diff options
| -rw-r--r-- | include/linux/uprobes.h | 5 | ||||
| -rw-r--r-- | kernel/events/uprobes.c | 259 | ||||
| -rw-r--r-- | kernel/trace/trace.c | 2 | ||||
| -rw-r--r-- | kernel/trace/trace_uprobe.c | 38 |
4 files changed, 293 insertions, 11 deletions
diff --git a/include/linux/uprobes.h b/include/linux/uprobes.h index bb9d2084af03..103a48a48872 100644 --- a/include/linux/uprobes.h +++ b/include/linux/uprobes.h @@ -123,6 +123,7 @@ extern unsigned long uprobe_get_swbp_addr(struct pt_regs *regs); extern unsigned long uprobe_get_trap_addr(struct pt_regs *regs); extern int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t); extern int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); +extern int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc); extern int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool); extern void uprobe_unregister(struct inode *inode, loff_t offset, struct uprobe_consumer *uc); extern int uprobe_mmap(struct vm_area_struct *vma); @@ -160,6 +161,10 @@ uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { return -ENOSYS; } +static inline int uprobe_register_refctr(struct inode *inode, loff_t offset, loff_t ref_ctr_offset, struct uprobe_consumer *uc) +{ + return -ENOSYS; +} static inline int uprobe_apply(struct inode *inode, loff_t offset, struct uprobe_consumer *uc, bool add) { diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c index 3207a4d26849..934feb39f6be 100644 --- a/kernel/events/uprobes.c +++ b/kernel/events/uprobes.c @@ -73,6 +73,7 @@ struct uprobe { struct uprobe_consumer *consumers; struct inode *inode; /* Also hold a ref to inode */ loff_t offset; + loff_t ref_ctr_offset; unsigned long flags; /* @@ -88,6 +89,15 @@ struct uprobe { struct arch_uprobe arch; }; +struct delayed_uprobe { + struct list_head list; + struct uprobe *uprobe; + struct mm_struct *mm; +}; + +static DEFINE_MUTEX(delayed_uprobe_lock); +static LIST_HEAD(delayed_uprobe_list); + /* * Execute out of line area: anonymous executable mapping installed * by the probed task to execute the copy of the original instruction @@ -282,6 +292,166 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t return 1; } +static struct delayed_uprobe * +delayed_uprobe_check(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct delayed_uprobe *du; + + list_for_each_entry(du, &delayed_uprobe_list, list) + if (du->uprobe == uprobe && du->mm == mm) + return du; + return NULL; +} + +static int delayed_uprobe_add(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct delayed_uprobe *du; + + if (delayed_uprobe_check(uprobe, mm)) + return 0; + + du = kzalloc(sizeof(*du), GFP_KERNEL); + if (!du) + return -ENOMEM; + + du->uprobe = uprobe; + du->mm = mm; + list_add(&du->list, &delayed_uprobe_list); + return 0; +} + +static void delayed_uprobe_delete(struct delayed_uprobe *du) +{ + if (WARN_ON(!du)) + return; + list_del(&du->list); + kfree(du); +} + +static void delayed_uprobe_remove(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct list_head *pos, *q; + struct delayed_uprobe *du; + + if (!uprobe && !mm) + return; + + list_for_each_safe(pos, q, &delayed_uprobe_list) { + du = list_entry(pos, struct delayed_uprobe, list); + + if (uprobe && du->uprobe != uprobe) + continue; + if (mm && du->mm != mm) + continue; + + delayed_uprobe_delete(du); + } +} + +static bool valid_ref_ctr_vma(struct uprobe *uprobe, + struct vm_area_struct *vma) +{ + unsigned long vaddr = offset_to_vaddr(vma, uprobe->ref_ctr_offset); + + return uprobe->ref_ctr_offset && + vma->vm_file && + file_inode(vma->vm_file) == uprobe->inode && + (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && + vma->vm_start <= vaddr && + vma->vm_end > vaddr; +} + +static struct vm_area_struct * +find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm) +{ + struct vm_area_struct *tmp; + + for (tmp = mm->mmap; tmp; tmp = tmp->vm_next) + if (valid_ref_ctr_vma(uprobe, tmp)) + return tmp; + + return NULL; +} + +static int +__update_ref_ctr(struct mm_struct *mm, unsigned long vaddr, short d) +{ + void *kaddr; + struct page *page; + struct vm_area_struct *vma; + int ret; + short *ptr; + + if (!vaddr || !d) + return -EINVAL; + + ret = get_user_pages_remote(NULL, mm, vaddr, 1, + FOLL_WRITE, &page, &vma, NULL); + if (unlikely(ret <= 0)) { + /* + * We are asking for 1 page. If get_user_pages_remote() fails, + * it may return 0, in that case we have to return error. + */ + return ret == 0 ? -EBUSY : ret; + } + + kaddr = kmap_atomic(page); + ptr = kaddr + (vaddr & ~PAGE_MASK); + + if (unlikely(*ptr + d < 0)) { + pr_warn("ref_ctr going negative. vaddr: 0x%lx, " + "curr val: %d, delta: %d\n", vaddr, *ptr, d); + ret = -EINVAL; + goto out; + } + + *ptr += d; + ret = 0; +out: + kunmap_atomic(kaddr); + put_page(page); + return ret; +} + +static void update_ref_ctr_warn(struct uprobe *uprobe, + struct mm_struct *mm, short d) +{ + pr_warn("ref_ctr %s failed for inode: 0x%lx offset: " + "0x%llx ref_ctr_offset: 0x%llx of mm: 0x%pK\n", + d > 0 ? "increment" : "decrement", uprobe->inode->i_ino, + (unsigned long long) uprobe->offset, + (unsigned long long) uprobe->ref_ctr_offset, mm); +} + +static int update_ref_ctr(struct uprobe *uprobe, struct mm_struct *mm, + short d) +{ + struct vm_area_struct *rc_vma; + unsigned long rc_vaddr; + int ret = 0; + + rc_vma = find_ref_ctr_vma(uprobe, mm); + + if (rc_vma) { + rc_vaddr = offset_to_vaddr(rc_vma, uprobe->ref_ctr_offset); + ret = __update_ref_ctr(mm, rc_vaddr, d); + if (ret) + update_ref_ctr_warn(uprobe, mm, d); + + if (d > 0) + return ret; + } + + mutex_lock(&delayed_uprobe_lock); + if (d > 0) + ret = delayed_uprobe_add(uprobe, mm); + else + delayed_uprobe_remove(uprobe, mm); + mutex_unlock(&delayed_uprobe_lock); + + return ret; +} + /* * NOTE: * Expect the breakpoint instruction to be the smallest size instruction for @@ -302,9 +472,13 @@ static int verify_opcode(struct page *page, unsigned long vaddr, uprobe_opcode_t int uprobe_write_opcode(struct arch_uprobe *auprobe, struct mm_struct *mm, unsigned long vaddr, uprobe_opcode_t opcode) { + struct uprobe *uprobe; struct page *old_page, *new_page; struct vm_area_struct *vma; - int ret; + int ret, is_register, ref_ctr_updated = 0; + + is_register = is_swbp_insn(&opcode); + uprobe = container_of(auprobe, struct uprobe, arch); retry: /* Read the page with vaddr into memory */ @@ -317,6 +491,15 @@ retry: if (ret <= 0) goto put_old; + /* We are going to replace instruction, update ref_ctr. */ + if (!ref_ctr_updated && uprobe->ref_ctr_offset) { + ret = update_ref_ctr(uprobe, mm, is_register ? 1 : -1); + if (ret) + goto put_old; + + ref_ctr_updated = 1; + } + ret = anon_vma_prepare(vma); if (ret) goto put_old; @@ -337,6 +520,11 @@ put_old: if (unlikely(ret == -EAGAIN)) goto retry; + + /* Revert back reference counter if instruction update failed. */ + if (ret && is_register && ref_ctr_updated) + update_ref_ctr(uprobe, mm, -1); + return ret; } @@ -378,8 +566,15 @@ static struct uprobe *get_uprobe(struct uprobe *uprobe) static void put_uprobe(struct uprobe *uprobe) { - if (atomic_dec_and_test(&uprobe->ref)) + if (atomic_dec_and_test(&uprobe->ref)) { + /* + * If application munmap(exec_vma) before uprobe_unregister() + * gets called, we don't get a chance to remove uprobe from + * delayed_uprobe_list from remove_breakpoint(). Do it here. + */ + delayed_uprobe_remove(uprobe, NULL); kfree(uprobe); + } } static int match_uprobe(struct uprobe *l, struct uprobe *r) @@ -484,7 +679,8 @@ static struct uprobe *insert_uprobe(struct uprobe *uprobe) return u; } -static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) +static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset, + loff_t ref_ctr_offset) { struct uprobe *uprobe, *cur_uprobe; @@ -494,6 +690,7 @@ static struct uprobe *alloc_uprobe(struct inode *inode, loff_t offset) uprobe->inode = inode; uprobe->offset = offset; + uprobe->ref_ctr_offset = ref_ctr_offset; init_rwsem(&uprobe->register_rwsem); init_rwsem(&uprobe->consumer_rwsem); @@ -895,7 +1092,7 @@ EXPORT_SYMBOL_GPL(uprobe_unregister); * else return 0 (success) */ static int __uprobe_register(struct inode *inode, loff_t offset, - struct uprobe_consumer *uc) + loff_t ref_ctr_offset, struct uprobe_consumer *uc) { struct uprobe *uprobe; int ret; @@ -912,7 +1109,7 @@ static int __uprobe_register(struct inode *inode, loff_t offset, return -EINVAL; retry: - uprobe = alloc_uprobe(inode, offset); + uprobe = alloc_uprobe(inode, offset, ref_ctr_offset); if (!uprobe) return -ENOMEM; /* @@ -938,10 +1135,17 @@ static int __uprobe_register(struct inode *inode, loff_t offset, int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *uc) { - return __uprobe_register(inode, offset, uc); + return __uprobe_register(inode, offset, 0, uc); } EXPORT_SYMBOL_GPL(uprobe_register); +int uprobe_register_refctr(struct inode *inode, loff_t offset, + loff_t ref_ctr_offset, struct uprobe_consumer *uc) +{ + return __uprobe_register(inode, offset, ref_ctr_offset, uc); +} +EXPORT_SYMBOL_GPL(uprobe_register_refctr); + /* * uprobe_apply - unregister an already registered probe. * @inode: the file in which the probe has to be removed. @@ -1060,6 +1264,35 @@ static void build_probe_list(struct inode *inode, spin_unlock(&uprobes_treelock); } +/* @vma contains reference counter, not the probed instruction. */ +static int delayed_ref_ctr_inc(struct vm_area_struct *vma) +{ + struct list_head *pos, *q; + struct delayed_uprobe *du; + unsigned long vaddr; + int ret = 0, err = 0; + + mutex_lock(&delayed_uprobe_lock); + list_for_each_safe(pos, q, &delayed_uprobe_list) { + du = list_entry(pos, struct delayed_uprobe, list); + + if (du->mm != vma->vm_mm || + !valid_ref_ctr_vma(du->uprobe, vma)) + continue; + + vaddr = offset_to_vaddr(vma, du->uprobe->ref_ctr_offset); + ret = __update_ref_ctr(vma->vm_mm, vaddr, 1); + if (ret) { + update_ref_ctr_warn(du->uprobe, vma->vm_mm, 1); + if (!err) + err = ret; + } + delayed_uprobe_delete(du); + } + mutex_unlock(&delayed_uprobe_lock); + return err; +} + /* * Called from mmap_region/vma_adjust with mm->mmap_sem acquired. * @@ -1072,7 +1305,15 @@ int uprobe_mmap(struct vm_area_struct *vma) struct uprobe *uprobe, *u; struct inode *inode; - if (no_uprobe_events() || !valid_vma(vma, true)) + if (no_uprobe_events()) + return 0; + + if (vma->vm_file && + (vma->vm_flags & (VM_WRITE|VM_SHARED)) == VM_WRITE && + test_bit(MMF_HAS_UPROBES, &vma->vm_mm->flags)) + delayed_ref_ctr_inc(vma); + + if (!valid_vma(vma, true)) return 0; inode = file_inode(vma->vm_file); @@ -1246,6 +1487,10 @@ void uprobe_clear_state(struct mm_struct *mm) { struct xol_area *area = mm->uprobes_state.xol_area; + mutex_lock(&delayed_uprobe_lock); + delayed_uprobe_remove(NULL, mm); + mutex_unlock(&delayed_uprobe_lock); + if (!area) return; diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index bf6f1d70484d..147be8523560 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -4621,7 +4621,7 @@ static const char readme_msg[] = "place (kretprobe): [<module>:]<symbol>[+<offset>]|<memaddr>\n" #endif #ifdef CONFIG_UPROBE_EVENTS - "\t place: <path>:<offset>\n" + " place (uprobe): <path>:<offset>[(ref_ctr_offset)]\n" #endif "\t args: <name>=fetcharg[:type]\n" "\t fetcharg: %<register>, @<address>, @<symbol>[+|-<offset>],\n" diff --git a/kernel/trace/trace_uprobe.c b/kernel/trace/trace_uprobe.c index e696667da29a..7b85172beab6 100644 --- a/kernel/trace/trace_uprobe.c +++ b/kernel/trace/trace_uprobe.c @@ -47,6 +47,7 @@ struct trace_uprobe { struct inode *inode; char *filename; unsigned long offset; + unsigned long ref_ctr_offset; unsigned long nhit; struct trace_probe tp; }; @@ -352,10 +353,10 @@ end: static int create_trace_uprobe(int argc, char **argv) { struct trace_uprobe *tu; - char *arg, *event, *group, *filename; + char *arg, *event, *group, *filename, *rctr, *rctr_end; char buf[MAX_EVENT_NAME_LEN]; struct path path; - unsigned long offset; + unsigned long offset, ref_ctr_offset; bool is_delete, is_return; int i, ret; @@ -364,6 +365,7 @@ static int create_trace_uprobe(int argc, char **argv) is_return = false; event = NULL; group = NULL; + ref_ctr_offset = 0; /* argc must be >= 1 */ if (argv[0][0] == '-') @@ -438,6 +440,26 @@ static int create_trace_uprobe(int argc, char **argv) goto fail_address_parse; } + /* Parse reference counter offset if specified. */ + rctr = strchr(arg, '('); + if (rctr) { + rctr_end = strchr(rctr, ')'); + if (rctr > rctr_end || *(rctr_end + 1) != 0) { + ret = -EINVAL; + pr_info("Invalid reference counter offset.\n"); + goto fail_address_parse; + } + + *rctr++ = '\0'; + *rctr_end = '\0'; + ret = kstrtoul(rctr, 0, &ref_ctr_offset); + if (ret) { + pr_info("Invalid reference counter offset.\n"); + goto fail_address_parse; + } + } + + /* Parse uprobe offset. */ ret = kstrtoul(arg, 0, &offset); if (ret) goto fail_address_parse; @@ -472,6 +494,7 @@ static int create_trace_uprobe(int argc, char **argv) goto fail_address_parse; } tu->offset = offset; + tu->ref_ctr_offset = ref_ctr_offset; tu->path = path; tu->filename = kstrdup(filename, GFP_KERNEL); @@ -590,6 +613,9 @@ static int probes_seq_show(struct seq_file *m, void *v) trace_event_name(&tu->tp.call), tu->filename, (int)(sizeof(void *) * 2), tu->offset); + if (tu->ref_ctr_offset) + seq_printf(m, "(0x%lx)", tu->ref_ctr_offset); + for (i = 0; i < tu->tp.nr_args; i++) seq_printf(m, " %s=%s", tu->tp.args[i].name, tu->tp.args[i].comm); @@ -905,7 +931,13 @@ probe_event_enable(struct trace_uprobe *tu, struct trace_event_file *file, tu->consumer.filter = filter; tu->inode = d_real_inode(tu->path.dentry); - ret = uprobe_register(tu->inode, tu->offset, &tu->consumer); + if (tu->ref_ctr_offset) { + ret = uprobe_register_refctr(tu->inode, tu->offset, + tu->ref_ctr_offset, &tu->consumer); + } else { + ret = uprobe_register(tu->inode, tu->offset, &tu->consumer); + } + if (ret) goto err_buffer; |