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Code Activity

examples: server check all keys in authorized_keys instead of one

Browse Source 
Fix read file with fgets and remove memory leaks

Remove use of ssh_pki_import_pubkey_file in ssh server and update max line size

Fix example server line no. and formatting

Fix check for leading whitespace in line

Reformat to avoid nesting

Remove setting sdata->authenticated to 0, the default is 0

Better error messages and handle case for fgets failing

Increment lineno at start

Signed-off-by: Gauravsingh Sisodia <xaerru@gmail.com>
Reviewed-by: Jakub Jelen <jjelen@redhat.com>
This commit is contained in:
Gauravsingh Sisodia
2024-01-10 10:42:23 +00:00
committed by Jakub Jelen
parent c0354c4689
commit 1176a71d61
1 changed files with 74 additions and 23 deletions
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77
examples/ssh_server.c
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@ -55,6 +55,7 @@ The goal is to show the API in action.
#define SESSION_END (SSH_CLOSED | SSH_CLOSED_ERROR)
#define SFTP_SERVER_PATH "/usr/lib/sftp-server"
#define AUTH_KEYS_MAX_LINE_SIZE 2048
static void set_default_keys(ssh_bind sshbind,
int rsa_already_set,
@ -541,6 +542,15 @@ static int auth_publickey(ssh_session session,
void *userdata)
{
struct session_data_struct *sdata = (struct session_data_struct *) userdata;
ssh_key key = NULL;
FILE *fp = NULL;
char line[AUTH_KEYS_MAX_LINE_SIZE] = {0};
char *p = NULL;
const char *q = NULL;
unsigned int lineno = 0;
int result;
int i;
enum ssh_keytypes_e type;
(void) user;
(void) session;
@ -553,31 +563,72 @@ static int auth_publickey(ssh_session session,
return SSH_AUTH_DENIED;
}
// valid so far. Now look through authorized keys for a match
if (authorizedkeys[0]) {
ssh_key key = NULL;
int result;
struct stat buf;
fp = fopen(authorizedkeys, "r");
if (fp == NULL) {
fprintf(stderr, "Error: opening authorized keys file %s failed, reason: %s\n",
authorizedkeys, strerror(errno));
return SSH_AUTH_DENIED;
}
if (stat(authorizedkeys, &buf) == 0) {
result = ssh_pki_import_pubkey_file( authorizedkeys, &key );
if ((result != SSH_OK) || (key==NULL)) {
while (fgets(line, sizeof(line), fp)) {
lineno++;
/* Skip leading whitespace and ignore comments */
p = line;
for (i = 0; i < AUTH_KEYS_MAX_LINE_SIZE; i++) {
if (!isspace((int)p[i])) {
break;
}
}
if (p[i] == '#' || p[i] == '\0' || p[i] == '\n') {
continue;
}
q = &p[i];
for (; i < AUTH_KEYS_MAX_LINE_SIZE; i++) {
if (isspace((int)p[i])) {
p[i] = '\0';
break;
}
}
type = ssh_key_type_from_name(q);
q = &p[i + 1];
for (; i < AUTH_KEYS_MAX_LINE_SIZE; i++) {
if (isspace((int)p[i])) {
p[i] = '\0';
break;
}
}
result = ssh_pki_import_pubkey_base64(q, type, &key);
if (result != SSH_OK) {
fprintf(stderr,
"Unable to import public key file %s\n",
"Warning: Cannot import key on line no. %d in authorized keys file: %s\n",
lineno,
authorizedkeys);
} else {
continue;
}
result = ssh_key_cmp(key, pubkey, SSH_KEY_CMP_PUBLIC);
ssh_key_free(key);
if (result == 0) {
sdata->authenticated = 1;
fclose(fp);
return SSH_AUTH_SUCCESS;
}
}
if (ferror(fp) != 0) {
fprintf(stderr,
"Error: Reading from authorized keys file %s failed, reason: %s\n",
authorizedkeys, strerror(errno));
}
}
fclose(fp);
// no matches
sdata->authenticated = 0;
/* no matches */
return SSH_AUTH_DENIED;
}