On 5/10/24 10:47, Ian Kent wrote:
Umm, let's try that again ...
Actually that's not quite right.
On 5/10/24 10:41, Ian Kent wrote:
Hi Steve,
On 5/10/24 03:54, Steve Dickson wrote:
Hello,
On 10/4/24 2:14 PM, Charles Hedrick wrote:
While looking into a problem that turns out to be somewhere else, I
noticed that in gssd_proc.c , getpwuid is used. The context is
threaded, and I verified with strace that the thread is sharing
memory with other threads. I believe this should be changed to
getpwuid_r. Similarly the following call to getpwnam.
Is this the right place for reports on nfs-utils?
Yes... but I'm not a fan of change code, that been around
for a while, without fixing a problem... What problem does changing
getpwuid to getpwuid_r fix?
Patches are always welcome!
steved.
Yeah, getpwuid(3) and getpwnam() aren't thread safe and presumably
gssd is a service so it
could have multiple concurrent callers.
You could use domething like this ...
nfs-utils: use getpwuid_r() and getpwnam_r() in gssd From: Ian Kent
<raven@xxxxxxxxxx> gssd uses getpwuid(3) and getpwnam(3) in a
pthreads context but these functions are not thread safe.
Signed-off-by: Ian Kent <raven@xxxxxxxxxx> --- utils/gssd/gssd_proc.c
| 28 +++++++++++++++++++++------- 1 file changed, 21 insertions(+), 7
deletions(-) diff --git a/utils/gssd/gssd_proc.c
b/utils/gssd/gssd_proc.c index 2ad84c59..c718be6f 100644 ---
a/utils/gssd/gssd_proc.c +++ b/utils/gssd/gssd_proc.c @@ -489,7
+489,10 @@ success: static int change_identity(uid_t uid) { - struct
passwd *pw; + struct passwd pw; + struct passwd *ppw; + char *pw_tmp;
+ long tmplen; int res; /* drop list of supplimentary groups first */
@@ -502,15 +505,25 @@ change_identity(uid_t uid) return errno; } +
tmplen = sysconf(_SC_GETPW_R_SIZE_MAX); + if (tmplen < 0) + bufsize =
16384; + + pw_tmp = malloc(tmplen); + if (!pw_tmp) { + printerr(0,
"WARNING: unable to allocate passwd buffer\n"); + return errno ?
errno : ENOMEM; + } + /* try to get pwent for user */ - pw =
getpwuid(uid); - if (!pw) { + res = getpwuid_r(uid, &pw, pw_tmp,
tmplen, &ppw); + if (!ppw) { /* if that doesn't work, try to get one
for "nobody" */ - errno = 0; - pw = getpwnam("nobody"); - if (!pw) {
+ res = getpwnam_r("nobody", &pw, pw_tmp, tmplen, &ppw); + if (!ppw)
{ printerr(0, "WARNING: unable to determine gid for uid %u\n", uid);
- return errno ? errno : ENOENT; + free(pw_tmp); + return res ? res :
ENOENT; } } @@ -525,6 +538,7 @@ change_identity(uid_t uid) #else res
= syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid); #endif
+ free(pw_tmp); if (res != 0) { printerr(0, "WARNING: failed to set
gid to %u!\n", pw->pw_gid); return errno;
You could use something like this ...
nfs-utils: use getpwuid_r() and getpwnam_r() in gssd
From: Ian Kent <raven@xxxxxxxxxx>
gssd uses getpwuid(3) and getpwnam(3) in a pthreads context but
these functions are not thread safe.
Signed-off-by: Ian Kent <raven@xxxxxxxxxx>
---
utils/gssd/gssd_proc.c | 28 +++++++++++++++++++++-------
1 file changed, 21 insertions(+), 7 deletions(-)
diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 2ad84c59..c718be6f 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -489,7 +489,10 @@ success:
static int
change_identity(uid_t uid)
{
- struct passwd *pw;
+ struct passwd pw;
+ struct passwd *ppw;
+ char *pw_tmp;
+ long tmplen;
int res;
/* drop list of supplimentary groups first */
@@ -502,15 +505,25 @@ change_identity(uid_t uid)
return errno;
}
+ tmplen = sysconf(_SC_GETPW_R_SIZE_MAX);
+ if (tmplen < 0)
+ bufsize = 16384;
+
+ pw_tmp = malloc(tmplen);
+ if (!pw_tmp) {
+ printerr(0, "WARNING: unable to allocate passwd
buffer\n");
+ return errno ? errno : ENOMEM;
+ }
+
/* try to get pwent for user */
- pw = getpwuid(uid);
- if (!pw) {
+ res = getpwuid_r(uid, &pw, pw_tmp, tmplen, &ppw);
+ if (!ppw) {
/* if that doesn't work, try to get one for "nobody" */
- errno = 0;
- pw = getpwnam("nobody");
- if (!pw) {
+ res = getpwnam_r("nobody", &pw, pw_tmp, tmplen, &ppw);
+ if (!ppw) {
printerr(0, "WARNING: unable to determine gid
for uid %u\n", uid);
- return errno ? errno : ENOENT;
+ free(pw_tmp);
+ return res ? res : ENOENT;
}
}
@@ -525,6 +538,7 @@ change_identity(uid_t uid)
#else
res = syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid);
#endif
+ free(pw_tmp);
if (res != 0) {
printerr(0, "WARNING: failed to set gid to %u!\n",
pw->pw_gid);
return errno;
