selftests/bpf: Add test for bpf_iter_task_vma
authorSong Liu <songliubraving@fb.com>
Fri, 12 Feb 2021 18:31:07 +0000 (10:31 -0800)
committerAlexei Starovoitov <ast@kernel.org>
Fri, 12 Feb 2021 20:56:54 +0000 (12:56 -0800)
The test dumps information similar to /proc/pid/maps. The first line of
the output is compared against the /proc file to make sure they match.

Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210212183107.50963-4-songliubraving@fb.com
tools/testing/selftests/bpf/prog_tests/bpf_iter.c
tools/testing/selftests/bpf/progs/bpf_iter.h
tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c [new file with mode: 0644]

index 0e58636..74c45d5 100644 (file)
@@ -7,6 +7,7 @@
 #include "bpf_iter_task.skel.h"
 #include "bpf_iter_task_stack.skel.h"
 #include "bpf_iter_task_file.skel.h"
+#include "bpf_iter_task_vma.skel.h"
 #include "bpf_iter_task_btf.skel.h"
 #include "bpf_iter_tcp4.skel.h"
 #include "bpf_iter_tcp6.skel.h"
@@ -64,6 +65,22 @@ free_link:
        bpf_link__destroy(link);
 }
 
+static int read_fd_into_buffer(int fd, char *buf, int size)
+{
+       int bufleft = size;
+       int len;
+
+       do {
+               len = read(fd, buf, bufleft);
+               if (len > 0) {
+                       buf += len;
+                       bufleft -= len;
+               }
+       } while (len > 0);
+
+       return len < 0 ? len : size - bufleft;
+}
+
 static void test_ipv6_route(void)
 {
        struct bpf_iter_ipv6_route *skel;
@@ -177,7 +194,7 @@ static int do_btf_read(struct bpf_iter_task_btf *skel)
 {
        struct bpf_program *prog = skel->progs.dump_task_struct;
        struct bpf_iter_task_btf__bss *bss = skel->bss;
-       int iter_fd = -1, len = 0, bufleft = TASKBUFSZ;
+       int iter_fd = -1, err;
        struct bpf_link *link;
        char *buf = taskbuf;
        int ret = 0;
@@ -190,14 +207,7 @@ static int do_btf_read(struct bpf_iter_task_btf *skel)
        if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
                goto free_link;
 
-       do {
-               len = read(iter_fd, buf, bufleft);
-               if (len > 0) {
-                       buf += len;
-                       bufleft -= len;
-               }
-       } while (len > 0);
-
+       err = read_fd_into_buffer(iter_fd, buf, TASKBUFSZ);
        if (bss->skip) {
                printf("%s:SKIP:no __builtin_btf_type_id\n", __func__);
                ret = 1;
@@ -205,7 +215,7 @@ static int do_btf_read(struct bpf_iter_task_btf *skel)
                goto free_link;
        }
 
-       if (CHECK(len < 0, "read", "read failed: %s\n", strerror(errno)))
+       if (CHECK(err < 0, "read", "read failed: %s\n", strerror(errno)))
                goto free_link;
 
        CHECK(strstr(taskbuf, "(struct task_struct)") == NULL,
@@ -1133,6 +1143,92 @@ static void test_buf_neg_offset(void)
                bpf_iter_test_kern6__destroy(skel);
 }
 
+#define CMP_BUFFER_SIZE 1024
+static char task_vma_output[CMP_BUFFER_SIZE];
+static char proc_maps_output[CMP_BUFFER_SIZE];
+
+/* remove \0 and \t from str, and only keep the first line */
+static void str_strip_first_line(char *str)
+{
+       char *dst = str, *src = str;
+
+       do {
+               if (*src == ' ' || *src == '\t')
+                       src++;
+               else
+                       *(dst++) = *(src++);
+
+       } while (*src != '\0' && *src != '\n');
+
+       *dst = '\0';
+}
+
+#define min(a, b) ((a) < (b) ? (a) : (b))
+
+static void test_task_vma(void)
+{
+       int err, iter_fd = -1, proc_maps_fd = -1;
+       struct bpf_iter_task_vma *skel;
+       int len, read_size = 4;
+       char maps_path[64];
+
+       skel = bpf_iter_task_vma__open();
+       if (CHECK(!skel, "bpf_iter_task_vma__open", "skeleton open failed\n"))
+               return;
+
+       skel->bss->pid = getpid();
+
+       err = bpf_iter_task_vma__load(skel);
+       if (CHECK(err, "bpf_iter_task_vma__load", "skeleton load failed\n"))
+               goto out;
+
+       skel->links.proc_maps = bpf_program__attach_iter(
+               skel->progs.proc_maps, NULL);
+
+       if (CHECK(IS_ERR(skel->links.proc_maps), "bpf_program__attach_iter",
+                 "attach iterator failed\n")) {
+               skel->links.proc_maps = NULL;
+               goto out;
+       }
+
+       iter_fd = bpf_iter_create(bpf_link__fd(skel->links.proc_maps));
+       if (CHECK(iter_fd < 0, "create_iter", "create_iter failed\n"))
+               goto out;
+
+       /* Read CMP_BUFFER_SIZE (1kB) from bpf_iter. Read in small chunks
+        * to trigger seq_file corner cases. The expected output is much
+        * longer than 1kB, so the while loop will terminate.
+        */
+       len = 0;
+       while (len < CMP_BUFFER_SIZE) {
+               err = read_fd_into_buffer(iter_fd, task_vma_output + len,
+                                         min(read_size, CMP_BUFFER_SIZE - len));
+               if (CHECK(err < 0, "read_iter_fd", "read_iter_fd failed\n"))
+                       goto out;
+               len += err;
+       }
+
+       /* read CMP_BUFFER_SIZE (1kB) from /proc/pid/maps */
+       snprintf(maps_path, 64, "/proc/%u/maps", skel->bss->pid);
+       proc_maps_fd = open(maps_path, O_RDONLY);
+       if (CHECK(proc_maps_fd < 0, "open_proc_maps", "open_proc_maps failed\n"))
+               goto out;
+       err = read_fd_into_buffer(proc_maps_fd, proc_maps_output, CMP_BUFFER_SIZE);
+       if (CHECK(err < 0, "read_prog_maps_fd", "read_prog_maps_fd failed\n"))
+               goto out;
+
+       /* strip and compare the first line of the two files */
+       str_strip_first_line(task_vma_output);
+       str_strip_first_line(proc_maps_output);
+
+       CHECK(strcmp(task_vma_output, proc_maps_output), "compare_output",
+             "found mismatch\n");
+out:
+       close(proc_maps_fd);
+       close(iter_fd);
+       bpf_iter_task_vma__destroy(skel);
+}
+
 void test_bpf_iter(void)
 {
        if (test__start_subtest("btf_id_or_null"))
@@ -1149,6 +1245,8 @@ void test_bpf_iter(void)
                test_task_stack();
        if (test__start_subtest("task_file"))
                test_task_file();
+       if (test__start_subtest("task_vma"))
+               test_task_vma();
        if (test__start_subtest("task_btf"))
                test_task_btf();
        if (test__start_subtest("tcp4"))
index 6a12554..3d83b18 100644 (file)
@@ -7,6 +7,7 @@
 #define bpf_iter__netlink bpf_iter__netlink___not_used
 #define bpf_iter__task bpf_iter__task___not_used
 #define bpf_iter__task_file bpf_iter__task_file___not_used
+#define bpf_iter__task_vma bpf_iter__task_vma___not_used
 #define bpf_iter__tcp bpf_iter__tcp___not_used
 #define tcp6_sock tcp6_sock___not_used
 #define bpf_iter__udp bpf_iter__udp___not_used
@@ -26,6 +27,7 @@
 #undef bpf_iter__netlink
 #undef bpf_iter__task
 #undef bpf_iter__task_file
+#undef bpf_iter__task_vma
 #undef bpf_iter__tcp
 #undef tcp6_sock
 #undef bpf_iter__udp
@@ -67,6 +69,12 @@ struct bpf_iter__task_file {
        struct file *file;
 } __attribute__((preserve_access_index));
 
+struct bpf_iter__task_vma {
+       struct bpf_iter_meta *meta;
+       struct task_struct *task;
+       struct vm_area_struct *vma;
+} __attribute__((preserve_access_index));
+
 struct bpf_iter__bpf_map {
        struct bpf_iter_meta *meta;
        struct bpf_map *map;
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c b/tools/testing/selftests/bpf/progs/bpf_iter_task_vma.c
new file mode 100644 (file)
index 0000000..11d1aa3
--- /dev/null
@@ -0,0 +1,58 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2020 Facebook */
+#include "bpf_iter.h"
+#include <bpf/bpf_helpers.h>
+#include <bpf/bpf_tracing.h>
+
+char _license[] SEC("license") = "GPL";
+
+/* Copied from mm.h */
+#define VM_READ                0x00000001
+#define VM_WRITE       0x00000002
+#define VM_EXEC                0x00000004
+#define VM_MAYSHARE    0x00000080
+
+/* Copied from kdev_t.h */
+#define MINORBITS      20
+#define MINORMASK      ((1U << MINORBITS) - 1)
+#define MAJOR(dev)     ((unsigned int) ((dev) >> MINORBITS))
+#define MINOR(dev)     ((unsigned int) ((dev) & MINORMASK))
+
+#define D_PATH_BUF_SIZE 1024
+char d_path_buf[D_PATH_BUF_SIZE] = {};
+__u32 pid = 0;
+
+SEC("iter/task_vma") int proc_maps(struct bpf_iter__task_vma *ctx)
+{
+       struct vm_area_struct *vma = ctx->vma;
+       struct seq_file *seq = ctx->meta->seq;
+       struct task_struct *task = ctx->task;
+       struct file *file;
+       char perm_str[] = "----";
+
+       if (task == (void *)0 || vma == (void *)0)
+               return 0;
+
+       file = vma->vm_file;
+       if (task->tgid != pid)
+               return 0;
+       perm_str[0] = (vma->vm_flags & VM_READ) ? 'r' : '-';
+       perm_str[1] = (vma->vm_flags & VM_WRITE) ? 'w' : '-';
+       perm_str[2] = (vma->vm_flags & VM_EXEC) ? 'x' : '-';
+       perm_str[3] = (vma->vm_flags & VM_MAYSHARE) ? 's' : 'p';
+       BPF_SEQ_PRINTF(seq, "%08llx-%08llx %s ", vma->vm_start, vma->vm_end, perm_str);
+
+       if (file) {
+               __u32 dev = file->f_inode->i_sb->s_dev;
+
+               bpf_d_path(&file->f_path, d_path_buf, D_PATH_BUF_SIZE);
+
+               BPF_SEQ_PRINTF(seq, "%08llx ", vma->vm_pgoff << 12);
+               BPF_SEQ_PRINTF(seq, "%02x:%02x %u", MAJOR(dev), MINOR(dev),
+                              file->f_inode->i_ino);
+               BPF_SEQ_PRINTF(seq, "\t%s\n", d_path_buf);
+       } else {
+               BPF_SEQ_PRINTF(seq, "%08llx 00:00 0\n", 0ULL);
+       }
+       return 0;
+}