diff options
Diffstat (limited to 'kernel/bpf/core.c')
| -rw-r--r-- | kernel/bpf/core.c | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c index 2831ba1e71c1..f45827e205d3 100644 --- a/kernel/bpf/core.c +++ b/kernel/bpf/core.c @@ -28,6 +28,9 @@ #include <linux/moduleloader.h> #include <linux/bpf.h> #include <linux/frame.h> +#include <linux/rbtree_latch.h> +#include <linux/kallsyms.h> +#include <linux/rcupdate.h> #include <asm/unaligned.h> @@ -95,6 +98,8 @@ struct bpf_prog *bpf_prog_alloc(unsigned int size, gfp_t gfp_extra_flags) fp->aux = aux; fp->aux->prog = fp; + INIT_LIST_HEAD_RCU(&fp->aux->ksym_lnode); + return fp; } EXPORT_SYMBOL_GPL(bpf_prog_alloc); @@ -290,6 +295,206 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off, } #ifdef CONFIG_BPF_JIT +static __always_inline void +bpf_get_prog_addr_region(const struct bpf_prog *prog, + unsigned long *symbol_start, + unsigned long *symbol_end) +{ + const struct bpf_binary_header *hdr = bpf_jit_binary_hdr(prog); + unsigned long addr = (unsigned long)hdr; + + WARN_ON_ONCE(!bpf_prog_ebpf_jited(prog)); + + *symbol_start = addr; + *symbol_end = addr + hdr->pages * PAGE_SIZE; +} + +static void bpf_get_prog_name(const struct bpf_prog *prog, char *sym) +{ + BUILD_BUG_ON(sizeof("bpf_prog_") + + sizeof(prog->tag) * 2 + 1 > KSYM_NAME_LEN); + + sym += snprintf(sym, KSYM_NAME_LEN, "bpf_prog_"); + sym = bin2hex(sym, prog->tag, sizeof(prog->tag)); + *sym = 0; +} + +static __always_inline unsigned long +bpf_get_prog_addr_start(struct latch_tree_node *n) +{ + unsigned long symbol_start, symbol_end; + const struct bpf_prog_aux *aux; + + aux = container_of(n, struct bpf_prog_aux, ksym_tnode); + bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end); + + return symbol_start; +} + +static __always_inline bool bpf_tree_less(struct latch_tree_node *a, + struct latch_tree_node *b) +{ + return bpf_get_prog_addr_start(a) < bpf_get_prog_addr_start(b); +} + +static __always_inline int bpf_tree_comp(void *key, struct latch_tree_node *n) +{ + unsigned long val = (unsigned long)key; + unsigned long symbol_start, symbol_end; + const struct bpf_prog_aux *aux; + + aux = container_of(n, struct bpf_prog_aux, ksym_tnode); + bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end); + + if (val < symbol_start) + return -1; + if (val >= symbol_end) + return 1; + + return 0; +} + +static const struct latch_tree_ops bpf_tree_ops = { + .less = bpf_tree_less, + .comp = bpf_tree_comp, +}; + +static DEFINE_SPINLOCK(bpf_lock); +static LIST_HEAD(bpf_kallsyms); +static struct latch_tree_root bpf_tree __cacheline_aligned; + +int bpf_jit_kallsyms __read_mostly; + +static void bpf_prog_ksym_node_add(struct bpf_prog_aux *aux) +{ + WARN_ON_ONCE(!list_empty(&aux->ksym_lnode)); + list_add_tail_rcu(&aux->ksym_lnode, &bpf_kallsyms); + latch_tree_insert(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops); +} + +static void bpf_prog_ksym_node_del(struct bpf_prog_aux *aux) +{ + if (list_empty(&aux->ksym_lnode)) + return; + + latch_tree_erase(&aux->ksym_tnode, &bpf_tree, &bpf_tree_ops); + list_del_rcu(&aux->ksym_lnode); +} + +static bool bpf_prog_kallsyms_candidate(const struct bpf_prog *fp) +{ + return fp->jited && !bpf_prog_was_classic(fp); +} + +static bool bpf_prog_kallsyms_verify_off(const struct bpf_prog *fp) +{ + return list_empty(&fp->aux->ksym_lnode) || + fp->aux->ksym_lnode.prev == LIST_POISON2; +} + +void bpf_prog_kallsyms_add(struct bpf_prog *fp) +{ + unsigned long flags; + + if (!bpf_prog_kallsyms_candidate(fp) || + !capable(CAP_SYS_ADMIN)) + return; + + spin_lock_irqsave(&bpf_lock, flags); + bpf_prog_ksym_node_add(fp->aux); + spin_unlock_irqrestore(&bpf_lock, flags); +} + +void bpf_prog_kallsyms_del(struct bpf_prog *fp) +{ + unsigned long flags; + + if (!bpf_prog_kallsyms_candidate(fp)) + return; + + spin_lock_irqsave(&bpf_lock, flags); + bpf_prog_ksym_node_del(fp->aux); + spin_unlock_irqrestore(&bpf_lock, flags); +} + +static struct bpf_prog *bpf_prog_kallsyms_find(unsigned long addr) +{ + struct latch_tree_node *n; + + if (!bpf_jit_kallsyms_enabled()) + return NULL; + + n = latch_tree_find((void *)addr, &bpf_tree, &bpf_tree_ops); + return n ? + container_of(n, struct bpf_prog_aux, ksym_tnode)->prog : + NULL; +} + +const char *__bpf_address_lookup(unsigned long addr, unsigned long *size, + unsigned long *off, char *sym) +{ + unsigned long symbol_start, symbol_end; + struct bpf_prog *prog; + char *ret = NULL; + + rcu_read_lock(); + prog = bpf_prog_kallsyms_find(addr); + if (prog) { + bpf_get_prog_addr_region(prog, &symbol_start, &symbol_end); + bpf_get_prog_name(prog, sym); + + ret = sym; + if (size) + *size = symbol_end - symbol_start; + if (off) + *off = addr - symbol_start; + } + rcu_read_unlock(); + + return ret; +} + +bool is_bpf_text_address(unsigned long addr) +{ + bool ret; + + rcu_read_lock(); + ret = bpf_prog_kallsyms_find(addr) != NULL; + rcu_read_unlock(); + + return ret; +} + +int bpf_get_kallsym(unsigned int symnum, unsigned long *value, char *type, + char *sym) +{ + unsigned long symbol_start, symbol_end; + struct bpf_prog_aux *aux; + unsigned int it = 0; + int ret = -ERANGE; + + if (!bpf_jit_kallsyms_enabled()) + return ret; + + rcu_read_lock(); + list_for_each_entry_rcu(aux, &bpf_kallsyms, ksym_lnode) { + if (it++ != symnum) + continue; + + bpf_get_prog_addr_region(aux->prog, &symbol_start, &symbol_end); + bpf_get_prog_name(aux->prog, sym); + + *value = symbol_start; + *type = BPF_SYM_ELF_TYPE; + + ret = 0; + break; + } + rcu_read_unlock(); + + return ret; +} + struct bpf_binary_header * bpf_jit_binary_alloc(unsigned int proglen, u8 **image_ptr, unsigned int alignment, @@ -326,6 +531,24 @@ void bpf_jit_binary_free(struct bpf_binary_header *hdr) module_memfree(hdr); } +/* This symbol is only overridden by archs that have different + * requirements than the usual eBPF JITs, f.e. when they only + * implement cBPF JIT, do not set images read-only, etc. + */ +void __weak bpf_jit_free(struct bpf_prog *fp) +{ + if (fp->jited) { + struct bpf_binary_header *hdr = bpf_jit_binary_hdr(fp); + + bpf_jit_binary_unlock_ro(hdr); + bpf_jit_binary_free(hdr); + + WARN_ON_ONCE(!bpf_prog_kallsyms_verify_off(fp)); + } + + bpf_prog_unlock_free(fp); +} + int bpf_jit_harden __read_mostly; static int bpf_jit_blind_insn(const struct bpf_insn *from, |
