| Message ID | 20190509112420.15671-4-roberto.sassu@huawei.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | initramfs: add support for xattrs in the initial ram disk | expand |
On Thu, May 09, 2019 at 01:24:20PM +0200, Roberto Sassu wrote: > This patch adds support for an alternative method to add xattrs to files in > the rootfs filesystem. Instead of extracting them directly from the ram > disk image, they are extracted from a regular file called .xattr-list, that > can be added by any ram disk generator available today. [...] > +struct path_hdr { > + char p_size[10]; /* total size including p_size field */ > + char p_data[]; /* <path>\0<xattrs> */ > +}; > + > +static int __init do_readxattrs(void) > +{ > + struct path_hdr hdr; > + char str[sizeof(hdr.p_size) + 1]; > + unsigned long file_entry_size; > + size_t size, name_buf_size, total_size; > + struct kstat st; > + int ret, fd; > + > + ret = vfs_lstat(XATTR_LIST_FILENAME, &st); > + if (ret < 0) > + return ret; > + > + total_size = st.size; > + > + fd = ksys_open(XATTR_LIST_FILENAME, O_RDONLY, 0); > + if (fd < 0) > + return fd; > + > + while (total_size) { > + size = ksys_read(fd, (char *)&hdr, sizeof(hdr)); [...] > + ksys_close(fd); > + > + if (ret < 0) > + error("Unable to parse xattrs"); > + > + return ret; > +} Please use something like filp_open()+kernel_read()+fput() instead of ksys_open()+ksys_read()+ksys_close(). I understand that some of the init code needs to use the syscall wrappers because no equivalent VFS functions are available, but please use the VFS functions when that's easy to do.
On 5/10/2019 11:33 PM, Jann Horn wrote: > On Thu, May 09, 2019 at 01:24:20PM +0200, Roberto Sassu wrote: >> This patch adds support for an alternative method to add xattrs to files in >> the rootfs filesystem. Instead of extracting them directly from the ram >> disk image, they are extracted from a regular file called .xattr-list, that >> can be added by any ram disk generator available today. > [...] >> +struct path_hdr { >> + char p_size[10]; /* total size including p_size field */ >> + char p_data[]; /* <path>\0<xattrs> */ >> +}; >> + >> +static int __init do_readxattrs(void) >> +{ >> + struct path_hdr hdr; >> + char str[sizeof(hdr.p_size) + 1]; >> + unsigned long file_entry_size; >> + size_t size, name_buf_size, total_size; >> + struct kstat st; >> + int ret, fd; >> + >> + ret = vfs_lstat(XATTR_LIST_FILENAME, &st); >> + if (ret < 0) >> + return ret; >> + >> + total_size = st.size; >> + >> + fd = ksys_open(XATTR_LIST_FILENAME, O_RDONLY, 0); >> + if (fd < 0) >> + return fd; >> + >> + while (total_size) { >> + size = ksys_read(fd, (char *)&hdr, sizeof(hdr)); > [...] >> + ksys_close(fd); >> + >> + if (ret < 0) >> + error("Unable to parse xattrs"); >> + >> + return ret; >> +} > > Please use something like filp_open()+kernel_read()+fput() instead of > ksys_open()+ksys_read()+ksys_close(). I understand that some of the init > code needs to use the syscall wrappers because no equivalent VFS > functions are available, but please use the VFS functions when that's > easy to do. Ok. Thanks for the suggestion. Roberto
diff --git a/init/initramfs.c b/init/initramfs.c index 98c2aa4b5ab4..91f35a84c592 100644 --- a/init/initramfs.c +++ b/init/initramfs.c @@ -11,6 +11,9 @@ #include <linux/utime.h> #include <linux/file.h> +#define XATTR_LIST_FILENAME ".xattr-list" + + static ssize_t __init xwrite(int fd, const char *p, size_t count) { ssize_t out = 0; @@ -451,6 +454,91 @@ static int __init do_setxattrs(void) return 0; } +struct path_hdr { + char p_size[10]; /* total size including p_size field */ + char p_data[]; /* <path>\0<xattrs> */ +}; + +static int __init do_readxattrs(void) +{ + struct path_hdr hdr; + char str[sizeof(hdr.p_size) + 1]; + unsigned long file_entry_size; + size_t size, name_buf_size, total_size; + struct kstat st; + int ret, fd; + + ret = vfs_lstat(XATTR_LIST_FILENAME, &st); + if (ret < 0) + return ret; + + total_size = st.size; + + fd = ksys_open(XATTR_LIST_FILENAME, O_RDONLY, 0); + if (fd < 0) + return fd; + + while (total_size) { + size = ksys_read(fd, (char *)&hdr, sizeof(hdr)); + if (size != sizeof(hdr)) { + ret = -EIO; + goto out; + } + + total_size -= size; + + memcpy(str, hdr.p_size, sizeof(hdr.p_size)); + ret = kstrtoul(str, 16, &file_entry_size); + if (ret < 0) + goto out; + + file_entry_size -= sizeof(sizeof(hdr.p_size)); + if (file_entry_size > total_size) { + ret = -EINVAL; + goto out; + } + + name_buf = vmalloc(file_entry_size); + if (!name_buf) { + ret = -ENOMEM; + goto out; + } + + size = ksys_read(fd, name_buf, file_entry_size); + if (size != file_entry_size) { + ret = -EIO; + goto out_free; + } + + total_size -= size; + + name_buf_size = strnlen(name_buf, file_entry_size); + if (name_buf_size == file_entry_size) { + ret = -EINVAL; + goto out_free; + } + + xattr_buf = name_buf + name_buf_size + 1; + xattr_len = file_entry_size - name_buf_size - 1; + + ret = do_setxattrs(); + vfree(name_buf); + name_buf = NULL; + + if (ret < 0) + break; + } +out_free: + vfree(name_buf); +out: + ksys_close(fd); + + if (ret < 0) + error("Unable to parse xattrs"); + + return ret; +} + static __initdata int (*actions[])(void) = { [Start] = do_start, [Collect] = do_collect, @@ -554,6 +642,7 @@ static char * __init unpack_to_rootfs(char *buf, unsigned long len) buf += my_inptr; len -= my_inptr; } + do_readxattrs(); dir_utime(); kfree(name_buf); kfree(symlink_buf);
This patch adds support for an alternative method to add xattrs to files in the rootfs filesystem. Instead of extracting them directly from the ram disk image, they are extracted from a regular file called .xattr-list, that can be added by any ram disk generator available today. .xattr-list can be generated by executing: $ getfattr --absolute-names -d -P -R -e hex -m - \ <file list> | xattr.awk -b > ${initdir}/.xattr-list where the content of the xattr.awk script is: #! /usr/bin/awk -f { if (!length($0)) { printf("%.10x%s\0", len, file); for (x in xattr) { printf("%.8x%s\0", xattr_len[x], x); for (i = 0; i < length(xattr[x]) / 2; i++) { printf("%c", strtonum("0x"substr(xattr[x], i * 2 + 1, 2))); } } i = 0; delete xattr; delete xattr_len; next; }; if (i == 0) { file=$3; len=length(file) + 8 + 1; } if (i > 0) { split($0, a, "="); xattr[a[1]]=substr(a[2], 3); xattr_len[a[1]]=length(a[1]) + 1 + 8 + length(xattr[a[1]]) / 2; len+=xattr_len[a[1]]; }; i++; } Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> --- init/initramfs.c | 89 ++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 89 insertions(+)