From: Alexei Starovoitov <alexei.starovoitov@gmail.com>
To: davem@davemloft.net
Cc: daniel@iogearbox.net, andrii@kernel.org,
john.fastabend@gmail.com, bpf@vger.kernel.org,
kernel-team@fb.com
Subject: [PATCH v4 bpf-next 16/22] libbpf: Cleanup temp FDs when intermediate sys_bpf fails.
Date: Fri, 7 May 2021 20:48:31 -0700 [thread overview]
Message-ID: <20210508034837.64585-17-alexei.starovoitov@gmail.com> (raw)
In-Reply-To: <20210508034837.64585-1-alexei.starovoitov@gmail.com>
From: Alexei Starovoitov <ast@kernel.org>
Fix loader program to close temporary FDs when intermediate
sys_bpf command fails.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
tools/lib/bpf/bpf_gen_internal.h | 1 +
tools/lib/bpf/gen_loader.c | 38 ++++++++++++++++++++++++++++----
2 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/tools/lib/bpf/bpf_gen_internal.h b/tools/lib/bpf/bpf_gen_internal.h
index f42a55efd559..da2c026a3f31 100644
--- a/tools/lib/bpf/bpf_gen_internal.h
+++ b/tools/lib/bpf/bpf_gen_internal.h
@@ -15,6 +15,7 @@ struct bpf_gen {
void *data_cur;
void *insn_start;
void *insn_cur;
+ size_t cleanup_label;
__u32 nr_progs;
__u32 nr_maps;
int log_level;
diff --git a/tools/lib/bpf/gen_loader.c b/tools/lib/bpf/gen_loader.c
index 585c672cc53e..b1709421ba90 100644
--- a/tools/lib/bpf/gen_loader.c
+++ b/tools/lib/bpf/gen_loader.c
@@ -97,8 +97,36 @@ static void bpf_gen__emit2(struct bpf_gen *gen, struct bpf_insn insn1, struct bp
void bpf_gen__init(struct bpf_gen *gen, int log_level)
{
+ size_t stack_sz = sizeof(struct loader_stack);
+ int i;
+
gen->log_level = log_level;
+ /* save ctx pointer into R6 */
bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_6, BPF_REG_1));
+
+ /* bzero stack */
+ bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_1, BPF_REG_10));
+ bpf_gen__emit(gen, BPF_ALU64_IMM(BPF_ADD, BPF_REG_1, -stack_sz));
+ bpf_gen__emit(gen, BPF_MOV64_IMM(BPF_REG_2, stack_sz));
+ bpf_gen__emit(gen, BPF_MOV64_IMM(BPF_REG_3, 0));
+ bpf_gen__emit(gen, BPF_EMIT_CALL(BPF_FUNC_probe_read_kernel));
+
+ /* jump over cleanup code */
+ bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0,
+ /* size of cleanup code below */
+ (stack_sz / 4) * 3 + 2));
+
+ /* remember the label where all error branches will jump to */
+ gen->cleanup_label = gen->insn_cur - gen->insn_start;
+ /* emit cleanup code: close all temp FDs */
+ for (i = 0; i < stack_sz; i+= 4) {
+ bpf_gen__emit(gen, BPF_LDX_MEM(BPF_W, BPF_REG_1, BPF_REG_10, -stack_sz + i));
+ bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSLE, BPF_REG_1, 0, 1));
+ bpf_gen__emit(gen, BPF_EMIT_CALL(BPF_FUNC_sys_close));
+ }
+ /* R7 contains the error code from sys_bpf. Copy it into R0 and exit. */
+ bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
+ bpf_gen__emit(gen, BPF_EXIT_INSN());
}
static int bpf_gen__add_data(struct bpf_gen *gen, const void *data, __u32 size)
@@ -179,10 +207,12 @@ static void bpf_gen__emit_sys_bpf(struct bpf_gen *gen, int cmd, int attr, int at
static void bpf_gen__emit_check_err(struct bpf_gen *gen)
{
- bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 2));
- bpf_gen__emit(gen, BPF_MOV64_REG(BPF_REG_0, BPF_REG_7));
- /* TODO: close intermediate FDs in case of error */
- bpf_gen__emit(gen, BPF_EXIT_INSN());
+ /* R7 contains result of last sys_bpf command.
+ * if (R7 < 0) goto cleanup;
+ */
+ bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JSGE, BPF_REG_7, 0, 1));
+ bpf_gen__emit(gen, BPF_JMP_IMM(BPF_JA, 0, 0,
+ -(gen->insn_cur - gen->insn_start - gen->cleanup_label) / 8 - 1));
}
/* reg1 and reg2 should not be R1 - R5. They can be R0, R6 - R10 */
--
2.30.2
next prev parent reply other threads:[~2021-05-08 3:49 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-08 3:48 [PATCH v4 bpf-next 00/22] bpf: syscall program, FD array, loader program, light skeleton Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 01/22] bpf: Introduce bpf_sys_bpf() helper and program type Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 02/22] bpf: Introduce bpfptr_t user/kernel pointer Alexei Starovoitov
2021-05-11 22:23 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 03/22] bpf: Prepare bpf syscall to be used from kernel and user space Alexei Starovoitov
2021-05-11 22:31 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 04/22] libbpf: Support for syscall program type Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 05/22] selftests/bpf: Test " Alexei Starovoitov
2021-05-11 22:36 ` Andrii Nakryiko
2021-05-11 22:44 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 06/22] bpf: Make btf_load command to be bpfptr_t compatible Alexei Starovoitov
2021-05-11 22:41 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 07/22] selftests/bpf: Test for btf_load command Alexei Starovoitov
2021-05-11 22:45 ` Andrii Nakryiko
2021-05-12 4:04 ` Alexei Starovoitov
2021-05-12 18:00 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 08/22] bpf: Introduce fd_idx Alexei Starovoitov
2021-05-11 22:47 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 09/22] libbpf: Support for fd_idx Alexei Starovoitov
2021-05-11 22:57 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 10/22] bpf: Add bpf_btf_find_by_name_kind() helper Alexei Starovoitov
2021-05-11 23:02 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 11/22] bpf: Add bpf_sys_close() helper Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 12/22] libbpf: Change the order of data and text relocations Alexei Starovoitov
2021-05-11 23:06 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 13/22] libbpf: Add bpf_object pointer to kernel_supports() Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 14/22] libbpf: Generate loader program out of BPF ELF file Alexei Starovoitov
2021-05-11 23:22 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 15/22] libbpf: Use fd_array only with gen_loader Alexei Starovoitov
2021-05-11 23:24 ` Andrii Nakryiko
2021-05-12 4:17 ` Alexei Starovoitov
2021-05-12 18:11 ` Andrii Nakryiko
2021-05-08 3:48 ` Alexei Starovoitov [this message]
2021-05-11 23:34 ` [PATCH v4 bpf-next 16/22] libbpf: Cleanup temp FDs when intermediate sys_bpf fails Andrii Nakryiko
2021-05-12 4:33 ` Alexei Starovoitov
2021-05-08 3:48 ` [PATCH v4 bpf-next 17/22] libbpf: Introduce bpf_map__get_initial_value() Alexei Starovoitov
2021-05-11 23:39 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 18/22] bpftool: Use syscall/loader program in "prog load" and "gen skeleton" command Alexei Starovoitov
2021-05-12 4:17 ` Andrii Nakryiko
2021-05-12 18:43 ` Alexei Starovoitov
2021-05-12 18:55 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 19/22] selftests/bpf: Convert few tests to light skeleton Alexei Starovoitov
2021-05-12 4:19 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 20/22] selftests/bpf: Convert atomics test " Alexei Starovoitov
2021-05-12 4:21 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 21/22] selftests/bpf: Convert test printk to use rodata Alexei Starovoitov
2021-05-12 4:23 ` Andrii Nakryiko
2021-05-08 3:48 ` [PATCH v4 bpf-next 22/22] selftests/bpf: Convert test trace_printk to lskel Alexei Starovoitov
2021-05-12 4:24 ` Andrii Nakryiko
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