| Message ID | 20200218143411.2389182-4-christian.brauner@ubuntu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | user_namespace: introduce fsid mappings | expand |
On Tue, Feb 18, 2020 at 03:33:49PM +0100, Christian Brauner wrote: > The /proc/<pid>/fsgid_map file can be written once to setup an fsgid mapping > for a user namespace. Writing to this file has the same restrictions as writing > to /proc/<pid>/fsgid_map. > > root@e1-vm:/# cat /proc/13023/fsgid_map > 0 300000 100000 > > Fsid mappings have always been around. They are currently always identical to > the id mappings for a user namespace. This means, currently whenever an fsid > needs to be looked up the kernel will use the id mapping of the user namespace. > With the introduction of fsid mappings the kernel will now lookup fsids in the > fsid mappings of the user namespace. If no fsid mapping exists the kernel will > continue looking up fsids in the id mappings of the user namespace. Hence, if a > system supports fsid mappings through /proc/<pid>/fs*id_map and a container > runtime is not aware of fsid mappings it or does not use them it will it will > continue to work just as before. > > Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> Acked-by: Serge Hallyn <serge@hallyn.com> > --- > /* v2 */ > unchanged > > /* v3 */ > - Christian Brauner <christian.brauner@ubuntu.com>: > - Fix grammar in commit message. > --- > fs/proc/base.c | 14 ++++++++++++++ > 1 file changed, 14 insertions(+) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index 5fb28004663e..1303cdd2e617 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -2975,6 +2975,11 @@ static int proc_fsuid_map_open(struct inode *inode, struct file *file) > { > return proc_id_map_open(inode, file, &proc_fsuid_seq_operations); > } > + > +static int proc_fsgid_map_open(struct inode *inode, struct file *file) > +{ > + return proc_id_map_open(inode, file, &proc_fsgid_seq_operations); > +} > #endif > > static const struct file_operations proc_uid_map_operations = { > @@ -3009,6 +3014,14 @@ static const struct file_operations proc_fsuid_map_operations = { > .llseek = seq_lseek, > .release = proc_id_map_release, > }; > + > +static const struct file_operations proc_fsgid_map_operations = { > + .open = proc_fsgid_map_open, > + .write = proc_fsgid_map_write, > + .read = seq_read, > + .llseek = seq_lseek, > + .release = proc_id_map_release, > +}; > #endif > > static int proc_setgroups_open(struct inode *inode, struct file *file) > @@ -3195,6 +3208,7 @@ static const struct pid_entry tgid_base_stuff[] = { > #ifdef CONFIG_USER_NS > #ifdef CONFIG_USER_NS_FSID > REG("fsuid_map", S_IRUGO|S_IWUSR, proc_fsuid_map_operations), > + REG("fsgid_map", S_IRUGO|S_IWUSR, proc_fsgid_map_operations), > #endif > REG("uid_map", S_IRUGO|S_IWUSR, proc_uid_map_operations), > REG("gid_map", S_IRUGO|S_IWUSR, proc_gid_map_operations), > -- > 2.25.0
diff --git a/fs/proc/base.c b/fs/proc/base.c index 5fb28004663e..1303cdd2e617 100644 --- a/fs/proc/base.c +++ b/fs/proc/base.c @@ -2975,6 +2975,11 @@ static int proc_fsuid_map_open(struct inode *inode, struct file *file) { return proc_id_map_open(inode, file, &proc_fsuid_seq_operations); } + +static int proc_fsgid_map_open(struct inode *inode, struct file *file) +{ + return proc_id_map_open(inode, file, &proc_fsgid_seq_operations); +} #endif static const struct file_operations proc_uid_map_operations = { @@ -3009,6 +3014,14 @@ static const struct file_operations proc_fsuid_map_operations = { .llseek = seq_lseek, .release = proc_id_map_release, }; + +static const struct file_operations proc_fsgid_map_operations = { + .open = proc_fsgid_map_open, + .write = proc_fsgid_map_write, + .read = seq_read, + .llseek = seq_lseek, + .release = proc_id_map_release, +}; #endif static int proc_setgroups_open(struct inode *inode, struct file *file) @@ -3195,6 +3208,7 @@ static const struct pid_entry tgid_base_stuff[] = { #ifdef CONFIG_USER_NS #ifdef CONFIG_USER_NS_FSID REG("fsuid_map", S_IRUGO|S_IWUSR, proc_fsuid_map_operations), + REG("fsgid_map", S_IRUGO|S_IWUSR, proc_fsgid_map_operations), #endif REG("uid_map", S_IRUGO|S_IWUSR, proc_uid_map_operations), REG("gid_map", S_IRUGO|S_IWUSR, proc_gid_map_operations),
The /proc/<pid>/fsgid_map file can be written once to setup an fsgid mapping for a user namespace. Writing to this file has the same restrictions as writing to /proc/<pid>/fsgid_map. root@e1-vm:/# cat /proc/13023/fsgid_map 0 300000 100000 Fsid mappings have always been around. They are currently always identical to the id mappings for a user namespace. This means, currently whenever an fsid needs to be looked up the kernel will use the id mapping of the user namespace. With the introduction of fsid mappings the kernel will now lookup fsids in the fsid mappings of the user namespace. If no fsid mapping exists the kernel will continue looking up fsids in the id mappings of the user namespace. Hence, if a system supports fsid mappings through /proc/<pid>/fs*id_map and a container runtime is not aware of fsid mappings it or does not use them it will it will continue to work just as before. Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com> --- /* v2 */ unchanged /* v3 */ - Christian Brauner <christian.brauner@ubuntu.com>: - Fix grammar in commit message. --- fs/proc/base.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+)