From cf9f151c7257683f489df85f94baf408d1d5694a Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Fri, 8 Dec 2006 02:39:55 -0800 Subject: [PATCH] [PATCH] sysctl: simplify sysctl_uts_string The binary interface to the namespace sysctls was never implemented resulting in some really weird things if you attempted to use sys_sysctl to read your hostname for example. This patch series simples the code a little and implements the binary sysctl interface. In testing this patch series I discovered that our 32bit compatibility for the binary sysctl interface is imperfect. In particular KERN_SHMMAX and KERN_SMMALL are size_t sized quantities and are returned as 8 bytes on to 32bit binaries using a x86_64 kernel. However this has existing for a long time so it is not a new regression with the namespace work. Gads the whole sysctl thing needs work before it stops being easy to shoot yourself in the foot. Looking forward a little bit we need a better way to handle sysctls and namespaces as our current technique will not work for the network namespace. I think something based on the current overlapping sysctl trees will work but the proc side needs to be redone before we can use it. This patch: Introduce get_uts() and put_uts() (used later) and remove most of the special cases for when UTS namespace is compiled in. Signed-off-by: Eric W. Biederman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/sysctl.c | 128 ++++++++++-------------------------------------- 1 file changed, 26 insertions(+), 102 deletions(-) diff --git a/kernel/sysctl.c b/kernel/sysctl.c index 9846db93a595..c8bcbfb2e069 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -163,6 +163,28 @@ extern ctl_table inotify_table[]; int sysctl_legacy_va_layout; #endif +static void *get_uts(ctl_table *table, int write) +{ + char *which = table->data; +#ifdef CONFIG_UTS_NS + struct uts_namespace *uts_ns = current->nsproxy->uts_ns; + which = (which - (char *)&init_uts_ns) + (char *)uts_ns; +#endif + if (!write) + down_read(&uts_sem); + else + down_write(&uts_sem); + return which; +} + +static void put_uts(ctl_table *table, int write, void *which) +{ + if (!write) + up_read(&uts_sem); + else + up_write(&uts_sem); +} + /* /proc declarations: */ #ifdef CONFIG_PROC_SYSCTL @@ -229,7 +251,6 @@ static ctl_table root_table[] = { }; static ctl_table kern_table[] = { -#ifndef CONFIG_UTS_NS { .ctl_name = KERN_OSTYPE, .procname = "ostype", @@ -275,54 +296,6 @@ static ctl_table kern_table[] = { .proc_handler = &proc_do_uts_string, .strategy = &sysctl_string, }, -#else /* !CONFIG_UTS_NS */ - { - .ctl_name = KERN_OSTYPE, - .procname = "ostype", - .data = NULL, - /* could maybe use __NEW_UTS_LEN here? */ - .maxlen = FIELD_SIZEOF(struct new_utsname, sysname), - .mode = 0444, - .proc_handler = &proc_do_uts_string, - .strategy = &sysctl_string, - }, - { - .ctl_name = KERN_OSRELEASE, - .procname = "osrelease", - .data = NULL, - .maxlen = FIELD_SIZEOF(struct new_utsname, release), - .mode = 0444, - .proc_handler = &proc_do_uts_string, - .strategy = &sysctl_string, - }, - { - .ctl_name = KERN_VERSION, - .procname = "version", - .data = NULL, - .maxlen = FIELD_SIZEOF(struct new_utsname, version), - .mode = 0444, - .proc_handler = &proc_do_uts_string, - .strategy = &sysctl_string, - }, - { - .ctl_name = KERN_NODENAME, - .procname = "hostname", - .data = NULL, - .maxlen = FIELD_SIZEOF(struct new_utsname, nodename), - .mode = 0644, - .proc_handler = &proc_do_uts_string, - .strategy = &sysctl_string, - }, - { - .ctl_name = KERN_DOMAINNAME, - .procname = "domainname", - .data = NULL, - .maxlen = FIELD_SIZEOF(struct new_utsname, domainname), - .mode = 0644, - .proc_handler = &proc_do_uts_string, - .strategy = &sysctl_string, - }, -#endif /* !CONFIG_UTS_NS */ { .ctl_name = KERN_PANIC, .procname = "panic", @@ -1753,66 +1726,17 @@ int proc_dostring(ctl_table *table, int write, struct file *filp, * Special case of dostring for the UTS structure. This has locks * to observe. Should this be in kernel/sys.c ???? */ - -#ifndef CONFIG_UTS_NS -static int proc_do_uts_string(ctl_table *table, int write, struct file *filp, - void __user *buffer, size_t *lenp, loff_t *ppos) -{ - int r; - if (!write) { - down_read(&uts_sem); - r=proc_dostring(table,0,filp,buffer,lenp, ppos); - up_read(&uts_sem); - } else { - down_write(&uts_sem); - r=proc_dostring(table,1,filp,buffer,lenp, ppos); - up_write(&uts_sem); - } - return r; -} -#else /* !CONFIG_UTS_NS */ static int proc_do_uts_string(ctl_table *table, int write, struct file *filp, void __user *buffer, size_t *lenp, loff_t *ppos) { int r; - struct uts_namespace* uts_ns = current->nsproxy->uts_ns; - char* which; - - switch (table->ctl_name) { - case KERN_OSTYPE: - which = uts_ns->name.sysname; - break; - case KERN_NODENAME: - which = uts_ns->name.nodename; - break; - case KERN_OSRELEASE: - which = uts_ns->name.release; - break; - case KERN_VERSION: - which = uts_ns->name.version; - break; - case KERN_DOMAINNAME: - which = uts_ns->name.domainname; - break; - default: - r = -EINVAL; - goto out; - } - - if (!write) { - down_read(&uts_sem); - r=_proc_do_string(which,table->maxlen,0,filp,buffer,lenp, ppos); - up_read(&uts_sem); - } else { - down_write(&uts_sem); - r=_proc_do_string(which,table->maxlen,1,filp,buffer,lenp, ppos); - up_write(&uts_sem); - } - out: + void *which; + which = get_uts(table, write); + r = _proc_do_string(which, table->maxlen,write,filp,buffer,lenp, ppos); + put_uts(table, write, which); return r; } -#endif /* !CONFIG_UTS_NS */ static int do_proc_dointvec_conv(int *negp, unsigned long *lvalp, int *valp, -- 2.20.1