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From 95924615ab42529e4dc7b95da1115346bf607fc6 Mon Sep 17 00:00:00 2001
From: Jeremy Lin <jjlin@cs.stanford.edu>
Date: Mon, 15 Sep 2014 21:16:46 -0700
Subject: [PATCH 1/2] 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.

Upstream-commit: fa7d04fed4d4578fe29bdff0b5465f6e4a7da81a
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 docs/MANUAL | 26 ++++++++++++++-------
 docs/curl.1 |  8 ++++++-
 lib/ssh.c   | 75 +++++++++++++++++++++++++++++++++++++++----------------------
 3 files changed, 73 insertions(+), 36 deletions(-)

diff --git a/docs/MANUAL b/docs/MANUAL
index 4ad2e13..3f8d9b8 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 38fa084..d1675a0 100644
--- a/docs/curl.1
+++ b/docs/curl.1
@@ -724,7 +724,8 @@ If this option is used several times, the last one will be used. If
 unspecified, the option defaults to 60 seconds.
 .IP "--key <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 <type>"
@@ -1124,6 +1125,11 @@ 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 43e3342..4ea7d9b 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -780,7 +780,7 @@ 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;
 
@@ -788,34 +788,55 @@ 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;
@@ -828,8 +849,8 @@ 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);
       }
-- 
2.5.2


From 2e18c6a12fc5dbab278670f22e58fcce51d32cac Mon Sep 17 00:00:00 2001
From: Kamil Dudka <kdudka@redhat.com>
Date: Fri, 15 Jan 2016 10:27:33 +0100
Subject: [PATCH 2/2] ssh: make CURLOPT_SSH_PUBLIC_KEYFILE treat "" as NULL

The CURLOPT_SSH_PUBLIC_KEYFILE option has been documented to handle
empty strings specially since curl-7_25_0-31-g05a443a but the behavior
was unintentionally removed in curl-7_38_0-47-gfa7d04f.

This commit restores the original behavior and clarifies it in the
documentation that NULL and "" have both the same meaning when passed
to CURLOPT_SSH_PUBLIC_KEYFILE.

Bug: http://curl.haxx.se/mail/lib-2016-01/0072.html

Upstream-commit: be538e07667e1ba880b7201014be706851428d40
Signed-off-by: Kamil Dudka <kdudka@redhat.com>
---
 docs/libcurl/curl_easy_setopt.3 | 6 +++---
 lib/ssh.c                       | 7 +++++--
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/docs/libcurl/curl_easy_setopt.3 b/docs/libcurl/curl_easy_setopt.3
index ad739e1..0a9375e 100644
--- a/docs/libcurl/curl_easy_setopt.3
+++ b/docs/libcurl/curl_easy_setopt.3
@@ -2446,9 +2446,9 @@ Pass a char * pointing to a file name for your public key. If not used,
 libcurl defaults to \fB$HOME/.ssh/id_dsa.pub\fP if the HOME environment
 variable is set, and just "id_dsa.pub" in the current directory if HOME is not
 set.  (Added in 7.16.1)
-If an empty string is passed, libcurl will pass no public key to libssh2
-which then tries to compute it from the private key, this is known to work
-when libssh2 1.4.0+ is linked against OpenSSL. (Added in 7.26.0)
+If NULL (or an empty string) is passed, libcurl will pass no public key to
+libssh2, which then tries to compute it from the private key.  This is known
+to work with libssh2 1.4.0+ linked against OpenSSL. (Added in 7.26.0)
 .IP CURLOPT_SSH_PRIVATE_KEYFILE
 Pass a char * pointing to a file name for your private key. If not used,
 libcurl defaults to \fB$HOME/.ssh/id_dsa\fP if the HOME environment variable
diff --git a/lib/ssh.c b/lib/ssh.c
index 4ea7d9b..589d4a3 100644
--- a/lib/ssh.c
+++ b/lib/ssh.c
@@ -828,7 +828,9 @@ static CURLcode ssh_statemach_act(struct connectdata *conn, bool *block)
          * 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]) {
+        if(data->set.str[STRING_SSH_PUBLIC_KEY]
+            /* treat empty string the same way as NULL */
+            && data->set.str[STRING_SSH_PUBLIC_KEY][0]) {
           sshc->rsa_pub = strdup(data->set.str[STRING_SSH_PUBLIC_KEY]);
           if(!sshc->rsa_pub)
             out_of_memory = TRUE;
@@ -849,7 +851,8 @@ 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);
+        if(sshc->rsa_pub)
+          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);
-- 
2.5.0