diff options
| author | Mykyta Yatsenko <yatsenko@meta.com> | 2025-03-17 17:40:36 +0000 |
|---|---|---|
| committer | Andrii Nakryiko <andrii@kernel.org> | 2025-03-17 13:45:11 -0700 |
| commit | 0de445d18e36ca5914337217c118016ba5db574d (patch) | |
| tree | e4524bbe1683861784add30e3447b4a53c7f69fb | |
| parent | 812f7702d83d84cdf776d75e2ba5386de9e8acc0 (diff) | |
bpf: BPF token support for BPF_BTF_GET_FD_BY_ID
Currently BPF_BTF_GET_FD_BY_ID requires CAP_SYS_ADMIN, which does not
allow running it from user namespace. This creates a problem when
freplace program running from user namespace needs to query target
program BTF.
This patch relaxes capable check from CAP_SYS_ADMIN to CAP_BPF and adds
support for BPF token that can be passed in attributes to syscall.
Signed-off-by: Mykyta Yatsenko <yatsenko@meta.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20250317174039.161275-2-mykyta.yatsenko5@gmail.com
| -rw-r--r-- | include/uapi/linux/bpf.h | 1 | ||||
| -rw-r--r-- | kernel/bpf/syscall.c | 23 | ||||
| -rw-r--r-- | tools/include/uapi/linux/bpf.h | 1 |
3 files changed, 23 insertions, 2 deletions
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index bb37897c0393..661de2444965 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -1652,6 +1652,7 @@ union bpf_attr { }; __u32 next_id; __u32 open_flags; + __s32 fd_by_id_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */ diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 6a8f20ee2851..419f82c78203 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -5120,15 +5120,34 @@ static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr, __u32 uattr_ return btf_new_fd(attr, uattr, uattr_size); } -#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD btf_id +#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD fd_by_id_token_fd static int bpf_btf_get_fd_by_id(const union bpf_attr *attr) { + struct bpf_token *token = NULL; + if (CHECK_ATTR(BPF_BTF_GET_FD_BY_ID)) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (attr->open_flags & ~BPF_F_TOKEN_FD) + return -EINVAL; + + if (attr->open_flags & BPF_F_TOKEN_FD) { + token = bpf_token_get_from_fd(attr->fd_by_id_token_fd); + if (IS_ERR(token)) + return PTR_ERR(token); + if (!bpf_token_allow_cmd(token, BPF_BTF_GET_FD_BY_ID)) { + bpf_token_put(token); + token = NULL; + } + } + + if (!bpf_token_capable(token, CAP_SYS_ADMIN)) { + bpf_token_put(token); return -EPERM; + } + + bpf_token_put(token); return btf_get_fd_by_id(attr->btf_id); } diff --git a/tools/include/uapi/linux/bpf.h b/tools/include/uapi/linux/bpf.h index bb37897c0393..661de2444965 100644 --- a/tools/include/uapi/linux/bpf.h +++ b/tools/include/uapi/linux/bpf.h @@ -1652,6 +1652,7 @@ union bpf_attr { }; __u32 next_id; __u32 open_flags; + __s32 fd_by_id_token_fd; }; struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */ |