diff mbox series

[bpf-next,7/8] bpf: Undo strict enforcement for walking untagged fields.

Message ID 20230404045029.82870-8-alexei.starovoitov@gmail.com (mailing list archive)
State Accepted
Commit afeebf9f57a4965e0be90e4dc87f8f3a1417376d
Delegated to: BPF
Headers show
Series bpf: Follow up to RCU enforcement in the verifier. | expand

Checks

Context Check Description
bpf/vmtest-bpf-next-VM_Test-20 success Logs for test_progs_no_alu32 on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-15 success Logs for test_progs on s390x with gcc
bpf/vmtest-bpf-next-VM_Test-10 success Logs for test_maps on s390x with gcc
netdev/series_format success Posting correctly formatted
netdev/tree_selection success Clearly marked for bpf-next, async
netdev/fixes_present success Fixes tag not required for -next series
netdev/header_inline success No static functions without inline keyword in header files
netdev/build_32bit success Errors and warnings before: 28 this patch: 28
netdev/cc_maintainers warning 12 maintainers not CCed: llvm@lists.linux.dev song@kernel.org sdf@google.com haoluo@google.com yhs@fb.com trix@redhat.com nathan@kernel.org john.fastabend@gmail.com ndesaulniers@google.com kpsingh@kernel.org jolsa@kernel.org martin.lau@linux.dev
netdev/build_clang success Errors and warnings before: 18 this patch: 18
netdev/verify_signedoff success Signed-off-by tag matches author and committer
netdev/deprecated_api success None detected
netdev/check_selftest success No net selftest shell script
netdev/verify_fixes success Fixes tag looks correct
netdev/build_allmodconfig_warn success Errors and warnings before: 28 this patch: 28
netdev/checkpatch warning WARNING: line length of 98 exceeds 80 columns
netdev/kdoc success Errors and warnings before: 0 this patch: 0
netdev/source_inline success Was 0 now: 0
bpf/vmtest-bpf-next-VM_Test-1 success Logs for ShellCheck
bpf/vmtest-bpf-next-VM_Test-2 success Logs for build for aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-3 success Logs for build for aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-5 success Logs for build for x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-6 success Logs for build for x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-7 success Logs for set-matrix
bpf/vmtest-bpf-next-VM_Test-4 success Logs for build for s390x with gcc
bpf/vmtest-bpf-next-VM_Test-8 success Logs for test_maps on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-9 success Logs for test_maps on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-11 success Logs for test_maps on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-12 success Logs for test_maps on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-13 success Logs for test_progs on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-14 success Logs for test_progs on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-16 fail Logs for test_progs on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-17 success Logs for test_progs on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-18 success Logs for test_progs_no_alu32 on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-19 success Logs for test_progs_no_alu32 on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-21 success Logs for test_progs_no_alu32 on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-22 success Logs for test_progs_no_alu32 on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-23 success Logs for test_progs_no_alu32_parallel on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-24 success Logs for test_progs_no_alu32_parallel on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-25 success Logs for test_progs_no_alu32_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-26 success Logs for test_progs_no_alu32_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-27 success Logs for test_progs_parallel on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-28 success Logs for test_progs_parallel on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-29 success Logs for test_progs_parallel on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-30 success Logs for test_progs_parallel on x86_64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-31 success Logs for test_verifier on aarch64 with gcc
bpf/vmtest-bpf-next-VM_Test-32 success Logs for test_verifier on aarch64 with llvm-16
bpf/vmtest-bpf-next-VM_Test-34 success Logs for test_verifier on x86_64 with gcc
bpf/vmtest-bpf-next-VM_Test-35 success Logs for test_verifier on x86_64 with llvm-16
bpf/vmtest-bpf-next-PR fail merge-conflict
bpf/vmtest-bpf-next-VM_Test-33 success Logs for test_verifier on s390x with gcc

Commit Message

Alexei Starovoitov April 4, 2023, 4:50 a.m. UTC 
From: Alexei Starovoitov <ast@kernel.org>

The commit 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
broke several tracing bpf programs. Even in clang compiled kernels there are
many fields that are not marked with __rcu that are safe to read and pass into
helpers, but the verifier doesn't know that they're safe. Aggressively marking
them as PTR_UNTRUSTED was premature.

Fixes: 6fcd486b3a0a ("bpf: Refactor RCU enforcement in the verifier.")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
---
 kernel/bpf/verifier.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index fd90ba498ccc..56f569811f70 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -4974,6 +4974,11 @@  static bool is_rcu_reg(const struct bpf_reg_state *reg)
 	return reg->type & MEM_RCU;
 }
 
+static void clear_trusted_flags(enum bpf_type_flag *flag)
+{
+	*flag &= ~(BPF_REG_TRUSTED_MODIFIERS | MEM_RCU);
+}
+
 static int check_pkt_ptr_alignment(struct bpf_verifier_env *env,
 				   const struct bpf_reg_state *reg,
 				   int off, int size, bool strict)
@@ -5602,8 +5607,8 @@  static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
 			} else if (flag & (MEM_PERCPU | MEM_USER)) {
 				/* keep as-is */
 			} else {
-				/* walking unknown pointers yields untrusted pointer */
-				flag = PTR_UNTRUSTED;
+				/* walking unknown pointers yields old deprecated PTR_TO_BTF_ID */
+				clear_trusted_flags(&flag);
 			}
 		} else {
 			/*
@@ -5617,7 +5622,7 @@  static int check_ptr_to_btf_access(struct bpf_verifier_env *env,
 		}
 	} else {
 		/* Old compat. Deprecated */
-		flag &= ~PTR_TRUSTED;
+		clear_trusted_flags(&flag);
 	}
 
 	if (atype == BPF_READ && value_regno >= 0)