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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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![Masami Hiramatsu (Google)](/assets/img/avatar_default.png)
Since commitab51e15d53
("fprobe: Introduce FPROBE_FL_KPROBE_SHARED flag for fprobe") introduced fprobe_kprobe_handler() for fprobe::ops::func, unregister_fprobe() fails to unregister the registered if user specifies FPROBE_FL_KPROBE_SHARED flag. Moreover, __register_ftrace_function() is possible to change the ftrace_ops::func, thus we have to check fprobe::ops::saved_func instead. To check it correctly, it should confirm the fprobe::ops::saved_func is either fprobe_handler() or fprobe_kprobe_handler(). Link: https://lore.kernel.org/all/166677683946.1459107.15997653945538644683.stgit@devnote3/ Fixes:cad9931f64
("fprobe: Add ftrace based probe APIs") Cc: stable@vger.kernel.org Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
327 lines
7.6 KiB
C
327 lines
7.6 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* fprobe - Simple ftrace probe wrapper for function entry.
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*/
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#define pr_fmt(fmt) "fprobe: " fmt
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#include <linux/err.h>
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#include <linux/fprobe.h>
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#include <linux/kallsyms.h>
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#include <linux/kprobes.h>
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#include <linux/rethook.h>
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#include <linux/slab.h>
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#include <linux/sort.h>
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#include "trace.h"
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struct fprobe_rethook_node {
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struct rethook_node node;
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unsigned long entry_ip;
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};
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static void fprobe_handler(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *ops, struct ftrace_regs *fregs)
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{
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struct fprobe_rethook_node *fpr;
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struct rethook_node *rh;
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struct fprobe *fp;
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int bit;
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fp = container_of(ops, struct fprobe, ops);
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if (fprobe_disabled(fp))
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return;
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bit = ftrace_test_recursion_trylock(ip, parent_ip);
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if (bit < 0) {
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fp->nmissed++;
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return;
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}
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if (fp->entry_handler)
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fp->entry_handler(fp, ip, ftrace_get_regs(fregs));
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if (fp->exit_handler) {
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rh = rethook_try_get(fp->rethook);
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if (!rh) {
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fp->nmissed++;
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goto out;
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}
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fpr = container_of(rh, struct fprobe_rethook_node, node);
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fpr->entry_ip = ip;
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rethook_hook(rh, ftrace_get_regs(fregs), true);
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}
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out:
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ftrace_test_recursion_unlock(bit);
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}
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NOKPROBE_SYMBOL(fprobe_handler);
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static void fprobe_kprobe_handler(unsigned long ip, unsigned long parent_ip,
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struct ftrace_ops *ops, struct ftrace_regs *fregs)
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{
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struct fprobe *fp = container_of(ops, struct fprobe, ops);
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if (unlikely(kprobe_running())) {
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fp->nmissed++;
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return;
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}
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kprobe_busy_begin();
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fprobe_handler(ip, parent_ip, ops, fregs);
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kprobe_busy_end();
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}
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static void fprobe_exit_handler(struct rethook_node *rh, void *data,
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struct pt_regs *regs)
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{
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struct fprobe *fp = (struct fprobe *)data;
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struct fprobe_rethook_node *fpr;
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if (!fp || fprobe_disabled(fp))
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return;
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fpr = container_of(rh, struct fprobe_rethook_node, node);
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fp->exit_handler(fp, fpr->entry_ip, regs);
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}
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NOKPROBE_SYMBOL(fprobe_exit_handler);
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static int symbols_cmp(const void *a, const void *b)
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{
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const char **str_a = (const char **) a;
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const char **str_b = (const char **) b;
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return strcmp(*str_a, *str_b);
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}
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/* Convert ftrace location address from symbols */
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static unsigned long *get_ftrace_locations(const char **syms, int num)
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{
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unsigned long *addrs;
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/* Convert symbols to symbol address */
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addrs = kcalloc(num, sizeof(*addrs), GFP_KERNEL);
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if (!addrs)
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return ERR_PTR(-ENOMEM);
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/* ftrace_lookup_symbols expects sorted symbols */
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sort(syms, num, sizeof(*syms), symbols_cmp, NULL);
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if (!ftrace_lookup_symbols(syms, num, addrs))
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return addrs;
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kfree(addrs);
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return ERR_PTR(-ENOENT);
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}
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static void fprobe_init(struct fprobe *fp)
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{
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fp->nmissed = 0;
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if (fprobe_shared_with_kprobes(fp))
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fp->ops.func = fprobe_kprobe_handler;
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else
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fp->ops.func = fprobe_handler;
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fp->ops.flags |= FTRACE_OPS_FL_SAVE_REGS;
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}
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static int fprobe_init_rethook(struct fprobe *fp, int num)
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{
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int i, size;
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if (num < 0)
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return -EINVAL;
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if (!fp->exit_handler) {
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fp->rethook = NULL;
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return 0;
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}
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/* Initialize rethook if needed */
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size = num * num_possible_cpus() * 2;
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if (size < 0)
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return -E2BIG;
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fp->rethook = rethook_alloc((void *)fp, fprobe_exit_handler);
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if (!fp->rethook)
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return -ENOMEM;
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for (i = 0; i < size; i++) {
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struct fprobe_rethook_node *node;
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node = kzalloc(sizeof(*node), GFP_KERNEL);
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if (!node) {
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rethook_free(fp->rethook);
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fp->rethook = NULL;
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return -ENOMEM;
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}
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rethook_add_node(fp->rethook, &node->node);
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}
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return 0;
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}
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static void fprobe_fail_cleanup(struct fprobe *fp)
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{
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if (fp->rethook) {
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/* Don't need to cleanup rethook->handler because this is not used. */
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rethook_free(fp->rethook);
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fp->rethook = NULL;
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}
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ftrace_free_filter(&fp->ops);
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}
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/**
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* register_fprobe() - Register fprobe to ftrace by pattern.
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* @fp: A fprobe data structure to be registered.
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* @filter: A wildcard pattern of probed symbols.
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* @notfilter: A wildcard pattern of NOT probed symbols.
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*
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* Register @fp to ftrace for enabling the probe on the symbols matched to @filter.
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* If @notfilter is not NULL, the symbols matched the @notfilter are not probed.
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*
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* Return 0 if @fp is registered successfully, -errno if not.
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*/
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int register_fprobe(struct fprobe *fp, const char *filter, const char *notfilter)
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{
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struct ftrace_hash *hash;
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unsigned char *str;
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int ret, len;
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if (!fp || !filter)
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return -EINVAL;
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fprobe_init(fp);
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len = strlen(filter);
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str = kstrdup(filter, GFP_KERNEL);
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ret = ftrace_set_filter(&fp->ops, str, len, 0);
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kfree(str);
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if (ret)
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return ret;
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if (notfilter) {
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len = strlen(notfilter);
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str = kstrdup(notfilter, GFP_KERNEL);
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ret = ftrace_set_notrace(&fp->ops, str, len, 0);
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kfree(str);
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if (ret)
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goto out;
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}
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/* TODO:
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* correctly calculate the total number of filtered symbols
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* from both filter and notfilter.
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*/
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hash = rcu_access_pointer(fp->ops.local_hash.filter_hash);
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if (WARN_ON_ONCE(!hash))
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goto out;
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ret = fprobe_init_rethook(fp, (int)hash->count);
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if (!ret)
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ret = register_ftrace_function(&fp->ops);
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out:
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if (ret)
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fprobe_fail_cleanup(fp);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_fprobe);
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/**
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* register_fprobe_ips() - Register fprobe to ftrace by address.
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* @fp: A fprobe data structure to be registered.
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* @addrs: An array of target ftrace location addresses.
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* @num: The number of entries of @addrs.
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*
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* Register @fp to ftrace for enabling the probe on the address given by @addrs.
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* The @addrs must be the addresses of ftrace location address, which may be
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* the symbol address + arch-dependent offset.
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* If you unsure what this mean, please use other registration functions.
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*
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* Return 0 if @fp is registered successfully, -errno if not.
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*/
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int register_fprobe_ips(struct fprobe *fp, unsigned long *addrs, int num)
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{
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int ret;
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if (!fp || !addrs || num <= 0)
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return -EINVAL;
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fprobe_init(fp);
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ret = ftrace_set_filter_ips(&fp->ops, addrs, num, 0, 0);
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if (ret)
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return ret;
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ret = fprobe_init_rethook(fp, num);
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if (!ret)
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ret = register_ftrace_function(&fp->ops);
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if (ret)
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fprobe_fail_cleanup(fp);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_fprobe_ips);
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/**
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* register_fprobe_syms() - Register fprobe to ftrace by symbols.
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* @fp: A fprobe data structure to be registered.
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* @syms: An array of target symbols.
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* @num: The number of entries of @syms.
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*
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* Register @fp to the symbols given by @syms array. This will be useful if
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* you are sure the symbols exist in the kernel.
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*
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* Return 0 if @fp is registered successfully, -errno if not.
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*/
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int register_fprobe_syms(struct fprobe *fp, const char **syms, int num)
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{
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unsigned long *addrs;
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int ret;
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if (!fp || !syms || num <= 0)
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return -EINVAL;
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addrs = get_ftrace_locations(syms, num);
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if (IS_ERR(addrs))
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return PTR_ERR(addrs);
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ret = register_fprobe_ips(fp, addrs, num);
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kfree(addrs);
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return ret;
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}
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EXPORT_SYMBOL_GPL(register_fprobe_syms);
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/**
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* unregister_fprobe() - Unregister fprobe from ftrace
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* @fp: A fprobe data structure to be unregistered.
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*
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* Unregister fprobe (and remove ftrace hooks from the function entries).
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*
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* Return 0 if @fp is unregistered successfully, -errno if not.
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*/
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int unregister_fprobe(struct fprobe *fp)
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{
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int ret;
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if (!fp || (fp->ops.saved_func != fprobe_handler &&
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fp->ops.saved_func != fprobe_kprobe_handler))
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return -EINVAL;
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/*
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* rethook_free() starts disabling the rethook, but the rethook handlers
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* may be running on other processors at this point. To make sure that all
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* current running handlers are finished, call unregister_ftrace_function()
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* after this.
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*/
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if (fp->rethook)
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rethook_free(fp->rethook);
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ret = unregister_ftrace_function(&fp->ops);
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if (ret < 0)
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return ret;
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ftrace_free_filter(&fp->ops);
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return ret;
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}
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EXPORT_SYMBOL_GPL(unregister_fprobe);
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