2019-01-06 12:34:42

by Sugar, David

[permalink] [raw]
Subject: [PATCH 1/2 v2] Allow greeter to start dbus

The display manager lightdm (and I think gdm) start a dbus binary.

This adds (and uses) new interface dbus_exec to start dbus in the xdm domain.

type=AVC msg=audit(1544626796.378:201): avc: denied { execute } for pid=9973 comm="dbus-launch" name="dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
type=AVC msg=audit(1544626796.378:201): avc: denied { read open } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
type=AVC msg=audit(1544626796.378:201): avc: denied { execute_no_trans } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
type=AVC msg=audit(1544626796.378:201): avc: denied { map } for pid=9973 comm="dbus-daemon" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
type=AVC msg=audit(1546551459.112:208): avc: denied { getcap } for pid=6275 comm="dbus-daemon" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tclass=process permissive=1

Signed-off-by: Dave Sugar <[email protected]>
---
policy/modules/services/dbus.if | 21 +++++++++++++++++++++
policy/modules/services/xserver.te | 1 +
2 files changed, 22 insertions(+)

diff --git a/policy/modules/services/dbus.if b/policy/modules/services/dbus.if
index ef829e30..d0eec745 100644
--- a/policy/modules/services/dbus.if
+++ b/policy/modules/services/dbus.if
@@ -17,6 +17,27 @@ interface(`dbus_stub',`
')
')

+########################################
+## <summary>
+## Execute dbus in the caller domain.
+## </summary>
+## <param name="domain">
+## <summary>
+## Domain allowed access.
+## </summary>
+## </param>
+#
+interface(`dbus_exec',`
+ gen_require(`
+ type dbusd_exec_t;
+ ')
+
+ corecmd_search_bin($1)
+ can_exec($1, dbusd_exec_t)
+
+ allow $1 self:process getcap;
+')
+
########################################
## <summary>
## Role access for dbus.
diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
index fa7ce88e..cc717e7f 100644
--- a/policy/modules/services/xserver.te
+++ b/policy/modules/services/xserver.te
@@ -566,6 +566,7 @@ optional_policy(`
')

optional_policy(`
+ dbus_exec(xdm_t)
dbus_system_bus_client(xdm_t)
dbus_connect_system_bus(xdm_t)

--
2.20.1



2019-01-06 12:34:44

by Sugar, David

[permalink] [raw]
Subject: [PATCH 2/2 v2] pam_faillock creates files in /run/faillock

These are changes needed when pam_fallock creates files in /run/faillock
(which is labeled faillog_t). sudo and xdm (and probably other domains)
will create files in this directory for successful and failed login
attempts.

type=AVC msg=audit(1545153126.899:210): avc: denied { search } for pid=8448 comm="lightdm" name="faillock" dev="tmpfs" ino=39318 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545153131.090:214): avc: denied { write } for pid=8448 comm="lightdm" name="faillock" dev="tmpfs" ino=39318 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545153131.090:214): avc: denied { add_name } for pid=8448 comm="lightdm" name="dsugar" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545153131.090:214): avc: denied { create } for pid=8448 comm="lightdm" name="dsugar" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=file permissive=1
type=AVC msg=audit(1545153131.091:215): avc: denied { setattr } for pid=8448 comm="lightdm" name="dsugar" dev="tmpfs" ino=87599 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=file permissive=1

type=AVC msg=audit(1545167205.531:626): avc: denied { search } for pid=8264 comm="sudo" name="faillock" dev="tmpfs" ino=35405 scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545167205.531:627): avc: denied { write } for pid=8264 comm="sudo" name="faillock" dev="tmpfs" ino=35405 scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545167205.531:627): avc: denied { add_name } for pid=8264 comm="sudo" name="root" scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
type=AVC msg=audit(1545167205.531:627): avc: denied { create } for pid=8264 comm="sudo" name="root" scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=sysadm_u:object_r:faillog_t:s0 tclass=file permissive=1

Signed-off-by: Dave Sugar <[email protected]>
---
policy/modules/admin/sudo.if | 2 +-
policy/modules/services/xserver.te | 1 -
policy/modules/system/authlogin.if | 21 +++++++++++++++++++++
3 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/policy/modules/admin/sudo.if b/policy/modules/admin/sudo.if
index 01f408ef..1c1fbe7b 100644
--- a/policy/modules/admin/sudo.if
+++ b/policy/modules/admin/sudo.if
@@ -116,8 +116,8 @@ template(`sudo_role_template',`
auth_run_chk_passwd($1_sudo_t, $2)
# sudo stores a token in the pam_pid directory
auth_manage_pam_pid($1_sudo_t)
+ auth_use_pam($1_sudo_t)
auth_pid_filetrans_pam_var_run($1_sudo_t, dir, "sudo")
- auth_use_nsswitch($1_sudo_t)

init_rw_utmp($1_sudo_t)

diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
index cc717e7f..37fb2a71 100644
--- a/policy/modules/services/xserver.te
+++ b/policy/modules/services/xserver.te
@@ -484,7 +484,6 @@ term_setattr_unallocated_ttys(xdm_t)
auth_domtrans_pam_console(xdm_t)
auth_manage_pam_pid(xdm_t)
auth_manage_pam_console_data(xdm_t)
-auth_rw_faillog(xdm_t)
auth_write_login_records(xdm_t)

# Run telinit->init to shutdown.
diff --git a/policy/modules/system/authlogin.if b/policy/modules/system/authlogin.if
index 9b5e0fe0..8d79af78 100644
--- a/policy/modules/system/authlogin.if
+++ b/policy/modules/system/authlogin.if
@@ -47,6 +47,7 @@ interface(`auth_use_pam',`
# for encrypted homedir
dev_read_sysfs($1)

+ auth_create_faillog($1)
auth_domtrans_chk_passwd($1)
auth_domtrans_upd_passwd($1)
auth_dontaudit_read_shadow($1)
@@ -744,6 +745,26 @@ interface(`auth_append_faillog',`
allow $1 faillog_t:file append_file_perms;
')

+########################################
+## <summary>
+## Create fail log lock (in /run/faillock).
+## </summary>
+## <param name="domain">
+## <summary>
+## Domain allowed access.
+## </summary>
+## </param>
+#
+interface(`auth_create_faillog',`
+ gen_require(`
+ type faillog_t;
+ ')
+
+ auth_rw_faillog($1)
+ create_files_pattern($1, faillog_t, faillog_t)
+ setattr_files_pattern($1, faillog_t, faillog_t)
+')
+
########################################
## <summary>
## Read and write the login failure log.
--
2.20.1


2019-01-06 12:40:34

by Dominick Grift

[permalink] [raw]
Subject: Re: [PATCH 1/2 v2] Allow greeter to start dbus

"Sugar, David" <[email protected]> writes:

> The display manager lightdm (and I think gdm) start a dbus binary.
>
> This adds (and uses) new interface dbus_exec to start dbus in the xdm domain.
>
> type=AVC msg=audit(1544626796.378:201): avc: denied { execute } for pid=9973 comm="dbus-launch" name="dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
> type=AVC msg=audit(1544626796.378:201): avc: denied { read open } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
> type=AVC msg=audit(1544626796.378:201): avc: denied { execute_no_trans } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
> type=AVC msg=audit(1544626796.378:201): avc: denied { map } for pid=9973 comm="dbus-daemon" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
> type=AVC msg=audit(1546551459.112:208): avc: denied { getcap } for pid=6275 comm="dbus-daemon" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tclass=process permissive=1
>
> Signed-off-by: Dave Sugar <[email protected]>
> ---
> policy/modules/services/dbus.if | 21 +++++++++++++++++++++
> policy/modules/services/xserver.te | 1 +
> 2 files changed, 22 insertions(+)
>
> diff --git a/policy/modules/services/dbus.if b/policy/modules/services/dbus.if
> index ef829e30..d0eec745 100644
> --- a/policy/modules/services/dbus.if
> +++ b/policy/modules/services/dbus.if
> @@ -17,6 +17,27 @@ interface(`dbus_stub',`
> ')
> ')
>
> +########################################
> +## <summary>
> +## Execute dbus in the caller domain.
> +## </summary>
> +## <param name="domain">
> +## <summary>
> +## Domain allowed access.
> +## </summary>
> +## </param>
> +#
> +interface(`dbus_exec',`
> + gen_require(`
> + type dbusd_exec_t;
> + ')
> +
> + corecmd_search_bin($1)
> + can_exec($1, dbusd_exec_t)
> +
> + allow $1 self:process getcap;

I would not enclose the getcap rule here. For example I do not believe
you need that permission to be able to `dbus-daemon --version`. Instead I
would add that rule to xserver.te:

allow xdm_t self:process getcap;

> +')
> +
> ########################################
> ## <summary>
> ## Role access for dbus.
> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
> index fa7ce88e..cc717e7f 100644
> --- a/policy/modules/services/xserver.te
> +++ b/policy/modules/services/xserver.te
> @@ -566,6 +566,7 @@ optional_policy(`
> ')
>
> optional_policy(`
> + dbus_exec(xdm_t)
> dbus_system_bus_client(xdm_t)
> dbus_connect_system_bus(xdm_t)

--
Key fingerprint = 5F4D 3CDB D3F8 3652 FBD8 02D5 3B6C 5F1D 2C7B 6B02
https://sks-keyservers.net/pks/lookup?op=get&search=0x3B6C5F1D2C7B6B02
Dominick Grift

2019-01-06 12:47:30

by Dominick Grift

[permalink] [raw]
Subject: Re: [PATCH 2/2 v2] pam_faillock creates files in /run/faillock

"Sugar, David" <[email protected]> writes:

> These are changes needed when pam_fallock creates files in /run/faillock
> (which is labeled faillog_t). sudo and xdm (and probably other domains)
> will create files in this directory for successful and failed login
> attempts.
>
> type=AVC msg=audit(1545153126.899:210): avc: denied { search } for pid=8448 comm="lightdm" name="faillock" dev="tmpfs" ino=39318 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545153131.090:214): avc: denied { write } for pid=8448 comm="lightdm" name="faillock" dev="tmpfs" ino=39318 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545153131.090:214): avc: denied { add_name } for pid=8448 comm="lightdm" name="dsugar" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545153131.090:214): avc: denied { create } for pid=8448 comm="lightdm" name="dsugar" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=file permissive=1
> type=AVC msg=audit(1545153131.091:215): avc: denied { setattr } for pid=8448 comm="lightdm" name="dsugar" dev="tmpfs" ino=87599 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=file permissive=1
>
> type=AVC msg=audit(1545167205.531:626): avc: denied { search } for pid=8264 comm="sudo" name="faillock" dev="tmpfs" ino=35405 scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545167205.531:627): avc: denied { write } for pid=8264 comm="sudo" name="faillock" dev="tmpfs" ino=35405 scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545167205.531:627): avc: denied { add_name } for pid=8264 comm="sudo" name="root" scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=system_u:object_r:faillog_t:s0 tclass=dir permissive=1
> type=AVC msg=audit(1545167205.531:627): avc: denied { create } for pid=8264 comm="sudo" name="root" scontext=sysadm_u:sysadm_r:cleaner_applyconfig_sudo_t:s0-s0:c0.c1023 tcontext=sysadm_u:object_r:faillog_t:s0 tclass=file permissive=1
>
> Signed-off-by: Dave Sugar <[email protected]>
> ---
> policy/modules/admin/sudo.if | 2 +-
> policy/modules/services/xserver.te | 1 -
> policy/modules/system/authlogin.if | 21 +++++++++++++++++++++
> 3 files changed, 22 insertions(+), 2 deletions(-)
>
> diff --git a/policy/modules/admin/sudo.if b/policy/modules/admin/sudo.if
> index 01f408ef..1c1fbe7b 100644
> --- a/policy/modules/admin/sudo.if
> +++ b/policy/modules/admin/sudo.if
> @@ -116,8 +116,8 @@ template(`sudo_role_template',`
> auth_run_chk_passwd($1_sudo_t, $2)
> # sudo stores a token in the pam_pid directory
> auth_manage_pam_pid($1_sudo_t)
> + auth_use_pam($1_sudo_t)
> auth_pid_filetrans_pam_var_run($1_sudo_t, dir, "sudo")
> - auth_use_nsswitch($1_sudo_t)
>
> init_rw_utmp($1_sudo_t)
>
> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
> index cc717e7f..37fb2a71 100644
> --- a/policy/modules/services/xserver.te
> +++ b/policy/modules/services/xserver.te
> @@ -484,7 +484,6 @@ term_setattr_unallocated_ttys(xdm_t)
> auth_domtrans_pam_console(xdm_t)
> auth_manage_pam_pid(xdm_t)
> auth_manage_pam_console_data(xdm_t)
> -auth_rw_faillog(xdm_t)
> auth_write_login_records(xdm_t)
>
> # Run telinit->init to shutdown.
> diff --git a/policy/modules/system/authlogin.if b/policy/modules/system/authlogin.if
> index 9b5e0fe0..8d79af78 100644
> --- a/policy/modules/system/authlogin.if
> +++ b/policy/modules/system/authlogin.if
> @@ -47,6 +47,7 @@ interface(`auth_use_pam',`
> # for encrypted homedir
> dev_read_sysfs($1)
>
> + auth_create_faillog($1)

auth_create_faillog_files($1)
auth_rw_faillog($1)
auth_setattr_faillog_files($1)

> auth_domtrans_chk_passwd($1)
> auth_domtrans_upd_passwd($1)
> auth_dontaudit_read_shadow($1)
> @@ -744,6 +745,26 @@ interface(`auth_append_faillog',`
> allow $1 faillog_t:file append_file_perms;
> ')
>
> +########################################
> +## <summary>
> +## Create fail log lock (in /run/faillock).
> +## </summary>
> +## <param name="domain">
> +## <summary>
> +## Domain allowed access.
> +## </summary>
> +## </param>
> +#
> +interface(`auth_create_faillog',`
> + gen_require(`
> + type faillog_t;
> + ')
> +
> + auth_rw_faillog($1)
> + create_files_pattern($1, faillog_t, faillog_t)
> + setattr_files_pattern($1, faillog_t, faillog_t)
> +')

interface name is not accurate: auth_create_faillog_files()
auth_rw_faillog does not belong here
setattr needs a seperate interface: auth_setattr_faillog_files()

> +
> ########################################
> ## <summary>
> ## Read and write the login failure log.

--
Key fingerprint = 5F4D 3CDB D3F8 3652 FBD8 02D5 3B6C 5F1D 2C7B 6B02
https://sks-keyservers.net/pks/lookup?op=get&search=0x3B6C5F1D2C7B6B02
Dominick Grift

2019-01-06 12:50:54

by Sugar, David

[permalink] [raw]
Subject: Re: [PATCH 1/2 v2] Allow greeter to start dbus


On 1/6/19 7:40 AM, Dominick Grift wrote:
> "Sugar, David" <[email protected]> writes:
>
>> The display manager lightdm (and I think gdm) start a dbus binary.
>>
>> This adds (and uses) new interface dbus_exec to start dbus in the xdm domain.
>>
>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute } for pid=9973 comm="dbus-launch" name="dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>> type=AVC msg=audit(1544626796.378:201): avc: denied { read open } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute_no_trans } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>> type=AVC msg=audit(1544626796.378:201): avc: denied { map } for pid=9973 comm="dbus-daemon" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>> type=AVC msg=audit(1546551459.112:208): avc: denied { getcap } for pid=6275 comm="dbus-daemon" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tclass=process permissive=1
>>
>> Signed-off-by: Dave Sugar <[email protected]>
>> ---
>> policy/modules/services/dbus.if | 21 +++++++++++++++++++++
>> policy/modules/services/xserver.te | 1 +
>> 2 files changed, 22 insertions(+)
>>
>> diff --git a/policy/modules/services/dbus.if b/policy/modules/services/dbus.if
>> index ef829e30..d0eec745 100644
>> --- a/policy/modules/services/dbus.if
>> +++ b/policy/modules/services/dbus.if
>> @@ -17,6 +17,27 @@ interface(`dbus_stub',`
>> ')
>> ')
>>
>> +########################################
>> +## <summary>
>> +## Execute dbus in the caller domain.
>> +## </summary>
>> +## <param name="domain">
>> +## <summary>
>> +## Domain allowed access.
>> +## </summary>
>> +## </param>
>> +#
>> +interface(`dbus_exec',`
>> + gen_require(`
>> + type dbusd_exec_t;
>> + ')
>> +
>> + corecmd_search_bin($1)
>> + can_exec($1, dbusd_exec_t)
>> +
>> + allow $1 self:process getcap;
> I would not enclose the getcap rule here. For example I do not believe
> you need that permission to be able to `dbus-daemon --version`. Instead I
> would add that rule to xserver.te:
>
> allow xdm_t self:process getcap;

I did it this way due to the fact that it is dbus-daemon needing the
getcap permission not lightdm.  So other processes that use the
dbus_exec interface will also need this permission.  I'm happy separate
just worry it won't be clear why getcap will be added in several places
due to this.

>> +')
>> +
>> ########################################
>> ## <summary>
>> ## Role access for dbus.
>> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
>> index fa7ce88e..cc717e7f 100644
>> --- a/policy/modules/services/xserver.te
>> +++ b/policy/modules/services/xserver.te
>> @@ -566,6 +566,7 @@ optional_policy(`
>> ')
>>
>> optional_policy(`
>> + dbus_exec(xdm_t)
>> dbus_system_bus_client(xdm_t)
>> dbus_connect_system_bus(xdm_t)

2019-01-06 12:55:01

by Dominick Grift

[permalink] [raw]
Subject: Re: [PATCH 1/2 v2] Allow greeter to start dbus

"Sugar, David" <[email protected]> writes:

> On 1/6/19 7:40 AM, Dominick Grift wrote:
>> "Sugar, David" <[email protected]> writes:
>>
>>> The display manager lightdm (and I think gdm) start a dbus binary.
>>>
>>> This adds (and uses) new interface dbus_exec to start dbus in the xdm domain.
>>>
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute } for pid=9973 comm="dbus-launch" name="dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { read open } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { execute_no_trans } for pid=9973 comm="dbus-launch" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1544626796.378:201): avc: denied { map } for pid=9973 comm="dbus-daemon" path="/usr/bin/dbus-daemon" dev="dm-1" ino=6695040 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:dbusd_exec_t:s0 tclass=file permissive=1
>>> type=AVC msg=audit(1546551459.112:208): avc: denied { getcap } for pid=6275 comm="dbus-daemon" scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tclass=process permissive=1
>>>
>>> Signed-off-by: Dave Sugar <[email protected]>
>>> ---
>>> policy/modules/services/dbus.if | 21 +++++++++++++++++++++
>>> policy/modules/services/xserver.te | 1 +
>>> 2 files changed, 22 insertions(+)
>>>
>>> diff --git a/policy/modules/services/dbus.if b/policy/modules/services/dbus.if
>>> index ef829e30..d0eec745 100644
>>> --- a/policy/modules/services/dbus.if
>>> +++ b/policy/modules/services/dbus.if
>>> @@ -17,6 +17,27 @@ interface(`dbus_stub',`
>>> ')
>>> ')
>>>
>>> +########################################
>>> +## <summary>
>>> +## Execute dbus in the caller domain.
>>> +## </summary>
>>> +## <param name="domain">
>>> +## <summary>
>>> +## Domain allowed access.
>>> +## </summary>
>>> +## </param>
>>> +#
>>> +interface(`dbus_exec',`
>>> + gen_require(`
>>> + type dbusd_exec_t;
>>> + ')
>>> +
>>> + corecmd_search_bin($1)
>>> + can_exec($1, dbusd_exec_t)
>>> +
>>> + allow $1 self:process getcap;
>> I would not enclose the getcap rule here. For example I do not believe
>> you need that permission to be able to `dbus-daemon --version`. Instead I
>> would add that rule to xserver.te:
>>
>> allow xdm_t self:process getcap;
>
> I did it this way due to the fact that it is dbus-daemon needing the
> getcap permission not lightdm.  So other processes that use the
> dbus_exec interface will also need this permission.  I'm happy separate
> just worry it won't be clear why getcap will be added in several places
> due to this.
>

`dbus-daemon --version` does not seem to require getcap

executing dbus potentially requires many permissions but that does not
mean that we should add these permissions to dbus_exec()

>>> +')
>>> +
>>> ########################################
>>> ## <summary>
>>> ## Role access for dbus.
>>> diff --git a/policy/modules/services/xserver.te b/policy/modules/services/xserver.te
>>> index fa7ce88e..cc717e7f 100644
>>> --- a/policy/modules/services/xserver.te
>>> +++ b/policy/modules/services/xserver.te
>>> @@ -566,6 +566,7 @@ optional_policy(`
>>> ')
>>>
>>> optional_policy(`
>>> + dbus_exec(xdm_t)
>>> dbus_system_bus_client(xdm_t)
>>> dbus_connect_system_bus(xdm_t)

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Dominick Grift