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bpf: Add "bool swap_uptrs" arg to bpf_local_storage_update() and bpf_selem_alloc()

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In a later patch, the task local storage will only accept uptr
from the syscall update_elem and will not accept uptr from
the bpf prog. The reason is the bpf prog does not have a way
to provide a valid user space address.

bpf_local_storage_update() and bpf_selem_alloc() are used by
both bpf prog bpf_task_storage_get(BPF_LOCAL_STORAGE_GET_F_CREATE)
and bpf syscall update_elem. "bool swap_uptrs" arg is added
to bpf_local_storage_update() and bpf_selem_alloc() to tell if
it is called by the bpf prog or by the bpf syscall. When
swap_uptrs==true, it is called by the syscall.

The arg is named (swap_)uptrs because the later patch will swap
the uptrs between the newly allocated selem and the user space
provided map_value. It will make error handling easier in case
map->ops->map_update_elem() fails and the caller can decide
if it needs to unpin the uptr in the user space provided
map_value or the bpf_local_storage_update() has already
taken the uptr ownership and will take care of unpinning it also.

Only swap_uptrs==false is passed now. The logic to handle
the true case will be added in a later patch.

Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20241023234759.860539-4-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau 2024-10-23 16:47:50 -07:00 committed by Alexei Starovoitov
parent 99dde42e37
commit b9a5a07aea
6 changed files with 15 additions and 15 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
include/linux/bpf_local_storage.h
View File

@ -181,7 +181,7 @@ void bpf_selem_link_map(struct bpf_local_storage_map *smap,
struct bpf_local_storage_elem *
bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, void *value,
bool charge_mem, gfp_t gfp_flags);
bool charge_mem, bool swap_uptrs, gfp_t gfp_flags);
void bpf_selem_free(struct bpf_local_storage_elem *selem,
struct bpf_local_storage_map *smap,
@ -195,7 +195,7 @@ bpf_local_storage_alloc(void *owner,
struct bpf_local_storage_data *
bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
void *value, u64 map_flags, gfp_t gfp_flags);
void *value, u64 map_flags, bool swap_uptrs, gfp_t gfp_flags);
u64 bpf_local_storage_map_mem_usage(const struct bpf_map *map);

4
kernel/bpf/bpf_cgrp_storage.c
View File

@ -107,7 +107,7 @@ static long bpf_cgrp_storage_update_elem(struct bpf_map *map, void *key,
bpf_cgrp_storage_lock();
sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
value, map_flags, GFP_ATOMIC);
value, map_flags, false, GFP_ATOMIC);
bpf_cgrp_storage_unlock();
cgroup_put(cgroup);
return PTR_ERR_OR_ZERO(sdata);
@ -181,7 +181,7 @@ BPF_CALL_5(bpf_cgrp_storage_get, struct bpf_map *, map, struct cgroup *, cgroup,
if (!percpu_ref_is_dying(&cgroup->self.refcnt) &&
(flags & BPF_LOCAL_STORAGE_GET_F_CREATE))
sdata = bpf_local_storage_update(cgroup, (struct bpf_local_storage_map *)map,
value, BPF_NOEXIST, gfp_flags);
value, BPF_NOEXIST, false, gfp_flags);
unlock:
bpf_cgrp_storage_unlock();

4
kernel/bpf/bpf_inode_storage.c
View File

@ -100,7 +100,7 @@ static long bpf_fd_inode_storage_update_elem(struct bpf_map *map, void *key,
sdata = bpf_local_storage_update(file_inode(fd_file(f)),
(struct bpf_local_storage_map *)map,
value, map_flags, GFP_ATOMIC);
value, map_flags, false, GFP_ATOMIC);
return PTR_ERR_OR_ZERO(sdata);
}
@ -154,7 +154,7 @@ BPF_CALL_5(bpf_inode_storage_get, struct bpf_map *, map, struct inode *, inode,
if (flags & BPF_LOCAL_STORAGE_GET_F_CREATE) {
sdata = bpf_local_storage_update(
inode, (struct bpf_local_storage_map *)map, value,
BPF_NOEXIST, gfp_flags);
BPF_NOEXIST, false, gfp_flags);
return IS_ERR(sdata) ? (unsigned long)NULL :
(unsigned long)sdata->data;
}

8
kernel/bpf/bpf_local_storage.c
View File

@ -73,7 +73,7 @@ static bool selem_linked_to_map(const struct bpf_local_storage_elem *selem)
struct bpf_local_storage_elem *
bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner,
void *value, bool charge_mem, gfp_t gfp_flags)
void *value, bool charge_mem, bool swap_uptrs, gfp_t gfp_flags)
{
struct bpf_local_storage_elem *selem;
@ -524,7 +524,7 @@ int bpf_local_storage_alloc(void *owner,
*/
struct bpf_local_storage_data *
bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
void *value, u64 map_flags, gfp_t gfp_flags)
void *value, u64 map_flags, bool swap_uptrs, gfp_t gfp_flags)
{
struct bpf_local_storage_data *old_sdata = NULL;
struct bpf_local_storage_elem *alloc_selem, *selem = NULL;
@ -550,7 +550,7 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
if (err)
return ERR_PTR(err);
selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
selem = bpf_selem_alloc(smap, owner, value, true, swap_uptrs, gfp_flags);
if (!selem)
return ERR_PTR(-ENOMEM);
@ -584,7 +584,7 @@ bpf_local_storage_update(void *owner, struct bpf_local_storage_map *smap,
/* A lookup has just been done before and concluded a new selem is
* needed. The chance of an unnecessary alloc is unlikely.
*/
alloc_selem = selem = bpf_selem_alloc(smap, owner, value, true, gfp_flags);
alloc_selem = selem = bpf_selem_alloc(smap, owner, value, true, swap_uptrs, gfp_flags);
if (!alloc_selem)
return ERR_PTR(-ENOMEM);

4
kernel/bpf/bpf_task_storage.c
View File

@ -147,7 +147,7 @@ static long bpf_pid_task_storage_update_elem(struct bpf_map *map, void *key,
bpf_task_storage_lock();
sdata = bpf_local_storage_update(
task, (struct bpf_local_storage_map *)map, value, map_flags,
GFP_ATOMIC);
false, GFP_ATOMIC);
bpf_task_storage_unlock();
err = PTR_ERR_OR_ZERO(sdata);
@ -219,7 +219,7 @@ static void *__bpf_task_storage_get(struct bpf_map *map,
(flags & BPF_LOCAL_STORAGE_GET_F_CREATE) && nobusy) {
sdata = bpf_local_storage_update(
task, (struct bpf_local_storage_map *)map, value,
BPF_NOEXIST, gfp_flags);
BPF_NOEXIST, false, gfp_flags);
return IS_ERR(sdata) ? NULL : sdata->data;
}

6
net/core/bpf_sk_storage.c
View File

@ -106,7 +106,7 @@ static long bpf_fd_sk_storage_update_elem(struct bpf_map *map, void *key,
if (sock) {
sdata = bpf_local_storage_update(
sock->sk, (struct bpf_local_storage_map *)map, value,
map_flags, GFP_ATOMIC);
map_flags, false, GFP_ATOMIC);
sockfd_put(sock);
return PTR_ERR_OR_ZERO(sdata);
}
@ -137,7 +137,7 @@ bpf_sk_storage_clone_elem(struct sock *newsk,
{
struct bpf_local_storage_elem *copy_selem;
copy_selem = bpf_selem_alloc(smap, newsk, NULL, true, GFP_ATOMIC);
copy_selem = bpf_selem_alloc(smap, newsk, NULL, true, false, GFP_ATOMIC);
if (!copy_selem)
return NULL;
@ -243,7 +243,7 @@ BPF_CALL_5(bpf_sk_storage_get, struct bpf_map *, map, struct sock *, sk,
refcount_inc_not_zero(&sk->sk_refcnt)) {
sdata = bpf_local_storage_update(
sk, (struct bpf_local_storage_map *)map, value,
BPF_NOEXIST, gfp_flags);
BPF_NOEXIST, false, gfp_flags);
/* sk must be a fullsock (guaranteed by verifier),
* so sock_gen_put() is unnecessary.
*/