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Stop leaks of memory and of privileges

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Fix several memory leaks and mishandling of the privilege status
where a function returned failure indication, and previously
allocated memory was not freed (and the referece was lost), or
previously droped privileges where not restored.
This commit is contained in:
Eugene Crosser 2013-04-20 15:50:51 +04:00 committed by Klas Lindfors
parent ba4e56667b
commit 2aaf0fdc23
3 changed files with 48 additions and 20 deletions
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29
drop_privs.c
View File

@ -55,7 +55,7 @@
static uid_t saved_euid;
static gid_t saved_egid;
static gid_t *saved_groups;
static gid_t *saved_groups = NULL;
static int saved_groups_length;
#endif /* HAVE_PAM_MODUTIL_DROP_PRIV */
@ -83,6 +83,11 @@ int drop_privileges(struct passwd *pw, pam_handle_t *pamh) {
saved_euid = geteuid();
saved_egid = getegid();
if ((saved_euid == pw->pw_uid) && (saved_egid == pw->pw_gid)) {
D (("Privilges already dropped, pretend it is all right"));
return 0;
}
saved_groups_length = getgroups(0, NULL);
if (saved_groups_length < 0) {
D (("getgroups: %s", strerror(errno)));
@ -90,6 +95,7 @@ int drop_privileges(struct passwd *pw, pam_handle_t *pamh) {
}
if (saved_groups_length > 0) {
if (saved_groups) free(saved_groups); /* size might have changed */
saved_groups = malloc(saved_groups_length * sizeof(gid_t));
if (saved_groups == NULL) {
D (("malloc: %s", strerror(errno)));
@ -98,26 +104,30 @@ int drop_privileges(struct passwd *pw, pam_handle_t *pamh) {
if (getgroups(saved_groups_length, saved_groups) < 0) {
D (("getgroups: %s", strerror(errno)));
return -1;
goto free_out;
}
}
if (initgroups(pw->pw_name, pw->pw_gid) < 0) {
D (("initgroups: %s", strerror(errno)));
return -1;
goto free_out;
}
if (setegid(pw->pw_gid) < 0) {
D (("setegid: %s", strerror(errno)));
return -1;
goto free_out;
}
if (seteuid(pw->pw_uid) < 0) {
D (("seteuid: %s", strerror(errno)));
return -1;
goto free_out;
}
return 0;
free_out:
free(saved_groups);
saved_groups = NULL;
return -1;
#endif /* HAVE_PAM_MODUTIL_DROP_PRIV */
}
@ -131,6 +141,11 @@ int restore_privileges(pam_handle_t *pamh) {
_privs_location(1);
return res;
#else
if ((saved_euid == geteuid()) && (saved_egid == getegid())) {
D (("Privilges already as requested, pretend it is all right"));
return 0;
}
if (seteuid(saved_euid) < 0) {
D (("seteuid: %s", strerror(errno)));
return -1;
@ -141,6 +156,10 @@ int restore_privileges(pam_handle_t *pamh) {
return -1;
}
if (saved_groups == NULL) {
D (("saved groups are empty, looks like a program error!"));
return -1;
}
if (setgroups(saved_groups_length, saved_groups) < 0) {
D (("setgroups: %s", strerror(errno)));
return -1;

35
pam_yubico.c
View File

@ -241,7 +241,8 @@ authorize_user_token (struct cfg *cfg,
if (drop_privileges(p, pamh) < 0) {
D (("could not drop privileges"));
return 0;
retval = 0;
goto free_out;
}
retval = check_user_token (cfg, userfile, username, otp_id);
@ -249,9 +250,11 @@ authorize_user_token (struct cfg *cfg,
if (restore_privileges(pamh) < 0)
{
DBG (("could not restore privileges"));
return 0;
retval = 0;
goto free_out;
}
free_out:
free (userfile);
}
@ -508,34 +511,34 @@ do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
fd = open(userfile, O_RDONLY, 0);
if (fd < 0) {
DBG (("Cannot open file: %s (%s)", userfile, strerror(errno)));
goto out;
goto restpriv_out;
}
if (fstat(fd, &st) < 0) {
DBG (("Cannot stat file: %s (%s)", userfile, strerror(errno)));
close(fd);
goto out;
goto restpriv_out;
}
if (!S_ISREG(st.st_mode)) {
DBG (("%s is not a regular file", userfile));
close(fd);
goto out;
goto restpriv_out;
}
f = fdopen(fd, "r");
if (f == NULL) {
DBG (("fdopen: %s", strerror(errno)));
close(fd);
goto out;
goto restpriv_out;
}
if (! load_chalresp_state(f, &state, cfg->debug))
goto out;
goto restpriv_out;
if (fclose(f) < 0) {
f = NULL;
goto out;
goto restpriv_out;
}
f = NULL;
@ -614,20 +617,20 @@ do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
/* Write out the new file */
tmpfile = malloc(strlen(userfile) + 1 + 4);
if (! tmpfile)
goto out;
goto restpriv_out;
strcpy(tmpfile, userfile);
strcat(tmpfile, ".tmp");
fd = open(tmpfile, O_WRONLY | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
if (fd < 0) {
DBG (("Cannot open file: %s (%s)", tmpfile, strerror(errno)));
goto out;
goto restpriv_out;
}
f = fdopen(fd, "w");
if (! f) {
close(fd);
goto out;
goto restpriv_out;
}
errstr = "Error updating Yubikey challenge, please check syslog or contact your system administrator";
@ -635,11 +638,11 @@ do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
goto out;
if (fclose(f) < 0) {
f = NULL;
goto out;
goto restpriv_out;
}
f = NULL;
if (rename(tmpfile, userfile) < 0) {
goto out;
goto restpriv_out;
}
if (restore_privileges(pamh) < 0) {
@ -650,6 +653,12 @@ do_challenge_response(pam_handle_t *pamh, struct cfg *cfg, const char *username)
DBG(("Challenge-response success!"));
errstr = NULL;
errno = 0;
goto out;
restpriv_out:
if (restore_privileges(pamh) < 0) {
DBG (("could not restore privileges"));
}
out:
if (yk_errno) {

4
util.c
View File

@ -37,6 +37,7 @@
#include <sys/types.h>
#include <pwd.h>
#include <unistd.h>
#include <alloca.h>
#include "util.h"
@ -213,11 +214,10 @@ get_user_challenge_file(YK_KEY *yk, const char *chalresp_path, const char *usern
int len;
/* 0xffffffff == 4294967295 == 10 digits */
len = strlen(chalresp_path == NULL ? "challenge" : username) + 1 + 10 + 1;
if ((filename = malloc(len)) != NULL) {
if ((filename = alloca(len)) != NULL) {
int res = snprintf(filename, len, "%s-%i", chalresp_path == NULL ? "challenge" : username, serial);
if (res < 0 || res > len) {
/* Not enough space, strangely enough. */
free(filename);
filename = NULL;
}
}