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rpc.gssd: truncates 32-bit UIDs/GIDs to 16 bits architectures.

PATCH In review Steve Dickson 2 participants 4 messages Jul 18, 2018

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Steve Dickson

author
#0 lore raw

PATCH 1/1 rpc.gssd: truncates 32-bit UIDs/GIDs to 16 bits architectures.

utils/gssd_proc.c uses SYS_setresuid and SYS_setresgid in change_identity when it should use SYS_setresuid32 and SYS_setresgid32 instead. This causes it to truncate UIDs/GIDs > 65536.

Fixes https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1779962
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1595927
Tested-by James Ettle <[email protected]>
Tested-by Sree <[email protected]>
Signed-off-by Steve Dickson <[email protected]>
---
 utils/gssd/gssd_proc.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)
utils/gssd/gssd_proc.c +14 -4
index 8767e26..7a57c4e 100644
@@ -434,6 +434,7 @@ static int
 change_identity(uid_t uid)
 {
 	struct passwd	*pw;
+	int res;
 
 	/* drop list of supplimentary groups first */
 	if (syscall(SYS_setgroups, 0, 0) != 0) {

@@ -459,14 +460,23 @@ change_identity(uid_t uid)
 	 * send a signal to all other threads to synchronize the uid in all
 	 * other threads. To bypass this, we have to call syscall() directly.
 	 */
-	if (syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresgid32, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#else 
+	res = syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#endif
+	if (res != 0) {
 		printerr(0, "WARNING: failed to set gid to %u!\n", pw->pw_gid);
 		return errno;
 	}
 
-	if (syscall(SYS_setresuid, uid, uid, uid) != 0) {
-		printerr(0, "WARNING: Failed to setuid for user with uid %u\n",
-				uid);
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresuid32, uid, uid, uid);
+#else 
+	res = syscall(SYS_setresuid, uid, uid, uid);
+#endif
+	if (res != 0) {
+		printerr(0, "WARNING: Failed to setuid for user with uid %u\n", uid);
 		return errno;
 	}
Signature · 1 line
2.17.1
#1 lore raw

utils/gssd/gssd_proc.c change_identity(uid_t uid) · line 467

Quoted 6 lines
utils/gssd/gssd_proc.c +5 -1
-	if (syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresgid32, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#else 
+	res = syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#endif

I think you want to simply call setresuid/setresgid from glibcs, which will do the right thing instead of doing hand crafted syscalls.

author
#2 lore raw
Quoted 9 lines · Christoph Hellwig

utils/gssd/gssd_proc.c change_identity(uid_t uid) · line 467

Quoted 6 lines
utils/gssd/gssd_proc.c +5 -1
-	if (syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresgid32, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#else 
+	res = syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#endif

I think you want to simply call setresuid/setresgid from glibcs, which will do the right thing instead of doing hand crafted syscalls.

Here is the comment above these calls

/* Switch the UIDs and GIDs. */
/* For the threaded version we have to set uid,gid per thread instead
* of per process. glibc setresuid() when called from a thread, it'll
* send a signal to all other threads to synchronize the uid in all
* other threads. To bypass this, we have to call syscall() directly. */

steved.

author
#3 lore raw
In reply to Steve Dickson
Quoted 11 lines · Steve Dickson

utils/gssd_proc.c uses SYS_setresuid and SYS_setresgid in change_identity when it should use SYS_setresuid32 and SYS_setresgid32 instead. This causes it to truncate UIDs/GIDs > 65536.

Fixes https://bugs.launchpad.net/ubuntu/+source/nfs-utils/+bug/1779962
Fixes https://bugzilla.redhat.com/show_bug.cgi?id=1595927
Tested-by James Ettle <[email protected]>
Tested-by Sree <[email protected]>
Signed-off-by Steve Dickson <[email protected]>

Committed...

steved.

Quoted 45 lines
---
 utils/gssd/gssd_proc.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)
utils/gssd/gssd_proc.c +14 -4
index 8767e26..7a57c4e 100644
@@ -434,6 +434,7 @@ static int
 change_identity(uid_t uid)
 {
 	struct passwd	*pw;
+	int res;
 
 	/* drop list of supplimentary groups first */
 	if (syscall(SYS_setgroups, 0, 0) != 0) {

@@ -459,14 +460,23 @@ change_identity(uid_t uid)
 	 * send a signal to all other threads to synchronize the uid in all
 	 * other threads. To bypass this, we have to call syscall() directly.
 	 */
-	if (syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid) != 0) {
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresgid32, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#else 
+	res = syscall(SYS_setresgid, pw->pw_gid, pw->pw_gid, pw->pw_gid);
+#endif
+	if (res != 0) {
 		printerr(0, "WARNING: failed to set gid to %u!\n", pw->pw_gid);
 		return errno;
 	}
 
-	if (syscall(SYS_setresuid, uid, uid, uid) != 0) {
-		printerr(0, "WARNING: Failed to setuid for user with uid %u\n",
-				uid);
+#ifdef __NR_setresuid32
+	res = syscall(SYS_setresuid32, uid, uid, uid);
+#else 
+	res = syscall(SYS_setresuid, uid, uid, uid);
+#endif
+	if (res != 0) {
+		printerr(0, "WARNING: Failed to setuid for user with uid %u\n", uid);
 		return errno;
 	}