[openssh-commits] [openssh] 01/04: upstream: Allow %-token and environment variable expansion in User,

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djm pushed a commit to branch master
in repository openssh.

commit bd30cf784d6e825ef71592fb723c41d4f2fd407b
Author: dtucker at openbsd.org <dtucker at openbsd.org>
AuthorDate: Sat Mar 1 06:11:26 2025 +0000

    upstream: Allow %-token and environment variable expansion in User,
    
    with the exception of %r and %C which are self-referential.  Requested in
    bz#3477, ok djm@, man page improvements jmc@
    
    OpenBSD-Commit-ID: caeb46251ee073662f6f5864c6f7b92d8ac80fa8
---
 ssh.c        | 23 +++++++++++++++++++----
 ssh_config.5 | 13 +++++++++++--
 sshconnect.h | 14 +++++++++-----
 3 files changed, 39 insertions(+), 11 deletions(-)

diff --git a/ssh.c b/ssh.c
index ff624927..f6505b03 100644
--- a/ssh.c
+++ b/ssh.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh.c,v 1.605 2025/02/21 18:22:41 deraadt Exp $ */
+/* $OpenBSD: ssh.c,v 1.606 2025/03/01 06:11:26 dtucker Exp $ */
 /*
  * Author: Tatu Ylonen <ylo at cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo at cs.hut.fi>, Espoo, Finland
@@ -1163,8 +1163,6 @@ main(int ac, char **av)
 
 	if (!valid_hostname(host))
 		fatal("hostname contains invalid characters");
-	if (options.user != NULL && !valid_ruser(options.user))
-		fatal("remote username contains invalid characters");
 	options.host_arg = xstrdup(host);
 
 	/* Initialize the command to execute on remote host. */
@@ -1445,11 +1443,28 @@ main(int ac, char **av)
 	    options.host_key_alias : options.host_arg);
 	cinfo->host_arg = xstrdup(options.host_arg);
 	cinfo->remhost = xstrdup(host);
-	cinfo->remuser = xstrdup(options.user);
 	cinfo->homedir = xstrdup(pw->pw_dir);
 	cinfo->locuser = xstrdup(pw->pw_name);
 	cinfo->jmphost = xstrdup(options.jump_host == NULL ?
 	    "" : options.jump_host);
+
+	/*
+	 * Expand User. It cannot contain %r (itself) or %C since User is
+	 * a component of the hash.
+	 */
+	if (options.user != NULL) {
+		if ((p = percent_dollar_expand(options.user,
+		    DEFAULT_CLIENT_PERCENT_EXPAND_ARGS_NOUSER(cinfo),
+	 	    (char *)NULL)) == NULL)
+			fatal("invalid environment variable expansion");
+		free(options.user);
+		options.user = p;
+		if (!valid_ruser(options.user))
+			fatal("remote username contains invalid characters");
+	}
+
+	/* Now User is expanded, store it an calculate hash. */
+	cinfo->remuser = xstrdup(options.user);
 	cinfo->conn_hash_hex = ssh_connection_hash(cinfo->thishost,
 	    cinfo->remhost, cinfo->portstr, cinfo->remuser, cinfo->jmphost);
 
diff --git a/ssh_config.5 b/ssh_config.5
index 5051d7b3..1c49ec7b 100644
--- a/ssh_config.5
+++ b/ssh_config.5
@@ -33,8 +33,8 @@
 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 .\"
-.\" $OpenBSD: ssh_config.5,v 1.411 2025/02/15 06:48:56 jmc Exp $
-.Dd $Mdocdate: February 15 2025 $
+.\" $OpenBSD: ssh_config.5,v 1.412 2025/03/01 06:11:26 dtucker Exp $
+.Dd $Mdocdate: March 1 2025 $
 .Dt SSH_CONFIG 5
 .Os
 .Sh NAME
@@ -2148,6 +2148,15 @@ Specifies the user to log in as.
 This can be useful when a different user name is used on different machines.
 This saves the trouble of
 having to remember to give the user name on the command line.
+Arguments to
+.Cm User
+may use the tokens described in the
+.Sx TOKENS
+section
+(with the exception of %r and %C)
+and environment variables as described in the
+.Sx ENVIRONMENT VARIABLES
+section.
 .It Cm UserKnownHostsFile
 Specifies one or more files to use for the user
 host key database, separated by whitespace.
diff --git a/sshconnect.h b/sshconnect.h
index 8b0466f2..30827016 100644
--- a/sshconnect.h
+++ b/sshconnect.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshconnect.h,v 1.48 2024/04/30 02:10:49 djm Exp $ */
+/* $OpenBSD: sshconnect.h,v 1.49 2025/03/01 06:11:26 dtucker Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -52,9 +52,8 @@ struct ssh;
 struct hostkeys;
 struct ssh_conn_info;
 
-/* default argument for client percent expansions */
-#define DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(conn_info) \
-	"C", conn_info->conn_hash_hex, \
+/* default argument for client percent expansions, minus remote user */
+#define DEFAULT_CLIENT_PERCENT_EXPAND_ARGS_NOUSER(conn_info) \
 	"L", conn_info->shorthost, \
 	"i", conn_info->uidstr, \
 	"k", conn_info->keyalias, \
@@ -63,10 +62,15 @@ struct ssh_conn_info;
 	"p", conn_info->portstr, \
 	"d", conn_info->homedir, \
 	"h", conn_info->remhost, \
-	"r", conn_info->remuser, \
 	"u", conn_info->locuser, \
 	"j", conn_info->jmphost
 
+/* same plus remote user and hash which has user as a component */
+#define DEFAULT_CLIENT_PERCENT_EXPAND_ARGS(conn_info) \
+	DEFAULT_CLIENT_PERCENT_EXPAND_ARGS_NOUSER(conn_info), \
+	"C", conn_info->conn_hash_hex, \
+	"r", conn_info->remuser
+
 int	 ssh_connect(struct ssh *, const char *, const char *,
 	    struct addrinfo *, struct sockaddr_storage *, u_short,
 	    int, int *, int);

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