bpf: Propagate modified uaddrlen from cgroup sockaddr programs

[ Upstream commit fefba7d1ae198dcbf8b3b432de46a4e29f8dbd8c ]

As prep for adding unix socket support to the cgroup sockaddr hooks,
let'

bpf: Propagate modified uaddrlen from cgroup sockaddr programs

[ Upstream commit fefba7d1ae198dcbf8b3b432de46a4e29f8dbd8c ]

As prep for adding unix socket support to the cgroup sockaddr hooks,
let's propagate the sockaddr length back to the caller after running
a bpf cgroup sockaddr hook program. While not important for AF_INET or
AF_INET6, the sockaddr length is important when working with AF_UNIX
sockaddrs as the size of the sockaddr cannot be determined just from the
address family or the sockaddr's contents.

__cgroup_bpf_run_filter_sock_addr() is modified to take the uaddrlen as
an input/output argument. After running the program, the modified sockaddr
length is stored in the uaddrlen pointer.

Signed-off-by: Daan De Meyer <daan.j.demeyer@gmail.com>
Link: https://lore.kernel.org/r/20231011185113.140426-3-daan.j.demeyer@gmail.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Stable-dep-of: c5114710c8ce ("xsk: fix usage of multi-buffer BPF helpers for ZC XDP")
Signed-off-by: Sasha Levin <sashal@kernel.org>

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bpf, cgroup: fix multiple kernel-doc warnings

Fix missing or extra function parameter kernel-doc warnings
in cgroup.c:

kernel/bpf/cgroup.c:1359: warning: Excess function parameter 'type' descriptio

bpf, cgroup: fix multiple kernel-doc warnings

Fix missing or extra function parameter kernel-doc warnings
in cgroup.c:

kernel/bpf/cgroup.c:1359: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_skb'
kernel/bpf/cgroup.c:1359: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_skb'
kernel/bpf/cgroup.c:1439: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sk'
kernel/bpf/cgroup.c:1439: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sk'
kernel/bpf/cgroup.c:1467: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sock_addr'
kernel/bpf/cgroup.c:1467: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sock_addr'
kernel/bpf/cgroup.c:1512: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sock_ops'
kernel/bpf/cgroup.c:1512: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sock_ops'
kernel/bpf/cgroup.c:1685: warning: Excess function parameter 'type' description in '__cgroup_bpf_run_filter_sysctl'
kernel/bpf/cgroup.c:1685: warning: Function parameter or member 'atype' not described in '__cgroup_bpf_run_filter_sysctl'
kernel/bpf/cgroup.c:795: warning: Excess function parameter 'type' description in '__cgroup_bpf_replace'
kernel/bpf/cgroup.c:795: warning: Function parameter or member 'new_prog' not described in '__cgroup_bpf_replace'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf@vger.kernel.org
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20230912060812.1715-1-rdunlap@infradead.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen

With the way the hooks implemented right now, we have a special
condition: optval larger than PAGE_SIZE will expose only first 4k into
BPF; an

bpf: Don't EFAULT for {g,s}setsockopt with wrong optlen

With the way the hooks implemented right now, we have a special
condition: optval larger than PAGE_SIZE will expose only first 4k into
BPF; any modifications to the optval are ignored. If the BPF program
doesn't handle this condition by resetting optlen to 0,
the userspace will get EFAULT.

The intention of the EFAULT was to make it apparent to the
developers that the program is doing something wrong.
However, this inadvertently might affect production workloads
with the BPF programs that are not too careful (i.e., returning EFAULT
for perfectly valid setsockopt/getsockopt calls).

Let's try to minimize the chance of BPF program screwing up userspace
by ignoring the output of those BPF programs (instead of returning
EFAULT to the userspace). pr_info_once those cases to
the dmesg to help with figuring out what's going wrong.

Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Suggested-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20230511170456.1759459-2-sdf@google.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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bpf: Don't EFAULT for getsockopt with optval=NULL

Some socket options do getsockopt with optval=NULL to estimate the size
of the final buffer (which is returned via optlen). This breaks BPF
getsocko

bpf: Don't EFAULT for getsockopt with optval=NULL

Some socket options do getsockopt with optval=NULL to estimate the size
of the final buffer (which is returned via optlen). This breaks BPF
getsockopt assumptions about permitted optval buffer size. Let's enforce
these assumptions only when non-NULL optval is provided.

Fixes: 0d01da6afc54 ("bpf: implement getsockopt and setsockopt hooks")
Reported-by: Martin KaFai Lau <martin.lau@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/ZD7Js4fj5YyI2oLd@google.com/T/#mb68daf700f87a9244a15d01d00c3f0e5b08f49f7
Link: https://lore.kernel.org/bpf/20230418225343.553806-2-sdf@google.com

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cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers

Replace mutex_[un]lock() with cgroup_[un]lock() wrappers to stay
consistent across cgroup core and other subsystem code, while
operating on th

cgroup: bpf: use cgroup_lock()/cgroup_unlock() wrappers

Replace mutex_[un]lock() with cgroup_[un]lock() wrappers to stay
consistent across cgroup core and other subsystem code, while
operating on the cgroup_mutex.

Signed-off-by: Kamalesh Babulal <kamalesh.babulal@oracle.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>

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bpf: allow ctx writes using BPF_ST_MEM instruction

Lift verifier restriction to use BPF_ST_MEM instructions to write to
context data structures. This requires the following changes:
- verifier.c:do

bpf: allow ctx writes using BPF_ST_MEM instruction

Lift verifier restriction to use BPF_ST_MEM instructions to write to
context data structures. This requires the following changes:
- verifier.c:do_check() for BPF_ST updated to:
- no longer forbid writes to registers of type PTR_TO_CTX;
- track dst_reg type in the env->insn_aux_data[...].ptr_type field
(same way it is done for BPF_STX and BPF_LDX instructions).
- verifier.c:convert_ctx_access() and various callbacks invoked by
it are updated to handled BPF_ST instruction alongside BPF_STX.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20230304011247.566040-2-eddyz87@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Make bpf_get_current_[ancestor_]cgroup_id() available for all program types

These helpers are safe to call from any context and there's no reason to
restrict access to them. Remove them from bp

bpf: Make bpf_get_current_[ancestor_]cgroup_id() available for all program types

These helpers are safe to call from any context and there's no reason to
restrict access to them. Remove them from bpf_trace and filter lists and add
to bpf_base_func_proto() under perfmon_capable().

v2: After consulting with Andrii, relocated in bpf_base_func_proto() so that
they require bpf_capable() but not perfomon_capable() as it doesn't read
from or affect others on the system.

Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/ZAD8QyoszMZiTzBY@slm.duckdns.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf, cgroup: Reject prog_attach_flags array when effective query

Attach flags is only valid for attached progs of this layer cgroup,
but not for effective progs. For querying with EFFECTIVE flags,
e

bpf, cgroup: Reject prog_attach_flags array when effective query

Attach flags is only valid for attached progs of this layer cgroup,
but not for effective progs. For querying with EFFECTIVE flags,
exporting attach flags does not make sense. So when effective query,
we reject prog_attach_flags array and don't need to populate it.
Also we limit attach_flags to output 0 during effective query.

Fixes: b79c9fc9551b ("bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP")
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Link: https://lore.kernel.org/r/20220921104604.2340580-2-pulehui@huaweicloud.com
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>

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bpf: expose bpf_strtol and bpf_strtoul to all program types

bpf_strncmp is already exposed everywhere. The motivation is to keep
those helpers in kernel/bpf/helpers.c. Otherwise it's tempting to mov

bpf: expose bpf_strtol and bpf_strtoul to all program types

bpf_strncmp is already exposed everywhere. The motivation is to keep
those helpers in kernel/bpf/helpers.c. Otherwise it's tempting to move
them under kernel/bpf/cgroup.c because they are currently only used
by sysctl prog types.

Suggested-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220823222555.523590-4-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Use cgroup_{common,current}_func_proto in more hooks

The following hooks are per-cgroup hooks but they are not
using cgroup_{common,current}_func_proto, fix it:

* BPF_PROG_TYPE_CGROUP_SKB (cg_

bpf: Use cgroup_{common,current}_func_proto in more hooks

The following hooks are per-cgroup hooks but they are not
using cgroup_{common,current}_func_proto, fix it:

* BPF_PROG_TYPE_CGROUP_SKB (cg_skb)
* BPF_PROG_TYPE_CGROUP_SOCK_ADDR (cg_sock_addr)
* BPF_PROG_TYPE_CGROUP_SOCK (cg_sock)
* BPF_PROG_TYPE_LSM+BPF_LSM_CGROUP

Also:

* move common func_proto's into cgroup func_proto handlers
* make sure bpf_{g,s}et_retval are not accessible from recvmsg,
getpeername and getsockname (return/errno is ignored in these
places)
* as a side effect, expose get_current_pid_tgid, get_current_comm_proto,
get_current_ancestor_cgroup_id, get_cgroup_classid to more cgroup
hooks

Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220823222555.523590-3-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Introduce cgroup_{common,current}_func_proto

Split cgroup_base_func_proto into the following:

* cgroup_common_func_proto - common helpers for all cgroup hooks
* cgroup_current_func_proto - com

bpf: Introduce cgroup_{common,current}_func_proto

Split cgroup_base_func_proto into the following:

* cgroup_common_func_proto - common helpers for all cgroup hooks
* cgroup_current_func_proto - common helpers for all cgroup hooks
running in the process context (== have meaningful 'current').

Move bpf_{g,s}et_retval and other cgroup-related helpers into
kernel/bpf/cgroup.c so they closer to where they are being used.

Signed-off-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/20220823222555.523590-2-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf, cgroup: Fix kernel BUG in purge_effective_progs

Syzkaller reported a triggered kernel BUG as follows:

------------[ cut here ]------------
kernel BUG at kernel/bpf/cgroup.c:925!
invalid

bpf, cgroup: Fix kernel BUG in purge_effective_progs

Syzkaller reported a triggered kernel BUG as follows:

------------[ cut here ]------------
kernel BUG at kernel/bpf/cgroup.c:925!
invalid opcode: 0000 [#1] PREEMPT SMP NOPTI
CPU: 1 PID: 194 Comm: detach Not tainted 5.19.0-14184-g69dac8e431af #8
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
RIP: 0010:__cgroup_bpf_detach+0x1f2/0x2a0
Code: 00 e8 92 60 30 00 84 c0 75 d8 4c 89 e0 31 f6 85 f6 74 19 42 f6 84
28 48 05 00 00 02 75 0e 48 8b 80 c0 00 00 00 48 85 c0 75 e5 <0f> 0b 48
8b 0c5
RSP: 0018:ffffc9000055bdb0 EFLAGS: 00000246
RAX: 0000000000000000 RBX: ffff888100ec0800 RCX: ffffc900000f1000
RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff888100ec4578
RBP: 0000000000000000 R08: ffff888100ec0800 R09: 0000000000000040
R10: 0000000000000000 R11: 0000000000000000 R12: ffff888100ec4000
R13: 000000000000000d R14: ffffc90000199000 R15: ffff888100effb00
FS: 00007f68213d2b80(0000) GS:ffff88813bc80000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000055f74a0e5850 CR3: 0000000102836000 CR4: 00000000000006e0
Call Trace:
<TASK>
cgroup_bpf_prog_detach+0xcc/0x100
__sys_bpf+0x2273/0x2a00
__x64_sys_bpf+0x17/0x20
do_syscall_64+0x3b/0x90
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f68214dbcb9
Code: 08 44 89 e0 5b 41 5c c3 66 0f 1f 84 00 00 00 00 00 48 89 f8 48 89
f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01
f0 ff8
RSP: 002b:00007ffeb487db68 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 000000000000000b RCX: 00007f68214dbcb9
RDX: 0000000000000090 RSI: 00007ffeb487db70 RDI: 0000000000000009
RBP: 0000000000000003 R08: 0000000000000012 R09: 0000000b00000003
R10: 00007ffeb487db70 R11: 0000000000000246 R12: 00007ffeb487dc20
R13: 0000000000000004 R14: 0000000000000001 R15: 000055f74a1011b0
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---

Repetition steps:

For the following cgroup tree,

root
|
cg1
|
cg2

1. attach prog2 to cg2, and then attach prog1 to cg1, both bpf progs
attach type is NONE or OVERRIDE.
2. write 1 to /proc/thread-self/fail-nth for failslab.
3. detach prog1 for cg1, and then kernel BUG occur.

Failslab injection will cause kmalloc fail and fall back to
purge_effective_progs. The problem is that cg2 have attached another prog,
so when go through cg2 layer, iteration will add pos to 1, and subsequent
operations will be skipped by the following condition, and cg will meet
NULL in the end.

`if (pos && !(cg->bpf.flags[atype] & BPF_F_ALLOW_MULTI))`

The NULL cg means no link or prog match, this is as expected, and it's not
a bug. So here just skip the no match situation.

Fixes: 4c46091ee985 ("bpf: Fix KASAN use-after-free Read in compute_effective_progs")
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20220813134030.1972696-1-pulehui@huawei.com

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bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP

We have two options:
1. Treat all BPF_LSM_CGROUP the same, regardless of attach_btf_id
2. Treat BPF_LSM_CGROUP+attach_btf_id as a separate hook point

bpf: implement BPF_PROG_QUERY for BPF_LSM_CGROUP

We have two options:
1. Treat all BPF_LSM_CGROUP the same, regardless of attach_btf_id
2. Treat BPF_LSM_CGROUP+attach_btf_id as a separate hook point

I was doing (2) in the original patch, but switching to (1) here:

* bpf_prog_query returns all attached BPF_LSM_CGROUP programs
regardless of attach_btf_id
* attach_btf_id is exported via bpf_prog_info

Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-6-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: minimize number of allocated lsm slots per program

Previous patch adds 1:1 mapping between all 211 LSM hooks
and bpf_cgroup program array. Instead of reserving a slot per
possible hook, reserve

bpf: minimize number of allocated lsm slots per program

Previous patch adds 1:1 mapping between all 211 LSM hooks
and bpf_cgroup program array. Instead of reserving a slot per
possible hook, reserve 10 slots per cgroup for lsm programs.
Those slots are dynamically allocated on demand and reclaimed.

struct cgroup_bpf {
struct bpf_prog_array * effective[33]; /* 0 264 */
/* --- cacheline 4 boundary (256 bytes) was 8 bytes ago --- */
struct hlist_head progs[33]; /* 264 264 */
/* --- cacheline 8 boundary (512 bytes) was 16 bytes ago --- */
u8 flags[33]; /* 528 33 */

/* XXX 7 bytes hole, try to pack */

struct list_head storages; /* 568 16 */
/* --- cacheline 9 boundary (576 bytes) was 8 bytes ago --- */
struct bpf_prog_array * inactive; /* 584 8 */
struct percpu_ref refcnt; /* 592 16 */
struct work_struct release_work; /* 608 72 */

/* size: 680, cachelines: 11, members: 7 */
/* sum members: 673, holes: 1, sum holes: 7 */
/* last cacheline: 40 bytes */
};

Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-5-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: per-cgroup lsm flavor

Allow attaching to lsm hooks in the cgroup context.

Attaching to per-cgroup LSM works exactly like attaching
to other per-cgroup hooks. New BPF_LSM_CGROUP is added
to tri

bpf: per-cgroup lsm flavor

Allow attaching to lsm hooks in the cgroup context.

Attaching to per-cgroup LSM works exactly like attaching
to other per-cgroup hooks. New BPF_LSM_CGROUP is added
to trigger new mode; the actual lsm hook we attach to is
signaled via existing attach_btf_id.

For the hooks that have 'struct socket' or 'struct sock' as its first
argument, we use the cgroup associated with that socket. For the rest,
we use 'current' cgroup (this is all on default hierarchy == v2 only).
Note that for some hooks that work on 'struct sock' we still
take the cgroup from 'current' because some of them work on the socket
that hasn't been properly initialized yet.

Behind the scenes, we allocate a shim program that is attached
to the trampoline and runs cgroup effective BPF programs array.
This shim has some rudimentary ref counting and can be shared
between several programs attaching to the same lsm hook from
different cgroups.

Note that this patch bloats cgroup size because we add 211
cgroup_bpf_attach_type(s) for simplicity sake. This will be
addressed in the subsequent patch.

Also note that we only add non-sleepable flavor for now. To enable
sleepable use-cases, bpf_prog_run_array_cg has to grab trace rcu,
shim programs have to be freed via trace rcu, cgroup_bpf.effective
should be also trace-rcu-managed + maybe some other changes that
I'm not aware of.

Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-4-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: convert cgroup_bpf.progs to hlist

This lets us reclaim some space to be used by new cgroup lsm slots.

Before:
struct cgroup_bpf {
struct bpf_prog_array * effective[23]; /* 0 1

bpf: convert cgroup_bpf.progs to hlist

This lets us reclaim some space to be used by new cgroup lsm slots.

Before:
struct cgroup_bpf {
struct bpf_prog_array * effective[23]; /* 0 184 */
/* --- cacheline 2 boundary (128 bytes) was 56 bytes ago --- */
struct list_head progs[23]; /* 184 368 */
/* --- cacheline 8 boundary (512 bytes) was 40 bytes ago --- */
u32 flags[23]; /* 552 92 */

/* XXX 4 bytes hole, try to pack */

/* --- cacheline 10 boundary (640 bytes) was 8 bytes ago --- */
struct list_head storages; /* 648 16 */
struct bpf_prog_array * inactive; /* 664 8 */
struct percpu_ref refcnt; /* 672 16 */
struct work_struct release_work; /* 688 32 */

/* size: 720, cachelines: 12, members: 7 */
/* sum members: 716, holes: 1, sum holes: 4 */
/* last cacheline: 16 bytes */
};

After:
struct cgroup_bpf {
struct bpf_prog_array * effective[23]; /* 0 184 */
/* --- cacheline 2 boundary (128 bytes) was 56 bytes ago --- */
struct hlist_head progs[23]; /* 184 184 */
/* --- cacheline 5 boundary (320 bytes) was 48 bytes ago --- */
u8 flags[23]; /* 368 23 */

/* XXX 1 byte hole, try to pack */

/* --- cacheline 6 boundary (384 bytes) was 8 bytes ago --- */
struct list_head storages; /* 392 16 */
struct bpf_prog_array * inactive; /* 408 8 */
struct percpu_ref refcnt; /* 416 16 */
struct work_struct release_work; /* 432 72 */

/* size: 504, cachelines: 8, members: 7 */
/* sum members: 503, holes: 1, sum holes: 1 */
/* last cacheline: 56 bytes */
};

Suggested-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Jakub Sitnicki <jakub@cloudflare.com>
Reviewed-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/20220628174314.1216643-3-sdf@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Fix KASAN use-after-free Read in compute_effective_progs

Syzbot found a Use After Free bug in compute_effective_progs().
The reproducer creates a number of BPF links, and causes a fault
injecte

bpf: Fix KASAN use-after-free Read in compute_effective_progs

Syzbot found a Use After Free bug in compute_effective_progs().
The reproducer creates a number of BPF links, and causes a fault
injected alloc to fail, while calling bpf_link_detach on them.
Link detach triggers the link to be freed by bpf_link_free(),
which calls __cgroup_bpf_detach() and update_effective_progs().
If the memory allocation in this function fails, the function restores
the pointer to the bpf_cgroup_link on the cgroup list, but the memory
gets freed just after it returns. After this, every subsequent call to
update_effective_progs() causes this already deallocated pointer to be
dereferenced in prog_list_length(), and triggers KASAN UAF error.

To fix this issue don't preserve the pointer to the prog or link in the
list, but remove it and replace it with a dummy prog without shrinking
the table. The subsequent call to __cgroup_bpf_detach() or
__cgroup_bpf_detach() will correct it.

Fixes: af6eea57437a ("bpf: Implement bpf_link-based cgroup BPF program attachment")
Reported-by: <syzbot+f264bffdfbd5614f3bb2@syzkaller.appspotmail.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Cc: <stable@vger.kernel.org>
Link: https://syzkaller.appspot.com/bug?id=8ebf179a95c2a2670f7cf1ba62429ec044369db4
Link: https://lore.kernel.org/bpf/20220517180420.87954-1-tadeusz.struk@linaro.org

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bpf: Use bpf_prog_run_array_cg_flags everywhere

Rename bpf_prog_run_array_cg_flags to bpf_prog_run_array_cg and
use it everywhere. check_return_code already enforces sane
return ranges for all cgrou

bpf: Use bpf_prog_run_array_cg_flags everywhere

Rename bpf_prog_run_array_cg_flags to bpf_prog_run_array_cg and
use it everywhere. check_return_code already enforces sane
return ranges for all cgroup types. (only egress and bind hooks have
uncanonical return ranges, the rest is using [0, 1])

No functional changes.

v2:
- 'func_ret & 1' under explicit test (Andrii & Martin)

Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220425220448.3669032-1-sdf@google.com

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bpf: Move rcu lock management out of BPF_PROG_RUN routines

Commit 7d08c2c91171 ("bpf: Refactor BPF_PROG_RUN_ARRAY family of macros
into functions") switched a bunch of BPF_PROG_RUN macros to inline

bpf: Move rcu lock management out of BPF_PROG_RUN routines

Commit 7d08c2c91171 ("bpf: Refactor BPF_PROG_RUN_ARRAY family of macros
into functions") switched a bunch of BPF_PROG_RUN macros to inline
routines. This changed the semantic a bit. Due to arguments expansion
of macros, it used to be:

rcu_read_lock();
array = rcu_dereference(cgrp->bpf.effective[atype]);
...

Now, with with inline routines, we have:
array_rcu = rcu_dereference(cgrp->bpf.effective[atype]);
/* array_rcu can be kfree'd here */
rcu_read_lock();
array = rcu_dereference(array_rcu);

I'm assuming in practice rcu subsystem isn't fast enough to trigger
this but let's use rcu API properly.

Also, rename to lower caps to not confuse with macros. Additionally,
drop and expand BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY.

See [1] for more context.

[1] https://lore.kernel.org/bpf/CAKH8qBs60fOinFdxiiQikK_q0EcVxGvNTQoWvHLEUGbgcj1UYg@mail.gmail.com/T/#u

v2
- keep rcu locks inside by passing cgroup_bpf

Fixes: 7d08c2c91171 ("bpf: Refactor BPF_PROG_RUN_ARRAY family of macros into functions")
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20220414161233.170780-1-sdf@google.com

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bpf: Cleanup comments

Add leading space to spdx tag
Use // for spdx c file comment

Replacements
resereved to reserved
inbetween to in between
everytime to every time
intutivie to intuitive
currenct

bpf: Cleanup comments

Add leading space to spdx tag
Use // for spdx c file comment

Replacements
resereved to reserved
inbetween to in between
everytime to every time
intutivie to intuitive
currenct to current
encontered to encountered
referenceing to referencing
upto to up to
exectuted to executed

Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20220220184055.3608317-1-trix@redhat.com

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cgroup/bpf: fast path skb BPF filtering

Even though there is a static key protecting from overhead from
cgroup-bpf skb filtering when there is nothing attached, in many cases
it's not enough as regi

cgroup/bpf: fast path skb BPF filtering

Even though there is a static key protecting from overhead from
cgroup-bpf skb filtering when there is nothing attached, in many cases
it's not enough as registering a filter for one type will ruin the fast
path for all others. It's observed in production servers I've looked
at but also in laptops, where registration is done during init by
systemd or something else.

Add a per-socket fast path check guarding from such overhead. This
affects both receive and transmit paths of TCP, UDP and other
protocols. It showed ~1% tx/s improvement in small payload UDP
send benchmarks using a real NIC and in a server environment and the
number jumps to 2-3% for preemtible kernels.

Reviewed-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/r/d8c58857113185a764927a46f4b5a058d36d3ec3.1643292455.git.asml.silence@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Add cgroup helpers bpf_{get,set}_retval to get/set syscall return value

The helpers continue to use int for retval because all the hooks
are int-returning rather than long-returning. The return

bpf: Add cgroup helpers bpf_{get,set}_retval to get/set syscall return value

The helpers continue to use int for retval because all the hooks
are int-returning rather than long-returning. The return value of
bpf_set_retval is int for future-proofing, in case in the future
there may be errors trying to set the retval.

After the previous patch, if a program rejects a syscall by
returning 0, an -EPERM will be generated no matter if the retval
is already set to -err. This patch change it being forced only if
retval is not -err. This is because we want to support, for
example, invoking bpf_set_retval(-EINVAL) and return 0, and have
the syscall return value be -EINVAL not -EPERM.

For BPF_PROG_CGROUP_INET_EGRESS_RUN_ARRAY, the prior behavior is
that, if the return value is NET_XMIT_DROP, the packet is silently
dropped. We preserve this behavior for backward compatibility
reasons, so even if an errno is set, the errno does not return to
caller. However, setting a non-err to retval cannot propagate so
this is not allowed and we return a -EFAULT in that case.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/b4013fd5d16bed0b01977c1fafdeae12e1de61fb.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Move getsockopt retval to struct bpf_cg_run_ctx

The retval value is moved to struct bpf_cg_run_ctx for ease of access
in different prog types with different context structs layouts. The
helper

bpf: Move getsockopt retval to struct bpf_cg_run_ctx

The retval value is moved to struct bpf_cg_run_ctx for ease of access
in different prog types with different context structs layouts. The
helper implementation (to be added in a later patch in the series) can
simply perform a container_of from current->bpf_ctx to retrieve
bpf_cg_run_ctx.

Unfortunately, there is no easy way to access the current task_struct
via the verifier BPF bytecode rewrite, aside from possibly calling a
helper, so a pointer to current task is added to struct bpf_sockopt_kern
so that the rewritten BPF bytecode can access struct bpf_cg_run_ctx with
an indirection.

For backward compatibility, if a getsockopt program rejects a syscall
by returning 0, an -EPERM will be generated, by having the
BPF_PROG_RUN_ARRAY_CG family macros automatically set the retval to
-EPERM. Unlike prior to this patch, this -EPERM will be visible to
ctx->retval for any other hooks down the line in the prog array.

Additionally, the restriction that getsockopt filters can only set
the retval to 0 is removed, considering that certain getsockopt
implementations may return optlen. Filters are now able to set the
value arbitrarily.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/73b0325f5c29912ccea7ea57ec1ed4d388fc1d37.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Make BPF_PROG_RUN_ARRAY return -err instead of allow boolean

Right now BPF_PROG_RUN_ARRAY and related macros return 1 or 0
for whether the prog array allows or rejects whatever is being
hooked.

bpf: Make BPF_PROG_RUN_ARRAY return -err instead of allow boolean

Right now BPF_PROG_RUN_ARRAY and related macros return 1 or 0
for whether the prog array allows or rejects whatever is being
hooked. The caller of these macros then return -EPERM or continue
processing based on thw macro's return value. Unforunately this is
inflexible, since -EPERM is the only err that can be returned.

This patch should be a no-op; it prepares for the next patch. The
returning of the -EPERM is moved to inside the macros, so the outer
functions are directly returning what the macros returned if they
are non-zero.

Signed-off-by: YiFei Zhu <zhuyifei@google.com>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Link: https://lore.kernel.org/r/788abcdca55886d1f43274c918eaa9f792a9f33b.1639619851.git.zhuyifei@google.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

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bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.

Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were

bpf: Add MEM_RDONLY for helper args that are pointers to rdonly mem.

Some helper functions may modify its arguments, for example,
bpf_d_path, bpf_get_stack etc. Previously, their argument types
were marked as ARG_PTR_TO_MEM, which is compatible with read-only
mem types, such as PTR_TO_RDONLY_BUF. Therefore it's legitimate,
but technically incorrect, to modify a read-only memory by passing
it into one of such helper functions.

This patch tags the bpf_args compatible with immutable memory with
MEM_RDONLY flag. The arguments that don't have this flag will be
only compatible with mutable memory types, preventing the helper
from modifying a read-only memory. The bpf_args that have
MEM_RDONLY are compatible with both mutable memory and immutable
memory.

Signed-off-by: Hao Luo <haoluo@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211217003152.48334-9-haoluo@google.com

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