From 33a154a96e71a34a1bcca9f40da343dbbf7b38b4 Mon Sep 17 00:00:00 2001 From: Alexei Starovoitov Date: Thu, 1 Oct 2026 14:52:55 +0000 Subject: selftests/bpf: Test packet range of pointers sharing an id Add tests where two packet pointers share an id and tightening one pointer's umax from its var_off would put it less than their constant distance from the other's umax: with an index & 0x38 capped at 50, the base pointer keeps umax 50, so the pointer 8 bytes further on must keep umax 58, even though its known bits allow at most 56. These refused a valid program or accepted an out-of-bounds access before the fix: - check the advanced copy, load through the base: valid, was refused; - check the base, load the byte at base + 1 through a copy advanced by 8: was accepted; - check base + 4, load 4 bytes at base + 2 through base + 8: reads two bytes past the checked range, was accepted; - the same as the second with data_meta pointers checked against data: was accepted. These pass with and without the fix and cover nearby paths: - subtract an unknown scalar from a checked pointer and load below it (the range is kept across a new id); - reach a load through two paths whose checks cover 8 and 7 bytes after the loaded pointer; the second path must not be pruned by the first; - spill a copy of a pointer, check the pointer, fill the copy and load one byte past the checked range: the load is refused, and the copy has the range of the check. Signed-off-by: Alexei Starovoitov Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com Signed-off-by: Kumar Kartikeya Dwivedi --- samples/check-exec/set-exec.c | 85 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 85 insertions(+) create mode 100644 samples/check-exec/set-exec.c (limited to 'samples/check-exec/set-exec.c') diff --git a/samples/check-exec/set-exec.c b/samples/check-exec/set-exec.c new file mode 100644 index 000000000..ba86a60a2 --- /dev/null +++ b/samples/check-exec/set-exec.c @@ -0,0 +1,85 @@ +// SPDX-License-Identifier: BSD-3-Clause +/* + * Simple tool to set SECBIT_EXEC_RESTRICT_FILE, SECBIT_EXEC_DENY_INTERACTIVE, + * before executing a command. + * + * Copyright © 2024 Microsoft Corporation + */ + +#define _GNU_SOURCE +#define __SANE_USERSPACE_TYPES__ +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void print_usage(const char *argv0) +{ + fprintf(stderr, "usage: %s -f|-i -- [args]...\n\n", argv0); + fprintf(stderr, "Execute a command with\n"); + fprintf(stderr, "- SECBIT_EXEC_RESTRICT_FILE set: -f\n"); + fprintf(stderr, "- SECBIT_EXEC_DENY_INTERACTIVE set: -i\n"); +} + +int main(const int argc, char *const argv[], char *const *const envp) +{ + const char *cmd_path; + char *const *cmd_argv; + int opt, secbits_cur, secbits_new; + bool has_policy = false; + + secbits_cur = prctl(PR_GET_SECUREBITS); + if (secbits_cur == -1) { + /* + * This should never happen, except with a buggy seccomp + * filter. + */ + perror("ERROR: Failed to get securebits"); + return 1; + } + + secbits_new = secbits_cur; + while ((opt = getopt(argc, argv, "fi")) != -1) { + switch (opt) { + case 'f': + secbits_new |= SECBIT_EXEC_RESTRICT_FILE | + SECBIT_EXEC_RESTRICT_FILE_LOCKED; + has_policy = true; + break; + case 'i': + secbits_new |= SECBIT_EXEC_DENY_INTERACTIVE | + SECBIT_EXEC_DENY_INTERACTIVE_LOCKED; + has_policy = true; + break; + default: + print_usage(argv[0]); + return 1; + } + } + + if (!argv[optind] || !has_policy) { + print_usage(argv[0]); + return 1; + } + + if (secbits_cur != secbits_new && + prctl(PR_SET_SECUREBITS, secbits_new)) { + perror("Failed to set secure bit(s)."); + fprintf(stderr, + "Hint: The running kernel may not support this feature.\n"); + return 1; + } + + cmd_path = argv[optind]; + cmd_argv = argv + optind; + fprintf(stderr, "Executing command...\n"); + execvpe(cmd_path, cmd_argv, envp); + fprintf(stderr, "Failed to execute \"%s\": %s\n", cmd_path, + strerror(errno)); + return 1; +} -- cgit v1.3.1