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fs/xattr.c
15.7 KB
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/* File: fs/xattr.c Extended attribute handling. Copyright (C) 2001 by Andreas Gruenbacher <a.gruenbacher@computer.org> Copyright (C) 2001 SGI - Silicon Graphics, Inc <linux-xfs@oss.sgi.com> Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> */ #include <linux/fs.h> #include <linux/slab.h> |
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#include <linux/file.h> #include <linux/xattr.h> |
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#include <linux/mount.h> |
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#include <linux/namei.h> #include <linux/security.h> #include <linux/syscalls.h> #include <linux/module.h> |
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#include <linux/fsnotify.h> |
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#include <linux/audit.h> |
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#include <asm/uaccess.h> |
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|
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/* * Check permissions for extended attribute access. This is a bit complicated * because different namespaces have very different rules. */ static int xattr_permission(struct inode *inode, const char *name, int mask) { /* * We can never set or remove an extended attribute on a read-only * filesystem or on an immutable / append-only inode. */ if (mask & MAY_WRITE) { |
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if (IS_IMMUTABLE(inode) || IS_APPEND(inode)) return -EPERM; } /* * No restriction for security.* and system.* from the VFS. Decision * on these is left to the underlying filesystem / security module. */ if (!strncmp(name, XATTR_SECURITY_PREFIX, XATTR_SECURITY_PREFIX_LEN) || !strncmp(name, XATTR_SYSTEM_PREFIX, XATTR_SYSTEM_PREFIX_LEN)) return 0; /* |
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* The trusted.* namespace can only be accessed by a privileged user. |
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*/ if (!strncmp(name, XATTR_TRUSTED_PREFIX, XATTR_TRUSTED_PREFIX_LEN)) return (capable(CAP_SYS_ADMIN) ? 0 : -EPERM); |
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/* In user.* namespace, only regular files and directories can have * extended attributes. For sticky directories, only the owner and * privileged user can write attributes. */ |
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if (!strncmp(name, XATTR_USER_PREFIX, XATTR_USER_PREFIX_LEN)) { |
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if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode)) return -EPERM; if (S_ISDIR(inode->i_mode) && (inode->i_mode & S_ISVTX) && |
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(mask & MAY_WRITE) && !inode_owner_or_capable(inode)) |
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return -EPERM; } |
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return inode_permission(inode, mask); |
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} |
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/** * __vfs_setxattr_noperm - perform setxattr operation without performing * permission checks. * * @dentry - object to perform setxattr on * @name - xattr name to set * @value - value to set @name to * @size - size of @value * @flags - flags to pass into filesystem operations * * returns the result of the internal setxattr or setsecurity operations. * * This function requires the caller to lock the inode's i_mutex before it * is executed. It also assumes that the caller will make the appropriate * permission checks. */ int __vfs_setxattr_noperm(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) |
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{ struct inode *inode = dentry->d_inode; |
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int error = -EOPNOTSUPP; |
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|
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if (inode->i_op->setxattr) { error = inode->i_op->setxattr(dentry, name, value, size, flags); if (!error) { fsnotify_xattr(dentry); security_inode_post_setxattr(dentry, name, value, size, flags); } } else if (!strncmp(name, XATTR_SECURITY_PREFIX, |
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XATTR_SECURITY_PREFIX_LEN)) { const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
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error = security_inode_setsecurity(inode, suffix, value, size, flags); if (!error) fsnotify_xattr(dentry); } |
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return error; } int vfs_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { struct inode *inode = dentry->d_inode; int error; error = xattr_permission(inode, name, MAY_WRITE); if (error) return error; mutex_lock(&inode->i_mutex); error = security_inode_setxattr(dentry, name, value, size, flags); if (error) goto out; error = __vfs_setxattr_noperm(dentry, name, value, size, flags); |
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out: mutex_unlock(&inode->i_mutex); return error; } EXPORT_SYMBOL_GPL(vfs_setxattr); ssize_t |
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xattr_getsecurity(struct inode *inode, const char *name, void *value, size_t size) { void *buffer = NULL; ssize_t len; if (!value || !size) { len = security_inode_getsecurity(inode, name, &buffer, false); goto out_noalloc; } len = security_inode_getsecurity(inode, name, &buffer, true); if (len < 0) return len; if (size < len) { len = -ERANGE; goto out; } memcpy(value, buffer, len); out: security_release_secctx(buffer, len); out_noalloc: return len; } EXPORT_SYMBOL_GPL(xattr_getsecurity); ssize_t |
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vfs_getxattr(struct dentry *dentry, const char *name, void *value, size_t size) |
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{ struct inode *inode = dentry->d_inode; int error; |
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error = xattr_permission(inode, name, MAY_READ); if (error) return error; |
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error = security_inode_getxattr(dentry, name); if (error) return error; |
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if (!strncmp(name, XATTR_SECURITY_PREFIX, |
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XATTR_SECURITY_PREFIX_LEN)) { const char *suffix = name + XATTR_SECURITY_PREFIX_LEN; |
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int ret = xattr_getsecurity(inode, suffix, value, size); |
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/* * Only overwrite the return value if a security module * is actually active. */ |
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if (ret == -EOPNOTSUPP) goto nolsm; return ret; |
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} |
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nolsm: if (inode->i_op->getxattr) error = inode->i_op->getxattr(dentry, name, value, size); else error = -EOPNOTSUPP; |
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return error; } EXPORT_SYMBOL_GPL(vfs_getxattr); |
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ssize_t vfs_listxattr(struct dentry *d, char *list, size_t size) { ssize_t error; error = security_inode_listxattr(d); if (error) return error; error = -EOPNOTSUPP; |
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if (d->d_inode->i_op->listxattr) { |
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error = d->d_inode->i_op->listxattr(d, list, size); } else { error = security_inode_listsecurity(d->d_inode, list, size); if (size && error > size) error = -ERANGE; } return error; } EXPORT_SYMBOL_GPL(vfs_listxattr); |
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int |
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vfs_removexattr(struct dentry *dentry, const char *name) |
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{ struct inode *inode = dentry->d_inode; int error; if (!inode->i_op->removexattr) return -EOPNOTSUPP; |
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error = xattr_permission(inode, name, MAY_WRITE); if (error) return error; |
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error = security_inode_removexattr(dentry, name); if (error) return error; mutex_lock(&inode->i_mutex); error = inode->i_op->removexattr(dentry, name); mutex_unlock(&inode->i_mutex); if (!error) fsnotify_xattr(dentry); return error; } EXPORT_SYMBOL_GPL(vfs_removexattr); |
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/* * Extended attribute SET operations */ static long |
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setxattr(struct dentry *d, const char __user *name, const void __user *value, |
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size_t size, int flags) { int error; void *kvalue = NULL; char kname[XATTR_NAME_MAX + 1]; if (flags & ~(XATTR_CREATE|XATTR_REPLACE)) return -EINVAL; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; if (size) { if (size > XATTR_SIZE_MAX) return -E2BIG; |
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kvalue = memdup_user(value, size); if (IS_ERR(kvalue)) return PTR_ERR(kvalue); |
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} |
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error = vfs_setxattr(d, kname, kvalue, size, flags); |
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kfree(kvalue); |
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return error; } |
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SYSCALL_DEFINE5(setxattr, const char __user *, pathname, const char __user *, name, const void __user *, value, size_t, size, int, flags) |
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{ |
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struct path path; |
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int error; |
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error = user_path(pathname, &path); |
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if (error) return error; |
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error = mnt_want_write(path.mnt); |
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if (!error) { |
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error = setxattr(path.dentry, name, value, size, flags); mnt_drop_write(path.mnt); |
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} |
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path_put(&path); |
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return error; } |
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SYSCALL_DEFINE5(lsetxattr, const char __user *, pathname, const char __user *, name, const void __user *, value, size_t, size, int, flags) |
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{ |
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struct path path; |
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int error; |
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error = user_lpath(pathname, &path); |
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if (error) return error; |
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error = mnt_want_write(path.mnt); |
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if (!error) { |
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error = setxattr(path.dentry, name, value, size, flags); mnt_drop_write(path.mnt); |
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} |
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path_put(&path); |
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return error; } |
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SYSCALL_DEFINE5(fsetxattr, int, fd, const char __user *, name, const void __user *,value, size_t, size, int, flags) |
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{ struct file *f; |
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struct dentry *dentry; |
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int error = -EBADF; f = fget(fd); if (!f) return error; |
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dentry = f->f_path.dentry; |
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audit_inode(NULL, dentry); |
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error = mnt_want_write_file(f); |
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if (!error) { error = setxattr(dentry, name, value, size, flags); mnt_drop_write(f->f_path.mnt); } |
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fput(f); return error; } /* * Extended attribute GET operations */ static ssize_t |
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getxattr(struct dentry *d, const char __user *name, void __user *value, size_t size) |
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{ ssize_t error; void *kvalue = NULL; char kname[XATTR_NAME_MAX + 1]; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; if (size) { if (size > XATTR_SIZE_MAX) size = XATTR_SIZE_MAX; |
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kvalue = kzalloc(size, GFP_KERNEL); |
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if (!kvalue) return -ENOMEM; } |
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error = vfs_getxattr(d, kname, kvalue, size); |
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if (error > 0) { if (size && copy_to_user(value, kvalue, error)) error = -EFAULT; } else if (error == -ERANGE && size >= XATTR_SIZE_MAX) { /* The file system tried to returned a value bigger than XATTR_SIZE_MAX bytes. Not possible. */ error = -E2BIG; |
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} |
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kfree(kvalue); |
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return error; } |
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SYSCALL_DEFINE4(getxattr, const char __user *, pathname, const char __user *, name, void __user *, value, size_t, size) |
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{ |
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struct path path; |
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ssize_t error; |
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error = user_path(pathname, &path); |
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if (error) return error; |
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error = getxattr(path.dentry, name, value, size); path_put(&path); |
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return error; } |
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SYSCALL_DEFINE4(lgetxattr, const char __user *, pathname, const char __user *, name, void __user *, value, size_t, size) |
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{ |
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struct path path; |
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ssize_t error; |
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error = user_lpath(pathname, &path); |
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if (error) return error; |
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error = getxattr(path.dentry, name, value, size); path_put(&path); |
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return error; } |
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SYSCALL_DEFINE4(fgetxattr, int, fd, const char __user *, name, void __user *, value, size_t, size) |
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{ struct file *f; ssize_t error = -EBADF; f = fget(fd); if (!f) return error; |
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audit_inode(NULL, f->f_path.dentry); |
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error = getxattr(f->f_path.dentry, name, value, size); |
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fput(f); return error; } /* * Extended attribute LIST operations */ static ssize_t listxattr(struct dentry *d, char __user *list, size_t size) { ssize_t error; char *klist = NULL; if (size) { if (size > XATTR_LIST_MAX) size = XATTR_LIST_MAX; klist = kmalloc(size, GFP_KERNEL); if (!klist) return -ENOMEM; } |
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error = vfs_listxattr(d, klist, size); |
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if (error > 0) { if (size && copy_to_user(list, klist, error)) error = -EFAULT; } else if (error == -ERANGE && size >= XATTR_LIST_MAX) { /* The file system tried to returned a list bigger than XATTR_LIST_MAX bytes. Not possible. */ error = -E2BIG; |
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} |
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kfree(klist); |
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return error; } |
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SYSCALL_DEFINE3(listxattr, const char __user *, pathname, char __user *, list, size_t, size) |
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{ |
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struct path path; |
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ssize_t error; |
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error = user_path(pathname, &path); |
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if (error) return error; |
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error = listxattr(path.dentry, list, size); path_put(&path); |
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return error; } |
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SYSCALL_DEFINE3(llistxattr, const char __user *, pathname, char __user *, list, size_t, size) |
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{ |
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struct path path; |
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ssize_t error; |
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error = user_lpath(pathname, &path); |
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if (error) return error; |
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error = listxattr(path.dentry, list, size); path_put(&path); |
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return error; } |
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SYSCALL_DEFINE3(flistxattr, int, fd, char __user *, list, size_t, size) |
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{ struct file *f; ssize_t error = -EBADF; f = fget(fd); if (!f) return error; |
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audit_inode(NULL, f->f_path.dentry); |
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error = listxattr(f->f_path.dentry, list, size); |
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fput(f); return error; } /* * Extended attribute REMOVE operations */ static long |
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removexattr(struct dentry *d, const char __user *name) |
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{ int error; char kname[XATTR_NAME_MAX + 1]; error = strncpy_from_user(kname, name, sizeof(kname)); if (error == 0 || error == sizeof(kname)) error = -ERANGE; if (error < 0) return error; |
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return vfs_removexattr(d, kname); |
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} |
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SYSCALL_DEFINE2(removexattr, const char __user *, pathname, const char __user *, name) |
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{ |
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struct path path; |
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int error; |
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error = user_path(pathname, &path); |
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if (error) return error; |
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error = mnt_want_write(path.mnt); |
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if (!error) { |
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error = removexattr(path.dentry, name); mnt_drop_write(path.mnt); |
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} |
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path_put(&path); |
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return error; } |
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SYSCALL_DEFINE2(lremovexattr, const char __user *, pathname, const char __user *, name) |
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493 |
{ |
2d8f30380 [PATCH] sanitize ... |
494 |
struct path path; |
1da177e4c Linux-2.6.12-rc2 |
495 |
int error; |
2d8f30380 [PATCH] sanitize ... |
496 |
error = user_lpath(pathname, &path); |
1da177e4c Linux-2.6.12-rc2 |
497 498 |
if (error) return error; |
2d8f30380 [PATCH] sanitize ... |
499 |
error = mnt_want_write(path.mnt); |
18f335aff [PATCH] r/o bind ... |
500 |
if (!error) { |
2d8f30380 [PATCH] sanitize ... |
501 502 |
error = removexattr(path.dentry, name); mnt_drop_write(path.mnt); |
18f335aff [PATCH] r/o bind ... |
503 |
} |
2d8f30380 [PATCH] sanitize ... |
504 |
path_put(&path); |
1da177e4c Linux-2.6.12-rc2 |
505 506 |
return error; } |
6a6160a7b [CVE-2009-0029] S... |
507 |
SYSCALL_DEFINE2(fremovexattr, int, fd, const char __user *, name) |
1da177e4c Linux-2.6.12-rc2 |
508 509 |
{ struct file *f; |
73241ccca [PATCH] Collect m... |
510 |
struct dentry *dentry; |
1da177e4c Linux-2.6.12-rc2 |
511 512 513 514 515 |
int error = -EBADF; f = fget(fd); if (!f) return error; |
0f7fc9e4d [PATCH] VFS: chan... |
516 |
dentry = f->f_path.dentry; |
5a190ae69 [PATCH] pass dent... |
517 |
audit_inode(NULL, dentry); |
96029c4e0 fs: introduce mnt... |
518 |
error = mnt_want_write_file(f); |
18f335aff [PATCH] r/o bind ... |
519 520 521 522 |
if (!error) { error = removexattr(dentry, name); mnt_drop_write(f->f_path.mnt); } |
1da177e4c Linux-2.6.12-rc2 |
523 524 525 526 527 528 529 530 531 532 533 534 535 536 537 538 539 540 541 542 543 544 545 546 547 548 549 550 551 552 553 554 |
fput(f); return error; } static const char * strcmp_prefix(const char *a, const char *a_prefix) { while (*a_prefix && *a == *a_prefix) { a++; a_prefix++; } return *a_prefix ? NULL : a; } /* * In order to implement different sets of xattr operations for each xattr * prefix with the generic xattr API, a filesystem should create a * null-terminated array of struct xattr_handler (one for each prefix) and * hang a pointer to it off of the s_xattr field of the superblock. * * The generic_fooxattr() functions will use this list to dispatch xattr * operations to the correct xattr_handler. */ #define for_each_xattr_handler(handlers, handler) \ for ((handler) = *(handlers)++; \ (handler) != NULL; \ (handler) = *(handlers)++) /* * Find the xattr_handler with the matching prefix. */ |
bb4354538 fs: xattr_handler... |
555 556 |
static const struct xattr_handler * xattr_resolve_name(const struct xattr_handler **handlers, const char **name) |
1da177e4c Linux-2.6.12-rc2 |
557 |
{ |
bb4354538 fs: xattr_handler... |
558 |
const struct xattr_handler *handler; |
1da177e4c Linux-2.6.12-rc2 |
559 560 561 562 563 564 565 566 567 568 569 570 571 572 573 574 575 576 577 578 |
if (!*name) return NULL; for_each_xattr_handler(handlers, handler) { const char *n = strcmp_prefix(*name, handler->prefix); if (n) { *name = n; break; } } return handler; } /* * Find the handler for the prefix and dispatch its get() operation. */ ssize_t generic_getxattr(struct dentry *dentry, const char *name, void *buffer, size_t size) { |
bb4354538 fs: xattr_handler... |
579 |
const struct xattr_handler *handler; |
1da177e4c Linux-2.6.12-rc2 |
580 |
|
431547b3c sanitize xattr ha... |
581 |
handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
1da177e4c Linux-2.6.12-rc2 |
582 583 |
if (!handler) return -EOPNOTSUPP; |
431547b3c sanitize xattr ha... |
584 |
return handler->get(dentry, name, buffer, size, handler->flags); |
1da177e4c Linux-2.6.12-rc2 |
585 586 587 588 589 590 591 592 593 |
} /* * Combine the results of the list() operation from every xattr_handler in the * list. */ ssize_t generic_listxattr(struct dentry *dentry, char *buffer, size_t buffer_size) { |
bb4354538 fs: xattr_handler... |
594 |
const struct xattr_handler *handler, **handlers = dentry->d_sb->s_xattr; |
1da177e4c Linux-2.6.12-rc2 |
595 596 597 |
unsigned int size = 0; if (!buffer) { |
431547b3c sanitize xattr ha... |
598 599 600 601 |
for_each_xattr_handler(handlers, handler) { size += handler->list(dentry, NULL, 0, NULL, 0, handler->flags); } |
1da177e4c Linux-2.6.12-rc2 |
602 603 604 605 |
} else { char *buf = buffer; for_each_xattr_handler(handlers, handler) { |
431547b3c sanitize xattr ha... |
606 607 |
size = handler->list(dentry, buf, buffer_size, NULL, 0, handler->flags); |
1da177e4c Linux-2.6.12-rc2 |
608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 |
if (size > buffer_size) return -ERANGE; buf += size; buffer_size -= size; } size = buf - buffer; } return size; } /* * Find the handler for the prefix and dispatch its set() operation. */ int generic_setxattr(struct dentry *dentry, const char *name, const void *value, size_t size, int flags) { |
bb4354538 fs: xattr_handler... |
624 |
const struct xattr_handler *handler; |
1da177e4c Linux-2.6.12-rc2 |
625 626 627 |
if (size == 0) value = ""; /* empty EA, do not remove */ |
431547b3c sanitize xattr ha... |
628 |
handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
1da177e4c Linux-2.6.12-rc2 |
629 630 |
if (!handler) return -EOPNOTSUPP; |
df7e13038 vfs: Pass setxatt... |
631 |
return handler->set(dentry, name, value, size, flags, handler->flags); |
1da177e4c Linux-2.6.12-rc2 |
632 633 634 635 636 637 638 639 640 |
} /* * Find the handler for the prefix and dispatch its set() operation to remove * any associated extended attribute. */ int generic_removexattr(struct dentry *dentry, const char *name) { |
bb4354538 fs: xattr_handler... |
641 |
const struct xattr_handler *handler; |
1da177e4c Linux-2.6.12-rc2 |
642 |
|
431547b3c sanitize xattr ha... |
643 |
handler = xattr_resolve_name(dentry->d_sb->s_xattr, &name); |
1da177e4c Linux-2.6.12-rc2 |
644 645 |
if (!handler) return -EOPNOTSUPP; |
431547b3c sanitize xattr ha... |
646 647 |
return handler->set(dentry, name, NULL, 0, XATTR_REPLACE, handler->flags); |
1da177e4c Linux-2.6.12-rc2 |
648 649 650 651 652 653 |
} EXPORT_SYMBOL(generic_getxattr); EXPORT_SYMBOL(generic_listxattr); EXPORT_SYMBOL(generic_setxattr); EXPORT_SYMBOL(generic_removexattr); |