diff options
author | Alexei Starovoitov <ast@kernel.org> | 2019-11-02 12:39:13 -0700 |
---|---|---|
committer | Alexei Starovoitov <ast@kernel.org> | 2019-11-02 12:45:15 -0700 |
commit | 358fdb456288d48874d44a064a82bfb0d9963fa0 (patch) | |
tree | 59237fefc66616b1656f1ade555b2365e8d89d88 /tools/include | |
parent | e1cb7d2d60d536baf24d2f0fd58786324ce92331 (diff) | |
parent | fa553d9b57d4a98a160d1926b4e263e7a78c0cf3 (diff) |
Merge branch 'bpf_probe_read_user'
Daniel Borkmann says:
====================
This set adds probe_read_{user,kernel}(), probe_read_str_{user,kernel}()
helpers, fixes probe_write_user() helper and selftests. For details please
see individual patches.
Thanks!
v2 -> v3:
- noticed two more things that are fixed in here:
- bpf uapi helper description used 'int size' for *_str helpers, now u32
- we need TASK_SIZE_MAX + guard page on x86-64 in patch 2 otherwise
we'll trigger the 00c42373d397 warn as well, so full range covered now
v1 -> v2:
- standardize unsafe_ptr terminology in uapi header comment (Andrii)
- probe_read_{user,kernel}[_str] naming scheme (Andrii)
- use global data in last test case, remove relaxed_maps (Andrii)
- add strict non-pagefault kernel read funcs to avoid warning in
kernel probe read helpers (Alexei)
====================
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'tools/include')
-rw-r--r-- | tools/include/uapi/linux/bpf.h | 122 |
1 files changed, 82 insertions, 40 deletions
diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index a6bf19dabaab..df6809a76404 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -563,10 +563,13 @@ union bpf_attr { * Return * 0 on success, or a negative error in case of failure. * - * int bpf_probe_read(void *dst, u32 size, const void *src) + * int bpf_probe_read(void *dst, u32 size, const void *unsafe_ptr) * Description * For tracing programs, safely attempt to read *size* bytes from - * address *src* and store the data in *dst*. + * kernel space address *unsafe_ptr* and store the data in *dst*. + * + * Generally, use bpf_probe_read_user() or bpf_probe_read_kernel() + * instead. * Return * 0 on success, or a negative error in case of failure. * @@ -1428,45 +1431,14 @@ union bpf_attr { * Return * 0 on success, or a negative error in case of failure. * - * int bpf_probe_read_str(void *dst, int size, const void *unsafe_ptr) + * int bpf_probe_read_str(void *dst, u32 size, const void *unsafe_ptr) * Description - * Copy a NUL terminated string from an unsafe address - * *unsafe_ptr* to *dst*. The *size* should include the - * terminating NUL byte. In case the string length is smaller than - * *size*, the target is not padded with further NUL bytes. If the - * string length is larger than *size*, just *size*-1 bytes are - * copied and the last byte is set to NUL. - * - * On success, the length of the copied string is returned. This - * makes this helper useful in tracing programs for reading - * strings, and more importantly to get its length at runtime. See - * the following snippet: - * - * :: - * - * SEC("kprobe/sys_open") - * void bpf_sys_open(struct pt_regs *ctx) - * { - * char buf[PATHLEN]; // PATHLEN is defined to 256 - * int res = bpf_probe_read_str(buf, sizeof(buf), - * ctx->di); - * - * // Consume buf, for example push it to - * // userspace via bpf_perf_event_output(); we - * // can use res (the string length) as event - * // size, after checking its boundaries. - * } - * - * In comparison, using **bpf_probe_read()** helper here instead - * to read the string would require to estimate the length at - * compile time, and would often result in copying more memory - * than necessary. + * Copy a NUL terminated string from an unsafe kernel address + * *unsafe_ptr* to *dst*. See bpf_probe_read_kernel_str() for + * more details. * - * Another useful use case is when parsing individual process - * arguments or individual environment variables navigating - * *current*\ **->mm->arg_start** and *current*\ - * **->mm->env_start**: using this helper and the return value, - * one can quickly iterate at the right offset of the memory area. + * Generally, use bpf_probe_read_user_str() or bpf_probe_read_kernel_str() + * instead. * Return * On success, the strictly positive length of the string, * including the trailing NUL character. On error, a negative @@ -2777,6 +2749,72 @@ union bpf_attr { * restricted to raw_tracepoint bpf programs. * Return * 0 on success, or a negative error in case of failure. + * + * int bpf_probe_read_user(void *dst, u32 size, const void *unsafe_ptr) + * Description + * Safely attempt to read *size* bytes from user space address + * *unsafe_ptr* and store the data in *dst*. + * Return + * 0 on success, or a negative error in case of failure. + * + * int bpf_probe_read_kernel(void *dst, u32 size, const void *unsafe_ptr) + * Description + * Safely attempt to read *size* bytes from kernel space address + * *unsafe_ptr* and store the data in *dst*. + * Return + * 0 on success, or a negative error in case of failure. + * + * int bpf_probe_read_user_str(void *dst, u32 size, const void *unsafe_ptr) + * Description + * Copy a NUL terminated string from an unsafe user address + * *unsafe_ptr* to *dst*. The *size* should include the + * terminating NUL byte. In case the string length is smaller than + * *size*, the target is not padded with further NUL bytes. If the + * string length is larger than *size*, just *size*-1 bytes are + * copied and the last byte is set to NUL. + * + * On success, the length of the copied string is returned. This + * makes this helper useful in tracing programs for reading + * strings, and more importantly to get its length at runtime. See + * the following snippet: + * + * :: + * + * SEC("kprobe/sys_open") + * void bpf_sys_open(struct pt_regs *ctx) + * { + * char buf[PATHLEN]; // PATHLEN is defined to 256 + * int res = bpf_probe_read_user_str(buf, sizeof(buf), + * ctx->di); + * + * // Consume buf, for example push it to + * // userspace via bpf_perf_event_output(); we + * // can use res (the string length) as event + * // size, after checking its boundaries. + * } + * + * In comparison, using **bpf_probe_read_user()** helper here + * instead to read the string would require to estimate the length + * at compile time, and would often result in copying more memory + * than necessary. + * + * Another useful use case is when parsing individual process + * arguments or individual environment variables navigating + * *current*\ **->mm->arg_start** and *current*\ + * **->mm->env_start**: using this helper and the return value, + * one can quickly iterate at the right offset of the memory area. + * Return + * On success, the strictly positive length of the string, + * including the trailing NUL character. On error, a negative + * value. + * + * int bpf_probe_read_kernel_str(void *dst, u32 size, const void *unsafe_ptr) + * Description + * Copy a NUL terminated string from an unsafe kernel address *unsafe_ptr* + * to *dst*. Same semantics as with bpf_probe_read_user_str() apply. + * Return + * On success, the strictly positive length of the string, including + * the trailing NUL character. On error, a negative value. */ #define __BPF_FUNC_MAPPER(FN) \ FN(unspec), \ @@ -2890,7 +2928,11 @@ union bpf_attr { FN(sk_storage_delete), \ FN(send_signal), \ FN(tcp_gen_syncookie), \ - FN(skb_output), + FN(skb_output), \ + FN(probe_read_user), \ + FN(probe_read_kernel), \ + FN(probe_read_user_str), \ + FN(probe_read_kernel_str), /* integer value in 'imm' field of BPF_CALL instruction selects which helper * function eBPF program intends to call |