git: e87848a8150e - main - mountd(8): Allow to pass {NGROUPS_MAX} + 1 groups
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Date: Mon, 16 Dec 2024 14:45:31 UTC
The branch main has been updated by olce:
URL: https://cgit.FreeBSD.org/src/commit/?id=e87848a8150ed75da29d99a7d0c0bba6cc5129b8
commit e87848a8150ed75da29d99a7d0c0bba6cc5129b8
Author: Olivier Certner <olce@FreeBSD.org>
AuthorDate: 2024-10-08 12:30:03 +0000
Commit: Olivier Certner <olce@FreeBSD.org>
CommitDate: 2024-12-16 14:42:31 +0000
mountd(8): Allow to pass {NGROUPS_MAX} + 1 groups
NGROUPS_MAX is just the minimum maximum of the number of allowed
supplementary groups. The actual runtime value may be greater. Allow
more groups to be specified accordingly (now that, a few commits ago,
nmount(2) has been changed similarly).
To this end, we just allocate once and for all a static array called
'tmp_groups' big enough to hold {NGROUPS_MAX} + 1 groups (the maximum
number of supplementary groups plus the effective GID, which we store in
a variable named 'tngroups_max' to avoid confusion with the kernel
variable 'ngroups_max' holding only the maximum number of
*supplementary* groups) in main() and use this temporary space in
get_exportlist_one(), do_opt() and parsecred(). Doing so in passing
fixes a (benign) memory leak in case "-maproot" and/or "-mapall" were
specified multiple times and the first option comprised more than
SMALLNGROUPS.
parsecred() does not use 'cr_smallgrps' anymore, but we have kept
'cr_smallgrps'/SMALLNGROUPS as 'struct expcred' is also included in
'struct exportlist' and 'struct grouplist', and thus this preallocated
field still results in an optimization for the common case of small
number of groups (although its real impact is probably negligible and
arguably was not worth the trouble).
While here, in do_mount(), remove some unnecessary groups array
allocation and copying.
Reviewed by: rmacklem (older version)
Approved by: markj (mentor)
MFC after: 2 weeks
Relnotes: yes
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47016
---
usr.sbin/mountd/mountd.c | 70 +++++++++++++++++++++++++-----------------------
1 file changed, 37 insertions(+), 33 deletions(-)
diff --git a/usr.sbin/mountd/mountd.c b/usr.sbin/mountd/mountd.c
index 27d22ba06fa4..cb87535f6c3b 100644
--- a/usr.sbin/mountd/mountd.c
+++ b/usr.sbin/mountd/mountd.c
@@ -57,6 +57,7 @@
#include <arpa/inet.h>
+#include <assert.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
@@ -245,7 +246,7 @@ static void huphandler(int sig);
static int makemask(struct sockaddr_storage *ssp, int bitlen);
static void mntsrv(struct svc_req *, SVCXPRT *);
static void nextfield(char **, char **);
-static void out_of_mem(void);
+static void out_of_mem(void) __dead2;
static void parsecred(char *, struct expcred *);
static int parsesec(char *, struct exportlist *);
static int put_exlist(struct dirlist *, XDR *, struct dirlist *,
@@ -302,6 +303,11 @@ static int has_publicfh = 0;
static int has_set_publicfh = 0;
static struct pidfh *pfh = NULL;
+
+/* Temporary storage for credentials' groups. */
+static long tngroups_max;
+static gid_t *tmp_groups = NULL;
+
/* Bits for opt_flags above */
#define OP_MAPROOT 0x01
#define OP_MAPALL 0x02
@@ -434,6 +440,18 @@ main(int argc, char **argv)
warn("cannot open or create pidfile");
}
+ openlog("mountd", LOG_PID, LOG_DAEMON);
+
+ /* How many groups do we support? */
+ tngroups_max = sysconf(_SC_NGROUPS_MAX);
+ if (tngroups_max == -1)
+ tngroups_max = NGROUPS_MAX;
+ /* Add space for the effective GID. */
+ ++tngroups_max;
+ tmp_groups = malloc(tngroups_max);
+ if (tmp_groups == NULL)
+ out_of_mem();
+
s = socket(AF_INET6, SOCK_DGRAM, IPPROTO_UDP);
if (s < 0)
have_v6 = 0;
@@ -539,7 +557,6 @@ main(int argc, char **argv)
exnames = argv;
else
exnames = exnames_default;
- openlog("mountd", LOG_PID, LOG_DAEMON);
if (debug)
warnx("getting export list");
get_exportlist(0);
@@ -1571,9 +1588,9 @@ get_exportlist_one(int passno)
int unvis_len;
v4root_phase = 0;
- anon.cr_groups = NULL;
dirhead = (struct dirlist *)NULL;
unvis_dir[0] = '\0';
+
while (get_line()) {
if (debug)
warnx("got line %s", line);
@@ -1586,9 +1603,9 @@ get_exportlist_one(int passno)
* Set defaults.
*/
has_host = FALSE;
- anon.cr_groups = anon.cr_smallgrps;
anon.cr_uid = UID_NOBODY;
anon.cr_ngroups = 1;
+ anon.cr_groups = tmp_groups;
anon.cr_groups[0] = nogroup();
exflags = MNT_EXPORTED;
got_nondir = 0;
@@ -1918,10 +1935,6 @@ nextline:
free_dir(dirhead);
dirhead = (struct dirlist *)NULL;
}
- if (anon.cr_groups != anon.cr_smallgrps) {
- free(anon.cr_groups);
- anon.cr_groups = NULL;
- }
}
}
@@ -3187,11 +3200,11 @@ do_mount(struct exportlist *ep, struct grouplist *grp, uint64_t exflags,
eap->ex_flags = exflags;
eap->ex_uid = anoncrp->cr_uid;
eap->ex_ngroups = anoncrp->cr_ngroups;
- if (eap->ex_ngroups > 0) {
- eap->ex_groups = malloc(eap->ex_ngroups * sizeof(gid_t));
- memcpy(eap->ex_groups, anoncrp->cr_groups, eap->ex_ngroups *
- sizeof(gid_t));
- }
+ /*
+ * Use the memory pointed to by 'anoncrp', as it outlives 'eap' which is
+ * local to this function.
+ */
+ eap->ex_groups = anoncrp->cr_groups;
LOGDEBUG("do_mount exflags=0x%jx", (uintmax_t)exflags);
eap->ex_indexfile = ep->ex_indexfile;
if (grp->gr_type == GT_HOST)
@@ -3381,7 +3394,6 @@ skip:
if (cp)
*cp = savedc;
error_exit:
- free(eap->ex_groups);
/* free strings allocated by strdup() in getmntopts.c */
if (iov != NULL) {
free(iov[0].iov_base); /* fstype */
@@ -3609,21 +3621,19 @@ get_line(void)
* Parse a description of a credential.
*/
static void
-parsecred(char *namelist, struct expcred *cr)
+parsecred(char *names, struct expcred *cr)
{
char *name;
- char *names;
struct passwd *pw;
- gid_t groups[NGROUPS_MAX + 1];
- int ngroups;
unsigned long name_ul;
char *end = NULL;
+ assert(cr->cr_groups == tmp_groups);
+
/*
* Parse the user and if possible get its password table entry.
* 'cr_uid' is filled when exiting this block.
*/
- names = namelist;
name = strsep_quote(&names, ":");
name_ul = strtoul(name, &end, 10);
if (*end != '\0' || end == name)
@@ -3650,17 +3660,13 @@ parsecred(char *namelist, struct expcred *cr)
"can't determine groups", name);
goto nogroup;
}
- cr->cr_uid = pw->pw_uid;
- ngroups = NGROUPS_MAX + 1;
- if (getgrouplist(pw->pw_name, pw->pw_gid, groups, &ngroups)) {
+
+ cr->cr_ngroups = tngroups_max;
+ if (getgrouplist(pw->pw_name, pw->pw_gid,
+ cr->cr_groups, &cr->cr_ngroups) != 0) {
syslog(LOG_ERR, "too many groups");
- ngroups = NGROUPS_MAX + 1;
+ cr->cr_ngroups = tngroups_max;
}
-
- if (ngroups > SMALLNGROUPS)
- cr->cr_groups = malloc(ngroups * sizeof(gid_t));
- cr->cr_ngroups = ngroups;
- memcpy(cr->cr_groups, groups, ngroups * sizeof(gid_t));
return;
}
@@ -3684,17 +3690,14 @@ parsecred(char *namelist, struct expcred *cr)
} else {
group = name_ul;
}
- if (cr->cr_ngroups == NGROUPS_MAX + 1) {
+ if (cr->cr_ngroups == tngroups_max) {
syslog(LOG_ERR, "too many groups");
break;
}
- groups[cr->cr_ngroups++] = group;
+ cr->cr_groups[cr->cr_ngroups++] = group;
}
if (cr->cr_ngroups == 0)
goto nogroup;
- if (cr->cr_ngroups > SMALLNGROUPS)
- cr->cr_groups = malloc(cr->cr_ngroups * sizeof(gid_t));
- memcpy(cr->cr_groups, groups, cr->cr_ngroups * sizeof(gid_t));
return;
nogroup:
@@ -4063,6 +4066,7 @@ huphandler(int sig __unused)
static void
terminate(int sig __unused)
{
+ free(tmp_groups);
pidfile_remove(pfh);
rpcb_unset(MOUNTPROG, MOUNTVERS, NULL);
rpcb_unset(MOUNTPROG, MOUNTVERS3, NULL);