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

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

[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 <theholyettlz@googlemail.com>
Tested-by: Sree <Sree@gmail.com>
Signed-off-by: Steve Dickson <steved@redhat.com>
---
 utils/gssd/gssd_proc.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
index 8767e26..7a57c4e 100644
--- a/utils/gssd/gssd_proc.c
+++ b/utils/gssd/gssd_proc.c
@@ -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;
 	}
 
-- 
2.17.1

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

[Christoph Hellwig]

> -	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.

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

[Steve Dickson]

On 07/18/2018 08:33 AM, Christoph Hellwig wrote:
>> -	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.

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

[Steve Dickson]

On 07/18/2018 08:11 AM, Steve Dickson wrote:
> 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 <theholyettlz@googlemail.com>
> Tested-by: Sree <Sree@gmail.com>
> Signed-off-by: Steve Dickson <steved@redhat.com>
Committed... 

steved.
> ---
>  utils/gssd/gssd_proc.c | 18 ++++++++++++++----
>  1 file changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/utils/gssd/gssd_proc.c b/utils/gssd/gssd_proc.c
> index 8767e26..7a57c4e 100644
> --- a/utils/gssd/gssd_proc.c
> +++ b/utils/gssd/gssd_proc.c
> @@ -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;
>  	}
>  
>