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os: Update GetLocalClientCreds to prefer getpeerucred() or SO_PEERCRED over getpeereid() 

GetLocalClientCreds() was preferring getpeereid() above other implementations.

getpeereid(), however, only returns the effective uid and gid of the peer,
leaving the pid unset.  When this happens, we are unable to use the pid to
determine the peer's command line arguments and incorrectly treat ssh-tunneled
traffic as local.

To address this, we now prioritize getpeerucred() or SO_PEERCRED as those two
implementations will return the pid in addition to uid and gid.

Signed-off-by: Jeremy Huddleston Sequoia <jeremyhu@apple.com>
This commit is contained in:
Jeremy Huddleston Sequoia 2023-01-18 12:02:54 -08:00
parent 2577291f01
commit 165d5c1260
1 changed files with 14 additions and 14 deletions
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28
os/access.c
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@ -1167,15 +1167,15 @@ GetLocalClientCreds(ClientPtr client, LocalClientCredRec ** lccp)
XtransConnInfo ci;
LocalClientCredRec *lcc;
#ifdef HAVE_GETPEEREID
uid_t uid;
gid_t gid;
#elif defined(HAVE_GETPEERUCRED)
#if defined(HAVE_GETPEERUCRED)
ucred_t *peercred = NULL;
const gid_t *gids;
#elif defined(SO_PEERCRED)
struct ucred peercred;
socklen_t so_len = sizeof(peercred);
#elif defined(HAVE_GETPEEREID)
uid_t uid;
gid_t gid;
#endif
if (client == NULL)
@ -1197,16 +1197,7 @@ GetLocalClientCreds(ClientPtr client, LocalClientCredRec ** lccp)
lcc = *lccp;
fd = _XSERVTransGetConnectionNumber(ci);
#ifdef HAVE_GETPEEREID
if (getpeereid(fd, &uid, &gid) == -1) {
FreeLocalClientCreds(lcc);
return -1;
}
lcc->euid = uid;
lcc->egid = gid;
lcc->fieldsSet = LCC_UID_SET | LCC_GID_SET;
return 0;
#elif defined(HAVE_GETPEERUCRED)
#if defined(HAVE_GETPEERUCRED)
if (getpeerucred(fd, &peercred) < 0) {
FreeLocalClientCreds(lcc);
return -1;
@ -1254,6 +1245,15 @@ GetLocalClientCreds(ClientPtr client, LocalClientCredRec ** lccp)
lcc->pid = peercred.pid;
lcc->fieldsSet = LCC_UID_SET | LCC_GID_SET | LCC_PID_SET;
return 0;
#elif defined(HAVE_GETPEEREID)
if (getpeereid(fd, &uid, &gid) == -1) {
FreeLocalClientCreds(lcc);
return -1;
}
lcc->euid = uid;
lcc->egid = gid;
lcc->fieldsSet = LCC_UID_SET | LCC_GID_SET;
return 0;
#endif
#else
/* No system call available to get the credentials of the peer */