// SPDX-License-Identifier: GPL-2.0-only /* * sysctl.c: General linux system control interface * * Begun 24 March 1995, Stephen Tweedie * Added /proc support, Dec 1995 * Added bdflush entry and intvec min/max checking, 2/23/96, Tom Dyas. * Added hooks for /proc/sys/net (minor, minor patch), 96/4/1, Mike Shaver. * Added kernel/java-{interpreter,appletviewer}, 96/5/10, Mike Shaver. * Dynamic registration fixes, Stephen Tweedie. * Added kswapd-interval, ctrl-alt-del, printk stuff, 1/8/97, Chris Horn. * Made sysctl support optional via CONFIG_SYSCTL, 1/10/97, Chris * Horn. * Added proc_doulongvec_ms_jiffies_minmax, 09/08/99, Carlos H. Bauer. * Added proc_doulongvec_minmax, 09/08/99, Carlos H. Bauer. * Changed linked lists to use list.h instead of lists.h, 02/24/00, Bill * Wendling. * The list_for_each() macro wasn't appropriate for the sysctl loop. * Removed it and replaced it with older style, 03/23/00, Bill Wendling */ #include <linux/module.h> #include <linux/mm.h> #include <linux/swap.h> #include <linux/slab.h> #include <linux/sysctl.h> #include <linux/bitmap.h> #include <linux/signal.h> #include <linux/panic.h> #include <linux/printk.h> #include <linux/proc_fs.h> #include <linux/security.h> #include <linux/ctype.h> #include <linux/kmemleak.h> #include <linux/filter.h> #include <linux/fs.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/kobject.h> #include <linux/net.h> #include <linux/sysrq.h> #include <linux/highuid.h> #include <linux/writeback.h> #include <linux/ratelimit.h> #include <linux/hugetlb.h> #include <linux/initrd.h> #include <linux/key.h> #include <linux/times.h> #include <linux/limits.h> #include <linux/dcache.h> #include <linux/syscalls.h> #include <linux/vmstat.h> #include <linux/nfs_fs.h> #include <linux/acpi.h> #include <linux/reboot.h> #include <linux/ftrace.h> #include <linux/perf_event.h> #include <linux/oom.h> #include <linux/kmod.h> #include <linux/capability.h> #include <linux/binfmts.h> #include <linux/sched/sysctl.h> #include <linux/mount.h> #include <linux/userfaultfd_k.h> #include <linux/pid.h> #include "../lib/kstrtox.h" #include <linux/uaccess.h> #include <asm/processor.h> #ifdef CONFIG_X86 #include <asm/nmi.h> #include <asm/stacktrace.h> #include <asm/io.h> #endif #ifdef CONFIG_SPARC #include <asm/setup.h> #endif #ifdef CONFIG_RT_MUTEXES #include <linux/rtmutex.h> #endif /* shared constants to be used in various sysctls */ const int sysctl_vals[] = …; EXPORT_SYMBOL(…); const unsigned long sysctl_long_vals[] = …; EXPORT_SYMBOL_GPL(…); #if defined(CONFIG_SYSCTL) /* Constants used for minimum and maximum */ #ifdef CONFIG_PERF_EVENTS static const int six_hundred_forty_kb = …; #endif static const int ngroups_max = …; static const int cap_last_cap = …; #ifdef CONFIG_PROC_SYSCTL /** * enum sysctl_writes_mode - supported sysctl write modes * * @SYSCTL_WRITES_LEGACY: each write syscall must fully contain the sysctl value * to be written, and multiple writes on the same sysctl file descriptor * will rewrite the sysctl value, regardless of file position. No warning * is issued when the initial position is not 0. * @SYSCTL_WRITES_WARN: same as above but warn when the initial file position is * not 0. * @SYSCTL_WRITES_STRICT: writes to numeric sysctl entries must always be at * file position 0 and the value must be fully contained in the buffer * sent to the write syscall. If dealing with strings respect the file * position, but restrict this to the max length of the buffer, anything * passed the max length will be ignored. Multiple writes will append * to the buffer. * * These write modes control how current file position affects the behavior of * updating sysctl values through the proc interface on each write. */ enum sysctl_writes_mode { … }; static enum sysctl_writes_mode sysctl_writes_strict = …; #endif /* CONFIG_PROC_SYSCTL */ #if defined(HAVE_ARCH_PICK_MMAP_LAYOUT) || \ defined(CONFIG_ARCH_WANT_DEFAULT_TOPDOWN_MMAP_LAYOUT) int sysctl_legacy_va_layout; #endif #endif /* CONFIG_SYSCTL */ /* * /proc/sys support */ #ifdef CONFIG_PROC_SYSCTL static int _proc_do_string(char *data, int maxlen, int write, char *buffer, size_t *lenp, loff_t *ppos) { … } static void warn_sysctl_write(const struct ctl_table *table) { … } /** * proc_first_pos_non_zero_ignore - check if first position is allowed * @ppos: file position * @table: the sysctl table * * Returns true if the first position is non-zero and the sysctl_writes_strict * mode indicates this is not allowed for numeric input types. String proc * handlers can ignore the return value. */ static bool proc_first_pos_non_zero_ignore(loff_t *ppos, const struct ctl_table *table) { … } /** * proc_dostring - read a string sysctl * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes a string from/to the user buffer. If the kernel * buffer provided is not large enough to hold the string, the * string is truncated. The copied string is %NULL-terminated. * If the string is being read by the user process, it is copied * and a newline '\n' is added. It is truncated if the buffer is * not large enough. * * Returns 0 on success. */ int proc_dostring(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } static void proc_skip_spaces(char **buf, size_t *size) { … } static void proc_skip_char(char **buf, size_t *size, const char v) { … } /** * strtoul_lenient - parse an ASCII formatted integer from a buffer and only * fail on overflow * * @cp: kernel buffer containing the string to parse * @endp: pointer to store the trailing characters * @base: the base to use * @res: where the parsed integer will be stored * * In case of success 0 is returned and @res will contain the parsed integer, * @endp will hold any trailing characters. * This function will fail the parse on overflow. If there wasn't an overflow * the function will defer the decision what characters count as invalid to the * caller. */ static int strtoul_lenient(const char *cp, char **endp, unsigned int base, unsigned long *res) { … } #define TMPBUFLEN … /** * proc_get_long - reads an ASCII formatted integer from a user buffer * * @buf: a kernel buffer * @size: size of the kernel buffer * @val: this is where the number will be stored * @neg: set to %TRUE if number is negative * @perm_tr: a vector which contains the allowed trailers * @perm_tr_len: size of the perm_tr vector * @tr: pointer to store the trailer character * * In case of success %0 is returned and @buf and @size are updated with * the amount of bytes read. If @tr is non-NULL and a trailing * character exists (size is non-zero after returning from this * function), @tr is updated with the trailing character. */ static int proc_get_long(char **buf, size_t *size, unsigned long *val, bool *neg, const char *perm_tr, unsigned perm_tr_len, char *tr) { … } /** * proc_put_long - converts an integer to a decimal ASCII formatted string * * @buf: the user buffer * @size: the size of the user buffer * @val: the integer to be converted * @neg: sign of the number, %TRUE for negative * * In case of success @buf and @size are updated with the amount of bytes * written. */ static void proc_put_long(void **buf, size_t *size, unsigned long val, bool neg) { … } #undef TMPBUFLEN static void proc_put_char(void **buf, size_t *size, char c) { … } static int do_proc_dointvec_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } static int do_proc_douintvec_conv(unsigned long *lvalp, unsigned int *valp, int write, void *data) { … } static const char proc_wspace_sep[] = …; static int __do_proc_dointvec(void *tbl_data, const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(bool *negp, unsigned long *lvalp, int *valp, int write, void *data), void *data) { … } static int do_proc_dointvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(bool *negp, unsigned long *lvalp, int *valp, int write, void *data), void *data) { … } static int do_proc_douintvec_w(unsigned int *tbl_data, const struct ctl_table *table, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(unsigned long *lvalp, unsigned int *valp, int write, void *data), void *data) { … } static int do_proc_douintvec_r(unsigned int *tbl_data, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(unsigned long *lvalp, unsigned int *valp, int write, void *data), void *data) { … } static int __do_proc_douintvec(void *tbl_data, const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(unsigned long *lvalp, unsigned int *valp, int write, void *data), void *data) { … } int do_proc_douintvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, int (*conv)(unsigned long *lvalp, unsigned int *valp, int write, void *data), void *data) { … } /** * proc_dobool - read/write a bool * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes one integer value from/to the user buffer, * treated as an ASCII string. * * table->data must point to a bool variable and table->maxlen must * be sizeof(bool). * * Returns 0 on success. */ int proc_dobool(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_dointvec - read a vector of integers * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) integer * values from/to the user buffer, treated as an ASCII string. * * Returns 0 on success. */ int proc_dointvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_douintvec - read a vector of unsigned integers * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer * values from/to the user buffer, treated as an ASCII string. * * Returns 0 on success. */ int proc_douintvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /* * Taint values can only be increased * This means we can safely use a temporary. */ static int proc_taint(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * struct do_proc_dointvec_minmax_conv_param - proc_dointvec_minmax() range checking structure * @min: pointer to minimum allowable value * @max: pointer to maximum allowable value * * The do_proc_dointvec_minmax_conv_param structure provides the * minimum and maximum values for doing range checking for those sysctl * parameters that use the proc_dointvec_minmax() handler. */ struct do_proc_dointvec_minmax_conv_param { … }; static int do_proc_dointvec_minmax_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } /** * proc_dointvec_minmax - read a vector of integers with min/max values * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) integer * values from/to the user buffer, treated as an ASCII string. * * This routine will ensure the values are within the range specified by * table->extra1 (min) and table->extra2 (max). * * Returns 0 on success or -EINVAL on write when the range check fails. */ int proc_dointvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * struct do_proc_douintvec_minmax_conv_param - proc_douintvec_minmax() range checking structure * @min: pointer to minimum allowable value * @max: pointer to maximum allowable value * * The do_proc_douintvec_minmax_conv_param structure provides the * minimum and maximum values for doing range checking for those sysctl * parameters that use the proc_douintvec_minmax() handler. */ struct do_proc_douintvec_minmax_conv_param { … }; static int do_proc_douintvec_minmax_conv(unsigned long *lvalp, unsigned int *valp, int write, void *data) { … } /** * proc_douintvec_minmax - read a vector of unsigned ints with min/max values * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) unsigned integer * values from/to the user buffer, treated as an ASCII string. Negative * strings are not allowed. * * This routine will ensure the values are within the range specified by * table->extra1 (min) and table->extra2 (max). There is a final sanity * check for UINT_MAX to avoid having to support wrap around uses from * userspace. * * Returns 0 on success or -ERANGE on write when the range check fails. */ int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_dou8vec_minmax - read a vector of unsigned chars with min/max values * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(u8) unsigned chars * values from/to the user buffer, treated as an ASCII string. Negative * strings are not allowed. * * This routine will ensure the values are within the range specified by * table->extra1 (min) and table->extra2 (max). * * Returns 0 on success or an error on write when the range check fails. */ int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } EXPORT_SYMBOL_GPL(…); #ifdef CONFIG_MAGIC_SYSRQ static int sysrq_sysctl_handler(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } #endif static int __do_proc_doulongvec_minmax(void *data, const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, unsigned long convmul, unsigned long convdiv) { … } static int do_proc_doulongvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos, unsigned long convmul, unsigned long convdiv) { … } /** * proc_doulongvec_minmax - read a vector of long integers with min/max values * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned long) unsigned long * values from/to the user buffer, treated as an ASCII string. * * This routine will ensure the values are within the range specified by * table->extra1 (min) and table->extra2 (max). * * Returns 0 on success. */ int proc_doulongvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_doulongvec_ms_jiffies_minmax - read a vector of millisecond values with min/max values * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned long) unsigned long * values from/to the user buffer, treated as an ASCII string. The values * are treated as milliseconds, and converted to jiffies when they are stored. * * This routine will ensure the values are within the range specified by * table->extra1 (min) and table->extra2 (max). * * Returns 0 on success. */ int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } static int do_proc_dointvec_jiffies_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } static int do_proc_dointvec_userhz_jiffies_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } static int do_proc_dointvec_ms_jiffies_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } static int do_proc_dointvec_ms_jiffies_minmax_conv(bool *negp, unsigned long *lvalp, int *valp, int write, void *data) { … } /** * proc_dointvec_jiffies - read a vector of integers as seconds * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) integer * values from/to the user buffer, treated as an ASCII string. * The values read are assumed to be in seconds, and are converted into * jiffies. * * Returns 0 on success. */ int proc_dointvec_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_dointvec_userhz_jiffies - read a vector of integers as 1/USER_HZ seconds * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: pointer to the file position * * Reads/writes up to table->maxlen/sizeof(unsigned int) integer * values from/to the user buffer, treated as an ASCII string. * The values read are assumed to be in 1/USER_HZ seconds, and * are converted into jiffies. * * Returns 0 on success. */ int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_dointvec_ms_jiffies - read a vector of integers as 1 milliseconds * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * @ppos: the current position in the file * * Reads/writes up to table->maxlen/sizeof(unsigned int) integer * values from/to the user buffer, treated as an ASCII string. * The values read are assumed to be in 1/1000 seconds, and * are converted into jiffies. * * Returns 0 on success. */ int proc_dointvec_ms_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } static int proc_do_cad_pid(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } /** * proc_do_large_bitmap - read/write from/to a large bitmap * @table: the sysctl table * @write: %TRUE if this is a write to the sysctl file * @buffer: the user buffer * @lenp: the size of the user buffer * @ppos: file position * * The bitmap is stored at table->data and the bitmap length (in bits) * in table->maxlen. * * We use a range comma separated format (e.g. 1,3-4,10-10) so that * large bitmaps may be represented in a compact manner. Writing into * the file will clear the bitmap then update it with the given input. * * Returns 0 on success. */ int proc_do_large_bitmap(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } #else /* CONFIG_PROC_SYSCTL */ int proc_dostring(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dobool(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_douintvec(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_douintvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dou8vec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec_ms_jiffies_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec_userhz_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_dointvec_ms_jiffies(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_doulongvec_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_doulongvec_ms_jiffies_minmax(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } int proc_do_large_bitmap(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { return -ENOSYS; } #endif /* CONFIG_PROC_SYSCTL */ #if defined(CONFIG_SYSCTL) int proc_do_static_key(const struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { … } static struct ctl_table kern_table[] = …; static struct ctl_table vm_table[] = …; int __init sysctl_init_bases(void) { … } #endif /* CONFIG_SYSCTL */ /* * No sense putting this after each symbol definition, twice, * exception granted :-) */ EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL_GPL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…); EXPORT_SYMBOL(…);
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