58 lines
1.2 KiB
Diff
58 lines
1.2 KiB
Diff
diff --git a/ssh.c b/ssh.c
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index 35c48e62..48d93ddf 100644
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--- a/ssh.c
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+++ b/ssh.c
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@@ -626,6 +626,41 @@ ssh_conn_info_free(struct ssh_conn_info *cinfo)
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}
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}
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+static int
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+valid_hostname(const char *s)
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+{
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+ size_t i;
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+
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+ if (*s == '-')
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+ return 0;
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+ for (i = 0; s[i] != 0; i++) {
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+ if (strchr("'`\"$\\;&<>|(){}", s[i]) != NULL ||
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+ isspace((u_char)s[i]) || iscntrl((u_char)s[i]))
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+ return 0;
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+ }
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+ return 1;
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+}
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+
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+static int
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+valid_ruser(const char *s)
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+{
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+ size_t i;
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+
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+ if (*s == '-')
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+ return 0;
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+ for (i = 0; s[i] != 0; i++) {
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+ if (strchr("'`\";&<>|(){}", s[i]) != NULL)
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+ return 0;
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+ /* Disallow '-' after whitespace */
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+ if (isspace((u_char)s[i]) && s[i + 1] == '-')
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+ return 0;
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+ /* Disallow \ in last position */
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+ if (s[i] == '\\' && s[i + 1] == '\0')
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+ return 0;
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+ }
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+ return 1;
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+}
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+
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/*
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* Main program for the ssh client.
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*/
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@@ -1118,6 +1153,10 @@ main(int ac, char **av)
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if (!host)
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usage();
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+ if (!valid_hostname(host))
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+ fatal("hostname contains invalid characters");
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+ if (options.user != NULL && !valid_ruser(options.user))
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+ fatal("remote username contains invalid characters");
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host_arg = xstrdup(host);
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/* Initialize the command to execute on remote host. */
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