1 files changed, 73 insertions, 1 deletions

diff --git a/modules/pam_shells/pam_shells.c b/modules/pam_shells/pam_shells.c
index 8b1397c..cce6824 100644
--- a/modules/pam_shells/pam_shells.c
+++ b/modules/pam_shells/pam_shells.c
@@ -11,8 +11,80 @@
 #include <security/pam_modules.h>
 #include <security/pam_mod_misc.h>
 
+#define SHELLS	"/etc/shells"
+
 PAM_EXTERN int
 pam_sm_authenticate(pam_handle_t * pamh, int flags,
-                int argc, const char * argv[]) 
+		int argc, const char * argv[]) 
+{
+	struct passwd *pwd;
+	struct stat shellfileinfo;
+	const char *user;
+	const char *shell; 
+	char shellfileline[256];
+	FILE *shellfile;
+	int pam_err;
+
+	if ( ( (pam_err = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS ) 
+			|| ( user == NULL ) )  {
+		PAM_ERROR("Error recovering username.");
+		return (pam_err);
+	}
+
+	if ( (pwd = getpwnam(user)) == NULL ) { 
+		PAM_ERROR("Could not get passwd entry for user [%s]",user);
+		return (PAM_SERVICE_ERR);
+	}
+	
+	shell = pwd->pw_shell; 
+
+	if ( stat(SHELLS, &shellfileinfo) ) { 
+		PAM_ERROR("Could not open SHELLS file :%s", SHELLS);
+		return (PAM_AUTH_ERR);
+	}
+
+	if ((shellfileinfo.st_mode & S_IWOTH) || !S_ISREG(shellfileinfo.st_mode)) {
+		/* File is either world writable or not a regural file */
+		PAM_ERROR("SHELLS file cannot be trusted!");
+		return (PAM_AUTH_ERR);
+	}
+	
+	/* Open read-only file with shells */
+	if ( (shellfile = fopen(SHELLS,"r")) ==  NULL ) { 
+		PAM_ERROR("Could not open SHELLS file :%s", SHELLS);
+		return (PAM_SERVICE_ERR);
+	}
+
+	pam_err = 1;
+
+	/* Search in SHELLS for user shell */
+	while (fgets(shellfileline, sizeof(shellfileline)-1, shellfile) != NULL 
+		&& pam_err) { 
+	        if (shellfileline[strlen(shellfileline) - 1] == '\n')
+	        	shellfileline[strlen(shellfileline) - 1] = '\0';
+
+		pam_err = strcmp(shellfileline, shell);
+
+	}
+
+	fclose(shellfile);
+
+	if (!pam_err) { 
+		/* user shell found in SHELLS. Allow access */
+		PAM_LOG("Access granted for %s with shell %s.", user, shell);
+		return (PAM_SUCCESS); 
+	}
+	
+	return (PAM_AUTH_ERR);
+}
+
+
+PAM_EXTERN int
+pam_sm_setcred(pam_handle_t *pamh , int flags ,
+		int argc , const char *argv[])
 {
 
+	                return (PAM_SUCCESS);
+}
+
+PAM_MODULE_ENTRY("pam_shells");