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bpf: Move bpf_get_file_xattr to fs/bpf_fs_kfuncs.c

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We are putting all fs kfuncs in fs/bpf_fs_kfuncs.c. Move existing
bpf_get_file_xattr to it.

Signed-off-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240806230904.71194-2-song@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Song Liu 2024-08-06 16:09:02 -07:00 committed by Alexei Starovoitov
parent 6e083ab095
commit fa4e5afa97
2 changed files with 38 additions and 68 deletions
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38
fs/bpf_fs_kfuncs.c
View File

@ -8,6 +8,7 @@
#include <linux/fs.h>
#include <linux/file.h>
#include <linux/mm.h>
#include <linux/xattr.h>
__bpf_kfunc_start_defs();
@ -92,6 +93,42 @@ __bpf_kfunc int bpf_path_d_path(struct path *path, char *buf, size_t buf__sz)
return len;
}
/**
* bpf_get_file_xattr - get xattr of a file
* @file: file to get xattr from
* @name__str: name of the xattr
* @value_p: output buffer of the xattr value
*
* Get xattr *name__str* of *file* and store the output in *value_ptr*.
*
* For security reasons, only *name__str* with prefix "user." is allowed.
*
* Return: 0 on success, a negative value on error.
*/
__bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str,
struct bpf_dynptr *value_p)
{
struct bpf_dynptr_kern *value_ptr = (struct bpf_dynptr_kern *)value_p;
struct dentry *dentry;
u32 value_len;
void *value;
int ret;
if (strncmp(name__str, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
return -EPERM;
value_len = __bpf_dynptr_size(value_ptr);
value = __bpf_dynptr_data_rw(value_ptr, value_len);
if (!value)
return -EINVAL;
dentry = file_dentry(file);
ret = inode_permission(&nop_mnt_idmap, dentry->d_inode, MAY_READ);
if (ret)
return ret;
return __vfs_getxattr(dentry, dentry->d_inode, name__str, value, value_len);
}
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(bpf_fs_kfunc_set_ids)
@ -99,6 +136,7 @@ BTF_ID_FLAGS(func, bpf_get_task_exe_file,
KF_ACQUIRE | KF_TRUSTED_ARGS | KF_RET_NULL)
BTF_ID_FLAGS(func, bpf_put_file, KF_RELEASE)
BTF_ID_FLAGS(func, bpf_path_d_path, KF_TRUSTED_ARGS)
BTF_ID_FLAGS(func, bpf_get_file_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS)
BTF_KFUNCS_END(bpf_fs_kfunc_set_ids)
static int bpf_fs_kfuncs_filter(const struct bpf_prog *prog, u32 kfunc_id)

68
kernel/trace/bpf_trace.c
View File

@ -24,7 +24,6 @@
#include <linux/key.h>
#include <linux/verification.h>
#include <linux/namei.h>
#include <linux/fileattr.h>
#include <net/bpf_sk_storage.h>
@ -1439,73 +1438,6 @@ static int __init bpf_key_sig_kfuncs_init(void)
late_initcall(bpf_key_sig_kfuncs_init);
#endif /* CONFIG_KEYS */
/* filesystem kfuncs */
__bpf_kfunc_start_defs();
/**
* bpf_get_file_xattr - get xattr of a file
* @file: file to get xattr from
* @name__str: name of the xattr
* @value_p: output buffer of the xattr value
*
* Get xattr *name__str* of *file* and store the output in *value_ptr*.
*
* For security reasons, only *name__str* with prefix "user." is allowed.
*
* Return: 0 on success, a negative value on error.
*/
__bpf_kfunc int bpf_get_file_xattr(struct file *file, const char *name__str,
struct bpf_dynptr *value_p)
{
struct bpf_dynptr_kern *value_ptr = (struct bpf_dynptr_kern *)value_p;
struct dentry *dentry;
u32 value_len;
void *value;
int ret;
if (strncmp(name__str, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN))
return -EPERM;
value_len = __bpf_dynptr_size(value_ptr);
value = __bpf_dynptr_data_rw(value_ptr, value_len);
if (!value)
return -EINVAL;
dentry = file_dentry(file);
ret = inode_permission(&nop_mnt_idmap, dentry->d_inode, MAY_READ);
if (ret)
return ret;
return __vfs_getxattr(dentry, dentry->d_inode, name__str, value, value_len);
}
__bpf_kfunc_end_defs();
BTF_KFUNCS_START(fs_kfunc_set_ids)
BTF_ID_FLAGS(func, bpf_get_file_xattr, KF_SLEEPABLE | KF_TRUSTED_ARGS)
BTF_KFUNCS_END(fs_kfunc_set_ids)
static int bpf_get_file_xattr_filter(const struct bpf_prog *prog, u32 kfunc_id)
{
if (!btf_id_set8_contains(&fs_kfunc_set_ids, kfunc_id))
return 0;
/* Only allow to attach from LSM hooks, to avoid recursion */
return prog->type != BPF_PROG_TYPE_LSM ? -EACCES : 0;
}
static const struct btf_kfunc_id_set bpf_fs_kfunc_set = {
.owner = THIS_MODULE,
.set = &fs_kfunc_set_ids,
.filter = bpf_get_file_xattr_filter,
};
static int __init bpf_fs_kfuncs_init(void)
{
return register_btf_kfunc_id_set(BPF_PROG_TYPE_LSM, &bpf_fs_kfunc_set);
}
late_initcall(bpf_fs_kfuncs_init);
static const struct bpf_func_proto *
bpf_tracing_func_proto(enum bpf_func_id func_id, const struct bpf_prog *prog)
{