[PATCH] orangefs: cleanup uses of strncpy

From: Justin Stitt
Date: Fri Mar 22 2024 - 17:41:29 EST

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strncpy() is deprecated for use on NUL-terminated destination strings
[1] and as such we should prefer more robust and less ambiguous string
interfaces.

There is some care taken to ensure these destination buffers are
NUL-terminated by bounding the strncpy()'s by ORANGEFS_NAME_MAX - 1 or
ORANGEFS_MAX_SERVER_ADDR_LEN - 1. Instead, we can use the new 2-argument
version of strscpy() to guarantee NUL-termination on the destination
buffers while simplifying the code.

Based on usage with printf-likes, we can see these buffers are expected
to be NUL-terminated:
| gossip_debug(GOSSIP_NAME_DEBUG,
| "%s: doing lookup on %s under %pU,%d\n",
| __func__,
| new_op->upcall.req.lookup.d_name,
| &new_op->upcall.req.lookup.parent_refn.khandle,
| new_op->upcall.req.lookup.parent_refn.fs_id);
..
| gossip_debug(GOSSIP_SUPER_DEBUG,
| "Attempting ORANGEFS Remount via host %s\n",
| new_op->upcall.req.fs_mount.orangefs_config_server);

NUL-padding isn't required for any of these destination buffers as
they've all been zero-allocated with op_alloc() or kzalloc().

Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1]
Link: https://manpages.debian.org/testing/linux-manual-4.8/strscpy.9.en.html [2]
Link: https://github.com/KSPP/linux/issues/90
Cc: linux-hardening@xxxxxxxxxxxxxxx
Signed-off-by: Justin Stitt <justinstitt@xxxxxxxxxx>
---
Note: build-tested only.

Found with: $ rg "strncpy\("
---
fs/orangefs/dcache.c | 4 +---
fs/orangefs/namei.c | 26 ++++++++------------------
fs/orangefs/super.c | 17 ++++++-----------
3 files changed, 15 insertions(+), 32 deletions(-)

diff --git a/fs/orangefs/dcache.c b/fs/orangefs/dcache.c
index 8bbe9486e3a6..395a00ed8ac7 100644
--- a/fs/orangefs/dcache.c
+++ b/fs/orangefs/dcache.c
@@ -33,9 +33,7 @@ static int orangefs_revalidate_lookup(struct dentry *dentry)

new_op->upcall.req.lookup.sym_follow = ORANGEFS_LOOKUP_LINK_NO_FOLLOW;
new_op->upcall.req.lookup.parent_refn = parent->refn;
- strncpy(new_op->upcall.req.lookup.d_name,
- dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name);

gossip_debug(GOSSIP_DCACHE_DEBUG,
"%s:%s:%d interrupt flag [%d]\n",
diff --git a/fs/orangefs/namei.c b/fs/orangefs/namei.c
index c9dfd5c6a097..200558ec72f0 100644
--- a/fs/orangefs/namei.c
+++ b/fs/orangefs/namei.c
@@ -41,8 +41,7 @@ static int orangefs_create(struct mnt_idmap *idmap,
fill_default_sys_attrs(new_op->upcall.req.create.attributes,
ORANGEFS_TYPE_METAFILE, mode);

- strncpy(new_op->upcall.req.create.d_name,
- dentry->d_name.name, ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.create.d_name, dentry->d_name.name);

ret = service_operation(new_op, __func__, get_interruptible_flag(dir));

@@ -137,8 +136,7 @@ static struct dentry *orangefs_lookup(struct inode *dir, struct dentry *dentry,
&parent->refn.khandle);
new_op->upcall.req.lookup.parent_refn = parent->refn;

- strncpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.lookup.d_name, dentry->d_name.name);

gossip_debug(GOSSIP_NAME_DEBUG,
"%s: doing lookup on %s under %pU,%d\n",
@@ -192,8 +190,7 @@ static int orangefs_unlink(struct inode *dir, struct dentry *dentry)
return -ENOMEM;

new_op->upcall.req.remove.parent_refn = parent->refn;
- strncpy(new_op->upcall.req.remove.d_name, dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.remove.d_name, dentry->d_name.name);

ret = service_operation(new_op, "orangefs_unlink",
get_interruptible_flag(inode));
@@ -247,10 +244,8 @@ static int orangefs_symlink(struct mnt_idmap *idmap,
ORANGEFS_TYPE_SYMLINK,
mode);

- strncpy(new_op->upcall.req.sym.entry_name,
- dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
- strncpy(new_op->upcall.req.sym.target, symname, ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.sym.entry_name, dentry->d_name.name);
+ strscpy(new_op->upcall.req.sym.target, symname);

ret = service_operation(new_op, __func__, get_interruptible_flag(dir));

@@ -324,8 +319,7 @@ static int orangefs_mkdir(struct mnt_idmap *idmap, struct inode *dir,
fill_default_sys_attrs(new_op->upcall.req.mkdir.attributes,
ORANGEFS_TYPE_DIRECTORY, mode);

- strncpy(new_op->upcall.req.mkdir.d_name,
- dentry->d_name.name, ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.mkdir.d_name, dentry->d_name.name);

ret = service_operation(new_op, __func__, get_interruptible_flag(dir));

@@ -405,12 +399,8 @@ static int orangefs_rename(struct mnt_idmap *idmap,
new_op->upcall.req.rename.old_parent_refn = ORANGEFS_I(old_dir)->refn;
new_op->upcall.req.rename.new_parent_refn = ORANGEFS_I(new_dir)->refn;

- strncpy(new_op->upcall.req.rename.d_old_name,
- old_dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
- strncpy(new_op->upcall.req.rename.d_new_name,
- new_dentry->d_name.name,
- ORANGEFS_NAME_MAX - 1);
+ strscpy(new_op->upcall.req.rename.d_old_name, old_dentry->d_name.name);
+ strscpy(new_op->upcall.req.rename.d_new_name, new_dentry->d_name.name);

ret = service_operation(new_op,
"orangefs_rename",
diff --git a/fs/orangefs/super.c b/fs/orangefs/super.c
index 34849b4a3243..fb4d09c2f531 100644
--- a/fs/orangefs/super.c
+++ b/fs/orangefs/super.c
@@ -253,9 +253,8 @@ int orangefs_remount(struct orangefs_sb_info_s *orangefs_sb)
new_op = op_alloc(ORANGEFS_VFS_OP_FS_MOUNT);
if (!new_op)
return -ENOMEM;
- strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
- orangefs_sb->devname,
- ORANGEFS_MAX_SERVER_ADDR_LEN);
+ strscpy(new_op->upcall.req.fs_mount.orangefs_config_server,
+ orangefs_sb->devname);

gossip_debug(GOSSIP_SUPER_DEBUG,
"Attempting ORANGEFS Remount via host %s\n",
@@ -400,8 +399,7 @@ static int orangefs_unmount(int id, __s32 fs_id, const char *devname)
return -ENOMEM;
op->upcall.req.fs_umount.id = id;
op->upcall.req.fs_umount.fs_id = fs_id;
- strncpy(op->upcall.req.fs_umount.orangefs_config_server,
- devname, ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+ strscpy(op->upcall.req.fs_umount.orangefs_config_server, devname);
r = service_operation(op, "orangefs_fs_umount", 0);
/* Not much to do about an error here. */
if (r)
@@ -494,9 +492,7 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
if (!new_op)
return ERR_PTR(-ENOMEM);

- strncpy(new_op->upcall.req.fs_mount.orangefs_config_server,
- devname,
- ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+ strscpy(new_op->upcall.req.fs_mount.orangefs_config_server, devname);

gossip_debug(GOSSIP_SUPER_DEBUG,
"Attempting ORANGEFS Mount via host %s\n",
@@ -543,9 +539,8 @@ struct dentry *orangefs_mount(struct file_system_type *fst,
* on successful mount, store the devname and data
* used
*/
- strncpy(ORANGEFS_SB(sb)->devname,
- devname,
- ORANGEFS_MAX_SERVER_ADDR_LEN - 1);
+ strscpy(ORANGEFS_SB(sb)->devname, devname);
+

/* mount_pending must be cleared */
ORANGEFS_SB(sb)->mount_pending = 0;

---
base-commit: 241590e5a1d1b6219c8d3045c167f2fbcc076cbb
change-id: 20240322-strncpy-fs-orangefs-dcache-c-9a0cf2d22dae

Best regards,
--
Justin Stitt <justinstitt@xxxxxxxxxx>

Next message: Guenter Roeck: "Re: [patch 3/4] x86/topology: Handle the !APIC case gracefully"
Previous message: David Hildenbrand: "Re: BUG: unable to handle kernel paging request in fuse_copy_do"
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