This patch introduce unprivileged BPF access. The access control is achieved via device /dev/bpf. Users with access to /dev/bpf are able to access BPF syscall.
Two ioctl command are added to /dev/bpf: The first two commands get/put permission to access sys_bpf. This permission is noted by setting bit TASK_BPF_FLAG_PERMITTED of current->bpf_flags. This permission cannot be inherited via fork(). Helper function bpf_capable() is added to check whether the task has got permission via /dev/bpf. Signed-off-by: Song Liu <songliubrav...@fb.com> --- Documentation/ioctl/ioctl-number.txt | 1 + include/linux/bpf.h | 12 +++++ include/linux/sched.h | 8 ++++ include/uapi/linux/bpf.h | 5 ++ kernel/bpf/arraymap.c | 2 +- kernel/bpf/cgroup.c | 2 +- kernel/bpf/core.c | 4 +- kernel/bpf/cpumap.c | 2 +- kernel/bpf/devmap.c | 2 +- kernel/bpf/hashtab.c | 4 +- kernel/bpf/lpm_trie.c | 2 +- kernel/bpf/offload.c | 2 +- kernel/bpf/queue_stack_maps.c | 2 +- kernel/bpf/reuseport_array.c | 2 +- kernel/bpf/stackmap.c | 2 +- kernel/bpf/syscall.c | 72 +++++++++++++++++++++------- kernel/bpf/verifier.c | 2 +- kernel/bpf/xskmap.c | 2 +- kernel/fork.c | 4 ++ net/core/filter.c | 6 +-- 20 files changed, 104 insertions(+), 34 deletions(-) diff --git a/Documentation/ioctl/ioctl-number.txt b/Documentation/ioctl/ioctl-number.txt index c9558146ac58..19998b99d603 100644 --- a/Documentation/ioctl/ioctl-number.txt +++ b/Documentation/ioctl/ioctl-number.txt @@ -327,6 +327,7 @@ Code Seq#(hex) Include File Comments 0xB4 00-0F linux/gpio.h <mailto:linux-g...@vger.kernel.org> 0xB5 00-0F uapi/linux/rpmsg.h <mailto:linux-remotep...@vger.kernel.org> 0xB6 all linux/fpga-dfl.h +0xBP 01-02 uapi/linux/bpf.h <mailto:b...@vger.kernel.org> 0xC0 00-0F linux/usb/iowarrior.h 0xCA 00-0F uapi/misc/cxl.h 0xCA 10-2F uapi/misc/ocxl.h diff --git a/include/linux/bpf.h b/include/linux/bpf.h index a62e7889b0b6..dbba7870f6df 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -14,6 +14,10 @@ #include <linux/numa.h> #include <linux/wait.h> #include <linux/u64_stats_sync.h> +#include <linux/sched.h> +#include <linux/capability.h> + +#include <asm/current.h> struct bpf_verifier_env; struct perf_event; @@ -742,6 +746,12 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr, int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, const union bpf_attr *kattr, union bpf_attr __user *uattr); + +static inline bool bpf_capable(int cap) +{ + return test_bit(TASK_BPF_FLAG_PERMITTED, ¤t->bpf_flags) || + capable(cap); +} #else /* !CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get(u32 ufd) { @@ -874,6 +884,8 @@ static inline int bpf_prog_test_run_flow_dissector(struct bpf_prog *prog, { return -ENOTSUPP; } + +#define bpf_capable(cap) capable((cap)) #endif /* CONFIG_BPF_SYSCALL */ static inline struct bpf_prog *bpf_prog_get_type(u32 ufd, diff --git a/include/linux/sched.h b/include/linux/sched.h index 11837410690f..ddd33d4476c5 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -1200,6 +1200,10 @@ struct task_struct { unsigned long prev_lowest_stack; #endif +#ifdef CONFIG_BPF_SYSCALL + unsigned long bpf_flags; +#endif + /* * New fields for task_struct should be added above here, so that * they are included in the randomized portion of task_struct. @@ -1772,6 +1776,10 @@ static inline void set_task_cpu(struct task_struct *p, unsigned int cpu) #endif /* CONFIG_SMP */ +enum task_struct_bpf_flags { + TASK_BPF_FLAG_PERMITTED, +}; + /* * In order to reduce various lock holder preemption latencies provide an * interface to see if a vCPU is currently running or not. diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h index b077507efa3f..ec3ae452cfd7 100644 --- a/include/uapi/linux/bpf.h +++ b/include/uapi/linux/bpf.h @@ -3541,4 +3541,9 @@ struct bpf_sysctl { */ }; +#define BPF_IOCTL 0xBF + +#define BPF_DEV_IOCTL_GET_PERM _IO(BPF_IOCTL, 0x01) +#define BPF_DEV_IOCTL_PUT_PERM _IO(BPF_IOCTL, 0x02) + #endif /* _UAPI__LINUX_BPF_H__ */ diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c index 1c65ce0098a9..9ae668fa9185 100644 --- a/kernel/bpf/arraymap.c +++ b/kernel/bpf/arraymap.c @@ -73,7 +73,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr) bool percpu = attr->map_type == BPF_MAP_TYPE_PERCPU_ARRAY; int ret, numa_node = bpf_map_attr_numa_node(attr); u32 elem_size, index_mask, max_entries; - bool unpriv = !capable(CAP_SYS_ADMIN); + bool unpriv = !bpf_capable(CAP_SYS_ADMIN); u64 cost, array_size, mask64; struct bpf_map_memory mem; struct bpf_array *array; diff --git a/kernel/bpf/cgroup.c b/kernel/bpf/cgroup.c index c225c42e114a..fd9bea70f8f3 100644 --- a/kernel/bpf/cgroup.c +++ b/kernel/bpf/cgroup.c @@ -777,7 +777,7 @@ cgroup_base_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog) case BPF_FUNC_get_current_cgroup_id: return &bpf_get_current_cgroup_id_proto; case BPF_FUNC_trace_printk: - if (capable(CAP_SYS_ADMIN)) + if (bpf_capable(CAP_SYS_ADMIN)) return bpf_get_trace_printk_proto(); /* fall through */ default: diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index ad3be85f1411..25c1e3c59699 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -646,7 +646,7 @@ static bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) void bpf_prog_kallsyms_add(struct bpf_prog *fp) { if (!bpf_prog_kallsyms_candidate(fp) || - !capable(CAP_SYS_ADMIN)) + !bpf_capable(CAP_SYS_ADMIN)) return; spin_lock_bh(&bpf_lock); @@ -768,7 +768,7 @@ static int bpf_jit_charge_modmem(u32 pages) { if (atomic_long_add_return(pages, &bpf_jit_current) > (bpf_jit_limit >> PAGE_SHIFT)) { - if (!capable(CAP_SYS_ADMIN)) { + if (!bpf_capable(CAP_SYS_ADMIN)) { atomic_long_sub(pages, &bpf_jit_current); return -EPERM; } diff --git a/kernel/bpf/cpumap.c b/kernel/bpf/cpumap.c index 8dff08768087..4c6054626b4f 100644 --- a/kernel/bpf/cpumap.c +++ b/kernel/bpf/cpumap.c @@ -83,7 +83,7 @@ static struct bpf_map *cpu_map_alloc(union bpf_attr *attr) u64 cost; int ret; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); /* check sanity of attributes */ diff --git a/kernel/bpf/devmap.c b/kernel/bpf/devmap.c index 40e86a7e0ef0..b7c3785be289 100644 --- a/kernel/bpf/devmap.c +++ b/kernel/bpf/devmap.c @@ -83,7 +83,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr) u64 cost; int err; - if (!capable(CAP_NET_ADMIN)) + if (!bpf_capable(CAP_NET_ADMIN)) return ERR_PTR(-EPERM); /* check sanity of attributes */ diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c index 22066a62c8c9..461a75c311a4 100644 --- a/kernel/bpf/hashtab.c +++ b/kernel/bpf/hashtab.c @@ -244,13 +244,13 @@ static int htab_map_alloc_check(union bpf_attr *attr) BUILD_BUG_ON(offsetof(struct htab_elem, fnode.next) != offsetof(struct htab_elem, hash_node.pprev)); - if (lru && !capable(CAP_SYS_ADMIN)) + if (lru && !bpf_capable(CAP_SYS_ADMIN)) /* LRU implementation is much complicated than other * maps. Hence, limit to CAP_SYS_ADMIN for now. */ return -EPERM; - if (zero_seed && !capable(CAP_SYS_ADMIN)) + if (zero_seed && !bpf_capable(CAP_SYS_ADMIN)) /* Guard against local DoS, and discourage production use. */ return -EPERM; diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c index 56e6c75d354d..571962022fdf 100644 --- a/kernel/bpf/lpm_trie.c +++ b/kernel/bpf/lpm_trie.c @@ -543,7 +543,7 @@ static struct bpf_map *trie_alloc(union bpf_attr *attr) u64 cost = sizeof(*trie), cost_per_node; int ret; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); /* check sanity of attributes */ diff --git a/kernel/bpf/offload.c b/kernel/bpf/offload.c index ba635209ae9a..d3e5378c5a15 100644 --- a/kernel/bpf/offload.c +++ b/kernel/bpf/offload.c @@ -366,7 +366,7 @@ struct bpf_map *bpf_map_offload_map_alloc(union bpf_attr *attr) struct bpf_offloaded_map *offmap; int err; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); if (attr->map_type != BPF_MAP_TYPE_ARRAY && attr->map_type != BPF_MAP_TYPE_HASH) diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c index f697647ceb54..01d848f1a783 100644 --- a/kernel/bpf/queue_stack_maps.c +++ b/kernel/bpf/queue_stack_maps.c @@ -45,7 +45,7 @@ static bool queue_stack_map_is_full(struct bpf_queue_stack *qs) /* Called from syscall */ static int queue_stack_map_alloc_check(union bpf_attr *attr) { - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; /* check sanity of attributes */ diff --git a/kernel/bpf/reuseport_array.c b/kernel/bpf/reuseport_array.c index 50c083ba978c..840f38a58c7d 100644 --- a/kernel/bpf/reuseport_array.c +++ b/kernel/bpf/reuseport_array.c @@ -154,7 +154,7 @@ static struct bpf_map *reuseport_array_alloc(union bpf_attr *attr) struct bpf_map_memory mem; u64 array_size; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); array_size = sizeof(*array); diff --git a/kernel/bpf/stackmap.c b/kernel/bpf/stackmap.c index 052580c33d26..1eab27b0bc17 100644 --- a/kernel/bpf/stackmap.c +++ b/kernel/bpf/stackmap.c @@ -90,7 +90,7 @@ static struct bpf_map *stack_map_alloc(union bpf_attr *attr) u64 cost, n_buckets; int err; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return ERR_PTR(-EPERM); if (attr->map_flags & ~STACK_CREATE_FLAG_MASK) diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c index 7713cf39795a..d80b04b6a5fa 100644 --- a/kernel/bpf/syscall.c +++ b/kernel/bpf/syscall.c @@ -23,6 +23,8 @@ #include <linux/timekeeping.h> #include <linux/ctype.h> #include <linux/nospec.h> +#include <linux/miscdevice.h> +#include <linux/resource.h> #define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \ (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \ @@ -1166,7 +1168,7 @@ static int map_freeze(const union bpf_attr *attr) err = -EBUSY; goto err_put; } - if (!capable(CAP_SYS_ADMIN)) { + if (!bpf_capable(CAP_SYS_ADMIN)) { err = -EPERM; goto err_put; } @@ -1616,7 +1618,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) && (attr->prog_flags & BPF_F_ANY_ALIGNMENT) && - !capable(CAP_SYS_ADMIN)) + !bpf_capable(CAP_SYS_ADMIN)) return -EPERM; /* copy eBPF program license from user space */ @@ -1629,11 +1631,12 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) is_gpl = license_is_gpl_compatible(license); if (attr->insn_cnt == 0 || - attr->insn_cnt > (capable(CAP_SYS_ADMIN) ? BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) + attr->insn_cnt > (bpf_capable(CAP_SYS_ADMIN) ? + BPF_COMPLEXITY_LIMIT_INSNS : BPF_MAXINSNS)) return -E2BIG; if (type != BPF_PROG_TYPE_SOCKET_FILTER && type != BPF_PROG_TYPE_CGROUP_SKB && - !capable(CAP_SYS_ADMIN)) + !bpf_capable(CAP_SYS_ADMIN)) return -EPERM; bpf_prog_load_fixup_attach_type(attr); @@ -1861,7 +1864,7 @@ static int bpf_prog_attach(const union bpf_attr *attr) struct bpf_prog *prog; int ret; - if (!capable(CAP_NET_ADMIN)) + if (!bpf_capable(CAP_NET_ADMIN)) return -EPERM; if (CHECK_ATTR(BPF_PROG_ATTACH)) @@ -1951,7 +1954,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) { enum bpf_prog_type ptype; - if (!capable(CAP_NET_ADMIN)) + if (!bpf_capable(CAP_NET_ADMIN)) return -EPERM; if (CHECK_ATTR(BPF_PROG_DETACH)) @@ -2007,7 +2010,7 @@ static int bpf_prog_detach(const union bpf_attr *attr) static int bpf_prog_query(const union bpf_attr *attr, union bpf_attr __user *uattr) { - if (!capable(CAP_NET_ADMIN)) + if (!bpf_capable(CAP_NET_ADMIN)) return -EPERM; if (CHECK_ATTR(BPF_PROG_QUERY)) return -EINVAL; @@ -2051,7 +2054,7 @@ static int bpf_prog_test_run(const union bpf_attr *attr, struct bpf_prog *prog; int ret = -ENOTSUPP; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; if (CHECK_ATTR(BPF_PROG_TEST_RUN)) return -EINVAL; @@ -2088,7 +2091,7 @@ static int bpf_obj_get_next_id(const union bpf_attr *attr, if (CHECK_ATTR(BPF_OBJ_GET_NEXT_ID) || next_id >= INT_MAX) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; next_id++; @@ -2114,7 +2117,7 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr) if (CHECK_ATTR(BPF_PROG_GET_FD_BY_ID)) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; spin_lock_bh(&prog_idr_lock); @@ -2148,7 +2151,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr) attr->open_flags & ~BPF_OBJ_FLAG_MASK) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; f_flags = bpf_get_file_flag(attr->open_flags); @@ -2323,7 +2326,7 @@ static int bpf_prog_get_info_by_fd(struct bpf_prog *prog, info.run_time_ns = stats.nsecs; info.run_cnt = stats.cnt; - if (!capable(CAP_SYS_ADMIN)) { + if (!bpf_capable(CAP_SYS_ADMIN)) { info.jited_prog_len = 0; info.xlated_prog_len = 0; info.nr_jited_ksyms = 0; @@ -2641,7 +2644,7 @@ static int bpf_btf_load(const union bpf_attr *attr) if (CHECK_ATTR(BPF_BTF_LOAD)) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; return btf_new_fd(attr); @@ -2654,7 +2657,7 @@ static int bpf_btf_get_fd_by_id(const union bpf_attr *attr) if (CHECK_ATTR(BPF_BTF_GET_FD_BY_ID)) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; return btf_get_fd_by_id(attr->btf_id); @@ -2723,7 +2726,7 @@ static int bpf_task_fd_query(const union bpf_attr *attr, if (CHECK_ATTR(BPF_TASK_FD_QUERY)) return -EINVAL; - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return -EPERM; if (attr->task_fd_query.flags != 0) @@ -2791,7 +2794,7 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz union bpf_attr attr = {}; int err; - if (sysctl_unprivileged_bpf_disabled && !capable(CAP_SYS_ADMIN)) + if (sysctl_unprivileged_bpf_disabled && !bpf_capable(CAP_SYS_ADMIN)) return -EPERM; err = bpf_check_uarg_tail_zero(uattr, sizeof(attr), size); @@ -2886,3 +2889,40 @@ SYSCALL_DEFINE3(bpf, int, cmd, union bpf_attr __user *, uattr, unsigned int, siz return err; } + +static long bpf_dev_ioctl(struct file *filp, + unsigned int ioctl, unsigned long arg) +{ + switch (ioctl) { + case BPF_DEV_IOCTL_GET_PERM: + set_bit(TASK_BPF_FLAG_PERMITTED, ¤t->bpf_flags); + break; + case BPF_DEV_IOCTL_PUT_PERM: + clear_bit(TASK_BPF_FLAG_PERMITTED, ¤t->bpf_flags); + break; + default: + return -EINVAL; + } + return 0; +} + +static const struct file_operations bpf_chardev_ops = { + .unlocked_ioctl = bpf_dev_ioctl, +}; + +static struct miscdevice bpf_dev = { + .minor = MISC_DYNAMIC_MINOR, + .name = "bpf", + .fops = &bpf_chardev_ops, + .mode = 0440, + .nodename = "bpf", +}; + +static int __init bpf_dev_init(void) +{ + if (misc_register(&bpf_dev)) + pr_warn("BPF: Failed to create /dev/bpf. Continue without it...\n"); + + return 0; +} +device_initcall(bpf_dev_init); diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 0e079b2298f8..79dc4d641cf3 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9134,7 +9134,7 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr, env->insn_aux_data[i].orig_idx = i; env->prog = *prog; env->ops = bpf_verifier_ops[env->prog->type]; - is_priv = capable(CAP_SYS_ADMIN); + is_priv = bpf_capable(CAP_SYS_ADMIN); /* grab the mutex to protect few globals used by verifier */ if (!is_priv) diff --git a/kernel/bpf/xskmap.c b/kernel/bpf/xskmap.c index ef7338cebd18..06063679c27a 100644 --- a/kernel/bpf/xskmap.c +++ b/kernel/bpf/xskmap.c @@ -21,7 +21,7 @@ static struct bpf_map *xsk_map_alloc(union bpf_attr *attr) int cpu, err; u64 cost; - if (!capable(CAP_NET_ADMIN)) + if (!bpf_capable(CAP_NET_ADMIN)) return ERR_PTR(-EPERM); if (attr->max_entries == 0 || attr->key_size != 4 || diff --git a/kernel/fork.c b/kernel/fork.c index 75675b9bf6df..18f914d54d92 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -923,6 +923,10 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) #ifdef CONFIG_MEMCG tsk->active_memcg = NULL; #endif + +#ifdef CONFIG_BPF_SYSCALL + tsk->bpf_flags = 0; +#endif return tsk; free_stack: diff --git a/net/core/filter.c b/net/core/filter.c index 2014d76e0d2a..01ccf031849c 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -5875,7 +5875,7 @@ bpf_base_func_proto(enum bpf_func_id func_id) break; } - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return NULL; switch (func_id) { @@ -6438,7 +6438,7 @@ static bool cg_skb_is_valid_access(int off, int size, return false; case bpf_ctx_range(struct __sk_buff, data): case bpf_ctx_range(struct __sk_buff, data_end): - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return false; break; } @@ -6450,7 +6450,7 @@ static bool cg_skb_is_valid_access(int off, int size, case bpf_ctx_range_till(struct __sk_buff, cb[0], cb[4]): break; case bpf_ctx_range(struct __sk_buff, tstamp): - if (!capable(CAP_SYS_ADMIN)) + if (!bpf_capable(CAP_SYS_ADMIN)) return false; break; default: -- 2.17.1
