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Message-Id: <20180227004121.3633-10-mic@digikod.net>
Date: Tue, 27 Feb 2018 01:41:19 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: linux-kernel@...r.kernel.org
Cc: Mickaël Salaün <mic@...ikod.net>,
Alexei Starovoitov <ast@...nel.org>,
Andy Lutomirski <luto@...capital.net>,
Arnaldo Carvalho de Melo <acme@...nel.org>,
Casey Schaufler <casey@...aufler-ca.com>,
Daniel Borkmann <daniel@...earbox.net>,
David Drysdale <drysdale@...gle.com>,
"David S . Miller" <davem@...emloft.net>,
"Eric W . Biederman" <ebiederm@...ssion.com>,
James Morris <james.l.morris@...cle.com>, Jann Horn <jann@...jh.net>,
Jonathan Corbet <corbet@....net>,
Michael Kerrisk <mtk.manpages@...il.com>,
Kees Cook <keescook@...omium.org>, Paul Moore <paul@...l-moore.com>,
Sargun Dhillon <sargun@...gun.me>,
"Serge E . Hallyn" <serge@...lyn.com>, Shuah Khan <shuah@...nel.org>,
Tejun Heo <tj@...nel.org>, Thomas Graf <tgraf@...g.ch>,
Tycho Andersen <tycho@...ho.ws>, Will Drewry <wad@...omium.org>,
kernel-hardening@...ts.openwall.com, linux-api@...r.kernel.org,
linux-security-module@...r.kernel.org, netdev@...r.kernel.org
Subject: [PATCH bpf-next v8 09/11] bpf: Add a Landlock sandbox example
Add a basic sandbox tool to launch a command which is only allowed to
access in a read only or read-write way a whitelist of file hierarchies.
Add to the bpf_load library the ability to handle a BPF program subtype.
Signed-off-by: Mickaël Salaün <mic@...ikod.net>
Cc: Alexei Starovoitov <ast@...nel.org>
Cc: Andy Lutomirski <luto@...capital.net>
Cc: Daniel Borkmann <daniel@...earbox.net>
Cc: David S. Miller <davem@...emloft.net>
Cc: James Morris <james.l.morris@...cle.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Serge E. Hallyn <serge@...lyn.com>
---
Changes since v7:
* rewrite the example using an inode map
* add to bpf_load the ability to handle subtypes per program type
Changes since v6:
* check return value of load_and_attach()
* allow to write on pipes
* rename BPF_PROG_TYPE_LANDLOCK to BPF_PROG_TYPE_LANDLOCK_RULE
* rename Landlock version to ABI to better reflect its purpose
* use const variable (suggested by Kees Cook)
* remove useless definitions (suggested by Kees Cook)
* add detailed explanations (suggested by Kees Cook)
Changes since v5:
* cosmetic fixes
* rebase
Changes since v4:
* write Landlock rule in C and compiled it with LLVM
* remove cgroup handling
* remove path handling: only handle a read-only environment
* remove errno return codes
Changes since v3:
* remove seccomp and origin field: completely free from seccomp programs
* handle more FS-related hooks
* handle inode hooks and directory traversal
* add faked but consistent view thanks to ENOENT
* add /lib64 in the example
* fix spelling
* rename some types and definitions (e.g. SECCOMP_ADD_LANDLOCK_RULE)
Changes since v2:
* use BPF_PROG_ATTACH for cgroup handling
---
samples/bpf/Makefile | 4 +
samples/bpf/bpf_load.c | 82 ++++++++++++++++++++-
samples/bpf/bpf_load.h | 7 ++
samples/bpf/landlock1.h | 14 ++++
samples/bpf/landlock1_kern.c | 171 +++++++++++++++++++++++++++++++++++++++++++
samples/bpf/landlock1_user.c | 164 +++++++++++++++++++++++++++++++++++++++++
6 files changed, 439 insertions(+), 3 deletions(-)
create mode 100644 samples/bpf/landlock1.h
create mode 100644 samples/bpf/landlock1_kern.c
create mode 100644 samples/bpf/landlock1_user.c
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index ec3fc8d88e87..015b1375daa5 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -43,6 +43,7 @@ hostprogs-y += xdp_redirect_cpu
hostprogs-y += xdp_monitor
hostprogs-y += xdp_rxq_info
hostprogs-y += syscall_tp
+hostprogs-y += landlock1
# Libbpf dependencies
LIBBPF := ../../tools/lib/bpf/bpf.o ../../tools/lib/bpf/nlattr.o
@@ -93,6 +94,7 @@ xdp_redirect_cpu-objs := bpf_load.o $(LIBBPF) xdp_redirect_cpu_user.o
xdp_monitor-objs := bpf_load.o $(LIBBPF) xdp_monitor_user.o
xdp_rxq_info-objs := bpf_load.o $(LIBBPF) xdp_rxq_info_user.o
syscall_tp-objs := bpf_load.o $(LIBBPF) syscall_tp_user.o
+landlock1-objs := bpf_load.o $(LIBBPF) landlock1_user.o
# Tell kbuild to always build the programs
always := $(hostprogs-y)
@@ -144,6 +146,7 @@ always += xdp_monitor_kern.o
always += xdp_rxq_info_kern.o
always += xdp2skb_meta_kern.o
always += syscall_tp_kern.o
+always += landlock1_kern.o
HOSTCFLAGS += -I$(objtree)/usr/include
HOSTCFLAGS += -I$(srctree)/tools/lib/
@@ -188,6 +191,7 @@ HOSTLOADLIBES_xdp_redirect_cpu += -lelf
HOSTLOADLIBES_xdp_monitor += -lelf
HOSTLOADLIBES_xdp_rxq_info += -lelf
HOSTLOADLIBES_syscall_tp += -lelf
+HOSTLOADLIBES_landlock1 += -lelf
# Allows pointing LLC/CLANG to a LLVM backend with bpf support, redefine on cmdline:
# make samples/bpf/ LLC=~/git/llvm/build/bin/llc CLANG=~/git/llvm/build/bin/clang
diff --git a/samples/bpf/bpf_load.c b/samples/bpf/bpf_load.c
index 5bb37db6054b..f7c91093b2f5 100644
--- a/samples/bpf/bpf_load.c
+++ b/samples/bpf/bpf_load.c
@@ -12,6 +12,7 @@
#include <stdlib.h>
#include <linux/bpf.h>
#include <linux/filter.h>
+#include <linux/landlock.h>
#include <linux/perf_event.h>
#include <linux/netlink.h>
#include <linux/rtnetlink.h>
@@ -43,6 +44,9 @@ int prog_array_fd = -1;
struct bpf_map_data map_data[MAX_MAPS];
int map_data_count = 0;
+struct bpf_subtype_data subtype_data[MAX_PROGS];
+int subtype_data_count = 0;
+
static int populate_prog_array(const char *event, int prog_fd)
{
int ind = atoi(event), err;
@@ -67,12 +71,14 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
bool is_cgroup_sk = strncmp(event, "cgroup/sock", 11) == 0;
bool is_sockops = strncmp(event, "sockops", 7) == 0;
bool is_sk_skb = strncmp(event, "sk_skb", 6) == 0;
+ bool is_landlock = strncmp(event, "landlock", 8) == 0;
size_t insns_cnt = size / sizeof(struct bpf_insn);
enum bpf_prog_type prog_type;
char buf[256];
int fd, efd, err, id;
struct perf_event_attr attr = {};
union bpf_prog_subtype *st = NULL;
+ struct bpf_subtype_data *sd = NULL;
attr.type = PERF_TYPE_TRACEPOINT;
attr.sample_type = PERF_SAMPLE_RAW;
@@ -97,6 +103,50 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
prog_type = BPF_PROG_TYPE_SOCK_OPS;
} else if (is_sk_skb) {
prog_type = BPF_PROG_TYPE_SK_SKB;
+ } else if (is_landlock) {
+ int i, prog_id;
+ const char *event_id = (event + 8);
+
+ if (!isdigit(*event_id)) {
+ printf("invalid prog number\n");
+ return -1;
+ }
+ prog_id = atoi(event_id);
+ for (i = 0; i < subtype_data_count; i++) {
+ if (subtype_data[i].name && strcmp(event,
+ subtype_data[i].name) == 0) {
+ /* save the prog_id for a next program */
+ sd = &subtype_data[i];
+ sd->prog_id = prog_id;
+ st = &sd->subtype;
+ free(sd->name);
+ sd->name = NULL;
+ break;
+ }
+ }
+ if (!st) {
+ printf("missing subtype\n");
+ return -1;
+ }
+ /* automatic conversion of program pointer to FD */
+ if (st->landlock_hook.options & LANDLOCK_OPTION_PREVIOUS) {
+ int previous = -1;
+
+ /* assume the previous program is already loaded */
+ for (i = 0; i < subtype_data_count; i++) {
+ if (subtype_data[i].prog_id ==
+ st->landlock_hook.previous) {
+ previous = subtype_data[i].prog_fd;
+ break;
+ }
+ }
+ if (previous == -1) {
+ printf("could not find the previous program\n");
+ return -1;
+ }
+ st->landlock_hook.previous = previous;
+ }
+ prog_type = BPF_PROG_TYPE_LANDLOCK_HOOK;
} else {
printf("Unknown event '%s'\n", event);
return -1;
@@ -108,10 +158,13 @@ static int load_and_attach(const char *event, struct bpf_insn *prog, int size)
printf("bpf_load_program() err=%d\n%s", errno, bpf_log_buf);
return -1;
}
+ if (sd)
+ sd->prog_fd = fd;
prog_fd[prog_cnt++] = fd;
- if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk)
+ if (is_xdp || is_perf_event || is_cgroup_skb || is_cgroup_sk ||
+ is_landlock)
return 0;
if (is_socket || is_sockops || is_sk_skb) {
@@ -515,6 +568,29 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
data_maps = data;
for (j = 0; j < MAX_MAPS; j++)
map_data[j].fd = -1;
+ } else if (strncmp(shname, "subtype", 7) == 0) {
+ processed_sec[i] = true;
+ if (*(shname + 7) != '/') {
+ printf("invalid name of subtype section");
+ return 1;
+ }
+ if (data->d_size != sizeof(union bpf_prog_subtype)) {
+ printf("invalid size of subtype section: %zd\n",
+ data->d_size);
+ printf("ref: %zd\n",
+ sizeof(union bpf_prog_subtype));
+ return 1;
+ }
+ if (subtype_data_count >= MAX_PROGS) {
+ printf("too many subtype sections");
+ return 1;
+ }
+ memcpy(&subtype_data[subtype_data_count].subtype,
+ data->d_buf,
+ sizeof(union bpf_prog_subtype));
+ subtype_data[subtype_data_count].name =
+ strdup((shname + 8));
+ subtype_data_count++;
} else if (shdr.sh_type == SHT_SYMTAB) {
strtabidx = shdr.sh_link;
symbols = data;
@@ -575,7 +651,6 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
/* load programs */
for (i = 1; i < ehdr.e_shnum; i++) {
-
if (processed_sec[i])
continue;
@@ -590,7 +665,8 @@ static int do_load_bpf_file(const char *path, fixup_map_cb fixup_map)
memcmp(shname, "socket", 6) == 0 ||
memcmp(shname, "cgroup/", 7) == 0 ||
memcmp(shname, "sockops", 7) == 0 ||
- memcmp(shname, "sk_skb", 6) == 0) {
+ memcmp(shname, "sk_skb", 6) == 0 ||
+ memcmp(shname, "landlock", 8) == 0) {
ret = load_and_attach(shname, data->d_buf,
data->d_size);
if (ret != 0)
diff --git a/samples/bpf/bpf_load.h b/samples/bpf/bpf_load.h
index 453c200b389b..b5abe793e271 100644
--- a/samples/bpf/bpf_load.h
+++ b/samples/bpf/bpf_load.h
@@ -24,6 +24,13 @@ struct bpf_map_data {
struct bpf_map_def def;
};
+struct bpf_subtype_data {
+ char *name;
+ int prog_id;
+ int prog_fd;
+ union bpf_prog_subtype subtype;
+};
+
typedef void (*fixup_map_cb)(struct bpf_map_data *map, int idx);
extern int prog_fd[MAX_PROGS];
diff --git a/samples/bpf/landlock1.h b/samples/bpf/landlock1.h
new file mode 100644
index 000000000000..6d0538816088
--- /dev/null
+++ b/samples/bpf/landlock1.h
@@ -0,0 +1,14 @@
+/*
+ * Landlock sample 1 - common header
+ *
+ * Copyright © 2018 Mickaël Salaün <mic@...ikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#define MAP_MARK_READ (1ULL << 63)
+#define MAP_MARK_WRITE (1ULL << 62)
+#define COOKIE_VALUE_FREEZED (1ULL << 61)
+#define _MAP_MARK_MASK (MAP_MARK_READ | MAP_MARK_WRITE | COOKIE_VALUE_FREEZED)
diff --git a/samples/bpf/landlock1_kern.c b/samples/bpf/landlock1_kern.c
new file mode 100644
index 000000000000..113243677ddd
--- /dev/null
+++ b/samples/bpf/landlock1_kern.c
@@ -0,0 +1,171 @@
+/*
+ * Landlock sample 1 - whitelist of read only or read-write file hierarchy
+ *
+ * Copyright © 2017-2018 Mickaël Salaün <mic@...ikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+/*
+ * This file contains a function that will be compiled to eBPF bytecode thanks
+ * to LLVM/Clang.
+ *
+ * Each SEC() means that the following function or variable will be part of a
+ * custom ELF section. This sections are then processed by the userspace part
+ * (see landlock1_user.c) to extract eBPF bytecode and take into account
+ * variables describing the eBPF program subtype or its license.
+ */
+
+#include <uapi/linux/bpf.h>
+#include <uapi/linux/landlock.h>
+
+#include "bpf_helpers.h"
+#include "landlock1.h" /* MAP_MARK_* */
+
+SEC("maps")
+struct bpf_map_def inode_map = {
+ .type = BPF_MAP_TYPE_INODE,
+ .key_size = sizeof(u32),
+ .value_size = sizeof(u64),
+ .max_entries = 20,
+};
+
+SEC("subtype/landlock1")
+static union bpf_prog_subtype _subtype1 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_WALK,
+ }
+};
+
+static __always_inline __u64 update_cookie(__u64 cookie, __u8 lookup,
+ void *inode, void *chain, bool freeze)
+{
+ __u64 map_allow = 0;
+
+ if (cookie == 0) {
+ cookie = bpf_inode_get_tag(inode, chain);
+ if (cookie)
+ return cookie;
+ /* only look for the first match in the map, ignore nested
+ * paths in this example */
+ map_allow = bpf_inode_map_lookup(&inode_map, inode);
+ if (map_allow)
+ cookie = 1 | map_allow;
+ } else {
+ if (cookie & COOKIE_VALUE_FREEZED)
+ return cookie;
+ map_allow = cookie & _MAP_MARK_MASK;
+ cookie &= ~_MAP_MARK_MASK;
+ switch (lookup) {
+ case LANDLOCK_CTX_FS_WALK_INODE_LOOKUP_DOTDOT:
+ cookie--;
+ break;
+ case LANDLOCK_CTX_FS_WALK_INODE_LOOKUP_DOT:
+ break;
+ default:
+ /* ignore _MAP_MARK_MASK overflow in this example */
+ cookie++;
+ break;
+ }
+ if (cookie >= 1)
+ cookie |= map_allow;
+ }
+ /* do not modify the cookie for each fs_pick */
+ if (freeze && cookie)
+ cookie |= COOKIE_VALUE_FREEZED;
+ return cookie;
+}
+
+/*
+ * The function fs_walk() is a simple Landlock program enforced on a set of
+ * processes. This program will be run for each walk through a file path.
+ *
+ * The argument ctx contains the context of the program when it is run, which
+ * enable to evaluate the file path. This context can change for each run of
+ * the program.
+ */
+SEC("landlock1")
+int fs_walk(struct landlock_ctx_fs_walk *ctx)
+{
+ ctx->cookie = update_cookie(ctx->cookie, ctx->inode_lookup,
+ (void *)ctx->inode, (void *)ctx->chain, false);
+ return LANDLOCK_RET_ALLOW;
+}
+
+SEC("subtype/landlock2")
+static union bpf_prog_subtype _subtype2 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .options = LANDLOCK_OPTION_PREVIOUS,
+ .previous = 1, /* landlock1 */
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_CHDIR |
+ LANDLOCK_TRIGGER_FS_PICK_GETATTR |
+ LANDLOCK_TRIGGER_FS_PICK_READDIR |
+ LANDLOCK_TRIGGER_FS_PICK_TRANSFER |
+ LANDLOCK_TRIGGER_FS_PICK_OPEN,
+ }
+};
+
+SEC("landlock2")
+int fs_pick_ro(struct landlock_ctx_fs_pick *ctx)
+{
+ ctx->cookie = update_cookie(ctx->cookie, ctx->inode_lookup,
+ (void *)ctx->inode, (void *)ctx->chain, true);
+ if (ctx->cookie & MAP_MARK_READ)
+ return LANDLOCK_RET_ALLOW;
+ return LANDLOCK_RET_DENY;
+}
+
+SEC("subtype/landlock3")
+static union bpf_prog_subtype _subtype3 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_PICK,
+ .options = LANDLOCK_OPTION_PREVIOUS,
+ .previous = 2, /* landlock2 */
+ .triggers = LANDLOCK_TRIGGER_FS_PICK_APPEND |
+ LANDLOCK_TRIGGER_FS_PICK_CREATE |
+ LANDLOCK_TRIGGER_FS_PICK_LINK |
+ LANDLOCK_TRIGGER_FS_PICK_LINKTO |
+ LANDLOCK_TRIGGER_FS_PICK_LOCK |
+ LANDLOCK_TRIGGER_FS_PICK_MOUNTON |
+ LANDLOCK_TRIGGER_FS_PICK_RENAME |
+ LANDLOCK_TRIGGER_FS_PICK_RENAMETO |
+ LANDLOCK_TRIGGER_FS_PICK_RMDIR |
+ LANDLOCK_TRIGGER_FS_PICK_SETATTR |
+ LANDLOCK_TRIGGER_FS_PICK_UNLINK |
+ LANDLOCK_TRIGGER_FS_PICK_WRITE,
+ }
+};
+
+SEC("landlock3")
+int fs_pick_rw(struct landlock_ctx_fs_pick *ctx)
+{
+ ctx->cookie = update_cookie(ctx->cookie, ctx->inode_lookup,
+ (void *)ctx->inode, (void *)ctx->chain, true);
+ if (ctx->cookie & MAP_MARK_WRITE)
+ return LANDLOCK_RET_ALLOW;
+ return LANDLOCK_RET_DENY;
+}
+
+SEC("subtype/landlock4")
+static union bpf_prog_subtype _subtype4 = {
+ .landlock_hook = {
+ .type = LANDLOCK_HOOK_FS_GET,
+ .options = LANDLOCK_OPTION_PREVIOUS,
+ .previous = 3, /* landlock3 */
+ }
+};
+
+SEC("landlock4")
+int fs_get(struct landlock_ctx_fs_get *ctx)
+{
+ /* save the cookie in the tag for relative path lookup */
+ bpf_landlock_set_tag((void *)ctx->tag_object, (void *)ctx->chain,
+ ctx->cookie & ~COOKIE_VALUE_FREEZED);
+ return LANDLOCK_RET_ALLOW;
+}
+
+SEC("license")
+static const char _license[] = "GPL";
diff --git a/samples/bpf/landlock1_user.c b/samples/bpf/landlock1_user.c
new file mode 100644
index 000000000000..e46e0ca182cd
--- /dev/null
+++ b/samples/bpf/landlock1_user.c
@@ -0,0 +1,164 @@
+/*
+ * Landlock sample 1 - partial read-only filesystem
+ *
+ * Copyright © 2017-2018 Mickaël Salaün <mic@...ikod.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2, as
+ * published by the Free Software Foundation.
+ */
+
+#include "bpf_load.h"
+#include "landlock1.h" /* MAP_MARK_* */
+#include "libbpf.h"
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <fcntl.h> /* open() */
+#include <linux/bpf.h>
+#include <linux/filter.h>
+#include <linux/landlock.h>
+#include <linux/prctl.h>
+#include <linux/seccomp.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/prctl.h>
+#include <sys/syscall.h>
+#include <unistd.h>
+
+#ifndef seccomp
+static int seccomp(unsigned int op, unsigned int flags, void *args)
+{
+ errno = 0;
+ return syscall(__NR_seccomp, op, flags, args);
+}
+#endif
+
+static int apply_sandbox(int prog_fd)
+{
+ int ret = 0;
+
+ /* set up the test sandbox */
+ if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0)) {
+ perror("prctl(no_new_priv)");
+ return 1;
+ }
+ if (seccomp(SECCOMP_PREPEND_LANDLOCK_PROG, 0, &prog_fd)) {
+ perror("seccomp(set_hook)");
+ ret = 1;
+ }
+ close(prog_fd);
+
+ return ret;
+}
+
+#define ENV_FS_PATH_RO_NAME "LL_PATH_RO"
+#define ENV_FS_PATH_RW_NAME "LL_PATH_RW"
+#define ENV_PATH_TOKEN ":"
+
+static int parse_path(char *env_path, const char ***path_list)
+{
+ int i, path_nb = 0;
+
+ if (env_path) {
+ path_nb++;
+ for (i = 0; env_path[i]; i++) {
+ if (env_path[i] == ENV_PATH_TOKEN[0])
+ path_nb++;
+ }
+ }
+ *path_list = malloc(path_nb * sizeof(**path_list));
+ for (i = 0; i < path_nb; i++)
+ (*path_list)[i] = strsep(&env_path, ENV_PATH_TOKEN);
+
+ return path_nb;
+}
+
+static int populate_map(const char *env_var, unsigned long long value,
+ int map_fd)
+{
+ int path_nb, ref_fd, i;
+ char *env_path_name;
+ const char **path_list = NULL;
+
+ env_path_name = getenv(env_var);
+ if (!env_path_name)
+ return 0;
+ env_path_name = strdup(env_path_name);
+ path_nb = parse_path(env_path_name, &path_list);
+
+ for (i = 0; i < path_nb; i++) {
+ ref_fd = open(path_list[i], O_RDONLY | O_CLOEXEC);
+ if (ref_fd < 0) {
+ fprintf(stderr, "Failed to open \"%s\": %s\n",
+ path_list[i],
+ strerror(errno));
+ return 1;
+ }
+ if (bpf_map_update_elem(map_fd, &ref_fd, &value, BPF_ANY)) {
+ fprintf(stderr, "Failed to update the map with"
+ " \"%s\": %s\n", path_list[i],
+ strerror(errno));
+ return 1;
+ }
+ close(ref_fd);
+ }
+ free(env_path_name);
+ return 0;
+}
+
+int main(int argc, char * const argv[], char * const *envp)
+{
+ char filename[256];
+ char *cmd_path;
+ char * const *cmd_argv;
+ int ll_prog;
+
+ if (argc < 2) {
+ fprintf(stderr, "usage: %s <cmd> [args]...\n\n", argv[0]);
+ fprintf(stderr, "Launch a command in a restricted environment.\n");
+ fprintf(stderr, "Environment variables containing paths, each separated by a colon:\n");
+ fprintf(stderr, "* %s: whitelist of allowed files and directories to be read\n",
+ ENV_FS_PATH_RO_NAME);
+ fprintf(stderr, "* %s: whitelist of allowed files and directories to be modified\n",
+ ENV_FS_PATH_RW_NAME);
+ fprintf(stderr, "\nexample:\n"
+ "%s=\"/bin:/lib:/lib64:/usr:${HOME}\" "
+ "%s=\"/tmp:/dev/urandom:/dev/random:/dev/null\" "
+ "%s /bin/sh -i\n",
+ ENV_FS_PATH_RO_NAME, ENV_FS_PATH_RW_NAME, argv[0]);
+ return 1;
+ }
+
+ snprintf(filename, sizeof(filename), "%s_kern.o", argv[0]);
+ if (load_bpf_file(filename)) {
+ printf("%s", bpf_log_buf);
+ return 1;
+ }
+ ll_prog = prog_fd[3]; /* fs_get */
+ if (!ll_prog) {
+ if (errno)
+ printf("load_bpf_file: %s\n", strerror(errno));
+ else
+ printf("load_bpf_file: Error\n");
+ return 1;
+ }
+
+ if (populate_map(ENV_FS_PATH_RO_NAME, MAP_MARK_READ, map_fd[0]))
+ return 1;
+ if (populate_map(ENV_FS_PATH_RW_NAME, MAP_MARK_READ | MAP_MARK_WRITE,
+ map_fd[0]))
+ return 1;
+ close(map_fd[0]);
+
+ fprintf(stderr, "Launching a new sandboxed process\n");
+ if (apply_sandbox(ll_prog))
+ return 1;
+ cmd_path = argv[1];
+ cmd_argv = argv + 1;
+ execve(cmd_path, cmd_argv, envp);
+ perror("Failed to call execve");
+ return 1;
+}
--
2.16.2
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