mirror of https://github.com/omar-polo/gmid.git
resurrect landlock support
this time targetting ABI level 3; partially based on how claudio@ handled it in rpki-client. Fun how this bit of code has come full circle (gmid inspired what I wrote for got, which inspired what was written for rpki-client, which has come back.)
This commit is contained in:
parent
cedef5b09c
commit
4d9d3093d4
8
Makefile
8
Makefile
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@ -43,7 +43,7 @@ GG_OBJS = ${GG_SRCS:.c=.o} ${COBJS}
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TITAN_SRCS = titan.c iri.c log.c utf8.c
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TITAN_OBJS = ${TITAN_SRCS:.c=.o} ${COBJS}
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SRCS = gmid.h log.h parse.y proc.h \
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SRCS = gmid.h landlock_shim.h log.h parse.y proc.h \
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${GMID_SRCS} ${GEMEXP_SRCS} ${GG_SRCS} ${TITAN_SRCS}
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DISTNAME = gmid-${VERSION}
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@ -130,9 +130,9 @@ lint:
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DISTFILES = .cirrus.yml .dockerignore .gitignore ChangeLog LICENSE \
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Makefile README.md config.c configure configure.local.example \
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crypto.c dirs.c fcgi.c ge.c gemexp.1 gg.1 gg.c gmid.8 gmid.c \
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gmid.conf.5 gmid.h iri.c iri.h log.c log.h logger.c mime.c \
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parse.y proc.c proc.h proxy.c puny.c sandbox.c server.c \
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titan.1 titan.c utf8.c utils.c y.tab.c
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gmid.conf.5 gmid.h iri.c iri.h landlock_shim.h log.c log.h \
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logger.c mime.c parse.y proc.c proc.h proxy.c puny.c \
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sandbox.c server.c titan.1 titan.c utf8.c utils.c y.tab.c
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release:
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sed -i -e '/^RELEASE=/s/no/yes' configure
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@ -289,6 +289,7 @@ runtest getdtablecount GETDTABLECOUNT || true
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runtest getdtablesize GETDTABLESIZE || true
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runtest getprogname GETPROGNAME || true
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runtest imsg IMSG "" -lutil libimsg || true
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runtest landlock LANDLOCK || true
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runtest libevent LIBEVENT "" -levent libevent_core|| true
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runtest memmem MEMMEM -D_GNU_SOURCE || true
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runtest openssl OPENSSL "" '-lcrypto -lssl' 'libcrypto libssl' || true
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@ -431,6 +432,7 @@ cat <<__HEREDOC__
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#define VERSION "${VERSION}"
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#define DISABLE_SANDBOX ${DISABLE_SANDBOX}
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#define HAVE_LANDLOCK ${HAVE_LANDLOCK}
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__HEREDOC__
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@ -15,6 +15,7 @@ DISTFILES = ASN1_time_parse.c \
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getentropy.c \
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getprogname.c \
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imsg.c \
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landlock.c \
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libevent.c \
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libevent2.c \
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libtls.c \
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@ -0,0 +1,42 @@
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/*
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* Copyright (c) 2023 Omar Polo <op@omarpolo.com>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <linux/landlock.h>
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#include <sys/prctl.h>
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#include <sys/stat.h>
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#include <sys/syscall.h>
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#ifndef landlock_create_ruleset
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static inline int
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landlock_create_ruleset(const struct landlock_ruleset_attr *attr, size_t size,
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__u32 flags)
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{
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return syscall(__NR_landlock_create_ruleset, attr, size, flags);
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}
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#endif
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int
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main(void)
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{
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int rfd;
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const struct landlock_ruleset_attr rsattr = {
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.handled_access_fs = LANDLOCK_ACCESS_FS_READ_FILE |
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LANDLOCK_ACCESS_FS_READ_DIR
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};
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rfd = landlock_create_ruleset(&rsattr, sizeof(rsattr), 0);
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return rfd == -1;
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}
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207
sandbox.c
207
sandbox.c
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@ -1,5 +1,6 @@
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/*
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* Copyright (c) 2021, 2023 Omar Polo <op@omarpolo.com>
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* Copyright (c) 2022 Claudio Jeker <claudio@openbsd.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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@ -49,6 +50,212 @@ sandbox_logger_process(void)
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fatal("pledge");
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}
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#elif HAVE_LANDLOCK
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#include <linux/landlock.h>
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#include <sys/prctl.h>
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#include <sys/syscall.h>
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#include <sys/types.h>
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#include <errno.h>
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/*
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* What's the deal with landlock? While distro with linux >= 5.13
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* have the struct declarations, libc wrappers are missing. The
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* sample landlock code provided by the authors includes these "shims"
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* in their example for the landlock API until libc provides them.
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*/
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#ifndef landlock_create_ruleset
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static inline int
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landlock_create_ruleset(const struct landlock_ruleset_attr *attr, size_t size,
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__u32 flags)
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{
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return syscall(__NR_landlock_create_ruleset, attr, size, flags);
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}
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#endif
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#ifndef landlock_add_rule
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static inline int
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landlock_add_rule(int ruleset_fd, enum landlock_rule_type type,
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const void *attr, __u32 flags)
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{
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return syscall(__NR_landlock_add_rule, ruleset_fd, type, attr, flags);
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}
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#endif
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#ifndef landlock_restrict_self
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static inline int
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landlock_restrict_self(int ruleset_fd, __u32 flags)
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{
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return syscall(__NR_landlock_restrict_self, ruleset_fd, flags);
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}
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#endif
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/*
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* Maybe we should ship with a full copy of the linux headers because
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* you never know...
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*/
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#ifndef LANDLOCK_ACCESS_FS_REFER
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#define LANDLOCK_ACCESS_FS_REFER (1ULL << 13)
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#endif
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#ifndef LANDLOCK_ACCESS_FS_TRUNCATE
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#define LANDLOCK_ACCESS_FS_TRUNCATE (1ULL << 14)
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#endif
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static int landlock_state;
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static int landlock_fd;
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/*
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* Initialize landlock, which is stupidly complicated.
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*/
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static int
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landlock_init(void)
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{
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struct landlock_ruleset_attr rattr = {
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/*
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* List all capabilities currently defined by landlock.
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* Failure in doing so will implicitly allow those actions
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* (i.e. omitting READ_FILE will allow to read _any_ file.)
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*/
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.handled_access_fs =
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LANDLOCK_ACCESS_FS_EXECUTE |
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LANDLOCK_ACCESS_FS_READ_FILE |
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LANDLOCK_ACCESS_FS_READ_DIR |
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LANDLOCK_ACCESS_FS_WRITE_FILE |
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LANDLOCK_ACCESS_FS_REMOVE_DIR |
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LANDLOCK_ACCESS_FS_REMOVE_FILE |
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LANDLOCK_ACCESS_FS_MAKE_CHAR |
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LANDLOCK_ACCESS_FS_MAKE_DIR |
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LANDLOCK_ACCESS_FS_MAKE_REG |
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LANDLOCK_ACCESS_FS_MAKE_SOCK |
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LANDLOCK_ACCESS_FS_MAKE_FIFO |
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LANDLOCK_ACCESS_FS_MAKE_BLOCK |
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LANDLOCK_ACCESS_FS_MAKE_SYM |
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LANDLOCK_ACCESS_FS_REFER |
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LANDLOCK_ACCESS_FS_TRUNCATE,
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};
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int fd, abi, saved_errno;
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if (prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0) == -1)
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return -1;
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abi = landlock_create_ruleset(NULL, 0, LANDLOCK_CREATE_RULESET_VERSION);
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if (abi == -1)
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return -1;
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if (abi < 2)
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rattr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_REFER;
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if (abi < 3)
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rattr.handled_access_fs &= ~LANDLOCK_ACCESS_FS_TRUNCATE;
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landlock_state = 1;
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return landlock_create_ruleset(&rattr, sizeof(rattr), 0);
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}
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static int
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landlock_lock(void)
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{
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int saved_errno;
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if (landlock_restrict_self(landlock_fd, 0)) {
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saved_errno = errno;
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close(landlock_fd);
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errno = saved_errno;
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landlock_state = -1;
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return -1;
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}
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landlock_state = 2;
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close(landlock_fd);
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return 0;
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}
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static int
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landlock_unveil(const char *path, const char *permissions)
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{
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struct landlock_path_beneath_attr lpba;
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int fd, saved_errno;
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if (landlock_state == 0) {
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if ((landlock_fd = landlock_init()) == -1) {
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landlock_state = -1;
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/* this kernel doesn't have landlock built in */
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if (errno == ENOSYS || errno == EOPNOTSUPP)
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return 0;
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return -1;
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}
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}
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/* no landlock available */
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if (landlock_state == -1)
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return 0;
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if (path == NULL && permissions == NULL)
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return landlock_lock();
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if (path == NULL || permissions == NULL || landlock_state != 1) {
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errno = EINVAL;
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return -1;
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}
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if (!strcmp(permissions, "r")) {
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fd = open(path, O_PATH | O_CLOEXEC);
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if (fd == -1)
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return -1;
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lpba = (struct landlock_path_beneath_attr){
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.allowed_access =
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LANDLOCK_ACCESS_FS_READ_FILE |
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LANDLOCK_ACCESS_FS_READ_DIR,
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.parent_fd = fd,
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};
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if (landlock_add_rule(landlock_fd, LANDLOCK_RULE_PATH_BENEATH,
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&lpba, 0) == -1) {
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saved_errno = errno;
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close(fd);
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errno = saved_errno;
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return -1;
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}
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close(fd);
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}
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return 0;
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}
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void
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sandbox_main_process(void)
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{
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return;
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}
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void
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sandbox_server_process(void)
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{
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if (landlock_unveil("/", "r") == -1)
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fatal("landlock_unveil(/)");
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if (landlock_unveil(NULL, NULL) == -1)
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fatal("landlock_unveil(NULL, NULL)");
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}
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void
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sandbox_crypto_process(void)
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{
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/* contrary to unveil(2), this removes all fs access. */
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if (landlock_unveil(NULL, NULL) == -1)
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fatal("landlock_unveil(NULL, NULL)");
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}
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void
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sandbox_logger_process(void)
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{
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/* contrary to unveil(2), this removes all fs access. */
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if (landlock_unveil(NULL, NULL) == -1)
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fatal("landlock_unveil(NULL, NULL)");
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}
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#else
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void
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