Which struct do we use for string expression? #2

gurugio · 2023-10-14T02:27:49Z

rust/kernel/str.rs에는 BStr, CStr, CString이 있다.
어느 것을 사용해야할까?
rust코드에서 문자열을 생성하고 커널의 C코드로 넘겨줄 때 어떤 방식을 사용해야하나?
현재 사용하는 방식

커널 코어에 전달할 때는 fmt 객체 생성해서 .as_char_ptr()메소드로 포인터 넘김
드라이버에서 문자열을 저장할 때는 CString으로 보관

fmt!("rust_ldd03{}", i) => fmt::Arguments<'_>타입
CString::try_from_fmt(fmt!("rust_ldd03{}", i)) => CString객체 생성

다른 드라이버나 개발자들은 어떤 방식을 사용하고있나 조사해서 결정할것

The text was updated successfully, but these errors were encountered:

At least it does not panic. I checked the pointer of proc_open and proc_ops->proc_open value. They are same. So I guess the function pointer setting is correct. And I added messages to check if open function is crashed. for _ in 0..10000 { pr_err!("proc_open is invoked\n"); } Then I found out that the read generates crash as below. / # insmod share/rust_proc.ko [ 6.944654] rust_proc: module verification failed: signature and/or required key missing - tainting kernel [ 6.946329] rust_proc: rust_proc is loaded [ 6.946981] proc_create_data: rust_proc_fs proc_open=ffffffffc0201040 [ 6.947959] rust_proc: succeeded to create a proc entry: 0xffff888005469780 proc_open=0xffffffffc0201040 / # cat /proc/rust_demo/rust_proc_fs ......... ......... [ 15.546497] rust_proc: proc_open is invoked [ 15.546836] rust_proc: proc_open is invoked [ 15.547176] rust_proc: proc_open is invoked [ 15.547530] rust_proc: proc_open is invoked [ 15.547866] rust_proc: proc_open is invoked [ 15.548204] rust_proc: proc_open is invoked [ 15.548544] rust_proc: proc_open is invoked [ 15.549052] BUG: kernel NULL pointer dereference, address: 0000000000000001 [ 15.549617] #PF: supervisor instruction fetch in kernel mode [ 15.549801] #PF: error_code(0x0010) - not-present page [ 15.549801] PGD 561e067 P4D 561e067 PUD 561c067 PMD 0 [ 15.549801] Oops: 0010 [#1] PREEMPT SMP NOPTI [ 15.549801] CPU: 0 PID: 120 Comm: cat Tainted: G E 6.3.0+ Rust-for-Linux#22 [ 15.549801] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 15.549801] RIP: 0010:0x1 [ 15.549801] Code: Unable to access opcode bytes at 0xffffffffffffffd7. [ 15.549801] RSP: 0018:ffff8880056b3e00 EFLAGS: 00010202 [ 15.549801] RAX: ffff888005733898 RBX: 0000000000000000 RCX: ffff8880056b3ef0 [ 15.549801] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: ffff888005729600 [ 15.549801] RBP: ffff8880056b3e48 R08: 00007ffc1f99b0a8 R09: 0000000000000000 [ 15.549801] R10: 0000000000000000 R11: 0000000000000001 R12: ffff888005469f00 [ 15.549801] R13: ffff888005729600 R14: 0000000000000001 R15: 0000000000000000 [ 15.549801] FS: 0000000001e153c0(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000 [ 15.549801] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.549801] CR2: ffffffffffffffd7 CR3: 0000000003c60000 CR4: 00000000000006f0 [ 15.549801] Call Trace: [ 15.549801] <TASK> [ 15.549801] ? proc_reg_read+0xe8/0x150 [ 15.549801] vfs_read+0xb4/0x260 [ 15.549801] ? do_sendfile+0x1cf/0x3f0 [ 15.549801] ksys_read+0x5f/0xb0 [ 15.549801] __x64_sys_read+0x1b/0x20 [ 15.549801] do_syscall_64+0x35/0x50 [ 15.549801] entry_SYSCALL_64_after_hwframe+0x63/0xcd [ 15.549801] RIP: 0033:0x4ad272 [ 15.549801] Code: 31 c0 e9 b1 fe ff ff 50 48 8d 3d c1 80 17 00 e8 54 8e 00 00 0f 1f 40 00 f3 0f 1e fa 64 8b 04 25 18 00 00 04 [ 15.549801] RSP: 002b:00007ffc1f99b048 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 15.549801] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004ad272 [ 15.549801] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: 0000000000000003 [ 15.549801] RBP: 00007ffc1f99b0a8 R08: 0000000000000001 R09: 0000000000000000 [ 15.549801] R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000 [ 15.549801] R13: 0000000001e153a0 R14: 0000000000000000 R15: 0000000000000001 [ 15.549801] </TASK> [ 15.549801] Modules linked in: rust_proc(E) [ 15.549801] CR2: 0000000000000001 [ 15.549801] ---[ end trace 0000000000000000 ]--- [ 15.549801] RIP: 0010:0x1 [ 15.549801] Code: Unable to access opcode bytes at 0xffffffffffffffd7. [ 15.549801] RSP: 0018:ffff8880056b3e00 EFLAGS: 00010202 [ 15.549801] RAX: ffff888005733898 RBX: 0000000000000000 RCX: ffff8880056b3ef0 [ 15.549801] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: ffff888005729600 [ 15.549801] RBP: ffff8880056b3e48 R08: 00007ffc1f99b0a8 R09: 0000000000000000 [ 15.549801] R10: 0000000000000000 R11: 0000000000000001 R12: ffff888005469f00 [ 15.549801] R13: ffff888005729600 R14: 0000000000000001 R15: 0000000000000000 [ 15.549801] FS: 0000000001e153c0(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000 [ 15.549801] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.549801] CR2: ffffffffffffffd7 CR3: 0000000003c60000 CR4: 00000000000006f0 [ 15.549801] note: cat[120] exited with irqs disabled [ 15.572950] BUG: kernel NULL pointer dereference, address: 0000000000000001 [ 15.573491] #PF: supervisor instruction fetch in kernel mode [ 15.573932] #PF: error_code(0x0010) - not-present page [ 15.574335] PGD 0 P4D 0 [ 15.574535] Oops: 0010 [#2] PREEMPT SMP NOPTI [ 15.574892] CPU: 0 PID: 120 Comm: cat Tainted: G D E 6.3.0+ Rust-for-Linux#22 [ 15.575462] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 15.576107] RIP: 0010:0x1 [ 15.576328] Code: Unable to access opcode bytes at 0xffffffffffffffd7. [ 15.576842] RSP: 0018:ffff8880056b3de8 EFLAGS: 00010246 [ 15.576842] RAX: ffff888005733898 RBX: 0000000000000000 RCX: 0000000000000001 [ 15.576842] RDX: ffff8880054ec800 RSI: ffff888005729600 RDI: ffff888004f7ce08 [ 15.576842] RBP: ffff8880056b3e30 R08: ffff888003c43c00 R09: ffff888004f7ce08 [ 15.576842] R10: ffffea00000f93c0 R11: 0000000000000001 R12: ffff8880056bae10 [ 15.576842] R13: 00000000000a800d R14: ffff888005469f00 R15: ffff888005469f18 [ 15.576842] FS: 0000000000000000(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000 [ 15.576842] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.576842] CR2: ffffffffffffffd7 CR3: 0000000002434000 CR4: 00000000000006f0 [ 15.576842] Call Trace: [ 15.576842] <TASK> [ 15.576842] ? close_pdeo+0x59/0x120 [ 15.576842] proc_reg_release+0x6f/0x80 [ 15.576842] __fput+0xf0/0x220 [ 15.576842] ____fput+0xe/0x10 [ 15.576842] task_work_run+0xc3/0xe0 [ 15.576842] do_exit+0x3e2/0xab0 [ 15.576842] make_task_dead+0x83/0x130 [ 15.576842] rewind_stack_and_make_dead+0x17/0x20 [ 15.576842] RIP: 0033:0x4ad272 [ 15.576842] Code: Unable to access opcode bytes at 0x4ad248. [ 15.576842] RSP: 002b:00007ffc1f99b048 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 15.576842] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004ad272 [ 15.576842] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: 0000000000000003 [ 15.576842] RBP: 00007ffc1f99b0a8 R08: 0000000000000001 R09: 0000000000000000 [ 15.576842] R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000 [ 15.576842] R13: 0000000001e153a0 R14: 0000000000000000 R15: 0000000000000001 [ 15.576842] </TASK> [ 15.576842] Modules linked in: rust_proc(E) [ 15.576842] CR2: 0000000000000001 [ 15.576842] ---[ end trace 0000000000000000 ]--- [ 15.576842] RIP: 0010:0x1 [ 15.576842] Code: Unable to access opcode bytes at 0xffffffffffffffd7. [ 15.576842] RSP: 0018:ffff8880056b3e00 EFLAGS: 00010202 [ 15.576842] RAX: ffff888005733898 RBX: 0000000000000000 RCX: ffff8880056b3ef0 [ 15.576842] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: ffff888005729600 [ 15.576842] RBP: ffff8880056b3e48 R08: 00007ffc1f99b0a8 R09: 0000000000000000 [ 15.576842] R10: 0000000000000000 R11: 0000000000000001 R12: ffff888005469f00 [ 15.576842] R13: ffff888005729600 R14: 0000000000000001 R15: 0000000000000000 [ 15.576842] FS: 0000000000000000(0000) GS:ffff888007a00000(0000) knlGS:0000000000000000 [ 15.576842] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 15.576842] CR2: ffffffffffffffd7 CR3: 0000000002434000 CR4: 00000000000006f0 [ 15.576842] note: cat[120] exited with irqs disabled [ 15.595880] Fixing recursive fault but reboot is needed! [ 15.596287] BUG: scheduling while atomic: cat/120/0x00000000 [ 15.596720] Modules linked in: rust_proc(E) [ 15.597039] CPU: 0 PID: 120 Comm: cat Tainted: G D E 6.3.0+ Rust-for-Linux#22 [ 15.597587] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 [ 15.598226] Call Trace: [ 15.598420] <TASK> [ 15.598592] dump_stack_lvl+0x58/0x70 [ 15.598883] dump_stack+0x10/0x20 [ 15.599141] __schedule_bug+0x62/0x70 [ 15.599449] __schedule+0x838/0x1450 [ 15.599731] ? vprintk_default+0x1d/0x20 [ 15.599849] ? vprintk+0x60/0x80 [ 15.599849] ? _printk+0x4b/0x50 [ 15.599849] do_task_dead+0x41/0x50 [ 15.599849] make_task_dead+0x129/0x130 [ 15.599849] rewind_stack_and_make_dead+0x17/0x20 [ 15.599849] RIP: 0033:0x4ad272 [ 15.599849] Code: Unable to access opcode bytes at 0x4ad248. [ 15.599849] RSP: 002b:00007ffc1f99b048 EFLAGS: 00000246 ORIG_RAX: 0000000000000000 [ 15.599849] RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00000000004ad272 [ 15.599849] RDX: 0000000000001000 RSI: 00007ffc1f99b0a8 RDI: 0000000000000003 [ 15.599849] RBP: 00007ffc1f99b0a8 R08: 0000000000000001 R09: 0000000000000000 [ 15.599849] R10: 0000000001000000 R11: 0000000000000246 R12: 0000000000001000 [ 15.599849] R13: 0000000001e153a0 R14: 0000000000000000 R15: 0000000000000001 [ 15.599849] </TASK> diff --git a/fs/proc/generic.c b/fs/proc/generic.c index 8379593fa4bb..bea879760ebc 100644 --- a/fs/proc/generic.c +++ b/fs/proc/generic.c @@ -573,7 +573,8 @@ struct proc_dir_entry *proc_create_data(const char *name, umode_t mode, p = proc_create_reg(name, mode, &parent, data); if (!p) return NULL; - p->proc_ops = proc_ops; + printk(KERN_ERR "proc_create_data: %s proc_open=%px\n", name, proc_ops->proc_open); + p->proc_ops = proc_ops; pde_set_flags(p); return proc_register(parent, p); }

gurugio · 2023-10-18T15:42:25Z

https://discord.com/channels/1025034006506520667/1164181022246719518/1164213774740373534

Use c_str! macro
https://github.com/gurugio/rust-for-linux/blob/rust-next-ldd-ch05/samples/rust/rust_ldd05.rs#L25

gurugio · 2023-10-18T15:43:30Z

그냥 CString을 만들면 널바이트가 들어가지 않음
반드시 c_str!매크로를 사용해야 널바이트가 추가됨

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

Which struct do we use for string expression? #2

Which struct do we use for string expression? #2

gurugio commented Oct 14, 2023

gurugio commented Oct 18, 2023

gurugio commented Oct 18, 2023

Which struct do we use for string expression? #2

Which struct do we use for string expression? #2

Comments

gurugio commented Oct 14, 2023

gurugio commented Oct 18, 2023

gurugio commented Oct 18, 2023