --pubkey ~/.ssh/id_dsa.pub \ - scp://shell.example.com/~/personal.txt + curl -u username: --key ~/.ssh/id_rsa \ + scp://example.com/~/file.txt + + Get a file from an SSH server using SCP using a private key + (password-protected) to authenticate: + + curl -u username: --key ~/.ssh/id_rsa --pass private_key_password \ + scp://example.com/~/file.txt Get the main page from an IPv6 web server: @@ -91,10 +98,13 @@ USING PASSWORDS SFTP / SCP - This is similar to FTP, but you can specify a private key to use instead of - a password. Note that the private key may itself be protected by a password - that is unrelated to the login password of the remote system. If you - provide a private key file you must also provide a public key file. + This is similar to FTP, but you can use the --key option to specify a + private key to use instead of a password. Note that the private key may + itself be protected by a password that is unrelated to the login password + of the remote system; this password is specified using the --pass option. + Typically, curl will automatically extract the public key from the private + key file, but in cases where curl does not have the proper library support, + a matching public key file must be specified using the --pubkey option. HTTP diff --git a/docs/curl.1 b/docs/curl.1 index 8f78570..ef3bd8f 100644 --- a/docs/curl.1 +++ b/docs/curl.1 @@ -817,7 +817,8 @@ If this option is used several times, the last one will be used. If unspecified, the option defaults to 60 seconds. .IP "--key " (SSL/SSH) Private key file name. Allows you to provide your private key in this -separate file. +separate file. For SSH, if not specified, curl tries the following candidates +in order: '~/.ssh/id_rsa', '~/.ssh/id_dsa', './id_rsa', './id_dsa'. If this option is used several times, the last one will be used. .IP "--key-type " @@ -1275,6 +1276,11 @@ protocol instead of the default HTTP 1.1. separate file. If this option is used several times, the last one will be used. + +(As of 7.39.0, curl attempts to automatically extract the public key from the +private key file, so passing this option is generally not required. Note that +this public key extraction requires libcurl to be linked against a copy of +libssh2 1.2.8 or higher that is itself linked against OpenSSL.) .IP "-q" If used as the first parameter on the command line, the \fIcurlrc\fP config file will not be read and used. See the \fI-K, --config\fP for details on the diff --git a/lib/ssh.c b/lib/ssh.c index 887e10f..0247462 100644 --- a/lib/ssh.c +++ b/lib/ssh.c @@ -786,7 +786,7 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block) if((data->set.ssh_auth_types & CURLSSH_AUTH_PUBLICKEY) && (strstr(sshc->authlist, "publickey") != NULL)) { char *home = NULL; - bool rsa_pub_empty_but_ok = FALSE; + bool out_of_memory = FALSE; sshc->rsa_pub = sshc->rsa = NULL; @@ -794,34 +794,54 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block) HOME environment variable etc? */ home = curl_getenv("HOME"); - if(data->set.str[STRING_SSH_PUBLIC_KEY] && - !*data->set.str[STRING_SSH_PUBLIC_KEY]) - rsa_pub_empty_but_ok = true; - else if(data->set.str[STRING_SSH_PUBLIC_KEY]) - sshc->rsa_pub = aprintf("%s", data->set.str[STRING_SSH_PUBLIC_KEY]); - else if(home) - sshc->rsa_pub = aprintf("%s/.ssh/id_dsa.pub", home); - else - /* as a final resort, try current dir! */ - sshc->rsa_pub = strdup("id_dsa.pub"); - - if(!rsa_pub_empty_but_ok && (sshc->rsa_pub == NULL)) { - Curl_safefree(home); - state(conn, SSH_SESSION_FREE); - sshc->actualcode = CURLE_OUT_OF_MEMORY; - break; + if(data->set.str[STRING_SSH_PRIVATE_KEY]) + sshc->rsa = strdup(data->set.str[STRING_SSH_PRIVATE_KEY]); + else { + /* If no private key file is specified, try some common paths. */ + if(home) { + /* Try ~/.ssh first. */ + sshc->rsa = aprintf("%s/.ssh/id_rsa", home); + if(!sshc->rsa) + out_of_memory = TRUE; + else if(access(sshc->rsa, R_OK) != 0) { + Curl_safefree(sshc->rsa); + sshc->rsa = aprintf("%s/.ssh/id_dsa", home); + if(!sshc->rsa) + out_of_memory = TRUE; + else if(access(sshc->rsa, R_OK) != 0) { + Curl_safefree(sshc->rsa); + } + } + } + if(!out_of_memory && !sshc->rsa) { + /* Nothing found; try the current dir. */ + sshc->rsa = strdup("id_rsa"); + if(sshc->rsa && access(sshc->rsa, R_OK) != 0) { + Curl_safefree(sshc->rsa); + sshc->rsa = strdup("id_dsa"); + if(sshc->rsa && access(sshc->rsa, R_OK) != 0) { + Curl_safefree(sshc->rsa); + /* Out of guesses. Set to the empty string to avoid + * surprising info messages. */ + sshc->rsa = strdup(""); + } + } + } } - if(data->set.str[STRING_SSH_PRIVATE_KEY]) - sshc->rsa = aprintf("%s", data->set.str[STRING_SSH_PRIVATE_KEY]); - else if(home) - sshc->rsa = aprintf("%s/.ssh/id_dsa", home); - else - /* as a final resort, try current dir! */ - sshc->rsa = strdup("id_dsa"); + /* + * Unless the user explicitly specifies a public key file, let + * libssh2 extract the public key from the private key file. + * This is done by simply passing sshc->rsa_pub = NULL. + */ + if(data->set.str[STRING_SSH_PUBLIC_KEY]) { + sshc->rsa_pub = strdup(data->set.str[STRING_SSH_PUBLIC_KEY]); + if (!sshc->rsa_pub) out_of_memory = TRUE; + } - if(sshc->rsa == NULL) { + if(out_of_memory || sshc->rsa == NULL) { Curl_safefree(home); + Curl_safefree(sshc->rsa); Curl_safefree(sshc->rsa_pub); state(conn, SSH_SESSION_FREE); sshc->actualcode = CURLE_OUT_OF_MEMORY; @@ -834,8 +854,8 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block) Curl_safefree(home); - infof(data, "Using ssh public key file %s\n", sshc->rsa_pub); - infof(data, "Using ssh private key file %s\n", sshc->rsa); + infof(data, "Using SSH public key file '%s'\n", sshc->rsa_pub); + infof(data, "Using SSH private key file '%s'\n", sshc->rsa); state(conn, SSH_AUTH_PKEY); } -- 2.1.0