shadow-utils/SOURCES/shadow-4.6-regular-user.patch

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2020-05-14 22:43:01 +00:00
From fd4405b763d26649339069532e79bd45013c8c38 Mon Sep 17 00:00:00 2001
From: Tomas Mraz <tmraz@fedoraproject.org>
Date: Mon, 20 Jan 2020 13:58:07 +0100
Subject: [PATCH] Do not mistake a regular user process for a namespaced one
In case there is a regular user with a process running on a system
with uid falling into a namespaced uid range of another user.
The user with the colliding namespaced uid range will not be
allowed to be deleted without forcing the action with -f.
The user_busy() is adjusted to check whether the suspected process
is really a namespaced process in a different namespace.
---
libmisc/user_busy.c | 44 ++++++++++++++++++++++++++++++++++++--------
1 file changed, 36 insertions(+), 8 deletions(-)
diff --git a/libmisc/user_busy.c b/libmisc/user_busy.c
index b0867568..324bb946 100644
--- a/libmisc/user_busy.c
+++ b/libmisc/user_busy.c
@@ -39,6 +39,7 @@
#include <sys/types.h>
#include <dirent.h>
#include <fcntl.h>
+#include <unistd.h>
#include "defines.h"
#include "prototypes.h"
#ifdef ENABLE_SUBIDS
@@ -106,6 +107,31 @@ static int user_busy_utmp (const char *name)
#endif /* !__linux__ */
#ifdef __linux__
+#ifdef ENABLE_SUBIDS
+#define in_parentuid_range(uid) ((uid) >= parentuid && (uid) < parentuid + range)
+static int different_namespace (const char *sname)
+{
+ /* 41: /proc/xxxxxxxxxx/task/xxxxxxxxxx/ns/user + \0 */
+ char path[41];
+ char buf[512], buf2[512];
+ ssize_t llen1, llen2;
+
+ snprintf (path, 41, "/proc/%s/ns/user", sname);
+
+ if ((llen1 = readlink (path, buf, sizeof(buf))) == -1)
+ return 0;
+
+ if ((llen2 = readlink ("/proc/self/ns/user", buf2, sizeof(buf2))) == -1)
+ return 0;
+
+ if (llen1 == llen2 && memcmp (buf, buf2, llen1) == 0)
+ return 0; /* same namespace */
+
+ return 1;
+}
+#endif /* ENABLE_SUBIDS */
+
+
static int check_status (const char *name, const char *sname, uid_t uid)
{
/* 40: /proc/xxxxxxxxxx/task/xxxxxxxxxx/status + \0 */
@@ -114,7 +140,6 @@ static int check_status (const char *name, const char *sname, uid_t uid)
FILE *sfile;
snprintf (status, 40, "/proc/%s/status", sname);
- status[39] = '\0';
sfile = fopen (status, "r");
if (NULL == sfile) {
@@ -123,26 +148,29 @@ static int check_status (const char *name, const char *sname, uid_t uid)
while (fgets (line, sizeof (line), sfile) == line) {
if (strncmp (line, "Uid:\t", 5) == 0) {
unsigned long ruid, euid, suid;
+
assert (uid == (unsigned long) uid);
+ (void) fclose (sfile);
if (sscanf (line,
"Uid:\t%lu\t%lu\t%lu\n",
&ruid, &euid, &suid) == 3) {
if ( (ruid == (unsigned long) uid)
|| (euid == (unsigned long) uid)
- || (suid == (unsigned long) uid)
+ || (suid == (unsigned long) uid) ) {
+ return 1;
+ }
#ifdef ENABLE_SUBIDS
- || have_sub_uids(name, ruid, 1)
- || have_sub_uids(name, euid, 1)
- || have_sub_uids(name, suid, 1)
-#endif /* ENABLE_SUBIDS */
+ if ( different_namespace (sname)
+ && ( have_sub_uids(name, ruid, 1)
+ || have_sub_uids(name, euid, 1)
+ || have_sub_uids(name, suid, 1))
) {
- (void) fclose (sfile);
return 1;
}
+#endif /* ENABLE_SUBIDS */
} else {
/* Ignore errors. This is just a best effort. */
}
- (void) fclose (sfile);
return 0;
}
}
--
2.25.2