[PATCH] ensure PKCS#11 library file is accessible before use

[sergeyb at tarantool.org]

From: Sergey Bronnikov <sergeyb at tarantool.org>

ssh-agent failed to use PKCS#11 provider when file is not accessible and
show message like like: 'Could not add card
"/usr/local/lib/pkcs11/opensc-pkcs11.so": agent refused operation'. This
commit adds to ssh-add utility check for existance of PKCS#11 library
file before passing it to ssh-agent.
---
 ssh-add.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/ssh-add.c b/ssh-add.c
index 936dc212..779bf8dd 100644
--- a/ssh-add.c
+++ b/ssh-add.c
@@ -816,6 +816,9 @@ main(int argc, char **argv)
 		goto done;
 	}
 	if (pkcs11provider != NULL) {
+		struct stat buf;
+		if (stat(pkcs11provider, &buf) != 0)
+			fatal("PKCS#11 shared library file is not accessible: %s", strerror(errno));
 		if (update_card(agent_fd, !deleting, pkcs11provider,
 		    qflag) == -1)
 			ret = 1;
-- 
2.26.2