Commit fa4e5afa authored by Song Liu's avatar Song Liu Committed by Alexei Starovoitov
Browse files

bpf: Move bpf_get_file_xattr to fs/bpf_fs_kfuncs.c 



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

Signed-off-by: default avatarSong Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20240806230904.71194-2-song@kernel.org


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent 6e083ab0

fs/bpf_fs_kfuncs.c

+38 −0
Original line number Diff line number Diff line
@@ -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)

kernel/trace/bpf_trace.c

+0 −68
Original line number Diff line number Diff line
@@ -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)

{