[PATCH v5 2/7] lsm: introduce new hooks for setting/getting inode fsxattr
From: Andrey Albershteyn <hidden>
Date: 2025-05-13 09:18:21
Also in:
linux-alpha, linux-api, linux-arch, linux-fsdevel, linux-m68k, linux-mips, linux-s390, linux-security-module, linux-sh, linux-unionfs, linux-xfs, lkml, selinux, sparclinux
Subsystem:
filesystems (vfs and infrastructure), security subsystem, the rest · Maintainers:
Alexander Viro, Christian Brauner, Paul Moore, James Morris, "Serge E. Hallyn", Linus Torvalds
Introduce new hooks for setting and getting filesystem extended attributes on inode (FS_IOC_FSGETXATTR). Cc: selinux@vger.kernel.org Cc: Paul Moore <paul@paul-moore.com> Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org> --- fs/file_attr.c | 19 ++++++++++++++++--- include/linux/lsm_hook_defs.h | 2 ++ include/linux/security.h | 16 ++++++++++++++++ security/security.c | 30 ++++++++++++++++++++++++++++++ 4 files changed, 64 insertions(+), 3 deletions(-)
diff --git a/fs/file_attr.c b/fs/file_attr.c
index 2910b7047721df893540ff8a7c992558390eaa3a..be62d97cc444a445deac1c8ac8331f4a3766126a 100644
--- a/fs/file_attr.c
+++ b/fs/file_attr.c@@ -76,10 +76,15 @@ EXPORT_SYMBOL(fileattr_fill_flags); int vfs_fileattr_get(struct dentry *dentry, struct fileattr *fa) { struct inode *inode = d_inode(dentry); + int error; if (!inode->i_op->fileattr_get) return -ENOIOCTLCMD; + error = security_inode_file_getattr(dentry, fa); + if (error) + return error; + return inode->i_op->fileattr_get(dentry, fa); } EXPORT_SYMBOL(vfs_fileattr_get);
@@ -242,12 +247,20 @@ int vfs_fileattr_set(struct mnt_idmap *idmap, struct dentry *dentry, } else { fa->flags |= old_ma.flags & ~FS_COMMON_FL; } + err = fileattr_set_prepare(inode, &old_ma, fa); - if (!err) - err = inode->i_op->fileattr_set(idmap, dentry, fa); + if (err) + goto out; + err = security_inode_file_setattr(dentry, fa); + if (err) + goto out; + err = inode->i_op->fileattr_set(idmap, dentry, fa); + if (err) + goto out; } + +out: inode_unlock(inode); - return err; } EXPORT_SYMBOL(vfs_fileattr_set);
diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index bf3bbac4e02a59a67de4ace85b93b1a878131f60..9600a4350e791f47006720765c199e35d3abafd4 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h@@ -157,6 +157,8 @@ LSM_HOOK(int, 0, inode_removexattr, struct mnt_idmap *idmap, struct dentry *dentry, const char *name) LSM_HOOK(void, LSM_RET_VOID, inode_post_removexattr, struct dentry *dentry, const char *name) +LSM_HOOK(int, 0, inode_file_setattr, struct dentry *dentry, struct fileattr *fa) +LSM_HOOK(int, 0, inode_file_getattr, struct dentry *dentry, struct fileattr *fa) LSM_HOOK(int, 0, inode_set_acl, struct mnt_idmap *idmap, struct dentry *dentry, const char *acl_name, struct posix_acl *kacl) LSM_HOOK(void, LSM_RET_VOID, inode_post_set_acl, struct dentry *dentry,
diff --git a/include/linux/security.h b/include/linux/security.h
index cc9b54d95d22cd11480c38148005ed778b7af1bd..d2da2f654345b36b20fbe68ce11468ca4a55d8b3 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h@@ -451,6 +451,10 @@ int security_inode_listxattr(struct dentry *dentry); int security_inode_removexattr(struct mnt_idmap *idmap, struct dentry *dentry, const char *name); void security_inode_post_removexattr(struct dentry *dentry, const char *name); +int security_inode_file_setattr(struct dentry *dentry, + struct fileattr *fa); +int security_inode_file_getattr(struct dentry *dentry, + struct fileattr *fa); int security_inode_need_killpriv(struct dentry *dentry); int security_inode_killpriv(struct mnt_idmap *idmap, struct dentry *dentry); int security_inode_getsecurity(struct mnt_idmap *idmap,
@@ -1053,6 +1057,18 @@ static inline void security_inode_post_removexattr(struct dentry *dentry, const char *name) { } +static inline int security_inode_file_setattr(struct dentry *dentry, + struct fileattr *fa) +{ + return 0; +} + +static inline int security_inode_file_getattr(struct dentry *dentry, + struct fileattr *fa) +{ + return 0; +} + static inline int security_inode_need_killpriv(struct dentry *dentry) { return cap_inode_need_killpriv(dentry);
diff --git a/security/security.c b/security/security.c
index fb57e8fddd911bbb417ed2e7db443979bf611f43..09c891e6027dc1803a3af024b2f676e263da8aec 100644
--- a/security/security.c
+++ b/security/security.c@@ -2622,6 +2622,36 @@ void security_inode_post_removexattr(struct dentry *dentry, const char *name) call_void_hook(inode_post_removexattr, dentry, name); } +/** + * security_inode_file_setattr() - check if setting fsxattr is allowed + * @dentry: file to set filesystem extended attributes on + * @fa: extended attributes to set on the inode + * + * Called when file_setattr() syscall or FS_IOC_FSSETXATTR ioctl() is called on + * inode + * + * Return: Returns 0 if permission is granted. + */ +int security_inode_file_setattr(struct dentry *dentry, struct fileattr *fa) +{ + return call_int_hook(inode_file_setattr, dentry, fa); +} + +/** + * security_inode_file_getattr() - check if retrieving fsxattr is allowed + * @dentry: file to retrieve filesystem extended attributes from + * @fa: extended attributes to get + * + * Called when file_getattr() syscall or FS_IOC_FSGETXATTR ioctl() is called on + * inode + * + * Return: Returns 0 if permission is granted. + */ +int security_inode_file_getattr(struct dentry *dentry, struct fileattr *fa) +{ + return call_int_hook(inode_file_getattr, dentry, fa); +} + /** * security_inode_need_killpriv() - Check if security_inode_killpriv() required * @dentry: associated dentry
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2.47.2