From 8580ac9404f6240668a026785d7d8856f0530409 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Tue, 15 Oct 2019 20:24:57 -0700 Subject: bpf: Process in-kernel BTF If in-kernel BTF exists parse it and prepare 'struct btf *btf_vmlinux' for further use by the verifier. In-kernel BTF is trusted just like kallsyms and other build artifacts embedded into vmlinux. Yet run this BTF image through BTF verifier to make sure that it is valid and it wasn't mangled during the build. If in-kernel BTF is incorrect it means either gcc or pahole or kernel are buggy. In such case disallow loading BPF programs. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Andrii Nakryiko Acked-by: Martin KaFai Lau Link: https://lore.kernel.org/bpf/20191016032505.2089704-4-ast@kernel.org --- include/linux/btf.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/btf.h') diff --git a/include/linux/btf.h b/include/linux/btf.h index 64cdf2a23d42..55d43bc856be 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -56,6 +56,7 @@ bool btf_type_is_void(const struct btf_type *t); #ifdef CONFIG_BPF_SYSCALL const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id); const char *btf_name_by_offset(const struct btf *btf, u32 offset); +struct btf *btf_parse_vmlinux(void); #else static inline const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) -- cgit v1.2.3 From 3820729160440158a014add69cc0d371061a96b2 Mon Sep 17 00:00:00 2001 From: Martin KaFai Lau Date: Thu, 24 Oct 2019 17:18:11 -0700 Subject: bpf: Prepare btf_ctx_access for non raw_tp use case This patch makes a few changes to btf_ctx_access() to prepare it for non raw_tp use case where the attach_btf_id is not necessary a BTF_KIND_TYPEDEF. It moves the "btf_trace_" prefix check and typedef-follow logic to a new function "check_attach_btf_id()" which is called only once during bpf_check(). btf_ctx_access() only operates on a BTF_KIND_FUNC_PROTO type now. That should also be more efficient since it is done only one instead of every-time check_ctx_access() is called. "check_attach_btf_id()" needs to find the func_proto type from the attach_btf_id. It needs to store the result into the newly added prog->aux->attach_func_proto. func_proto btf type has no name, so a proper name should be stored into "attach_func_name" also. v2: - Move the "btf_trace_" check to an earlier verifier phase (Alexei) Signed-off-by: Martin KaFai Lau Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20191025001811.1718491-1-kafai@fb.com --- include/linux/bpf.h | 5 ++++ include/linux/btf.h | 31 ++++++++++++++++++++ kernel/bpf/btf.c | 73 +++++++++--------------------------------------- kernel/bpf/syscall.c | 4 +-- kernel/bpf/verifier.c | 52 +++++++++++++++++++++++++++++++++- kernel/trace/bpf_trace.c | 2 ++ 6 files changed, 103 insertions(+), 64 deletions(-) (limited to 'include/linux/btf.h') diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 2c2c29b49845..171be30fe0ae 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -392,6 +392,11 @@ struct bpf_prog_aux { u32 attach_btf_id; /* in-kernel BTF type id to attach to */ bool verifier_zext; /* Zero extensions has been inserted by verifier. */ bool offload_requested; + bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */ + /* BTF_KIND_FUNC_PROTO for valid attach_btf_id */ + const struct btf_type *attach_func_proto; + /* function name for valid attach_btf_id */ + const char *attach_func_name; struct bpf_prog **func; void *jit_data; /* JIT specific data. arch dependent */ struct latch_tree_node ksym_tnode; diff --git a/include/linux/btf.h b/include/linux/btf.h index 55d43bc856be..9dee00859c5f 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -5,6 +5,7 @@ #define _LINUX_BTF_H 1 #include +#include struct btf; struct btf_member; @@ -53,6 +54,36 @@ bool btf_member_is_reg_int(const struct btf *btf, const struct btf_type *s, int btf_find_spin_lock(const struct btf *btf, const struct btf_type *t); bool btf_type_is_void(const struct btf_type *t); +static inline bool btf_type_is_ptr(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_PTR; +} + +static inline bool btf_type_is_int(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_INT; +} + +static inline bool btf_type_is_enum(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_ENUM; +} + +static inline bool btf_type_is_typedef(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_TYPEDEF; +} + +static inline bool btf_type_is_func(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC; +} + +static inline bool btf_type_is_func_proto(const struct btf_type *t) +{ + return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO; +} + #ifdef CONFIG_BPF_SYSCALL const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id); const char *btf_name_by_offset(const struct btf *btf, u32 offset); diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index f7557af39756..128d89601d73 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -336,16 +336,6 @@ static bool btf_type_is_fwd(const struct btf_type *t) return BTF_INFO_KIND(t->info) == BTF_KIND_FWD; } -static bool btf_type_is_func(const struct btf_type *t) -{ - return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC; -} - -static bool btf_type_is_func_proto(const struct btf_type *t) -{ - return BTF_INFO_KIND(t->info) == BTF_KIND_FUNC_PROTO; -} - static bool btf_type_nosize(const struct btf_type *t) { return btf_type_is_void(t) || btf_type_is_fwd(t) || @@ -377,16 +367,6 @@ static bool btf_type_is_array(const struct btf_type *t) return BTF_INFO_KIND(t->info) == BTF_KIND_ARRAY; } -static bool btf_type_is_ptr(const struct btf_type *t) -{ - return BTF_INFO_KIND(t->info) == BTF_KIND_PTR; -} - -static bool btf_type_is_int(const struct btf_type *t) -{ - return BTF_INFO_KIND(t->info) == BTF_KIND_INT; -} - static bool btf_type_is_var(const struct btf_type *t) { return BTF_INFO_KIND(t->info) == BTF_KIND_VAR; @@ -3442,54 +3422,27 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, const struct bpf_prog *prog, struct bpf_insn_access_aux *info) { + const struct btf_type *t = prog->aux->attach_func_proto; + const char *tname = prog->aux->attach_func_name; struct bpf_verifier_log *log = info->log; - u32 btf_id = prog->aux->attach_btf_id; const struct btf_param *args; - const struct btf_type *t; - const char prefix[] = "btf_trace_"; - const char *tname; u32 nr_args, arg; - if (!btf_id) - return true; - - if (IS_ERR(btf_vmlinux)) { - bpf_log(log, "btf_vmlinux is malformed\n"); - return false; - } - - t = btf_type_by_id(btf_vmlinux, btf_id); - if (!t || BTF_INFO_KIND(t->info) != BTF_KIND_TYPEDEF) { - bpf_log(log, "btf_id is invalid\n"); - return false; - } - - tname = __btf_name_by_offset(btf_vmlinux, t->name_off); - if (strncmp(prefix, tname, sizeof(prefix) - 1)) { - bpf_log(log, "btf_id points to wrong type name %s\n", tname); - return false; - } - tname += sizeof(prefix) - 1; - - t = btf_type_by_id(btf_vmlinux, t->type); - if (!btf_type_is_ptr(t)) - return false; - t = btf_type_by_id(btf_vmlinux, t->type); - if (!btf_type_is_func_proto(t)) - return false; - if (off % 8) { - bpf_log(log, "raw_tp '%s' offset %d is not multiple of 8\n", + bpf_log(log, "func '%s' offset %d is not multiple of 8\n", tname, off); return false; } arg = off / 8; args = (const struct btf_param *)(t + 1); - /* skip first 'void *__data' argument in btf_trace_##name typedef */ - args++; - nr_args = btf_type_vlen(t) - 1; + nr_args = btf_type_vlen(t); + if (prog->aux->attach_btf_trace) { + /* skip first 'void *__data' argument in btf_trace_##name typedef */ + args++; + nr_args--; + } if (arg >= nr_args) { - bpf_log(log, "raw_tp '%s' doesn't have %d-th argument\n", + bpf_log(log, "func '%s' doesn't have %d-th argument\n", tname, arg); return false; } @@ -3503,7 +3456,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, return true; if (!btf_type_is_ptr(t)) { bpf_log(log, - "raw_tp '%s' arg%d '%s' has type %s. Only pointer access is allowed\n", + "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n", tname, arg, __btf_name_by_offset(btf_vmlinux, t->name_off), btf_kind_str[BTF_INFO_KIND(t->info)]); @@ -3526,11 +3479,11 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, t = btf_type_by_id(btf_vmlinux, t->type); if (!btf_type_is_struct(t)) { bpf_log(log, - "raw_tp '%s' arg%d type %s is not a struct\n", + "func '%s' arg%d type %s is not a struct\n", tname, arg, btf_kind_str[BTF_INFO_KIND(t->info)]); return false; } - bpf_log(log, "raw_tp '%s' arg%d has btf_id %d type %s '%s'\n", + bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n", tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)], __btf_name_by_offset(btf_vmlinux, t->name_off)); return true; diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 16ea3c0db4f6..ff5225759553 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1848,9 +1848,7 @@ static int bpf_raw_tracepoint_open(const union bpf_attr *attr) goto out_put_prog; } /* raw_tp name is taken from type name instead */ - tp_name = kernel_type_name(prog->aux->attach_btf_id); - /* skip the prefix */ - tp_name += sizeof("btf_trace_") - 1; + tp_name = prog->aux->attach_func_name; } else { if (strncpy_from_user(buf, u64_to_user_ptr(attr->raw_tracepoint.name), diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 556e82f8869b..c59778c0fc4d 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9372,6 +9372,52 @@ static void print_verification_stats(struct bpf_verifier_env *env) env->peak_states, env->longest_mark_read_walk); } +static int check_attach_btf_id(struct bpf_verifier_env *env) +{ + struct bpf_prog *prog = env->prog; + u32 btf_id = prog->aux->attach_btf_id; + const struct btf_type *t; + const char *tname; + + if (prog->type == BPF_PROG_TYPE_RAW_TRACEPOINT && btf_id) { + const char prefix[] = "btf_trace_"; + + t = btf_type_by_id(btf_vmlinux, btf_id); + if (!t) { + verbose(env, "attach_btf_id %u is invalid\n", btf_id); + return -EINVAL; + } + if (!btf_type_is_typedef(t)) { + verbose(env, "attach_btf_id %u is not a typedef\n", + btf_id); + return -EINVAL; + } + tname = btf_name_by_offset(btf_vmlinux, t->name_off); + if (!tname || strncmp(prefix, tname, sizeof(prefix) - 1)) { + verbose(env, "attach_btf_id %u points to wrong type name %s\n", + btf_id, tname); + return -EINVAL; + } + tname += sizeof(prefix) - 1; + t = btf_type_by_id(btf_vmlinux, t->type); + if (!btf_type_is_ptr(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + t = btf_type_by_id(btf_vmlinux, t->type); + if (!btf_type_is_func_proto(t)) + /* should never happen in valid vmlinux build */ + return -EINVAL; + + /* remember two read only pointers that are valid for + * the life time of the kernel + */ + prog->aux->attach_func_name = tname; + prog->aux->attach_func_proto = t; + prog->aux->attach_btf_trace = true; + } + return 0; +} + int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, union bpf_attr __user *uattr) { @@ -9435,9 +9481,13 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, /* Either gcc or pahole or kernel are broken. */ verbose(env, "in-kernel BTF is malformed\n"); ret = PTR_ERR(btf_vmlinux); - goto err_unlock; + goto skip_full_check; } + ret = check_attach_btf_id(env); + if (ret) + goto skip_full_check; + env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT); if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)) env->strict_alignment = true; diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c index c3240898cc44..571c25d60710 100644 --- a/kernel/trace/bpf_trace.c +++ b/kernel/trace/bpf_trace.c @@ -1080,6 +1080,8 @@ static bool raw_tp_prog_is_valid_access(int off, int size, return false; if (off % size != 0) return false; + if (!prog->aux->attach_btf_id) + return true; return btf_ctx_access(off, size, type, prog, info); } -- cgit v1.2.3 From 5b92a28aae4dd0f88778d540ecfdcdaec5a41723 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 14 Nov 2019 10:57:17 -0800 Subject: bpf: Support attaching tracing BPF program to other BPF programs Allow FENTRY/FEXIT BPF programs to attach to other BPF programs of any type including their subprograms. This feature allows snooping on input and output packets in XDP, TC programs including their return values. In order to do that the verifier needs to track types not only of vmlinux, but types of other BPF programs as well. The verifier also needs to translate uapi/linux/bpf.h types used by networking programs into kernel internal BTF types used by FENTRY/FEXIT BPF programs. In some cases LLVM optimizations can remove arguments from BPF subprograms without adjusting BTF info that LLVM backend knows. When BTF info disagrees with actual types that the verifiers sees the BPF trampoline has to fallback to conservative and treat all arguments as u64. The FENTRY/FEXIT program can still attach to such subprograms, but it won't be able to recognize pointer types like 'struct sk_buff *' and it won't be able to pass them to bpf_skb_output() for dumping packets to user space. The FENTRY/FEXIT program would need to use bpf_probe_read_kernel() instead. The BPF_PROG_LOAD command is extended with attach_prog_fd field. When it's set to zero the attach_btf_id is one vmlinux BTF type ids. When attach_prog_fd points to previously loaded BPF program the attach_btf_id is BTF type id of main function or one of its subprograms. Signed-off-by: Alexei Starovoitov Signed-off-by: Daniel Borkmann Acked-by: Song Liu Link: https://lore.kernel.org/bpf/20191114185720.1641606-18-ast@kernel.org --- arch/x86/net/bpf_jit_comp.c | 3 +- include/linux/bpf.h | 1 + include/linux/btf.h | 1 + include/uapi/linux/bpf.h | 1 + kernel/bpf/btf.c | 70 +++++++++++++++++++++++++++++++++----- kernel/bpf/core.c | 2 ++ kernel/bpf/syscall.c | 19 ++++++++--- kernel/bpf/verifier.c | 83 +++++++++++++++++++++++++++++++++++++-------- 8 files changed, 152 insertions(+), 28 deletions(-) (limited to 'include/linux/btf.h') diff --git a/arch/x86/net/bpf_jit_comp.c b/arch/x86/net/bpf_jit_comp.c index c06096df9118..2e586f579945 100644 --- a/arch/x86/net/bpf_jit_comp.c +++ b/arch/x86/net/bpf_jit_comp.c @@ -504,7 +504,8 @@ int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t, u8 *prog; int ret; - if (!is_kernel_text((long)ip)) + if (!is_kernel_text((long)ip) && + !is_bpf_text_address((long)ip)) /* BPF trampoline in modules is not supported */ return -EINVAL; diff --git a/include/linux/bpf.h b/include/linux/bpf.h index c70bf04726b4..5b81cde47314 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -495,6 +495,7 @@ struct bpf_prog_aux { u32 func_cnt; /* used by non-func prog as the number of func progs */ u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */ u32 attach_btf_id; /* in-kernel BTF type id to attach to */ + struct bpf_prog *linked_prog; bool verifier_zext; /* Zero extensions has been inserted by verifier. */ bool offload_requested; bool attach_btf_trace; /* true if attaching to BTF-enabled raw tp */ diff --git a/include/linux/btf.h b/include/linux/btf.h index 9dee00859c5f..79d4abc2556a 100644 --- a/include/linux/btf.h +++ b/include/linux/btf.h @@ -88,6 +88,7 @@ static inline bool btf_type_is_func_proto(const struct btf_type *t) const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id); const char *btf_name_by_offset(const struct btf *btf, u32 offset); struct btf *btf_parse_vmlinux(void); +struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog); #else static inline const struct btf_type *btf_type_by_id(const struct btf *btf, u32 type_id) diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index 69c200e6e696..4842a134b202 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -425,6 +425,7 @@ union bpf_attr { __aligned_u64 line_info; /* line info */ __u32 line_info_cnt; /* number of bpf_line_info records */ __u32 attach_btf_id; /* in-kernel BTF type id to attach to */ + __u32 attach_prog_fd; /* 0 to attach to vmlinux */ }; struct { /* anonymous struct used by BPF_OBJ_* commands */ diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index 4620267b186e..40efde5eedcb 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3530,6 +3530,20 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf, return ctx_type; } +static int btf_translate_to_vmlinux(struct bpf_verifier_log *log, + struct btf *btf, + const struct btf_type *t, + enum bpf_prog_type prog_type) +{ + const struct btf_member *prog_ctx_type, *kern_ctx_type; + + prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type); + if (!prog_ctx_type) + return -ENOENT; + kern_ctx_type = prog_ctx_type + 1; + return kern_ctx_type->type; +} + struct btf *btf_parse_vmlinux(void) { struct btf_verifier_env *env = NULL; @@ -3602,15 +3616,29 @@ errout: return ERR_PTR(err); } +struct btf *bpf_prog_get_target_btf(const struct bpf_prog *prog) +{ + struct bpf_prog *tgt_prog = prog->aux->linked_prog; + + if (tgt_prog) { + return tgt_prog->aux->btf; + } else { + return btf_vmlinux; + } +} + bool btf_ctx_access(int off, int size, enum bpf_access_type type, const struct bpf_prog *prog, struct bpf_insn_access_aux *info) { const struct btf_type *t = prog->aux->attach_func_proto; + struct bpf_prog *tgt_prog = prog->aux->linked_prog; + struct btf *btf = bpf_prog_get_target_btf(prog); const char *tname = prog->aux->attach_func_name; struct bpf_verifier_log *log = info->log; const struct btf_param *args; u32 nr_args, arg; + int ret; if (off % 8) { bpf_log(log, "func '%s' offset %d is not multiple of 8\n", @@ -3619,7 +3647,8 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, } arg = off / 8; args = (const struct btf_param *)(t + 1); - nr_args = btf_type_vlen(t); + /* if (t == NULL) Fall back to default BPF prog with 5 u64 arguments */ + nr_args = t ? btf_type_vlen(t) : 5; if (prog->aux->attach_btf_trace) { /* skip first 'void *__data' argument in btf_trace_##name typedef */ args++; @@ -3628,18 +3657,24 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, if (prog->expected_attach_type == BPF_TRACE_FEXIT && arg == nr_args) { + if (!t) + /* Default prog with 5 args. 6th arg is retval. */ + return true; /* function return type */ - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); } else if (arg >= nr_args) { bpf_log(log, "func '%s' doesn't have %d-th argument\n", tname, arg + 1); return false; } else { - t = btf_type_by_id(btf_vmlinux, args[arg].type); + if (!t) + /* Default prog with 5 args */ + return true; + t = btf_type_by_id(btf, args[arg].type); } /* skip modifiers */ while (btf_type_is_modifier(t)) - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); if (btf_type_is_int(t)) /* accessing a scalar */ return true; @@ -3647,7 +3682,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, bpf_log(log, "func '%s' arg%d '%s' has type %s. Only pointer access is allowed\n", tname, arg, - __btf_name_by_offset(btf_vmlinux, t->name_off), + __btf_name_by_offset(btf, t->name_off), btf_kind_str[BTF_INFO_KIND(t->info)]); return false; } @@ -3662,10 +3697,19 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, info->reg_type = PTR_TO_BTF_ID; info->btf_id = t->type; - t = btf_type_by_id(btf_vmlinux, t->type); + if (tgt_prog) { + ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type); + if (ret > 0) { + info->btf_id = ret; + return true; + } else { + return false; + } + } + t = btf_type_by_id(btf, t->type); /* skip modifiers */ while (btf_type_is_modifier(t)) - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); if (!btf_type_is_struct(t)) { bpf_log(log, "func '%s' arg%d type %s is not a struct\n", @@ -3674,7 +3718,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type, } bpf_log(log, "func '%s' arg%d has btf_id %d type %s '%s'\n", tname, arg, info->btf_id, btf_kind_str[BTF_INFO_KIND(t->info)], - __btf_name_by_offset(btf_vmlinux, t->name_off)); + __btf_name_by_offset(btf, t->name_off)); return true; } @@ -3954,6 +3998,16 @@ int btf_distill_func_proto(struct bpf_verifier_log *log, u32 i, nargs; int ret; + if (!func) { + /* BTF function prototype doesn't match the verifier types. + * Fall back to 5 u64 args. + */ + for (i = 0; i < 5; i++) + m->arg_size[i] = 8; + m->ret_size = 8; + m->nr_args = 5; + return 0; + } args = (const struct btf_param *)(func + 1); nargs = btf_type_vlen(func); if (nargs >= MAX_BPF_FUNC_ARGS) { diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index da5a8b8e278f..b5945c3aaa8e 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -2031,6 +2031,8 @@ void bpf_prog_free(struct bpf_prog *fp) { struct bpf_prog_aux *aux = fp->aux; + if (aux->linked_prog) + bpf_prog_put(aux->linked_prog); INIT_WORK(&aux->work, bpf_prog_free_deferred); schedule_work(&aux->work); } diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 43ba647de720..c88c815c2154 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -1577,7 +1577,7 @@ static void bpf_prog_load_fixup_attach_type(union bpf_attr *attr) static int bpf_prog_load_check_attach(enum bpf_prog_type prog_type, enum bpf_attach_type expected_attach_type, - u32 btf_id) + u32 btf_id, u32 prog_fd) { switch (prog_type) { case BPF_PROG_TYPE_TRACING: @@ -1585,7 +1585,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type, return -EINVAL; break; default: - if (btf_id) + if (btf_id || prog_fd) return -EINVAL; break; } @@ -1636,7 +1636,7 @@ bpf_prog_load_check_attach(enum bpf_prog_type prog_type, } /* last field in 'union bpf_attr' used by this command */ -#define BPF_PROG_LOAD_LAST_FIELD attach_btf_id +#define BPF_PROG_LOAD_LAST_FIELD attach_prog_fd static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) { @@ -1679,7 +1679,8 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) bpf_prog_load_fixup_attach_type(attr); if (bpf_prog_load_check_attach(type, attr->expected_attach_type, - attr->attach_btf_id)) + attr->attach_btf_id, + attr->attach_prog_fd)) return -EINVAL; /* plain bpf_prog allocation */ @@ -1689,6 +1690,16 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) prog->expected_attach_type = attr->expected_attach_type; prog->aux->attach_btf_id = attr->attach_btf_id; + if (attr->attach_prog_fd) { + struct bpf_prog *tgt_prog; + + tgt_prog = bpf_prog_get(attr->attach_prog_fd); + if (IS_ERR(tgt_prog)) { + err = PTR_ERR(tgt_prog); + goto free_prog_nouncharge; + } + prog->aux->linked_prog = tgt_prog; + } prog->aux->offload_requested = !!attr->prog_ifindex; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 11910149ca2f..e9dc95a18d44 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9390,13 +9390,17 @@ static void print_verification_stats(struct bpf_verifier_env *env) static int check_attach_btf_id(struct bpf_verifier_env *env) { struct bpf_prog *prog = env->prog; + struct bpf_prog *tgt_prog = prog->aux->linked_prog; u32 btf_id = prog->aux->attach_btf_id; const char prefix[] = "btf_trace_"; + int ret = 0, subprog = -1, i; struct bpf_trampoline *tr; const struct btf_type *t; + bool conservative = true; const char *tname; - int ret = 0; + struct btf *btf; long addr; + u64 key; if (prog->type != BPF_PROG_TYPE_TRACING) return 0; @@ -9405,19 +9409,47 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) verbose(env, "Tracing programs must provide btf_id\n"); return -EINVAL; } - t = btf_type_by_id(btf_vmlinux, btf_id); + btf = bpf_prog_get_target_btf(prog); + if (!btf) { + verbose(env, + "FENTRY/FEXIT program can only be attached to another program annotated with BTF\n"); + return -EINVAL; + } + t = btf_type_by_id(btf, btf_id); if (!t) { verbose(env, "attach_btf_id %u is invalid\n", btf_id); return -EINVAL; } - tname = btf_name_by_offset(btf_vmlinux, t->name_off); + tname = btf_name_by_offset(btf, t->name_off); if (!tname) { verbose(env, "attach_btf_id %u doesn't have a name\n", btf_id); return -EINVAL; } + if (tgt_prog) { + struct bpf_prog_aux *aux = tgt_prog->aux; + + for (i = 0; i < aux->func_info_cnt; i++) + if (aux->func_info[i].type_id == btf_id) { + subprog = i; + break; + } + if (subprog == -1) { + verbose(env, "Subprog %s doesn't exist\n", tname); + return -EINVAL; + } + conservative = aux->func_info_aux[subprog].unreliable; + key = ((u64)aux->id) << 32 | btf_id; + } else { + key = btf_id; + } switch (prog->expected_attach_type) { case BPF_TRACE_RAW_TP: + if (tgt_prog) { + verbose(env, + "Only FENTRY/FEXIT progs are attachable to another BPF prog\n"); + return -EINVAL; + } if (!btf_type_is_typedef(t)) { verbose(env, "attach_btf_id %u is not a typedef\n", btf_id); @@ -9429,11 +9461,11 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) return -EINVAL; } tname += sizeof(prefix) - 1; - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); if (!btf_type_is_ptr(t)) /* should never happen in valid vmlinux build */ return -EINVAL; - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) /* should never happen in valid vmlinux build */ return -EINVAL; @@ -9452,30 +9484,51 @@ static int check_attach_btf_id(struct bpf_verifier_env *env) btf_id); return -EINVAL; } - t = btf_type_by_id(btf_vmlinux, t->type); + t = btf_type_by_id(btf, t->type); if (!btf_type_is_func_proto(t)) return -EINVAL; - tr = bpf_trampoline_lookup(btf_id); + tr = bpf_trampoline_lookup(key); if (!tr) return -ENOMEM; prog->aux->attach_func_name = tname; + /* t is either vmlinux type or another program's type */ prog->aux->attach_func_proto = t; mutex_lock(&tr->mutex); if (tr->func.addr) { prog->aux->trampoline = tr; goto out; } - ret = btf_distill_func_proto(&env->log, btf_vmlinux, t, + if (tgt_prog && conservative) { + prog->aux->attach_func_proto = NULL; + t = NULL; + } + ret = btf_distill_func_proto(&env->log, btf, t, tname, &tr->func.model); if (ret < 0) goto out; - addr = kallsyms_lookup_name(tname); - if (!addr) { - verbose(env, - "The address of function %s cannot be found\n", - tname); - ret = -ENOENT; - goto out; + if (tgt_prog) { + if (!tgt_prog->jited) { + /* for now */ + verbose(env, "Can trace only JITed BPF progs\n"); + ret = -EINVAL; + goto out; + } + if (tgt_prog->type == BPF_PROG_TYPE_TRACING) { + /* prevent cycles */ + verbose(env, "Cannot recursively attach\n"); + ret = -EINVAL; + goto out; + } + addr = (long) tgt_prog->aux->func[subprog]->bpf_func; + } else { + addr = kallsyms_lookup_name(tname); + if (!addr) { + verbose(env, + "The address of function %s cannot be found\n", + tname); + ret = -ENOENT; + goto out; + } } tr->func.addr = (void *)addr; prog->aux->trampoline = tr; -- cgit v1.2.3