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bh=nGqi3SN32stCXF5/qmcRGZpat5DOF5S0r6YBTnx6GI4=; b=Gd2A8bE7wt3txVGwtywm39BuVK1ezNQ4oHZQKdvtFc61qaSdxj4V/5fdxuNyeUBFiFJOIE zGgChgmQFkNp0FHhnob2P1/5M6KgLLRqCWwdZpCd7YGEuUETGQAlRu2TPS6jnRQP6j0y3R Hc0KTKAkP+EtXlSb2TflFPJABzDQAYs= X-MC-Unique: Jq6HaIslNGejucH0sOrMQw-1 From: "Dr. David Alan Gilbert (git)" To: qemu-devel@nongnu.org, quintela@redhat.com, zhukeqian1@huawei.com, stefanha@redhat.com Subject: [PULL 3/5] virtiofsd: Allow addition or removal of capabilities Date: Fri, 3 Jul 2020 16:27:46 +0100 Message-Id: <20200703152748.277255-4-dgilbert@redhat.com> In-Reply-To: <20200703152748.277255-1-dgilbert@redhat.com> References: <20200703152748.277255-1-dgilbert@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Transfer-Encoding: quoted-printable Received-SPF: pass (zohomail.com: domain of gnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; 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charset="utf-8" From: "Dr. David Alan Gilbert" Allow capabilities to be added or removed from the allowed set for the daemon; e.g. default: CapPrm: 00000000880000df CapEff: 00000000880000df -o modcaps=3D+sys_admin CapPrm: 00000000882000df CapEff: 00000000882000df -o modcaps=3D+sys_admin:-chown CapPrm: 00000000882000de CapEff: 00000000882000de Signed-off-by: Dr. David Alan Gilbert Message-Id: <20200629115420.98443-4-dgilbert@redhat.com> Acked-by: Vivek Goyal Reviewed-by: Stefan Hajnoczi Signed-off-by: Dr. David Alan Gilbert --- docs/tools/virtiofsd.rst | 5 +++ tools/virtiofsd/helper.c | 2 ++ tools/virtiofsd/passthrough_ll.c | 53 ++++++++++++++++++++++++++++++-- 3 files changed, 58 insertions(+), 2 deletions(-) diff --git a/docs/tools/virtiofsd.rst b/docs/tools/virtiofsd.rst index 378594c422..824e713491 100644 --- a/docs/tools/virtiofsd.rst +++ b/docs/tools/virtiofsd.rst @@ -54,6 +54,11 @@ Options * flock|no_flock - Enable/disable flock. The default is ``no_flock``. =20 + * modcaps=3DCAPLIST + Modify the list of capabilities allowed; CAPLIST is a colon separated + list of capabilities, each preceded by either + or -, e.g. + ''+sys_admin:-chown''. + * log_level=3DLEVEL - Print only log messages matching LEVEL or more severe. LEVEL is one of ``err``, ``warn``, ``info``, or ``debug``. The default is ``info``. diff --git a/tools/virtiofsd/helper.c b/tools/virtiofsd/helper.c index 00a1ef666a..3105b6c23a 100644 --- a/tools/virtiofsd/helper.c +++ b/tools/virtiofsd/helper.c @@ -174,6 +174,8 @@ void fuse_cmdline_help(void) " default: no_writeback\n" " -o xattr|no_xattr enable/disable xattr\n" " default: no_xattr\n" + " -o modcaps=3DCAPLIST Modify the list of capabiliti= es\n" + " e.g. -o modcaps=3D+sys_admin:-c= hown\n" " --rlimit-nofile=3D set maximum number of file de= scriptors\n" " (0 leaves rlimit unchanged)\n" " default: min(1000000, fs.file-m= ax - 16384)\n" diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough= _ll.c index 99d562046a..94e0de2d2b 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -145,6 +145,7 @@ struct lo_data { int posix_lock; int xattr; char *source; + char *modcaps; double timeout; int cache; int timeout_set; @@ -170,6 +171,7 @@ static const struct fuse_opt lo_opts[] =3D { { "no_posix_lock", offsetof(struct lo_data, posix_lock), 0 }, { "xattr", offsetof(struct lo_data, xattr), 1 }, { "no_xattr", offsetof(struct lo_data, xattr), 0 }, + { "modcaps=3D%s", offsetof(struct lo_data, modcaps), 0 }, { "timeout=3D%lf", offsetof(struct lo_data, timeout), 0 }, { "timeout=3D", offsetof(struct lo_data, timeout_set), 1 }, { "cache=3Dnone", offsetof(struct lo_data, cache), CACHE_NONE }, @@ -2570,9 +2572,11 @@ static void setup_mounts(const char *source) =20 /* * Only keep whitelisted capabilities that are needed for file system oper= ation + * The (possibly NULL) modcaps_in string passed in is free'd before exit. */ -static void setup_capabilities(void) +static void setup_capabilities(char *modcaps_in) { + char *modcaps =3D modcaps_in; pthread_mutex_lock(&cap.mutex); capng_restore_state(&cap.saved); =20 @@ -2604,6 +2608,51 @@ static void setup_capabilities(void) exit(1); } =20 + /* + * The modcaps option is a colon separated list of caps, + * each preceded by either + or -. + */ + while (modcaps) { + capng_act_t action; + int cap; + + char *next =3D strchr(modcaps, ':'); + if (next) { + *next =3D '\0'; + next++; + } + + switch (modcaps[0]) { + case '+': + action =3D CAPNG_ADD; + break; + + case '-': + action =3D CAPNG_DROP; + break; + + default: + fuse_log(FUSE_LOG_ERR, + "%s: Expecting '+'/'-' in modcaps but found '%c'\n", + __func__, modcaps[0]); + exit(1); + } + cap =3D capng_name_to_capability(modcaps + 1); + if (cap < 0) { + fuse_log(FUSE_LOG_ERR, "%s: Unknown capability '%s'\n", __func= __, + modcaps); + exit(1); + } + if (capng_update(action, CAPNG_PERMITTED | CAPNG_EFFECTIVE, cap)) { + fuse_log(FUSE_LOG_ERR, "%s: capng_update failed for '%s'\n", + __func__, modcaps); + exit(1); + } + + modcaps =3D next; + } + g_free(modcaps_in); + if (capng_apply(CAPNG_SELECT_BOTH)) { fuse_log(FUSE_LOG_ERR, "%s: capng_apply failed\n", __func__); exit(1); @@ -2627,7 +2676,7 @@ static void setup_sandbox(struct lo_data *lo, struct = fuse_session *se, setup_namespaces(lo, se); setup_mounts(lo->source); setup_seccomp(enable_syslog); - setup_capabilities(); + setup_capabilities(g_strdup(lo->modcaps)); } =20 /* Set the maximum number of open file descriptors */ --=20 2.26.2