From 5fe821a9dee241fa450703ab7015d970ee0cfb8d Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Mon, 19 May 2014 14:56:14 -0700 Subject: [PATCH] net: filter: cleanup invocation of internal BPF Kernel API for classic BPF socket filters is: sk_unattached_filter_create() - validate classic BPF, convert, JIT SK_RUN_FILTER() - run it sk_unattached_filter_destroy() - destroy socket filter Cleanup internal BPF kernel API as following: sk_filter_select_runtime() - final step of internal BPF creation. Try to JIT internal BPF program, if JIT is not available select interpreter SK_RUN_FILTER() - run it sk_filter_free() - free internal BPF program Disallow direct calls to BPF interpreter. Execution of the BPF program should be done with SK_RUN_FILTER() macro. Example of internal BPF create, run, destroy: struct sk_filter *fp; fp = kzalloc(sk_filter_size(prog_len), GFP_KERNEL); memcpy(fp->insni, prog, prog_len * sizeof(fp->insni[0])); fp->len = prog_len; sk_filter_select_runtime(fp); SK_RUN_FILTER(fp, ctx); sk_filter_free(fp); Sockets, seccomp, testsuite, tracing are using different ways to populate sk_filter, so first steps of program creation are not common. Signed-off-by: Alexei Starovoitov Acked-by: Daniel Borkmann Signed-off-by: David S. Miller --- include/linux/filter.h | 6 ++---- kernel/seccomp.c | 6 ++---- lib/test_bpf.c | 4 ++-- net/core/filter.c | 44 +++++++++++++++++++++++++++--------------- 4 files changed, 34 insertions(+), 26 deletions(-) diff --git a/include/linux/filter.h b/include/linux/filter.h index 9d5ae0a2c954..7977b3958e25 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -184,10 +184,8 @@ static inline unsigned int sk_filter_size(unsigned int proglen) int sk_filter(struct sock *sk, struct sk_buff *skb); -u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx, - const struct sock_filter_int *insni); -u32 sk_run_filter_int_skb(const struct sk_buff *ctx, - const struct sock_filter_int *insni); +void sk_filter_select_runtime(struct sk_filter *fp); +void sk_filter_free(struct sk_filter *fp); int sk_convert_filter(struct sock_filter *prog, int len, struct sock_filter_int *new_prog, int *new_len); diff --git a/kernel/seccomp.c b/kernel/seccomp.c index 7e02d624cc50..1036b6f2fded 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -273,10 +273,8 @@ static long seccomp_attach_filter(struct sock_fprog *fprog) atomic_set(&filter->usage, 1); filter->prog->len = new_len; - filter->prog->bpf_func = (void *)sk_run_filter_int_seccomp; - /* JIT internal BPF into native HW instructions */ - bpf_int_jit_compile(filter->prog); + sk_filter_select_runtime(filter->prog); /* * If there is an existing filter, make it the prev and don't drop its @@ -340,7 +338,7 @@ void put_seccomp_filter(struct task_struct *tsk) while (orig && atomic_dec_and_test(&orig->usage)) { struct seccomp_filter *freeme = orig; orig = orig->prev; - bpf_jit_free(freeme->prog); + sk_filter_free(freeme->prog); kfree(freeme); } } diff --git a/lib/test_bpf.c b/lib/test_bpf.c index 3603ebcd5d65..e160934430eb 100644 --- a/lib/test_bpf.c +++ b/lib/test_bpf.c @@ -1489,7 +1489,7 @@ static __init int test_bpf(void) memcpy(fp_ext->insns, tests[i].insns_int, fprog.len * 8); fp->len = fprog.len; - fp->bpf_func = sk_run_filter_int_skb; + sk_filter_select_runtime(fp); } else { err = sk_unattached_filter_create(&fp, &fprog); if (tests[i].data_type == EXPECTED_FAIL) { @@ -1516,7 +1516,7 @@ static __init int test_bpf(void) if (tests[i].data_type != SKB_INT) sk_unattached_filter_destroy(fp); else - kfree(fp); + sk_filter_free(fp); if (err) { pr_cont("FAIL %d\n", err); diff --git a/net/core/filter.c b/net/core/filter.c index 32c5b44c537e..7067cb240d3e 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -153,7 +153,7 @@ noinline u64 __bpf_call_base(u64 r1, u64 r2, u64 r3, u64 r4, u64 r5) * keep, 0 for none. @ctx is the data we are operating on, @insn is the * array of filter instructions. */ -unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn) +static unsigned int __sk_run_filter(void *ctx, const struct sock_filter_int *insn) { u64 stack[MAX_BPF_STACK / sizeof(u64)]; u64 regs[MAX_BPF_REG], tmp; @@ -571,15 +571,6 @@ load_byte: return 0; } -u32 sk_run_filter_int_seccomp(const struct seccomp_data *ctx, - const struct sock_filter_int *insni) - __attribute__ ((alias ("__sk_run_filter"))); - -u32 sk_run_filter_int_skb(const struct sk_buff *ctx, - const struct sock_filter_int *insni) - __attribute__ ((alias ("__sk_run_filter"))); -EXPORT_SYMBOL_GPL(sk_run_filter_int_skb); - /* Helper to find the offset of pkt_type in sk_buff structure. We want * to make sure its still a 3bit field starting at a byte boundary; * taken from arch/x86/net/bpf_jit_comp.c. @@ -1397,7 +1388,7 @@ static void sk_filter_release_rcu(struct rcu_head *rcu) struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); sk_release_orig_filter(fp); - bpf_jit_free(fp); + sk_filter_free(fp); } /** @@ -1497,7 +1488,6 @@ static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp, goto out_err_free; } - fp->bpf_func = sk_run_filter_int_skb; fp->len = new_len; /* 2nd pass: remap sock_filter insns into sock_filter_int insns. */ @@ -1510,6 +1500,8 @@ static struct sk_filter *__sk_migrate_filter(struct sk_filter *fp, */ goto out_err_free; + sk_filter_select_runtime(fp); + kfree(old_prog); return fp; @@ -1528,6 +1520,29 @@ void __weak bpf_int_jit_compile(struct sk_filter *prog) { } +/** + * sk_filter_select_runtime - select execution runtime for BPF program + * @fp: sk_filter populated with internal BPF program + * + * try to JIT internal BPF program, if JIT is not available select interpreter + * BPF program will be executed via SK_RUN_FILTER() macro + */ +void sk_filter_select_runtime(struct sk_filter *fp) +{ + fp->bpf_func = (void *) __sk_run_filter; + + /* Probe if internal BPF can be JITed */ + bpf_int_jit_compile(fp); +} +EXPORT_SYMBOL_GPL(sk_filter_select_runtime); + +/* free internal BPF program */ +void sk_filter_free(struct sk_filter *fp) +{ + bpf_jit_free(fp); +} +EXPORT_SYMBOL_GPL(sk_filter_free); + static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp, struct sock *sk) { @@ -1548,12 +1563,9 @@ static struct sk_filter *__sk_prepare_filter(struct sk_filter *fp, /* JIT compiler couldn't process this filter, so do the * internal BPF translation for the optimized interpreter. */ - if (!fp->jited) { + if (!fp->jited) fp = __sk_migrate_filter(fp, sk); - /* Probe if internal BPF can be jit-ed */ - bpf_int_jit_compile(fp); - } return fp; } -- 2.30.2