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Message-ID: <20240806230904.71194-2-song@kernel.org>
Date: Tue, 6 Aug 2024 16:09:02 -0700
From: Song Liu <song@...nel.org>
To: bpf@...r.kernel.org,
linux-fsdevel@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: kernel-team@...a.com,
andrii@...nel.org,
eddyz87@...il.com,
ast@...nel.org,
daniel@...earbox.net,
martin.lau@...ux.dev,
viro@...iv.linux.org.uk,
brauner@...nel.org,
jack@...e.cz,
kpsingh@...nel.org,
liamwisehart@...a.com,
lltang@...a.com,
shankaran@...a.com,
Song Liu <song@...nel.org>
Subject: [PATCH v4 bpf-next 1/3] 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: Song Liu <song@...nel.org>
---
fs/bpf_fs_kfuncs.c | 38 ++++++++++++++++++++++
kernel/trace/bpf_trace.c | 68 ----------------------------------------
2 files changed, 38 insertions(+), 68 deletions(-)
diff --git a/fs/bpf_fs_kfuncs.c b/fs/bpf_fs_kfuncs.c
index 1e6e08667758..b13d00f7ad2b 100644
--- a/fs/bpf_fs_kfuncs.c
+++ b/fs/bpf_fs_kfuncs.c
@@ -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)
diff --git a/kernel/trace/bpf_trace.c b/kernel/trace/bpf_trace.c
index cd098846e251..d557bb11e0ff 100644
--- a/kernel/trace/bpf_trace.c
+++ b/kernel/trace/bpf_trace.c
@@ -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)
{
--
2.43.5
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