[PATCH 1/2] linux-user: Implement SOL_ALG encryption support

[PATCH 1/2] linux-user: Implement SOL_ALG encryption support

[Helge Deller]

Add suport to handle SOL_ALG packets via sendmsg() and recvmsg().
This allows emulated userspace to use encryption functionality.

Tested with the debian ell package with hppa guest on x86_64 host.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/syscall.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 71ae867024..a365903a3a 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -1871,6 +1871,14 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
             __get_user(cred->pid, &target_cred->pid);
             __get_user(cred->uid, &target_cred->uid);
             __get_user(cred->gid, &target_cred->gid);
+        } else if (cmsg->cmsg_level == SOL_ALG) {
+            uint32_t *dst = (uint32_t *)data;
+
+            memcpy(dst, target_data, len);
+            /* fix endianess of first 32-bit word */
+            if (len >= sizeof(uint32_t)) {
+                *dst = tswap32(*dst);
+            }
         } else {
             qemu_log_mask(LOG_UNIMP, "Unsupported ancillary data: %d/%d\n",
                           cmsg->cmsg_level, cmsg->cmsg_type);
--
2.38.1

[PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Helge Deller]

Applications do call sendmsg() without any IOV, e.g.:
 sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
            msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
            msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
 sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
            msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
            msg_controllen=24, msg_flags=0}, 0) = 183

The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
and calls lock_iovec() to lock the IOV into memory. For the first
sendmsg() above it returns NULL and thus wrongly skips the call the host
sendmsg() syscall, which will break the calling application.

Fix this issue by:
- allowing sendmsg() even with empty IOV
- skip recvmsg() if IOV is NULL
- skip both if the return code of do_sendrecvmsg_locked() != 0, which
  indicates some failure like EFAULT on the IOV

Tested with the debian "ell" package with hppa guest on x86_64 host.

Signed-off-by: Helge Deller <deller@gmx.de>
---
 linux-user/syscall.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index a365903a3a..9e2c0a18fc 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
                      target_vec, count, send);
     if (vec == NULL) {
         ret = -host_to_target_errno(errno);
-        goto out2;
+        /* allow sending packet without any iov, e.g. with MSG_MORE flag */
+        if (!send || ret) {
+            goto out2;
+        }
     }
     msg.msg_iovlen = count;
     msg.msg_iov = vec;
@@ -3382,7 +3385,9 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
     }

 out:
-    unlock_iovec(vec, target_vec, count, !send);
+    if (vec) {
+        unlock_iovec(vec, target_vec, count, !send);
+    }
 out2:
     return ret;
 }
--
2.38.1

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Laurent Vivier]

Le 12/12/2022 à 18:34, Helge Deller a écrit :
> Applications do call sendmsg() without any IOV, e.g.:
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>              msg_controllen=24, msg_flags=0}, 0) = 183
> 
> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
> and calls lock_iovec() to lock the IOV into memory. For the first
> sendmsg() above it returns NULL and thus wrongly skips the call the host
> sendmsg() syscall, which will break the calling application.
> 
> Fix this issue by:
> - allowing sendmsg() even with empty IOV
> - skip recvmsg() if IOV is NULL
> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>    indicates some failure like EFAULT on the IOV
> 
> Tested with the debian "ell" package with hppa guest on x86_64 host.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index a365903a3a..9e2c0a18fc 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>                        target_vec, count, send);
>       if (vec == NULL) {
>           ret = -host_to_target_errno(errno);
> -        goto out2;
> +        /* allow sending packet without any iov, e.g. with MSG_MORE flag */

why don't you check only for count is 0?
Somehing like:

if (vec == NULL && (count || !send)) {
...

Thanks,
Laurent

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Helge Deller]

On 1/31/23 13:28, Laurent Vivier wrote:
> Le 12/12/2022 à 18:34, Helge Deller a écrit :
>> Applications do call sendmsg() without any IOV, e.g.:
>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
>>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>>              msg_controllen=24, msg_flags=0}, 0) = 183
>>
>> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
>> and calls lock_iovec() to lock the IOV into memory. For the first
>> sendmsg() above it returns NULL and thus wrongly skips the call the host
>> sendmsg() syscall, which will break the calling application.
>>
>> Fix this issue by:
>> - allowing sendmsg() even with empty IOV
>> - skip recvmsg() if IOV is NULL
>> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>>    indicates some failure like EFAULT on the IOV
>>
>> Tested with the debian "ell" package with hppa guest on x86_64 host.
>>
>> Signed-off-by: Helge Deller <deller@gmx.de>
>> ---
>>   linux-user/syscall.c | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>> index a365903a3a..9e2c0a18fc 100644
>> --- a/linux-user/syscall.c
>> +++ b/linux-user/syscall.c
>> @@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>>                        target_vec, count, send);
>>       if (vec == NULL) {
>>           ret = -host_to_target_errno(errno);
>> -        goto out2;
>> +        /* allow sending packet without any iov, e.g. with MSG_MORE flag */
>
> why don't you check only for count is 0?
> Somehing like:
>
> if (vec == NULL && (count || !send)) {

You mean:
if (vec == NULL && (!count || !send)) {
	goto out2;

lock_iovec() sets errno=0 if count==0, but for invalid addresses it sets errno!=0,
so my current check (for which ret is the same as errno):
         if (!send || ret) {
             goto out2;
exits on memfaults too, while a check for just count==0 would succeed.

Helge

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Helge Deller]

On 1/31/23 14:34, Helge Deller wrote:
> On 1/31/23 13:28, Laurent Vivier wrote:
>> Le 12/12/2022 à 18:34, Helge Deller a écrit :
>>> Applications do call sendmsg() without any IOV, e.g.:
>>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>>>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>>>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
>>>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>>>              msg_controllen=24, msg_flags=0}, 0) = 183
>>>
>>> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
>>> and calls lock_iovec() to lock the IOV into memory. For the first
>>> sendmsg() above it returns NULL and thus wrongly skips the call the host
>>> sendmsg() syscall, which will break the calling application.
>>>
>>> Fix this issue by:
>>> - allowing sendmsg() even with empty IOV
>>> - skip recvmsg() if IOV is NULL
>>> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>>>    indicates some failure like EFAULT on the IOV
>>>
>>> Tested with the debian "ell" package with hppa guest on x86_64 host.
>>>
>>> Signed-off-by: Helge Deller <deller@gmx.de>
>>> ---
>>>   linux-user/syscall.c | 9 +++++++--
>>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>> index a365903a3a..9e2c0a18fc 100644
>>> --- a/linux-user/syscall.c
>>> +++ b/linux-user/syscall.c
>>> @@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>>>                        target_vec, count, send);
>>>       if (vec == NULL) {
>>>           ret = -host_to_target_errno(errno);
>>> -        goto out2;
>>> +        /* allow sending packet without any iov, e.g. with MSG_MORE flag */
>>
>> why don't you check only for count is 0?
>> Somehing like:
>>
>> if (vec == NULL && (count || !send)) {
>
> You mean:
> if (vec == NULL && (!count || !send)) {
>      goto out2;
>
> lock_iovec() sets errno=0 if count==0, but for invalid addresses it sets errno!=0,
> so my current check (for which ret is the same as errno):
>          if (!send || ret) {
>              goto out2;
> exits on memfaults too, while a check for just count==0 would succeed.

forget the above...
Maybe just checking for count==0 would be sufficient. I don't know yet if
there are any other corner cases where replacing the check of
           if (!send || ret) {
with
           if (!send || count==0) {
would behave different.
Checking against errno which is reported back from lock_iovec() seemed more
logical for me. This patch has been as-is in the buildd trees now since weeks
without any problems so far at least.

Helge

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Laurent Vivier]

Le 31/01/2023 à 14:50, Helge Deller a écrit :
> On 1/31/23 14:34, Helge Deller wrote:
>> On 1/31/23 13:28, Laurent Vivier wrote:
>>> Le 12/12/2022 à 18:34, Helge Deller a écrit :
>>>> Applications do call sendmsg() without any IOV, e.g.:
>>>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>>>>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>>>>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>>>>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over 
>>>> t"..., iov_len=183}],
>>>>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>>>>              msg_controllen=24, msg_flags=0}, 0) = 183
>>>>
>>>> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
>>>> and calls lock_iovec() to lock the IOV into memory. For the first
>>>> sendmsg() above it returns NULL and thus wrongly skips the call the host
>>>> sendmsg() syscall, which will break the calling application.
>>>>
>>>> Fix this issue by:
>>>> - allowing sendmsg() even with empty IOV
>>>> - skip recvmsg() if IOV is NULL
>>>> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>>>>    indicates some failure like EFAULT on the IOV
>>>>
>>>> Tested with the debian "ell" package with hppa guest on x86_64 host.
>>>>
>>>> Signed-off-by: Helge Deller <deller@gmx.de>
>>>> ---
>>>>   linux-user/syscall.c | 9 +++++++--
>>>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>>>
>>>> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
>>>> index a365903a3a..9e2c0a18fc 100644
>>>> --- a/linux-user/syscall.c
>>>> +++ b/linux-user/syscall.c
>>>> @@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>>>>                        target_vec, count, send);
>>>>       if (vec == NULL) {
>>>>           ret = -host_to_target_errno(errno);
>>>> -        goto out2;
>>>> +        /* allow sending packet without any iov, e.g. with MSG_MORE flag */
>>>
>>> why don't you check only for count is 0?
>>> Somehing like:
>>>
>>> if (vec == NULL && (count || !send)) {
>>
>> You mean:
>> if (vec == NULL && (!count || !send)) {
>>      goto out2;
>>
>> lock_iovec() sets errno=0 if count==0, but for invalid addresses it sets errno!=0,
>> so my current check (for which ret is the same as errno):
>>          if (!send || ret) {
>>              goto out2;
>> exits on memfaults too, while a check for just count==0 would succeed.
> 
> forget the above...
> Maybe just checking for count==0 would be sufficient. I don't know yet if
> there are any other corner cases where replacing the check of
>            if (!send || ret) {
> with
>            if (!send || count==0) {
> would behave different.
> Checking against errno which is reported back from lock_iovec() seemed more
> logical for me. This patch has been as-is in the buildd trees now since weeks
> without any problems so far at least.
> 

It seems kernel also checks for the invalid address even with count=0, so I'm going to apply this 
patch as-is.

Thanks,
Laurent

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Laurent Vivier]

Le 12/12/2022 à 18:34, Helge Deller a écrit :
> Applications do call sendmsg() without any IOV, e.g.:
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>              msg_controllen=24, msg_flags=0}, 0) = 183
> 
> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
> and calls lock_iovec() to lock the IOV into memory. For the first
> sendmsg() above it returns NULL and thus wrongly skips the call the host
> sendmsg() syscall, which will break the calling application.
> 
> Fix this issue by:
> - allowing sendmsg() even with empty IOV
> - skip recvmsg() if IOV is NULL
> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>    indicates some failure like EFAULT on the IOV
> 
> Tested with the debian "ell" package with hppa guest on x86_64 host.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Re: [PATCH 2/2] linux-user: Allow sendmsg() without IOV

[Laurent Vivier]

Le 12/12/2022 à 18:34, Helge Deller a écrit :
> Applications do call sendmsg() without any IOV, e.g.:
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=NULL, msg_iovlen=0,
>              msg_control=[{cmsg_len=36, cmsg_level=SOL_ALG, cmsg_type=0x2}],
>              msg_controllen=40, msg_flags=0}, MSG_MORE) = 0
>   sendmsg(4, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="The quick brown fox jumps over t"..., iov_len=183}],
>              msg_iovlen=1, msg_control=[{cmsg_len=20, cmsg_level=SOL_ALG, cmsg_type=0x3}],
>              msg_controllen=24, msg_flags=0}, 0) = 183
> 
> The function do_sendrecvmsg_locked() is used for sndmsg() and recvmsg()
> and calls lock_iovec() to lock the IOV into memory. For the first
> sendmsg() above it returns NULL and thus wrongly skips the call the host
> sendmsg() syscall, which will break the calling application.
> 
> Fix this issue by:
> - allowing sendmsg() even with empty IOV
> - skip recvmsg() if IOV is NULL
> - skip both if the return code of do_sendrecvmsg_locked() != 0, which
>    indicates some failure like EFAULT on the IOV
> 
> Tested with the debian "ell" package with hppa guest on x86_64 host.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 9 +++++++--
>   1 file changed, 7 insertions(+), 2 deletions(-)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index a365903a3a..9e2c0a18fc 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -3330,7 +3330,10 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>                        target_vec, count, send);
>       if (vec == NULL) {
>           ret = -host_to_target_errno(errno);
> -        goto out2;
> +        /* allow sending packet without any iov, e.g. with MSG_MORE flag */
> +        if (!send || ret) {
> +            goto out2;
> +        }
>       }
>       msg.msg_iovlen = count;
>       msg.msg_iov = vec;
> @@ -3382,7 +3385,9 @@ static abi_long do_sendrecvmsg_locked(int fd, struct target_msghdr *msgp,
>       }
> 
>   out:
> -    unlock_iovec(vec, target_vec, count, !send);
> +    if (vec) {
> +        unlock_iovec(vec, target_vec, count, !send);
> +    }
>   out2:
>       return ret;
>   }
> --
> 2.38.1
> 
> 

Applied to my linux-user-for-8.0 branch.

Thanks,
Laurent

Re: [PATCH 1/2] linux-user: Implement SOL_ALG encryption support

[Laurent Vivier]

Le 12/12/2022 à 18:34, Helge Deller a écrit :
> Add suport to handle SOL_ALG packets via sendmsg() and recvmsg().
> This allows emulated userspace to use encryption functionality.
> 
> Tested with the debian ell package with hppa guest on x86_64 host.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 71ae867024..a365903a3a 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1871,6 +1871,14 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
>               __get_user(cred->pid, &target_cred->pid);
>               __get_user(cred->uid, &target_cred->uid);
>               __get_user(cred->gid, &target_cred->gid);
> +        } else if (cmsg->cmsg_level == SOL_ALG) {
> +            uint32_t *dst = (uint32_t *)data;
> +
> +            memcpy(dst, target_data, len);
> +            /* fix endianess of first 32-bit word */
> +            if (len >= sizeof(uint32_t)) {
> +                *dst = tswap32(*dst);
> +            }
>           } else {
>               qemu_log_mask(LOG_UNIMP, "Unsupported ancillary data: %d/%d\n",
>                             cmsg->cmsg_level, cmsg->cmsg_type);
> --
> 2.38.1
> 
> 

Reviewed-by: Laurent Vivier <laurent@vivier.eu>

Re: [PATCH 1/2] linux-user: Implement SOL_ALG encryption support

[Laurent Vivier]

Le 12/12/2022 à 18:34, Helge Deller a écrit :
> Add suport to handle SOL_ALG packets via sendmsg() and recvmsg().
> This allows emulated userspace to use encryption functionality.
> 
> Tested with the debian ell package with hppa guest on x86_64 host.
> 
> Signed-off-by: Helge Deller <deller@gmx.de>
> ---
>   linux-user/syscall.c | 8 ++++++++
>   1 file changed, 8 insertions(+)
> 
> diff --git a/linux-user/syscall.c b/linux-user/syscall.c
> index 71ae867024..a365903a3a 100644
> --- a/linux-user/syscall.c
> +++ b/linux-user/syscall.c
> @@ -1871,6 +1871,14 @@ static inline abi_long target_to_host_cmsg(struct msghdr *msgh,
>               __get_user(cred->pid, &target_cred->pid);
>               __get_user(cred->uid, &target_cred->uid);
>               __get_user(cred->gid, &target_cred->gid);
> +        } else if (cmsg->cmsg_level == SOL_ALG) {
> +            uint32_t *dst = (uint32_t *)data;
> +
> +            memcpy(dst, target_data, len);
> +            /* fix endianess of first 32-bit word */
> +            if (len >= sizeof(uint32_t)) {
> +                *dst = tswap32(*dst);
> +            }
>           } else {
>               qemu_log_mask(LOG_UNIMP, "Unsupported ancillary data: %d/%d\n",
>                             cmsg->cmsg_level, cmsg->cmsg_type);
> --
> 2.38.1
> 
> 

Applied to my linux-user-for-8.0 branch.

Thanks,
Laurent