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bpf: Extend BPF syscall with common attributes support

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Add generic BPF syscall support for passing common attributes.

The initial set of common attributes includes:

1. 'log_buf': User-provided buffer for storing logs.
2. 'log_size': Size of the log buffer.
3. 'log_level': Log verbosity level.
4. 'log_true_size': Actual log size reported by kernel.

The common-attribute pointer and its size are passed as the 4th and 5th
syscall arguments. A new command bit, 'BPF_COMMON_ATTRS' ('1 << 16'),
indicates that common attributes are supplied.

This commit adds syscall and uapi plumbing. Command-specific handling is
added in follow-up patches.

Signed-off-by: Leon Hwang <leon.hwang@linux.dev>
Link: https://lore.kernel.org/r/20260512153157.28382-2-leon.hwang@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Leon Hwang 2026-05-12 23:31:50 +08:00 committed by Alexei Starovoitov
parent 25bb05dd06
commit f28771c069
4 changed files with 39 additions and 5 deletions
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3
include/linux/syscalls.h
View File

@ -936,7 +936,8 @@ asmlinkage long sys_seccomp(unsigned int op, unsigned int flags,
asmlinkage long sys_getrandom(char __user *buf, size_t count,
unsigned int flags);
asmlinkage long sys_memfd_create(const char __user *uname_ptr, unsigned int flags);
asmlinkage long sys_bpf(int cmd, union bpf_attr __user *attr, unsigned int size);
asmlinkage long sys_bpf(int cmd, union bpf_attr __user *attr, unsigned int size,
struct bpf_common_attr __user *attr_common, unsigned int size_common);
asmlinkage long sys_execveat(int dfd, const char __user *filename,
const char __user *const __user *argv,
const char __user *const __user *envp, int flags);

8
include/uapi/linux/bpf.h
View File

@ -994,6 +994,7 @@ enum bpf_cmd {
BPF_PROG_STREAM_READ_BY_FD,
BPF_PROG_ASSOC_STRUCT_OPS,
__MAX_BPF_CMD,
BPF_COMMON_ATTRS = 1 << 16, /* Indicate carrying syscall common attrs. */
};
enum bpf_map_type {
@ -1500,6 +1501,13 @@ struct bpf_stack_build_id {
};
};
struct bpf_common_attr {
__aligned_u64 log_buf;
__u32 log_size;
__u32 log_level;
__u32 log_true_size;
};
#define BPF_OBJ_NAME_LEN 16U
enum {

25
kernel/bpf/syscall.c
View File

@ -6211,8 +6211,10 @@ static int prog_assoc_struct_ops(union bpf_attr *attr)
return ret;
}
static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size)
static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size,
bpfptr_t uattr_common, unsigned int size_common)
{
struct bpf_common_attr attr_common;
union bpf_attr attr;
int err;
@ -6226,6 +6228,20 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size)
if (copy_from_bpfptr(&attr, uattr, size) != 0)
return -EFAULT;
memset(&attr_common, 0, sizeof(attr_common));
if (cmd & BPF_COMMON_ATTRS) {
err = bpf_check_uarg_tail_zero(uattr_common, sizeof(attr_common), size_common);
if (err)
return err;
cmd &= ~BPF_COMMON_ATTRS;
size_common = min_t(u32, size_common, sizeof(attr_common));
if (copy_from_bpfptr(&attr_common, uattr_common, size_common) != 0)
return -EFAULT;
} else {
size_common = 0;
}
err = security_bpf(cmd, &attr, size, uattr.is_kernel);
if (err < 0)
return err;
@ -6361,9 +6377,10 @@ static int __sys_bpf(enum bpf_cmd cmd, bpfptr_t uattr, unsigned int size)
return err;
}
SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size)
SYSCALL_DEFINE5(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, size,
struct bpf_common_attr __user *, uattr_common, unsigned int, size_common)
{
return __sys_bpf(cmd, USER_BPFPTR(uattr), size);
return __sys_bpf(cmd, USER_BPFPTR(uattr), size, USER_BPFPTR(uattr_common), size_common);
}
static bool syscall_prog_is_valid_access(int off, int size,
@ -6393,7 +6410,7 @@ BPF_CALL_3(bpf_sys_bpf, int, cmd, union bpf_attr *, attr, u32, attr_size)
default:
return -EINVAL;
}
return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size);
return __sys_bpf(cmd, KERNEL_BPFPTR(attr), attr_size, KERNEL_BPFPTR(NULL), 0);
}

8
tools/include/uapi/linux/bpf.h
View File

@ -994,6 +994,7 @@ enum bpf_cmd {
BPF_PROG_STREAM_READ_BY_FD,
BPF_PROG_ASSOC_STRUCT_OPS,
__MAX_BPF_CMD,
BPF_COMMON_ATTRS = 1 << 16, /* Indicate carrying syscall common attrs. */
};
enum bpf_map_type {
@ -1500,6 +1501,13 @@ struct bpf_stack_build_id {
};
};
struct bpf_common_attr {
__aligned_u64 log_buf;
__u32 log_size;
__u32 log_level;
__u32 log_true_size;
};
#define BPF_OBJ_NAME_LEN 16U
enum {