In Linux, multiple slashes in the file path have the same effect as a single slash character. For example, "/home//foo/" is the same as "/home/foo/". ssh-keygen doesn't work with filenames containing multiple slashes. Behavior of ssh-keygen With double slashes: # su - foo -c "ssh-keygen -t rsa -f /home/foo//.ssh/id_rsa -N ''" Generating public/private rsa key pair. open /home/foo//.ssh/id_rsa failed: No such file or directory. Saving the key failed: /home/foo//.ssh/id_rsa. # su - foo -c "ssh-keygen -t rsa -f /home/foo/.ssh/id_rsa -N ''" Generating public/private rsa key pair. Created directory '/home/foo/.ssh'. Your identification has been saved in /home/foo/.ssh/id_rsa. Your public key has been saved in /home/foo/.ssh/id_rsa.pub. The key fingerprint is: 3a:1b:5a:af:3a:0a:f4:32:da:87:a9:e6:98:b0:d4:87 foo@toruk The key's randomart image is: +--[ RSA 2048]----+ | | | | | | | | | . S | |. o . . | |o+ E .= | |=*= +o = | |Ooooooo.. | +-----------------+ # getent passwd foo foo:x:1004:100::/home/foo:/bin/bash # ssh -V OpenSSH_5.2p1, OpenSSL 0.9.8k 25 Mar 2009 I have also seen the same behavior with OpenSSH_4.2p1.
It looks like the following code snippet might be the cause: 1896: /* Create ~/.ssh directory if it doesn't already exist. */ 1897: snprintf(dotsshdir, sizeof dotsshdir, "%s/%s", 1898: pw->pw_dir, _PATH_SSH_USER_DIR); 1899: if (strstr(identity_file, dotsshdir) != NULL) { From: http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/ssh-keygen.c?annotate=1.190 dotsshdir is expected to be a substring of identity_file. I think before calling strstr() on the 2 strings, identity_file should be canonicalized - either by realpath() or canonicalize_file_name() On the same note, ssh-keygen will fail if the identity_file contains a relative path: # su - foo -c "ssh-keygen -t rsa -f /home/foo/bin/../.ssh/id_rsa -N ''" Generating public/private rsa key pair. open /home/foo/bin/../.ssh/id_rsa failed: No such file or directory. Saving the key failed: /home/foo/bin/../.ssh/id_rsa.
If you are explicitly passing a path to ssh-keygen then don't count on it to create the directory components for you. I don't think this is worth complicating our code to fix.
Move resolved bugs to CLOSED after 5.7 release