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| author | Alexei Starovoitov <ast@kernel.org> | 2024-04-27 03:25:44 +0300 |
|---|---|---|
| committer | Martin KaFai Lau <martin.lau@kernel.org> | 2024-04-30 00:16:41 +0300 |
| commit | 0db63c0b86e981a1e97d2596d64ceceba1a5470e (patch) | |
| tree | d7e6ddaca356bbd5069fe7a5a8aab2cfa0fe97d7 /kernel/bpf | |
| parent | 89de2db19317fb89a6e9163f33c3a7b23ee75a18 (diff) | |
| download | linux-0db63c0b86e981a1e97d2596d64ceceba1a5470e.tar.xz | |
bpf: Fix verifier assumptions about socket->sk
The verifier assumes that 'sk' field in 'struct socket' is valid
and non-NULL when 'socket' pointer itself is trusted and non-NULL.
That may not be the case when socket was just created and
passed to LSM socket_accept hook.
Fix this verifier assumption and adjust tests.
Reported-by: Liam Wisehart <liamwisehart@meta.com>
Acked-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Fixes: 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20240427002544.68803-1-alexei.starovoitov@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 87ff414899cf..5d42db05315e 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2368,6 +2368,8 @@ static void mark_btf_ld_reg(struct bpf_verifier_env *env, regs[regno].type = PTR_TO_BTF_ID | flag; regs[regno].btf = btf; regs[regno].btf_id = btf_id; + if (type_may_be_null(flag)) + regs[regno].id = ++env->id_gen; } #define DEF_NOT_SUBREG (0) @@ -5400,8 +5402,6 @@ static int check_map_kptr_access(struct bpf_verifier_env *env, u32 regno, */ mark_btf_ld_reg(env, cur_regs(env), value_regno, PTR_TO_BTF_ID, kptr_field->kptr.btf, kptr_field->kptr.btf_id, btf_ld_kptr_type(env, kptr_field)); - /* For mark_ptr_or_null_reg */ - val_reg->id = ++env->id_gen; } else if (class == BPF_STX) { val_reg = reg_state(env, value_regno); if (!register_is_null(val_reg) && @@ -5719,7 +5719,8 @@ static bool is_trusted_reg(const struct bpf_reg_state *reg) return true; /* Types listed in the reg2btf_ids are always trusted */ - if (reg2btf_ids[base_type(reg->type)]) + if (reg2btf_ids[base_type(reg->type)] && + !bpf_type_has_unsafe_modifiers(reg->type)) return true; /* If a register is not referenced, it is trusted if it has the @@ -6339,6 +6340,7 @@ static int bpf_map_direct_read(struct bpf_map *map, int off, int size, u64 *val, #define BTF_TYPE_SAFE_RCU(__type) __PASTE(__type, __safe_rcu) #define BTF_TYPE_SAFE_RCU_OR_NULL(__type) __PASTE(__type, __safe_rcu_or_null) #define BTF_TYPE_SAFE_TRUSTED(__type) __PASTE(__type, __safe_trusted) +#define BTF_TYPE_SAFE_TRUSTED_OR_NULL(__type) __PASTE(__type, __safe_trusted_or_null) /* * Allow list few fields as RCU trusted or full trusted. @@ -6402,7 +6404,7 @@ BTF_TYPE_SAFE_TRUSTED(struct dentry) { struct inode *d_inode; }; -BTF_TYPE_SAFE_TRUSTED(struct socket) { +BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket) { struct sock *sk; }; @@ -6437,11 +6439,20 @@ static bool type_is_trusted(struct bpf_verifier_env *env, BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct linux_binprm)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct file)); BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct dentry)); - BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED(struct socket)); return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, "__safe_trusted"); } +static bool type_is_trusted_or_null(struct bpf_verifier_env *env, + struct bpf_reg_state *reg, + const char *field_name, u32 btf_id) +{ + BTF_TYPE_EMIT(BTF_TYPE_SAFE_TRUSTED_OR_NULL(struct socket)); + + return btf_nested_type_is_trusted(&env->log, reg, field_name, btf_id, + "__safe_trusted_or_null"); +} + static int check_ptr_to_btf_access(struct bpf_verifier_env *env, struct bpf_reg_state *regs, int regno, int off, int size, @@ -6550,6 +6561,8 @@ static int check_ptr_to_btf_access(struct bpf_verifier_env *env, */ if (type_is_trusted(env, reg, field_name, btf_id)) { flag |= PTR_TRUSTED; + } else if (type_is_trusted_or_null(env, reg, field_name, btf_id)) { + flag |= PTR_TRUSTED | PTR_MAYBE_NULL; } else if (in_rcu_cs(env) && !type_may_be_null(reg->type)) { if (type_is_rcu(env, reg, field_name, btf_id)) { /* ignore __rcu tag and mark it MEM_RCU */ |