path: root/fs/ext2
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2012-05-23 17:42:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-05-23 17:42:39 -0700
commit644473e9c60c1ff4f6351fed637a6e5551e3dce7 (patch)
tree10316518bedc735a2c6552886658d69dfd9f1eb0 /fs/ext2
parentfb827ec68446c83e9e8754fa9b55aed27ecc4661 (diff)
parent4b06a81f1daee668fbd6de85557bfb36dd36078f (diff)
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace
Pull user namespace enhancements from Eric Biederman: "This is a course correction for the user namespace, so that we can reach an inexpensive, maintainable, and reasonably complete implementation. Highlights: - Config guards make it impossible to enable the user namespace and code that has not been converted to be user namespace safe. - Use of the new kuid_t type ensures the if you somehow get past the config guards the kernel will encounter type errors if you enable user namespaces and attempt to compile in code whose permission checks have not been updated to be user namespace safe. - All uids from child user namespaces are mapped into the initial user namespace before they are processed. Removing the need to add an additional check to see if the user namespace of the compared uids remains the same. - With the user namespaces compiled out the performance is as good or better than it is today. - For most operations absolutely nothing changes performance or operationally with the user namespace enabled. - The worst case performance I could come up with was timing 1 billion cache cold stat operations with the user namespace code enabled. This went from 156s to 164s on my laptop (or 156ns to 164ns per stat operation). - (uid_t)-1 and (gid_t)-1 are reserved as an internal error value. Most uid/gid setting system calls treat these value specially anyway so attempting to use -1 as a uid would likely cause entertaining failures in userspace. - If setuid is called with a uid that can not be mapped setuid fails. I have looked at sendmail, login, ssh and every other program I could think of that would call setuid and they all check for and handle the case where setuid fails. - If stat or a similar system call is called from a context in which we can not map a uid we lie and return overflowuid. The LFS experience suggests not lying and returning an error code might be better, but the historical precedent with uids is different and I can not think of anything that would break by lying about a uid we can't map. - Capabilities are localized to the current user namespace making it safe to give the initial user in a user namespace all capabilities. My git tree covers all of the modifications needed to convert the core kernel and enough changes to make a system bootable to runlevel 1." Fix up trivial conflicts due to nearby independent changes in fs/stat.c * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits) userns: Silence silly gcc warning. cred: use correct cred accessor with regards to rcu read lock userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq userns: Convert cgroup permission checks to use uid_eq userns: Convert tmpfs to use kuid and kgid where appropriate userns: Convert sysfs to use kgid/kuid where appropriate userns: Convert sysctl permission checks to use kuid and kgids. userns: Convert proc to use kuid/kgid where appropriate userns: Convert ext4 to user kuid/kgid where appropriate userns: Convert ext3 to use kuid/kgid where appropriate userns: Convert ext2 to use kuid/kgid where appropriate. userns: Convert devpts to use kuid/kgid where appropriate userns: Convert binary formats to use kuid/kgid where appropriate userns: Add negative depends on entries to avoid building code that is userns unsafe userns: signal remove unnecessary map_cred_ns userns: Teach inode_capable to understand inodes whose uids map to other namespaces. userns: Fail exec for suid and sgid binaries with ids outside our user namespace. userns: Convert stat to return values mapped from kuids and kgids userns: Convert user specfied uids and gids in chown into kuids and kgid userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs ...
Diffstat (limited to 'fs/ext2')
4 files changed, 42 insertions, 22 deletions
diff --git a/fs/ext2/balloc.c b/fs/ext2/balloc.c
index a8cbe1bc6ad..030c6d277e1 100644
--- a/fs/ext2/balloc.c
+++ b/fs/ext2/balloc.c
@@ -1193,8 +1193,9 @@ static int ext2_has_free_blocks(struct ext2_sb_info *sbi)
free_blocks = percpu_counter_read_positive(&sbi->s_freeblocks_counter);
root_blocks = le32_to_cpu(sbi->s_es->s_r_blocks_count);
if (free_blocks < root_blocks + 1 && !capable(CAP_SYS_RESOURCE) &&
- sbi->s_resuid != current_fsuid() &&
- (sbi->s_resgid == 0 || !in_group_p (sbi->s_resgid))) {
+ !uid_eq(sbi->s_resuid, current_fsuid()) &&
+ (gid_eq(sbi->s_resgid, GLOBAL_ROOT_GID) ||
+ !in_group_p (sbi->s_resgid))) {
return 0;
return 1;
diff --git a/fs/ext2/ext2.h b/fs/ext2/ext2.h
index 0b2b4db5bdc..d9a17d0b124 100644
--- a/fs/ext2/ext2.h
+++ b/fs/ext2/ext2.h
@@ -82,8 +82,8 @@ struct ext2_sb_info {
struct buffer_head ** s_group_desc;
unsigned long s_mount_opt;
unsigned long s_sb_block;
- uid_t s_resuid;
- gid_t s_resgid;
+ kuid_t s_resuid;
+ kgid_t s_resgid;
unsigned short s_mount_state;
unsigned short s_pad;
int s_addr_per_block_bits;
@@ -637,8 +637,8 @@ static inline void verify_offsets(void)
struct ext2_mount_options {
unsigned long s_mount_opt;
- uid_t s_resuid;
- gid_t s_resgid;
+ kuid_t s_resuid;
+ kgid_t s_resgid;
diff --git a/fs/ext2/inode.c b/fs/ext2/inode.c
index 740cad8dcd8..f9fa95f8443 100644
--- a/fs/ext2/inode.c
+++ b/fs/ext2/inode.c
@@ -1293,6 +1293,8 @@ struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
struct inode *inode;
long ret = -EIO;
int n;
+ uid_t i_uid;
+ gid_t i_gid;
inode = iget_locked(sb, ino);
if (!inode)
@@ -1310,12 +1312,14 @@ struct inode *ext2_iget (struct super_block *sb, unsigned long ino)
inode->i_mode = le16_to_cpu(raw_inode->i_mode);
- inode->i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
- inode->i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
+ i_uid = (uid_t)le16_to_cpu(raw_inode->i_uid_low);
+ i_gid = (gid_t)le16_to_cpu(raw_inode->i_gid_low);
if (!(test_opt (inode->i_sb, NO_UID32))) {
- inode->i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
- inode->i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
+ i_uid |= le16_to_cpu(raw_inode->i_uid_high) << 16;
+ i_gid |= le16_to_cpu(raw_inode->i_gid_high) << 16;
+ i_uid_write(inode, i_uid);
+ i_gid_write(inode, i_gid);
set_nlink(inode, le16_to_cpu(raw_inode->i_links_count));
inode->i_size = le32_to_cpu(raw_inode->i_size);
inode->i_atime.tv_sec = (signed)le32_to_cpu(raw_inode->i_atime);
@@ -1413,8 +1417,8 @@ static int __ext2_write_inode(struct inode *inode, int do_sync)
struct ext2_inode_info *ei = EXT2_I(inode);
struct super_block *sb = inode->i_sb;
ino_t ino = inode->i_ino;
- uid_t uid = inode->i_uid;
- gid_t gid = inode->i_gid;
+ uid_t uid = i_uid_read(inode);
+ gid_t gid = i_gid_read(inode);
struct buffer_head * bh;
struct ext2_inode * raw_inode = ext2_get_inode(sb, ino, &bh);
int n;
@@ -1529,8 +1533,8 @@ int ext2_setattr(struct dentry *dentry, struct iattr *iattr)
if (is_quota_modification(inode, iattr))
- if ((iattr->ia_valid & ATTR_UID && iattr->ia_uid != inode->i_uid) ||
- (iattr->ia_valid & ATTR_GID && iattr->ia_gid != inode->i_gid)) {
+ if ((iattr->ia_valid & ATTR_UID && !uid_eq(iattr->ia_uid, inode->i_uid)) ||
+ (iattr->ia_valid & ATTR_GID && !gid_eq(iattr->ia_gid, inode->i_gid))) {
error = dquot_transfer(inode, iattr);
if (error)
return error;
diff --git a/fs/ext2/super.c b/fs/ext2/super.c
index e1025c7a437..38f816071dd 100644
--- a/fs/ext2/super.c
+++ b/fs/ext2/super.c
@@ -228,13 +228,15 @@ static int ext2_show_options(struct seq_file *seq, struct dentry *root)
seq_puts(seq, ",grpid");
if (!test_opt(sb, GRPID) && (def_mount_opts & EXT2_DEFM_BSDGROUPS))
seq_puts(seq, ",nogrpid");
- if (sbi->s_resuid != EXT2_DEF_RESUID ||
+ if (!uid_eq(sbi->s_resuid, make_kuid(&init_user_ns, EXT2_DEF_RESUID)) ||
le16_to_cpu(es->s_def_resuid) != EXT2_DEF_RESUID) {
- seq_printf(seq, ",resuid=%u", sbi->s_resuid);
+ seq_printf(seq, ",resuid=%u",
+ from_kuid_munged(&init_user_ns, sbi->s_resuid));
- if (sbi->s_resgid != EXT2_DEF_RESGID ||
+ if (!gid_eq(sbi->s_resgid, make_kgid(&init_user_ns, EXT2_DEF_RESGID)) ||
le16_to_cpu(es->s_def_resgid) != EXT2_DEF_RESGID) {
- seq_printf(seq, ",resgid=%u", sbi->s_resgid);
+ seq_printf(seq, ",resgid=%u",
+ from_kgid_munged(&init_user_ns, sbi->s_resgid));
if (test_opt(sb, ERRORS_RO)) {
int def_errors = le16_to_cpu(es->s_errors);
@@ -436,6 +438,8 @@ static int parse_options(char *options, struct super_block *sb)
struct ext2_sb_info *sbi = EXT2_SB(sb);
substring_t args[MAX_OPT_ARGS];
int option;
+ kuid_t uid;
+ kgid_t gid;
if (!options)
return 1;
@@ -462,12 +466,23 @@ static int parse_options(char *options, struct super_block *sb)
case Opt_resuid:
if (match_int(&args[0], &option))
return 0;
- sbi->s_resuid = option;
+ uid = make_kuid(current_user_ns(), option);
+ if (!uid_valid(uid)) {
+ ext2_msg(sb, KERN_ERR, "Invalid uid value %d", option);
+ return -1;
+ }
+ sbi->s_resuid = uid;
case Opt_resgid:
if (match_int(&args[0], &option))
return 0;
- sbi->s_resgid = option;
+ gid = make_kgid(current_user_ns(), option);
+ if (!gid_valid(gid)) {
+ ext2_msg(sb, KERN_ERR, "Invalid gid value %d", option);
+ return -1;
+ }
+ sbi->s_resgid = gid;
case Opt_sb:
/* handled by get_sb_block() instead of here */
@@ -841,8 +856,8 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
set_opt(sbi->s_mount_opt, ERRORS_RO);
- sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
- sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
+ sbi->s_resuid = make_kuid(&init_user_ns, le16_to_cpu(es->s_def_resuid));
+ sbi->s_resgid = make_kgid(&init_user_ns, le16_to_cpu(es->s_def_resgid));
set_opt(sbi->s_mount_opt, RESERVATION);