Use some macros to increase readabiltiy of BPF rules
This commit is contained in:
bovenliggende
77adf09d34
commit
ca0f82790c
122
exile.h
122
exile.h
@ -68,13 +68,6 @@
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#error Seccomp support has not been tested for exile.h for this platform yet
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#endif
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#define SYSCALL(nr, jt) \
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (nr), 0, 1), jt
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#define EXILE_BPF_NOP \
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BPF_STMT(BPF_JMP+BPF_JA,0)
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#define EXILE_UNSHARE_NETWORK 1<<1
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#define EXILE_UNSHARE_USER 1<<2
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#define EXILE_UNSHARE_MOUNT 1<<3
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@ -263,6 +256,34 @@ struct exile_path_policy
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#define EXILE_SYSCALL_DENY_KILL_PROCESS 2
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#define EXILE_SYSCALL_DENY_RET_ERROR 3
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#define EXILE_BPF_NOP \
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BPF_STMT(BPF_JMP+BPF_JA,0)
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#define EXILE_BPF_LOAD_SECCOMP_ARG(nr) \
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[nr])))
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#define EXILE_BPF_CMP_EQ(val,t,f) \
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, val, t, f)
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#define EXILE_BPF_CMP_SET(val,t,f) \
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, val, t, f)
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/* Immediatly go to the syscall action, do not process any other arg filters */
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#define EXILE_BPF_MATCH(argval) \
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EXILE_BPF_CMP_EQ(argval, EXILE_SYSCALL_EXIT_BPF_RETURN, 0)
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#define EXILE_BPF_MATCH_SET(argval) \
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EXILE_BPF_CMP_SET(argval, EXILE_SYSCALL_EXIT_BPF_RETURN, 0)
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/* Immediatly go beyond the syscall action, do not process any other arg filters. What to do with this syscall
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is thus up to the default policy */
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#define EXILE_BPF_NO_MATCH(argval) \
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EXILE_BPF_CMP_EQ(argval, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0)
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#define EXILE_BPF_NO_MATCH_SET(argval) \
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EXILE_BPF_CMP_SET(argval, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0)
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/* Pledge definitions */
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#define EXILE_SYSCALL_PLEDGE_CHOWN ((uint64_t)1<<1)
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#define EXILE_SYSCALL_PLEDGE_CLONE ((uint64_t)1<<2)
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@ -645,64 +666,71 @@ int exile_append_syscall_default_policy(struct exile_policy *exile_policy, unsig
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static int get_pledge_argfilter(long syscall, uint64_t pledge_promises, struct sock_filter *filter)
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{
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/* How to read this:
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* Keep in mind our default action is do deny, unless it's a syscall from an pledge promise. Then it will be
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* accepted if the argument values are good (if we care about them at all).
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* EXILE_BPF_MATCH() means the argument value is good, and the syscall can be accepted
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* EXILE_BPF_NO_MATCH() means the syscall won't be allowed because the value is illegal
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*/
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struct sock_filter mmap_no_exec[] = {
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[2]))),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, PROT_EXEC, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0)};
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EXILE_BPF_LOAD_SECCOMP_ARG(2),
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EXILE_BPF_NO_MATCH(PROT_EXEC)
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};
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struct sock_filter ioctl_default[] = {
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[1]))),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, FIONREAD, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, FIONBIO, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, FIOCLEX, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, FIONCLEX, EXILE_SYSCALL_EXIT_BPF_RETURN, EXILE_SYSCALL_EXIT_BPF_NO_MATCH)
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};
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EXILE_BPF_LOAD_SECCOMP_ARG(1),
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EXILE_BPF_MATCH(FIONREAD),
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EXILE_BPF_MATCH(FIONBIO),
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EXILE_BPF_MATCH(FIOCLEX),
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EXILE_BPF_CMP_EQ(FIONCLEX, EXILE_SYSCALL_EXIT_BPF_RETURN, EXILE_SYSCALL_EXIT_BPF_NO_MATCH)
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};
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/* open() and friends with read-only flags */
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struct sock_filter open_rdonly[] = {
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[1]))),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, O_CREAT, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, O_TMPFILE, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, O_WRONLY, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, O_RDWR, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, O_APPEND, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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EXILE_BPF_LOAD_SECCOMP_ARG(1),
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EXILE_BPF_NO_MATCH_SET(O_CREAT),
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EXILE_BPF_NO_MATCH_SET(O_TMPFILE),
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EXILE_BPF_NO_MATCH_SET(O_WRONLY),
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EXILE_BPF_NO_MATCH_SET(O_RDWR),
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EXILE_BPF_NO_MATCH_SET(O_APPEND),
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};
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struct sock_filter socket_filter[4] = {
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[0]))),
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EXILE_BPF_LOAD_SECCOMP_ARG(0),
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EXILE_BPF_NOP,
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EXILE_BPF_NOP,
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EXILE_BPF_NOP
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};
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struct sock_filter setsockopt_filter[] = {
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[2]))),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, SO_DEBUG, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, SO_SNDBUFFORCE, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0)
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EXILE_BPF_LOAD_SECCOMP_ARG(2),
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EXILE_BPF_NO_MATCH(SO_DEBUG),
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EXILE_BPF_NO_MATCH(SO_SNDBUFFORCE)
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};
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struct sock_filter clone_filter[] = {
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/* It's the first argument for x86_64 */
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[0]))),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_VM, 0, EXILE_SYSCALL_EXIT_BPF_NO_MATCH),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_THREAD, 0, EXILE_SYSCALL_EXIT_BPF_NO_MATCH),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWCGROUP, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWIPC, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWNET, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWNS, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWPID, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWUSER, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0),
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BPF_JUMP(BPF_JMP+BPF_JSET+BPF_K, CLONE_NEWUTS, EXILE_SYSCALL_EXIT_BPF_NO_MATCH, 0)
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EXILE_BPF_LOAD_SECCOMP_ARG(0),
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EXILE_BPF_NO_MATCH_SET(CLONE_VM),
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EXILE_BPF_NO_MATCH_SET(CLONE_THREAD),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWCGROUP),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWIPC),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWNET),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWNS),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWPID),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWUSER),
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EXILE_BPF_NO_MATCH_SET(CLONE_NEWUTS),
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};
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struct sock_filter prctl_default[] ={
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BPF_STMT(BPF_LD+BPF_W+BPF_ABS, (offsetof(struct seccomp_data, args[0]))),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_SET_NO_NEW_PRIVS, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_GET_NO_NEW_PRIVS, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_GET_NAME, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_SET_NAME, EXILE_SYSCALL_EXIT_BPF_RETURN, 0),
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EXILE_BPF_NOP,
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BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_CAPBSET_READ, EXILE_SYSCALL_EXIT_BPF_RETURN, EXILE_SYSCALL_EXIT_BPF_NO_MATCH),
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EXILE_BPF_LOAD_SECCOMP_ARG(0),
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EXILE_BPF_MATCH(PR_SET_NO_NEW_PRIVS),
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EXILE_BPF_MATCH(PR_GET_NO_NEW_PRIVS),
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EXILE_BPF_MATCH(PR_GET_NAME),
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EXILE_BPF_MATCH(PR_SET_NAME),
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EXILE_BPF_CMP_EQ(PR_CAPBSET_READ, EXILE_SYSCALL_EXIT_BPF_RETURN, EXILE_SYSCALL_EXIT_BPF_NO_MATCH),
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};
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int result = 0;
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@ -769,14 +797,14 @@ static int get_pledge_argfilter(long syscall, uint64_t pledge_promises, struct s
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case EXILE_SYS(socket):
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if(pledge_promises & EXILE_SYSCALL_PLEDGE_UNIX)
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{
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socket_filter[current_filter_index] = (struct sock_filter) BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, AF_UNIX, EXILE_SYSCALL_EXIT_BPF_RETURN, 0);
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socket_filter[current_filter_index] = (struct sock_filter) EXILE_BPF_MATCH(AF_UNIX);
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++current_filter_index;
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}
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if(pledge_promises & EXILE_SYSCALL_PLEDGE_INET)
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{
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socket_filter[current_filter_index] = (struct sock_filter) BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, AF_INET, EXILE_SYSCALL_EXIT_BPF_RETURN, 0);
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socket_filter[current_filter_index] = (struct sock_filter) EXILE_BPF_MATCH(AF_INET);
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++current_filter_index;
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socket_filter[current_filter_index] = (struct sock_filter) BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, AF_INET6, EXILE_SYSCALL_EXIT_BPF_RETURN, 0);
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socket_filter[current_filter_index] = (struct sock_filter) EXILE_BPF_MATCH(AF_INET6);
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++current_filter_index;
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}
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socket_filter[current_filter_index-1].jf = EXILE_SYSCALL_EXIT_BPF_NO_MATCH;
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@ -804,7 +832,7 @@ static int get_pledge_argfilter(long syscall, uint64_t pledge_promises, struct s
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}
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if(pledge_promises & EXILE_SYSCALL_PLEDGE_SECCOMP_INSTALL)
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{
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prctl_default[3] = (struct sock_filter) BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, PR_SET_SECCOMP, EXILE_SYSCALL_EXIT_BPF_RETURN, 0);
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prctl_default[3] = (struct sock_filter) EXILE_BPF_MATCH(PR_SET_SECCOMP);
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}
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result = sizeof(prctl_default)/sizeof(prctl_default[0]);
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memcpy(filter, prctl_default, sizeof(prctl_default));
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@ -1278,7 +1306,7 @@ static void append_syscall_to_bpf(struct exile_syscall_policy *syscallpolicy, st
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/* TODO: Return error */
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return;
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}
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struct sock_filter syscall_check = BPF_JUMP(BPF_JMP+BPF_JEQ+BPF_K, (unsigned int) syscall, 0, next_syscall_pc);
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struct sock_filter syscall_check = EXILE_BPF_CMP_EQ((unsigned int) syscall, 0, next_syscall_pc);
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filter[(*start_index)++] = syscall_check;
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--next_syscall_pc;
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