On 03/01/2013 03:25 PM, Serge Hallyn wrote: > This patch enables lxc-attach to join the profile of the container it > is attaching to. Builds/runs fine with apparmor enabled and disabled. > > Export new aa_get_profile(), and use it for attach_apparmor, but also > handle profile names longer than 100 chars in lxc_start apparmor > support. > > Signed-off-by: Serge Hallyn <serge.hal...@ubuntu.com>
Looks good, test built with/without apparmor to confirm that we don't
get weird failures and it all looks good.
Acked-by: Stéphane Graber <stgra...@ubuntu.com>
> ---
> src/lxc/apparmor.c | 105
> ++++++++++++++++++++++++++++++++++++++++-----------
> src/lxc/apparmor.h | 22 ++++++++++-
> src/lxc/attach.c | 2 +
> src/lxc/attach.h | 1 +
> src/lxc/lxc_attach.c | 6 +++
> 5 files changed, 111 insertions(+), 25 deletions(-)
>
> diff --git a/src/lxc/apparmor.c b/src/lxc/apparmor.c
> index ae3d8f7..c2d1d2f 100644
> --- a/src/lxc/apparmor.c
> +++ b/src/lxc/apparmor.c
> @@ -1,4 +1,5 @@
> #include <stdio.h>
> +#include <stdlib.h>
> #include <unistd.h>
> #include <errno.h>
> #include <sys/types.h>
> @@ -16,21 +17,58 @@ lxc_log_define(lxc_apparmor, lxc);
> #define AA_MOUNT_RESTR "/sys/kernel/security/apparmor/features/mount/mask"
> #define AA_ENABLED_FILE "/sys/module/apparmor/parameters/enabled"
>
> -static int aa_am_unconfined(void)
> +
> +/* caller must free the returned profile */
> +extern char *aa_get_profile(pid_t pid)
> {
> + char path[100], *space;
> int ret;
> - char path[100], p[100];
> - sprintf(path, "/proc/%d/attr/current", getpid());
> - FILE *f = fopen(path, "r");
> - if (!f)
> - return 0;
> - ret = fscanf(f, "%99s", p);
> + char *buf = NULL;
> + int sz = 0;
> + FILE *f;
> +
> + ret = snprintf(path, 100, "/proc/%d/attr/current", pid);
> + if (ret < 0 || ret >= 100) {
> + ERROR("path name too long");
> + return NULL;
> + }
> +again:
> + f = fopen(path, "r");
> + if (!f) {
> + SYSERROR("opening %s\n", path);
> + return NULL;
> + }
> + sz += 1024;
> + buf = realloc(buf, sz);
> + if (!buf) {
> + ERROR("out of memory");
> + fclose(f);
> + return NULL;
> + }
> + ret = fread(buf, 1, sz, f);
> fclose(f);
> - if (ret < 1)
> - return 0;
> - if (strcmp(p, "unconfined") == 0)
> - return 1;
> - return 0;
> + if (ret >= sz)
> + goto again;
> + if (ret < 0) {
> + ERROR("reading %s\n", path);
> + free(buf);
> + return NULL;
> + }
> + space = index(buf, ' ');
> + if (space)
> + *space = '\0';
> + return buf;
> +}
> +
> +static int aa_am_unconfined(void)
> +{
> + char *p = aa_get_profile(getpid());
> + int ret = 0;
> + if (!p || strcmp(p, "unconfined") == 0)
> + ret = 1;
> + if (p)
> + free(p);
> + return ret;
> }
>
> /* aa_getcon is not working right now. Use our hand-rolled version below */
> @@ -61,36 +99,57 @@ extern void apparmor_handler_init(struct lxc_handler
> *handler)
> }
>
> #define AA_DEF_PROFILE "lxc-container-default"
> -extern int apparmor_load(struct lxc_handler *handler)
> +
> +extern int do_apparmor_load(int aa_enabled, char *aa_profile,
> + int umount_proc, int dropprivs)
> {
> - if (!handler->aa_enabled) {
> + if (!aa_enabled) {
> INFO("apparmor not enabled");
> return 0;
> }
> INFO("setting up apparmor");
>
> - if (!handler->conf->aa_profile)
> - handler->conf->aa_profile = AA_DEF_PROFILE;
> + if (!aa_profile)
> + aa_profile = AA_DEF_PROFILE;
>
> - if (strcmp(handler->conf->aa_profile, "unconfined") == 0 &&
> - aa_am_unconfined()) {
> + if (strcmp(aa_profile, "unconfined") == 0 && !dropprivs &&
> aa_am_unconfined()) {
> INFO("apparmor profile unchanged");
> return 0;
> }
>
> - //if (aa_change_onexec(handler->conf->aa_profile) < 0) {
> - if (aa_change_profile(handler->conf->aa_profile) < 0) {
> - SYSERROR("failed to change apparmor profile to %s",
> handler->conf->aa_profile);
> + //if (aa_change_onexec(aa_profile) < 0) {
> + if (aa_change_profile(aa_profile) < 0) {
> + SYSERROR("failed to change apparmor profile to %s", aa_profile);
> return -1;
> }
> - if (handler->conf->lsm_umount_proc == 1)
> + if (umount_proc == 1)
> umount("/proc");
>
> - INFO("changed apparmor profile to %s", handler->conf->aa_profile);
> + INFO("changed apparmor profile to %s", aa_profile);
>
> return 0;
> }
>
> +extern int apparmor_load(struct lxc_handler *handler)
> +{
> + if (!handler->conf->aa_profile)
> + handler->conf->aa_profile = AA_DEF_PROFILE;
> + return do_apparmor_load(handler->aa_enabled,
> + handler->conf->aa_profile,
> + handler->conf->lsm_umount_proc, 0);
> +}
> +
> +extern int attach_apparmor(char *profile)
> +{
> + if (!profile)
> + return 0;
> + if (!check_apparmor_enabled())
> + return 0;
> + if (strcmp(profile, "unconfined") == 0)
> + return 0;
> + return do_apparmor_load(1, profile, 0, 1);
> +}
> +
> /*
> * this will likely move to a generic lsm.c, as selinux and smack will both
> * also want proc mounted in the container so as to transition
> diff --git a/src/lxc/apparmor.h b/src/lxc/apparmor.h
> index af879c0..d714478 100644
> --- a/src/lxc/apparmor.h
> +++ b/src/lxc/apparmor.h
> @@ -3,16 +3,34 @@
>
> struct lxc_handler;
>
> +/*
> + * apparmor_handler_init is really just a wrapper around
> check_apparmor_enabled
> + * to allow us to keep from having #ifdef APPARMOR in start.c
> + */
> +extern void apparmor_handler_init(struct lxc_handler *handler);
> +
> #if HAVE_APPARMOR
> +extern char *aa_get_profile(pid_t pid);
> +extern int do_apparmor_load(int aa_enabled, char *aa_profile,
> + int umount_proc, int dropprivs);
> extern int apparmor_load(struct lxc_handler *handler);
> +extern int attach_apparmor(char *profile);
> extern int lsm_mount_proc_if_needed(char *root_src, char *rootfs_tgt);
> -extern void apparmor_handler_init(struct lxc_handler *handler);
> #else
> +static inline char *aa_get_profile(pid_t pid) {
> + return NULL;
> +}
> +static inline int do_apparmor_load(int aa_enabled, char *aa_profile,
> + int umount_proc, int dropprivs) {
> + return 0;
> +}
> +static inline int attach_apparmor(char *profile) {
> + return 0;
> +}
> static inline int apparmor_load(struct lxc_handler *handler) {
> return 0;
> }
> static inline int lsm_mount_proc_if_needed(char *root_src, char *rootfs_tgt)
> {
> return 0;
> }
> -extern void apparmor_handler_init(struct lxc_handler *handler);
> #endif
> diff --git a/src/lxc/attach.c b/src/lxc/attach.c
> index b86d2f4..af3d7a0 100644
> --- a/src/lxc/attach.c
> +++ b/src/lxc/attach.c
> @@ -44,6 +44,7 @@
> #include "caps.h"
> #include "cgroup.h"
> #include "config.h"
> +#include "apparmor.h"
>
> lxc_log_define(lxc_attach, lxc);
>
> @@ -137,6 +138,7 @@ struct lxc_proc_context_info
> *lxc_proc_get_context_info(pid_t pid)
> errno = ENOENT;
> goto out_error;
> }
> + info->aa_profile = aa_get_profile(pid);
>
> return info;
>
> diff --git a/src/lxc/attach.h b/src/lxc/attach.h
> index aab47e3..4d4f719 100644
> --- a/src/lxc/attach.h
> +++ b/src/lxc/attach.h
> @@ -27,6 +27,7 @@
> #include <sys/types.h>
>
> struct lxc_proc_context_info {
> + char *aa_profile;
> unsigned long personality;
> unsigned long long capability_mask;
> };
> diff --git a/src/lxc/lxc_attach.c b/src/lxc/lxc_attach.c
> index 370bfbc..e1511ef 100644
> --- a/src/lxc/lxc_attach.c
> +++ b/src/lxc/lxc_attach.c
> @@ -41,6 +41,7 @@
> #include "sync.h"
> #include "log.h"
> #include "namespace.h"
> +#include "apparmor.h"
>
> #if HAVE_SYS_PERSONALITY_H
> #include <sys/personality.h>
> @@ -265,6 +266,11 @@ int main(int argc, char *argv[])
> lxc_sync_fini_parent(handler);
> lxc_cgroup_dispose_attach(cgroup_data);
>
> + if (attach_apparmor(init_ctx->aa_profile) < 0) {
> + ERROR("failed switching apparmor profiles");
> + return -1;
> + }
> +
> /* A description of the purpose of this functionality is
> * provided in the lxc-attach(1) manual page. We have to
> * remount here and not in the parent process, otherwise
>
--
Stéphane Graber
Ubuntu developer
http://www.ubuntu.com
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