On 09/10/2014 07:10 AM, Alexei Starovoitov wrote:
eBPF programs are similar to kernel modules. They are loaded by the user process and automatically unloaded when process exits. Each eBPF program is a safe run-to-completion set of instructions. eBPF verifier statically determines that the program terminates and is safe to execute. The following syscall wrapper can be used to load the program: int bpf_prog_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns, int insn_cnt, const char *license) { union bpf_attr attr = { .prog_type = prog_type, .insns = insns, .insn_cnt = insn_cnt, .license = license, }; return bpf(BPF_PROG_LOAD, &attr, sizeof(attr)); } where 'insns' is an array of eBPF instructions and 'license' is a string that must be GPL compatible to call helper functions marked gpl_only Upon succesful load the syscall returns prog_fd. Use close(prog_fd) to unload the program. User space tests and examples follow in the later patches Signed-off-by: Alexei Starovoitov <ast@xxxxxxxxxxxx>
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diff --git a/include/linux/filter.h b/include/linux/filter.h index 4b59edead908..9727616693e5 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -15,6 +15,7 @@ struct sk_buff; struct sock; struct seccomp_data; +struct bpf_prog_info; /* ArgX, context and stack frame pointer register positions. Note, * Arg1, Arg2, Arg3, etc are used as argument mappings of function @@ -302,8 +303,12 @@ struct bpf_work_struct { struct bpf_prog { u16 pages; /* Number of allocated pages */ bool jited; /* Is our filter JIT'ed? */ + bool has_info; /* whether 'info' is valid */ u32 len; /* Number of filter blocks */ - struct sock_fprog_kern *orig_prog; /* Original BPF program */ + union { + struct sock_fprog_kern *orig_prog; /* Original BPF program */ + struct bpf_prog_info *info; + };
All members of this bpf_prog_info should go into bpf_work_struct, as I have intended this to be a ancillary structure here. Since we already allocate this anyway, you can reduce complexity by doing the additional allocation plus remove the has_info member.
struct bpf_work_struct *work; /* Deferred free work struct */ unsigned int (*bpf_func)(const struct sk_buff *skb, const struct bpf_insn *filter); diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 3a03fdf4db0e..1d0411965576 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -99,12 +99,23 @@ enum bpf_cmd {
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+/* called by sockets/tracing/seccomp before attaching program to an event + * pairs with bpf_prog_put() + */
But seccomp already does refcounting on each BPF filter. Or, is the intention to remove this from seccomp?
+struct bpf_prog *bpf_prog_get(u32 ufd) +{ + struct fd f = fdget(ufd); + struct bpf_prog *prog; + + prog = get_prog(f); + + if (IS_ERR(prog)) + return prog; + + atomic_inc(&prog->info->refcnt); + fdput(f); + return prog; +}
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diff --git a/net/core/filter.c b/net/core/filter.c index dfc716ffa44b..d771e4f03745 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -835,6 +835,7 @@ static void bpf_release_orig_filter(struct bpf_prog *fp) { struct sock_fprog_kern *fprog = fp->orig_prog; + BUG_ON(fp->has_info);
Why BUG_ON() (also in so many other places)?
if (fprog) { kfree(fprog->filter); kfree(fprog); @@ -973,6 +974,7 @@ static struct bpf_prog *bpf_prepare_filter(struct bpf_prog *fp) fp->bpf_func = NULL; fp->jited = false; + fp->has_info = false; err = bpf_check_classic(fp->insns, fp->len); if (err) {
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