| Message ID | 20220208204813.682906-11-vgoyal@redhat.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | virtiofsd: Add support for file security context at file creation | expand |
* Vivek Goyal (vgoyal@redhat.com) wrote: > Provide an option "-o security_label/no_security_label" to enable/disable > security label functionality. By default these are turned off. > > If enabled, server will indicate to client that it is capable of handling > one security label during file creation. Typically this is expected to > be a SELinux label. File server will set this label on the file. It will > try to set it atomically wherever possible. But its not possible in > all the cases. > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> OK, but you have missed some of the docs typos I mentined in the last review; they can be cleared up any time. > --- > docs/tools/virtiofsd.rst | 32 ++++++++++++++++++++++++++++++++ > tools/virtiofsd/helper.c | 1 + > tools/virtiofsd/passthrough_ll.c | 15 +++++++++++++++ > 3 files changed, 48 insertions(+) > > diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst > index 07ac0be551..0c0560203c 100644 > --- a/docs/tools/virtiofsd.rst > +++ b/docs/tools/virtiofsd.rst > @@ -104,6 +104,13 @@ Options > * posix_acl|no_posix_acl - > Enable/disable posix acl support. Posix ACLs are disabled by default. > > + * security_label|no_security_label - > + Enable/disable security label support. Security labels are disabled by > + default. This will allow client to send a MAC label of file during > + file creation. Typically this is expected to be SELinux security > + label. Server will try to set that label on newly created file > + atomically wherever possible. > + > .. option:: --socket-path=PATH > > Listen on vhost-user UNIX domain socket at PATH. > @@ -348,6 +355,31 @@ client arguments or lists returned from the host. This stops > the client seeing any 'security.' attributes on the server and > stops it setting any. > > +SELinux support > +--------------- > +One can enable support for SELinux by running virtiofsd with option > +"-o security_label". But this will try to save guest's security context > +in xattr security.selinux on host and it might fail if host's SELinux > +policy does not permit virtiofsd to do this operation. > + > +Hence, it is preferred to remap guest's "security.selinux" xattr to say > +"trusted.virtiofs.security.selinux" on host. > + > +"-o xattrmap=:map:security.selinux:trusted.virtiofs.:" > + > +This will make sure that guest and host's SELinux xattrs on same file > +remain separate and not interfere with each other. And will allow both > +host and guest to implement their own separate SELinux policies. > + > +Setting trusted xattr on host requires CAP_SYS_ADMIN. So one will need > +add this capability to daemon. > + > +"-o modcaps=+sys_admin" > + > +Giving CAP_SYS_ADMIN increases the risk on system. Now virtiofsd is more > +powerful and if gets compromised, it can do lot of damage to host system. > +So keep this trade-off in my mind while making a decision. > + > Examples > -------- > > diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c > index a8295d975a..e226fc590f 100644 > --- a/tools/virtiofsd/helper.c > +++ b/tools/virtiofsd/helper.c > @@ -187,6 +187,7 @@ void fuse_cmdline_help(void) > " default: no_allow_direct_io\n" > " -o announce_submounts Announce sub-mount points to the guest\n" > " -o posix_acl/no_posix_acl Enable/Disable posix_acl. (default: disabled)\n" > + " -o security_label/no_security_label Enable/Disable security label. (default: disabled)\n" > ); > } > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > index d49128a58d..f3ec6aafe5 100644 > --- a/tools/virtiofsd/passthrough_ll.c > +++ b/tools/virtiofsd/passthrough_ll.c > @@ -181,6 +181,7 @@ struct lo_data { > int user_posix_acl, posix_acl; > /* Keeps track if /proc/<pid>/attr/fscreate should be used or not */ > bool use_fscreate; > + int user_security_label; > }; > > static const struct fuse_opt lo_opts[] = { > @@ -215,6 +216,8 @@ static const struct fuse_opt lo_opts[] = { > { "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 }, > { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 }, > { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 }, > + { "security_label", offsetof(struct lo_data, user_security_label), 1 }, > + { "no_security_label", offsetof(struct lo_data, user_security_label), 0 }, > FUSE_OPT_END > }; > static bool use_syslog = false; > @@ -808,6 +811,17 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) > fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n"); > conn->want &= ~FUSE_CAP_POSIX_ACL; > } > + > + if (lo->user_security_label == 1) { > + if (!(conn->capable & FUSE_CAP_SECURITY_CTX)) { > + fuse_log(FUSE_LOG_ERR, "lo_init: Can not enable security label." > + " kernel does not support FUSE_SECURITY_CTX capability.\n"); > + } > + conn->want |= FUSE_CAP_SECURITY_CTX; > + } else { > + fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling security label\n"); > + conn->want &= ~FUSE_CAP_SECURITY_CTX; > + } > } > > static void lo_getattr(fuse_req_t req, fuse_ino_t ino, > @@ -4279,6 +4293,7 @@ int main(int argc, char *argv[]) > .proc_self_task = -1, > .user_killpriv_v2 = -1, > .user_posix_acl = -1, > + .user_security_label = -1, > }; > struct lo_map_elem *root_elem; > struct lo_map_elem *reserve_elem; > -- > 2.34.1 >
On Mon, Feb 14, 2022 at 01:32:38PM +0000, Dr. David Alan Gilbert wrote: > * Vivek Goyal (vgoyal@redhat.com) wrote: > > Provide an option "-o security_label/no_security_label" to enable/disable > > security label functionality. By default these are turned off. > > > > If enabled, server will indicate to client that it is capable of handling > > one security label during file creation. Typically this is expected to > > be a SELinux label. File server will set this label on the file. It will > > try to set it atomically wherever possible. But its not possible in > > all the cases. > > > > Signed-off-by: Vivek Goyal <vgoyal@redhat.com> > > Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com> > > OK, but you have missed some of the docs typos I mentined in the last > review; they can be cleared up any time. Hi David, I could not find any comments in V5 w.r.t doc typos. I am not sure which email I have missed. Anyway, will be nice if I can take care of these typos in a follow up patch and these patches can be merged. Thanks Vivek > > > --- > > docs/tools/virtiofsd.rst | 32 ++++++++++++++++++++++++++++++++ > > tools/virtiofsd/helper.c | 1 + > > tools/virtiofsd/passthrough_ll.c | 15 +++++++++++++++ > > 3 files changed, 48 insertions(+) > > > > diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst > > index 07ac0be551..0c0560203c 100644 > > --- a/docs/tools/virtiofsd.rst > > +++ b/docs/tools/virtiofsd.rst > > @@ -104,6 +104,13 @@ Options > > * posix_acl|no_posix_acl - > > Enable/disable posix acl support. Posix ACLs are disabled by default. > > > > + * security_label|no_security_label - > > + Enable/disable security label support. Security labels are disabled by > > + default. This will allow client to send a MAC label of file during > > + file creation. Typically this is expected to be SELinux security > > + label. Server will try to set that label on newly created file > > + atomically wherever possible. > > + > > .. option:: --socket-path=PATH > > > > Listen on vhost-user UNIX domain socket at PATH. > > @@ -348,6 +355,31 @@ client arguments or lists returned from the host. This stops > > the client seeing any 'security.' attributes on the server and > > stops it setting any. > > > > +SELinux support > > +--------------- > > +One can enable support for SELinux by running virtiofsd with option > > +"-o security_label". But this will try to save guest's security context > > +in xattr security.selinux on host and it might fail if host's SELinux > > +policy does not permit virtiofsd to do this operation. > > + > > +Hence, it is preferred to remap guest's "security.selinux" xattr to say > > +"trusted.virtiofs.security.selinux" on host. > > + > > +"-o xattrmap=:map:security.selinux:trusted.virtiofs.:" > > + > > +This will make sure that guest and host's SELinux xattrs on same file > > +remain separate and not interfere with each other. And will allow both > > +host and guest to implement their own separate SELinux policies. > > + > > +Setting trusted xattr on host requires CAP_SYS_ADMIN. So one will need > > +add this capability to daemon. > > + > > +"-o modcaps=+sys_admin" > > + > > +Giving CAP_SYS_ADMIN increases the risk on system. Now virtiofsd is more > > +powerful and if gets compromised, it can do lot of damage to host system. > > +So keep this trade-off in my mind while making a decision. > > + > > Examples > > -------- > > > > diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c > > index a8295d975a..e226fc590f 100644 > > --- a/tools/virtiofsd/helper.c > > +++ b/tools/virtiofsd/helper.c > > @@ -187,6 +187,7 @@ void fuse_cmdline_help(void) > > " default: no_allow_direct_io\n" > > " -o announce_submounts Announce sub-mount points to the guest\n" > > " -o posix_acl/no_posix_acl Enable/Disable posix_acl. (default: disabled)\n" > > + " -o security_label/no_security_label Enable/Disable security label. (default: disabled)\n" > > ); > > } > > > > diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c > > index d49128a58d..f3ec6aafe5 100644 > > --- a/tools/virtiofsd/passthrough_ll.c > > +++ b/tools/virtiofsd/passthrough_ll.c > > @@ -181,6 +181,7 @@ struct lo_data { > > int user_posix_acl, posix_acl; > > /* Keeps track if /proc/<pid>/attr/fscreate should be used or not */ > > bool use_fscreate; > > + int user_security_label; > > }; > > > > static const struct fuse_opt lo_opts[] = { > > @@ -215,6 +216,8 @@ static const struct fuse_opt lo_opts[] = { > > { "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 }, > > { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 }, > > { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 }, > > + { "security_label", offsetof(struct lo_data, user_security_label), 1 }, > > + { "no_security_label", offsetof(struct lo_data, user_security_label), 0 }, > > FUSE_OPT_END > > }; > > static bool use_syslog = false; > > @@ -808,6 +811,17 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) > > fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n"); > > conn->want &= ~FUSE_CAP_POSIX_ACL; > > } > > + > > + if (lo->user_security_label == 1) { > > + if (!(conn->capable & FUSE_CAP_SECURITY_CTX)) { > > + fuse_log(FUSE_LOG_ERR, "lo_init: Can not enable security label." > > + " kernel does not support FUSE_SECURITY_CTX capability.\n"); > > + } > > + conn->want |= FUSE_CAP_SECURITY_CTX; > > + } else { > > + fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling security label\n"); > > + conn->want &= ~FUSE_CAP_SECURITY_CTX; > > + } > > } > > > > static void lo_getattr(fuse_req_t req, fuse_ino_t ino, > > @@ -4279,6 +4293,7 @@ int main(int argc, char *argv[]) > > .proc_self_task = -1, > > .user_killpriv_v2 = -1, > > .user_posix_acl = -1, > > + .user_security_label = -1, > > }; > > struct lo_map_elem *root_elem; > > struct lo_map_elem *reserve_elem; > > -- > > 2.34.1 > > > -- > Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK >
diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst index 07ac0be551..0c0560203c 100644 --- a/docs/tools/virtiofsd.rst +++ b/docs/tools/virtiofsd.rst @@ -104,6 +104,13 @@ Options * posix_acl|no_posix_acl - Enable/disable posix acl support. Posix ACLs are disabled by default. + * security_label|no_security_label - + Enable/disable security label support. Security labels are disabled by + default. This will allow client to send a MAC label of file during + file creation. Typically this is expected to be SELinux security + label. Server will try to set that label on newly created file + atomically wherever possible. + .. option:: --socket-path=PATH Listen on vhost-user UNIX domain socket at PATH. @@ -348,6 +355,31 @@ client arguments or lists returned from the host. This stops the client seeing any 'security.' attributes on the server and stops it setting any. +SELinux support +--------------- +One can enable support for SELinux by running virtiofsd with option +"-o security_label". But this will try to save guest's security context +in xattr security.selinux on host and it might fail if host's SELinux +policy does not permit virtiofsd to do this operation. + +Hence, it is preferred to remap guest's "security.selinux" xattr to say +"trusted.virtiofs.security.selinux" on host. + +"-o xattrmap=:map:security.selinux:trusted.virtiofs.:" + +This will make sure that guest and host's SELinux xattrs on same file +remain separate and not interfere with each other. And will allow both +host and guest to implement their own separate SELinux policies. + +Setting trusted xattr on host requires CAP_SYS_ADMIN. So one will need +add this capability to daemon. + +"-o modcaps=+sys_admin" + +Giving CAP_SYS_ADMIN increases the risk on system. Now virtiofsd is more +powerful and if gets compromised, it can do lot of damage to host system. +So keep this trade-off in my mind while making a decision. + Examples -------- diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index a8295d975a..e226fc590f 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -187,6 +187,7 @@ void fuse_cmdline_help(void) " default: no_allow_direct_io\n" " -o announce_submounts Announce sub-mount points to the guest\n" " -o posix_acl/no_posix_acl Enable/Disable posix_acl. (default: disabled)\n" + " -o security_label/no_security_label Enable/Disable security label. (default: disabled)\n" ); } diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index d49128a58d..f3ec6aafe5 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -181,6 +181,7 @@ struct lo_data { int user_posix_acl, posix_acl; /* Keeps track if /proc/<pid>/attr/fscreate should be used or not */ bool use_fscreate; + int user_security_label; }; static const struct fuse_opt lo_opts[] = { @@ -215,6 +216,8 @@ static const struct fuse_opt lo_opts[] = { { "no_killpriv_v2", offsetof(struct lo_data, user_killpriv_v2), 0 }, { "posix_acl", offsetof(struct lo_data, user_posix_acl), 1 }, { "no_posix_acl", offsetof(struct lo_data, user_posix_acl), 0 }, + { "security_label", offsetof(struct lo_data, user_security_label), 1 }, + { "no_security_label", offsetof(struct lo_data, user_security_label), 0 }, FUSE_OPT_END }; static bool use_syslog = false; @@ -808,6 +811,17 @@ static void lo_init(void *userdata, struct fuse_conn_info *conn) fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling posix_acl\n"); conn->want &= ~FUSE_CAP_POSIX_ACL; } + + if (lo->user_security_label == 1) { + if (!(conn->capable & FUSE_CAP_SECURITY_CTX)) { + fuse_log(FUSE_LOG_ERR, "lo_init: Can not enable security label." + " kernel does not support FUSE_SECURITY_CTX capability.\n"); + } + conn->want |= FUSE_CAP_SECURITY_CTX; + } else { + fuse_log(FUSE_LOG_DEBUG, "lo_init: disabling security label\n"); + conn->want &= ~FUSE_CAP_SECURITY_CTX; + } } static void lo_getattr(fuse_req_t req, fuse_ino_t ino, @@ -4279,6 +4293,7 @@ int main(int argc, char *argv[]) .proc_self_task = -1, .user_killpriv_v2 = -1, .user_posix_acl = -1, + .user_security_label = -1, }; struct lo_map_elem *root_elem; struct lo_map_elem *reserve_elem;
Provide an option "-o security_label/no_security_label" to enable/disable security label functionality. By default these are turned off. If enabled, server will indicate to client that it is capable of handling one security label during file creation. Typically this is expected to be a SELinux label. File server will set this label on the file. It will try to set it atomically wherever possible. But its not possible in all the cases. Signed-off-by: Vivek Goyal <vgoyal@redhat.com> --- docs/tools/virtiofsd.rst | 32 ++++++++++++++++++++++++++++++++ tools/virtiofsd/helper.c | 1 + tools/virtiofsd/passthrough_ll.c | 15 +++++++++++++++ 3 files changed, 48 insertions(+)